Research ArticleHeterogeneous Enhancement Pattern in DCE-MRI Reveals theMorphology of Normal Lymph Nodes An Experimental Study

Pietro Bontempi 12 Alice Busato2 Giamaica Conti3 Sabino Walter Della Sala4

Pasquina Marzola 2 and Paolo Farace1

1Proton erapy Department S Chiara Hospital Trento Italy2Department of Computer Science University of Verona Verona Italy3Department of Neuroscience and Biomedicine University of Verona Verona Italy4Radiology Department S Maria del Carmine Hospital Rovereto Italy

Correspondence should be addressed to Pietro Bontempi pietrobontempiunivrit

Received 25 September 2018 Revised 7 February 2019 Accepted 27 February 2019 Published 4 April 2019

Academic Editor Marıa L Garcıa-Martın

Copyright copy 2019 Pietro Bontempi et al is is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work isproperly cited

Purpose To investigate the heterogeneous enhancement pattern in normal lymph nodes of healthy mice by dierent albumin-binding contrast agentsMethods e enhancement of normal lymph nodes was assessed in mice by dynamic contrast-enhancedMRI (DCE-MRI) after the administration of two contrast agents characterized by dierent albumin-binding propertiesgadopentetate dimeglumine (Gd-DTPA) and gadobenate dimeglumine (Gd-BOPTA) To take into account potential hetero-geneities of the contrast uptake in the lymph nodes k-means cluster analysis was performed on DCE-MRI data Cluster spatialdistribution was visually assessed Statistical comparison among clusters and contrast agents was performed on semiquantitativeparameters (AUC wash-in rate and wash-out rate) and on the relative size of the segmented clusters Results Cluster analysis ofDCE-MRI data revealed at least two main clusters localized in the outer portion and in the inner portion of each lymph nodeWith both contrast agents AUC (plt 001) and wash-in (plt 005) rates were greater in the inner cluster which also showed asteeper wash-out rate than the outer cluster (Gd-BOPTA plt 001 Gd-DTPA p 0056)e size of the outer cluster was greaterthan that of the inner cluster by Gd-DTPA (plt 005) and Gd-BOPTA (plt 001) e enhancement pattern of Gd-DTPA was notsignicantly dierent from the enhancement pattern of Gd-BOPTA Conclusion DCE-MRI in normal lymph nodes shows acharacteristic heterogeneous pattern discriminating the periphery and the central portion of the lymph nodes Such a patterndeserves to be investigated as a diagnostic marker for lymph node staging

1 Introduction

Dynamic contrast-enhanced MRI (DCE-MRI) has beenwidely used to quantify tissue perfusion in preclinical [1 2]and clinical studies In DCE-MRI multiple T1-weightedimages are acquired before and at dierent time pointsafter the administration of a Gd-based contrast agentallowing the quantication of parameters related to perfu-sion [1 2] e diagnostic usefulness of DCE-MRI in tumorslargely relies on the peculiar features of the tumor tissueincreased blood volume fraction and vessel permeability

anks to high-resolution T1-weighted images DCE-MRI has been extensively applied in clinical studies to

characterize the breast [3] and solitary pulmonary nodules [4]and in general in cancer diagnosis including the prostate [5]and liver [6] Moreover DCE-MRI can have a role for thedetection and characterization of lymph nodes Quantitativeor semiquantitative parameters extracted from DCE-MRIdata (describing for example the uptake and wash-out ofthe contrast agent) are expected to discriminate betweenpositive and negative nodes Accordingly DCE-MRI showedpromising performance to assess suspicious lymph nodes atdierent sites such as the head and neck [7ndash9] rectal [10 11]and cervical [12ndash14] and in the axillary lymph nodes in breastcancer patients [15ndash19] for which the role of MRI includingDCE-MRI was recently reviewed [20]

HindawiContrast Media amp Molecular ImagingVolume 2019 Article ID 4096706 9 pageshttpsdoiorg10115520194096706

e overarching aim of our study is to define the di-agnostic potential of DCE-MRI for lymph node staging Forthis purpose the first step is investigation of normal lymphnodes since the definition of the enhancement pattern ofnormal nodal tissue is a needed preparatory knowledge toreliably detect alterations induced by metastasization eaim of the present study is therefore obtaining the definitionof the enhancement pattern in DCE-MRI of normal lymphnodes through systematic investigation in healthy mice Afurther aim is to develop a semiautomatic and operator-independent image analysis procedure by using clusteranalysis of DCE-MRI enhancement patterns

Moreover Gd-based contrast agents can have differentbinding properties to albumin and consequently differentcapability to reveal blood vessels [21 22] potentially gen-erating a different lymphatic uptakedrainage pattern Inorder to investigate if and how different protein binding mayaffect DCE-MRI findings in normal lymph nodes two Gd-based contrast agents were administered namely (i) gado-pentetate dimeglumine (Gd-DTPA) and (ii) gadobenatedimeglumine (Gd-BOPTA) Specifically Gd-BOPTA can beclassified as an albumin-bound contrast agent [23] whileGd-DTPA is a non-albumin-bound extracellular contrastagent

2 Methods

21MRI Acquisition Athymic nude mice were anesthetizedby inhalation of a mixture of N2 and O2 containing 05ndash1isoflurane (Forane Abbott) and were cannulated in the tailvein for contrast agent injection during DCE-MRI scan Asingle birdcage coil (35 cm id) configuration was used forradiofrequency excitation and MRI signal detection Imageswere acquired using a BioSpec tomograph (Bruker Karls-ruhe Germany) equipped with a 47 T 33 cm bore hori-zontal magnet (Oxford Ltd Oxford United Kingdom) Forthe imaging session mice were placed in a prone positionover a heated bed body temperature and respiratory ratewere monitored by using an MRI-compatible physiologicalmonitor (PC-SAM Small Animal Instruments Inc NY)

Before the administration of the contrast agent astandard non-fat-suppressed T1-weighted sequence (mul-tislice RARE with TRTE 55076ms flip angle 180deg matrixsize 175times100 number of slices 6 field-of-view35times 20mm2 slice thickness 05mm number of aver-ages 8 and RARE factor 8) was applied to investigate thepresence of a fatty hilum which has been often reported inhuman lymph nodes [24 25]

Afterwards a dynamic series of multislice T1-weightedRARE images were acquired with fat suppression and withthe following parameters TRTE 55076ms flip angle180deg matrix size 175times100 number of slices 6 field-of-view35times 20mm2 slice thickness 05mm number of averages8 RARE factor 8 number of scans 70 and total acquisi-tion time approximately 46minutes TwoGd-based contrastagents were tested in different sessions by bolus injection(100 micromolkg) during the time interval between the thirdand fourth scan of the dynamic series (i) Gd-DTPA and(ii) Gd-BOPTA

DCE-MRI was performed in total on 9 healthy mice (5mice were injected by Gd-DTPA and 4 by Gd-BOPTA)

e experimental plan received authorization from theItalian Ministry of Health (approval number 6762018-PR)and was approved by the Animal Care and Use Committeeof the University of Verona Animal work was conductedfollowing the Italian law (DL no 26 of 4 March 2014) andthe European Union normative (201063EU) Major effortswere performed to minimize the number of animals and toavoid their suffering

22 Image Analysis Some DCE-MRI scans were affected byperistalsis and breath-induced motion To compensate forthese displacements a linear registration approach wasadopted by means of the MCFLIRT tool of FSL [26] Eventhough that tool is designed for brain imaging it proved tobe effective even in the abdominal region e 2nd volumeafter the contrast agent injection was used as a referenceimage for the registration of the whole time series When thelinear registration approach was not sufficient a nonlinearapproach was adopted carrying out nonlinear registrationby the FNIRT tool of FLS and finely tuning the registrationparameters to obtain a ldquogentlerdquo warp field

e subsequent postprocessing was performed byMATLAB (MathWorksreg Natick MA) For each nodenormalized differential enhancement (NDE) curves werecalculated on a pixel-by-pixel basis subtracting the signalintensity before contrast injection (SIPRE) from the signalintensity at a given time point SI(t) and normalizing it by(DEMAX)MUSCLE that is the maximal differential en-hancement over an area drawn on the tight muscle

NDE(t) SI(t)minus SIPRE1113858 1113859

DEMAX( 1113857MUSCLE (1)

NDE was normalized by the signal intensity of themuscle to compensate at least partially any possible dif-ference in the effectively administered dosage of the contrastagents

For each lymph node the central slice was identified anda ROI was manually drawn to cover the entire nodal tissue

To investigate the enhancement pattern in the nodescluster analysis was performed pixel by pixel on the NDEcurves by means of a k-means algorithm is algorithmrequires as an input the number of clusters to be identifiedand the minimum value (two clusters) was chosen to detectpotential heterogeneities To verify whether this arbitrarychoice could be appropriate principal component analysis(PCA) was performed on the same set of NDE curves toobtain the data variance explanation as a function of thenumber of components

Segmented colour-coded maps were obtained for eachlymph node to visualize the spatial distribution of eachcluster obtained by cluster analysis

After cluster analysis in each lymph node the NDEcurves of each pixel belonging to a specific cluster wereaveraged to obtain the cluster-averaged NDE curvesSemiquantitative parameters were then extracted from thesecurves namely area under the curve (AUC) wash-in rate

2 Contrast Media amp Molecular Imaging

and wash-out rate e wash-in rate was defined as themaximum slope of the NDE curve between two consecutivetime points comprised between the last baseline point andthe point of maximal enhancement [27] e wash-out ratewas defined as the slope of the line that best fits the last 40time points (ie scans 31 ndash 70) of the enhancement curve[21] Both wash-out and wash-in rates were normalized bythe maximal enhancement in each lymph node

Statistical differences in the semiquantitative curve pa-rameters (between clusters and between contrast agents)were assessed by two-way ANOVA and the results werecorrected for multiple comparisons with the Bonferronimethod

23 Histological Analysis For histological investigationlymph nodes were excised and fixed in 4 para-formaldehyde for four hours After fixation and embeddingin paraffin 7 μm thick sections were cut and stained withhematoxylin and eosin (HampE) e sections were observedusing an optical microscope (Olympus BX63 Life ScienceSolutions Centre Valley PA) at 4x and 10x magnifications

3 Results

Only superficial inguinal lymph nodes clearly visible onDCE-MRI were considered Due to motion induced bybreathing and bowel peristalsis during the MRI acquisitionthe registration procedure was applied in 9 nodes In 2 casesthe linear registration approach was not sufficient being theimages affected by bowel motion really close to the node and

they required nonlinear correction In one case motionproduced a very large shift that was not fully recovered bythe motion correction procedure and the lymph node wasexcluded from the successive analysis In total 15 nodes weresuccessfully identified and included in the analysis (9 by Gd-DTPA and 6 by Gd-BOPTA) Representative fat-suppressedDCE-MRI images of a healthy node are reported inFigures 1(a)ndash1(c) with the corresponding standard T1-weighted images (Figures 1(d)ndash1(f )) e node indicatedby the green arrow was the one excluded from the analysisbecause of a clear displacement of its position during thescan session Of note within our spatial resolution none ofthe observed lymph nodes showed a fatty hilum as exem-plarily shown in Figures 1(d)ndash1(f )

Cluster analysis revealed a heterogeneous structure inthe enhancement pattern of the lymph nodes PCA per-formed on the NDE curves demonstrated that two maincomponents were necessary and sufficient to explain at least90 of the variance in all the 15 nodes (Figure 2) Additionalcomponents negligibly increased variance explanationConsequently the successive k-means clustering was per-formed by using two clusters Of relevance these twoclusters were localized in the outer portion and in the innerportion of each lymph node in most of the investigatednodese spatial distribution and different enhancement ofthe identified clusters are shown in Figure 3 for a repre-sentative lymph node with the corresponding description ofthe segmentation performed by k-means clustering ecurves clearly show different shapes with the inner clusterbeing characterized by greater contrast uptake with respectto the outer cluster (Figure 3(d))

(a) (b) (c)

(d) (e) (f )

Figure 1 Precontrast (a) early (b) and late (c) enhancement of DCE-MRI images acquired respectively before 80 and 800 seconds after theadministration of Gd-BOPTA and after a motion correction procedure e lymph nodes are indicated by red arrows Unsaturated fat T1-weighted images (same slice as (a)ndash(c)) before (d) and about 50minutes after (e) the administration of the contrast agent ie after theacquisition of the DCE-MRI scan (f ) is the same as (e) after a nonlinear motion correction procedure Green arrows indicate a largedisplacement of the left node from (d) to (e) that was not fully recovered in (f) and consequently was excluded from the successive analysisFrames (d)ndash(f ) also show that a fatty hilum is not present e white strip indicated by the violet arrow is a vial filled by gadolinium solutionused as a standard signal in all DCE-MRI sequences

Contrast Media amp Molecular Imaging 3

e cluster-averaged NDE curves and the correspondingcoloured segmented maps of all the 15 examined lymphnodes are shown in Figure 4 conrming the peculiar het-erogeneous enhancement pattern

e parameters calculated on the cluster-averaged NDEcurves are reported in Table 1 and the corresponding meanvalues are shown in Figure 5

Two-way ANOVA was applied to compare the semi-quantitative perfusion parameters averaged over the twoclusters (signicant dierences are reported in Figure 5) Asapparent from Figure 5 AUCs and wash-in rates were sig-nicantly smaller in the outer cluster regardless of the ad-ministered contrast agent e size of the outer cluster wassignicantly greater than the size of the inner cluster witheither Gd-DTPA or Gd-BOPTA e wash-out rates weresignicantly dierent between the two clusters with Gd-BOPTA but close to be signicant (p 0056) with Gd-DTPA

Two-way ANOVA performed through contrast agentsrevealed no statistically signicant dierences in the en-hancement pattern of the two contrast agents tested here

Histological analysis performed with HampE stainingconrmed a heterogeneous structure of the normal node(Figures 6(a) and 6(b) (at 4x and 10x magnication)) ecortex (highlighted with blue dotted line in Figure 6) and themedulla of the node are clearly distinguishable

4 Discussion

In this study cluster analysis was applied on DCE-MRI dataacquired on normal nodes of healthy mice by two Gd-basedcontrast agents characterized by dierent albumin-bindingproperties k-Means clustering was applied to identify po-tential heterogeneities and the minimum number of clusterswas utilized in the algorithm Of note PCA suggested thatmost of the variability of the lymph node contrast enhance-ment could be accounted for by two main components withboth contrast agentse applied clustering method was basedonly on the enhancement pattern and not on the spatialposition of each pixel assigned to the cluster that is neigh-borhood connectivity was not considered by the algorithm

0 10 20 30 40 50 60 7006

065

07

075

08

085

09

095

1

123

456

789

101112

131415

1 2 3 4 506

065

07

075

08

085

09

095

1

Figure 2 Principal component analysis (PCA) demonstrates that two principal components are suumlcient to explain at least 90 of thevariance in all the 15 nodes Additional components negligibly increase variance explanation e percentage of variance is reported inordinate and the component number (equal to the number of dynamic scans) is reported in abscissa e whole range and a detailed range(in the inset) are shown

4 Contrast Media amp Molecular Imaging

Of relevance such a heterogeneous enhancement pat-tern arising from k-means evidenced a marked anatomicalstructure regardless of the contrast agent used In fact thetwo clusters identied in each node resulted clearly localizedin the outer portion and in the inner portion of the nodesrespectively e observed pattern seems to be compatiblewith the functional organization of a normal lymph nodecomposed of two main functional units the cortex and themedulla Since the lymphatic ordfow is directed from thecapsule and the cortex of the lymph node towards themedulla and the hilum in this latter portion the contrastagents might accumulate also because of interstitial diu-sion at least partially explaining the greater contrast uptakein the inner region of the lymph nodes

e observed spatial pattern characterized the heteroge-neous distribution of the enhancement in all the assessedlymph nodes Independently from the contrast agent usedAUC and wash-in rate were greater in the inner cluster whichalso showed a steeper wash-out rate than the outer cluster

both with Gd-BOPTA and by Gd-DTPA On the contrary theenhancement of Gd-DTPA was not signicantly dierentfrom the enhancement pattern of Gd-BOPTA

Many studies investigated the role of postcontrast T1imaging in assessing the lymph node status includingquantitative assessment on DCE-MRI but to ourknowledge the peculiar heterogeneity of contrast en-hancement in normal nodes has not been reported beforeTo the best of our knowledge only one study focused onnormal nodes analysing axillary lymph nodes in breastcancer patients [28] However that study focused on theenhancement curve of a single region of interest placedinside the cortex of the healthy nodes without covering thehilum to assess potential heterogeneity As shown in nativeprecontrast T1-weighted images in our study none of theassessed mice nodes showed a fatty hilum allowing toinclude the whole nodes in the analysis of the contrastenhancement heterogeneity and the subsequent segmen-tation procedure

5 m

m

(a)

5 m

m

(b)

5 m

m

(c)

0 10 20 30 40 50 60 70ndash05

0

05

1

15

2

25

3

35

4

45

Inner

Outer

(d)

5 m

m

(e)

Figure 3 Precontrast (a) early (b) and late (c) DCE-MRI images (the same slice reported in Figures 1(a)ndash1(c) is shown) of a representativelymph node (15) e region of interest (in yellow in (a)ndash(c)) was manually drawn to encompass the whole lymph node e long-axis sizeof this lymph node was around 25mm k-means clustering assigned each pixel-based NDE curve (thin dashed lines) to one of the twoclusters (d) cluster-averaged NDE curves are also shown (thick black continuous lines) e obtained segmentation map is shown with thecorresponding colours (e)

Contrast Media amp Molecular Imaging 5

Interestingly in a study aiming at classifying axillarylymph nodes in breast cancer patients [18] the best per-forming feature was a morphological feature described as thedegree to which the enhancement structure extends in aradial pattern originating from the centre of the node lesionIn our study which of course needs to be conrmed on

human subjects an intrinsic radial structure on normalnodes was revealed and it is reasonable to speculate thatsuch a structure might be altered in metastatic nodes

It is worth noting that the identication of a normalenhancement pattern might have a role in the detection ofpossible alterations induced by the metastatic transformation

0 20 40 600

2

4

0 20 40 600

1

2

3

2

0 20 40 600123

3

0 20 40 600

1

2

3

0 20 40 600

1

2

5

0 20 40 600

1

2

6

0 20 40 600

1

2

0 20 40 600

1

2

3

8

0 20 40 600

1

2

3

9

0 20 40 600

2

4

0 20 40 600

2

4

11

0 20 40 600

1

2

12

0 20 40 600

1

2

1

4

7

10

13

0 20 40 600

1

2

14

0 20 40 600

1

2

3

15

Figure 4 Enhancement pattern-based k-means clustering on 15 healthy nodes with Gd-DTPA (nodes 1ndash9) and with Gd-BOPTA (nodes10ndash15) e redgreen colours used to report the cluster-averaged NDE curves correspond to the colour used to localize them in thecorresponding segmentation maps (on the right of each plot)

Table 1 Semiquantitative parameters on segmented clusters

NodeAUC (au) Wash-in (aumin) Wash-out (aumin) Volume ()

Inner Outer Inner Outer Inner Outer Inner Outer

Gd-DTPA

1 217plusmn 41 100plusmn 25 13plusmn 03 08plusmn 03 minus38plusmn 08 minus15plusmn 06 25 752 124plusmn 16 71plusmn 12 19plusmn 03 12plusmn 05 minus30plusmn 05 minus16plusmn 04 19 813 101plusmn 14 58plusmn 13 26plusmn 04 12plusmn 03 minus19plusmn 02 minus12plusmn 03 21 794 143plusmn 23 74plusmn 17 16plusmn 05 09plusmn 04 minus06plusmn 06 minus05plusmn 04 26 745 100plusmn 9 69plusmn 9 11plusmn 07 11plusmn 04 minus07plusmn 03 minus04plusmn 03 49 516 91plusmn 9 63plusmn 6 17plusmn 05 12plusmn 05 minus05plusmn 03 minus03plusmn 02 32 687 98plusmn 11 66plusmn 9 14plusmn 04 12plusmn 05 minus07plusmn 04 minus04plusmn 02 33 678 178plusmn 26 99plusmn 22 11plusmn 03 10plusmn 03 minus11plusmn 06 minus05plusmn 04 29 719 149plusmn 27 91plusmn 18 15plusmn 05 10plusmn 05 minus04plusmn 07 minus06plusmn 03 25 75

Gd-BOPTA

10 211plusmn 33 109plusmn 29 14plusmn 03 12plusmn 02 minus27plusmn 05 minus12plusmn 04 47 5311 157plusmn 23 97plusmn 14 23plusmn 04 13plusmn 04 minus22plusmn 06 minus12plusmn 03 14 8612 88plusmn 14 51plusmn 12 13plusmn 03 10plusmn 03 minus23plusmn 12 minus12plusmn 07 40 6013 51plusmn 9 29plusmn 7 19plusmn 04 13plusmn 04 minus21plusmn 04 minus13plusmn 03 38 6214 61plusmn 7 36plusmn 8 15plusmn 05 13plusmn 07 minus14plusmn 02 minus09plusmn 03 43 5715 109plusmn 18 48plusmn 16 17plusmn 03 11plusmn 04 minus35plusmn 08 minus13plusmn 05 29 71

6 Contrast Media amp Molecular Imaging

For example the accuracy obtained by lymphotropic ironoxide nanoparticles for nodal staging [29 30] was based onthe negative enhancement observed in normal nodes which

was modied by the presence of a metastatic lesion in thenodes Similarly in gadofosveset-enhanced MRI the aspectof the chemical shift artefact encircling the lymph nodes

Gd-DTPA Gd-BOPTA0

20

40

60

80

Inner

Outer

lowastlowast

lowast

(a)

Gd-DTPA Gd-BOPTA0

50

100

150

Inner

Outer

lowastlowast

lowastlowast

(b)

Gd-DTPA Gd-BOPTA0

05

1

15

2

Inner

Outer

lowastlowast

lowast

(c)

Gd-DTPA Gd-BOPTAndash25

ndash2

ndash15

ndash1

ndash05

0

Inner

Outer

lowastlowast

(d)

Figure 5 Mean parameter values calculated averaging on the lymph nodes evaluated with the same contrast agent Statistical signicancelevels obtained comparing by two-way ANOVA the two segmented clusters are also shown (lowastlowastplt 001 and lowastplt 005) (a) Volume ()(b) AUC (au) (c) Wash-in rate (aumin) (d) Wash-out rate (aumin)

(a) (b)

Figure 6 HampE staining of normal lymph nodes (a) e lymphatic cell is clearly visible and the lymph node structure is preserved both inthe cortex (violet-surrounded area) and in the medulla (4x magnication) (b) 10x magnication of the boxed area shown in (a)

Contrast Media amp Molecular Imaging 7

(ldquothe chemical shift criterionrdquo) on enhanced images wasconsidered a sign of benign normal nodes [31 32] Par-ticularly the benign nodes fell into the category of ldquosharplydelineated and intact chemical shift artefactrdquo whereas anirregular or optically ldquointerruptedrdquo chemical shift artefact ora pronounced enhancing rim encircling the entire node wasconsidered as a malignant criterion

5 Conclusions

In conclusion the results obtained showed a heterogeneouspattern of enhancement in normal lymph nodes in-dependently of the contrast agent used Semiautomaticcluster analysis of signal intensity vs time data showed theexistence of two clusters characterized by different signalintensity dynamics belonging to the inner and outer regionsof lymph nodes

is heterogeneous pattern might be peculiar of normallymph nodes and if confirmed on human lymph nodesshould be deeply investigated to assess any alteration pos-sibly induced by the metastatic transformation and con-sequently its potential role for nodal staging

Data Availability

e MRI data used to support the findings of this study areavailable from the corresponding author upon request

Conflicts of Interest

e authors declare that they have no conflicts of interest

Acknowledgments

is work was supported by the University of Verona andAzienda Provinciale per i Servizi Sanitari Trento (JointProject JPVR17YEPM 2017)

References

[1] P Marzola A Degrassi L Calderan et al ldquoIn vivo assessmentof antiangiogenic activity of SU6668 in an experimental coloncarcinoma modelrdquo Clinical Cancer Research vol 10 no 2pp 739ndash750 2004

[2] P Marzola A Degrassi L Calderan et al ldquoEarly anti-angiogenic activity of SU11248 evaluated in vivo by dynamiccontrast-enhanced magnetic resonance imaging in an ex-perimental model of colon carcinomardquo Clinical Cancer Re-search vol 11 no 16 pp 5827ndash5832 2005

[3] H Degani V Gusis D Weinstein S Fields and S StranoldquoMapping pathophysiological features of breast tumors byMRI at high spatial resolutionrdquo Nature Medicine vol 3 no 7pp 780ndash782 1997

[4] J F Schaefer V Schneider J Vollmar et al ldquoSolitary pul-monary nodules association between signal characteristics indynamic contrast enhanced MRI and tumor angiogenesisrdquoLung Cancer vol 53 no 1 pp 39ndash49 2006

[5] X Wu P Reinikainen M Kapanen T Vierikko P Ryyminand P L Kellokumpu-Lehtinen ldquoDynamic contrast-enhanced imaging as a prognostic tool in early diagnosis ofprostate cancer correlation with PSA and clinical stagerdquo

Contrast Media Mol Imaging vol 2018 Article ID 31812587 pages 2018

[6] S J Hectors M Wagner C Besa W Huang and B TaoulildquoMultiparametric FDG-PETMRI of hepatocellular carci-noma initial experiencerdquo Contrast Media Mol Imagingvol 2018 Article ID 5638283 10 pages 2018

[7] S Yan Z Wang L Li et al ldquoCharacterization of cervicallymph nodes using DCE-MRI differentiation between me-tastases from SCC of head and neck and benign lymph nodesrdquoClinical Hemorheology and Microcirculation vol 64 no 2pp 213ndash222 2016

[8] C M Wendl S Muller J Meier et al ldquoHigh resolutioncontrast-enhanced ultrasound and 3-tesla dynamic contrast-enhanced magnetic resonance imaging for the preoperativecharacterization of cervical lymph nodes first resultsrdquoClinical Hemorheology and Microcirculation vol 52 no 2ndash4pp 153ndash166 2012

[9] N J Fischbein S M Noworolski R G Henry M J KaplanW P Dillon and S J Nelson ldquoAssessment of metastaticcervical adenopathy using dynamic contrast-enhanced MRimagingrdquo AJNR American Journal of Neuroradiology vol 24no 3 pp 301ndash311 2003

[10] W J Alberda H P N Dassen R S Dwarkasing et alldquoPrediction of tumor stage and lymph node involvement withdynamic contrast-enhancedMRI after chemoradiotherapy forlocally advanced rectal cancerrdquo International Journal of Co-lorectal Disease vol 28 no 4 pp 573ndash580 2013

[11] T Vag J Slotta-Huspenina R Rosenberg et al ldquoComput-erized analysis of enhancement kinetics for preoperativelymph node staging in rectal cancer using dynamic contrast-enhanced magnetic resonance imagingrdquo Clinical Imagingvol 38 no 6 pp 845ndash849 2014

[12] S M Noworolski N J Fischbein M J Kaplan et alldquoChallenges in dynamic contrast-enhanced MRI imaging ofcervical lymph nodes to detect metastatic diseaserdquo Journal ofMagnetic Resonance Imaging vol 17 no 4 pp 455ndash462 2003

[13] W T Yang W W M Lam M Y Yu T H Cheung andC Metreweli ldquoComparison of dynamic helical CT and dy-namic MR imaging in the evaluation of pelvic lymph nodes incervical carcinomardquo American Journal of Roentgenologyvol 175 no 3 pp 759ndash766 2000

[14] B Huang D L Kwong V Lai Q Chan B Whitcher andP L Khong ldquoDynamic contrast-enhanced magnetic reso-nance imaging of regional nodal metastasis in nasopharyngealcarcinoma correlation with nodal stagingrdquo Contrast Media ampMolecular Imaging vol 2017 Article ID 4519653 6 pages2017

[15] A D Murray R T Staff T W Redpath et al ldquoDynamiccontrast enhanced MRI of the axilla in women with breastcancer comparison with pathology of excised nodesrdquo eBritish Journal of Radiology vol 75 no 891 pp 220ndash2282002

[16] H Rahbar J L Conlin S Parsian et al ldquoSuspicious axillarylymph nodes identified on clinical breast MRI in patientsnewly diagnosed with breast cancerrdquo Academic Radiologyvol 22 no 4 pp 430ndash438 2015

[17] K A Kvistad J Rydland H-B Smethurst S LundgrenH E Fjoslashsne and O Haraldseth ldquoAxillary lymph node me-tastases in breast cancer preoperative detection with dynamiccontrast-enhanced MRIrdquo European Radiology vol 10 no 9pp 1464ndash1471 2000

[18] D V Schacht K Drukker I Pak H Abe and M L GigerldquoUsing quantitative image analysis to classify axillary lymphnodes on breast MRI a new application for the Z 0011 erardquo

8 Contrast Media amp Molecular Imaging

European Journal of Radiology vol 84 no 3 pp 392ndash3972015

[19] J Krammer K Wasser A Schnitzer T HenzlerS O Schoenberg and C G Kaiser ldquoAxillary lymph nodecharacterization in breast cancer patients using magneticresonance mammography a prospective comparative studywith FDG PET-CTand healthy womenrdquo European Journal ofRadiology vol 82 no 12 pp 2194ndash2198 2013

[20] V J L Kuijs M Moossdorff R J Schipper et al ldquoe role ofMRI in axillary lymph node imaging in breast cancer patientsa systematic reviewrdquo Insights into Imaging vol 6 no 2pp 203ndash215 2015

[21] P Farace F Merigo S Fiorini et al ldquoDCE-MRI using small-molecular and albumin-binding contrast agents in experi-mental carcinomas with different stromal contentrdquo EuropeanJournal of Radiology vol 78 no 1 pp 52ndash59 2011

[22] F Boschi P Marzola M Sandri et al ldquoTumor microvas-culature observed using different contrast agents a com-parison between Gd-DTPA-Albumin and B-229561 in anexperimental model of mammary carcinomardquo MagneticResonance Materials in Physics Biology and Medicine vol 21no 3 pp 169ndash176 2008

[23] C Corot X Violas P Robert and M Port ldquoPharmacoki-netics of three gadolinium chelates with different molecularsizes shortly after intravenous injection in rabbitsrdquo In-vestigative Radiology vol 35 no 4 pp 213ndash218 2000

[24] HW Lee and S H Kim ldquoBreast magnetic resonance imagingfor assessment of internal mammary lymph node status inbreast cancerrdquo Journal of Breast Cancer vol 19 no 2pp 191ndash198 2016

[25] E J Kim S H Kim B J Kang B G Choi B J Song andJ J Choi ldquoDiagnostic value of breast MRI for predictingmetastatic axillary lymph nodes in breast cancer patientsdiffusion-weighted MRI and conventional MRIrdquo MagneticResonance Imaging vol 32 no 10 pp 1230ndash1236 2014

[26] S M Smith M Jenkinson M W Woolrich et al ldquoAdvancesin functional and structural MR image analysis and imple-mentation as FSLrdquo NeuroImage vol 23 no 1 pp 208ndash2192004

[27] J K Kim S S Hong Y J Choi et al ldquoWash-in rate on thebasis of dynamic contrast-enhanced MRI usefulness forprostate cancer detection and localizationrdquo Journal of Mag-netic Resonance Imaging vol 22 no 5 pp 639ndash646 2005

[28] J Krammer D Engel J Nissen et al ldquoCharacteristics ofaxillary lymph nodes apparent on dynamic contrast-enhancedbreast MRI in healthy womenrdquo Clinical Imaging vol 36no 4 pp 249ndash254 2012

[29] M G Harisinghani J Barentsz P F Hahn et al ldquoNon-invasive detection of clinically occult lymph-node metastasesin prostate cancerrdquo New England Journal of Medicinevol 348 no 25 pp 2491ndash2499 2003

[30] O Will S Purkayastha C Chan et al ldquoDiagnostic precisionof nanoparticle-enhanced MRI for lymph-node metastases ameta-analysisrdquo e Lancet Oncology vol 7 no 1 pp 52ndash602006

[31] D M Lambregts L A Heijnen M Maas et alldquoGadofosveset-enhanced MRI for the assessment of rectalcancer lymph nodes predictive criteriardquo Abdominal Imagingvol 38 no 4 pp 720ndash727 2012

[32] R-J Schipper M L Smidt L M van Roozendaal et alldquoNoninvasive nodal staging in patients with breast cancerusing gadofosveset-enhanced magnetic resonance imagingrdquoInvestigative Radiology vol 48 no 3 pp 134ndash139 2013

Contrast Media amp Molecular Imaging 9

Stem Cells International

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

MEDIATORSINFLAMMATION

of

EndocrinologyInternational Journal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Disease Markers

Hindawiwwwhindawicom Volume 2018

BioMed Research International

OncologyJournal of

Hindawiwwwhindawicom Volume 2013

Hindawiwwwhindawicom Volume 2018

Oxidative Medicine and Cellular Longevity

Hindawiwwwhindawicom Volume 2018

PPAR Research

Hindawi Publishing Corporation httpwwwhindawicom Volume 2013Hindawiwwwhindawicom

The Scientific World Journal

Volume 2018

Immunology ResearchHindawiwwwhindawicom Volume 2018

Journal of

ObesityJournal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Computational and Mathematical Methods in Medicine

Hindawiwwwhindawicom Volume 2018

Behavioural Neurology

OphthalmologyJournal of

Hindawiwwwhindawicom Volume 2018

Diabetes ResearchJournal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Research and TreatmentAIDS

Hindawiwwwhindawicom Volume 2018

Gastroenterology Research and Practice

Hindawiwwwhindawicom Volume 2018

Parkinsonrsquos Disease

Evidence-Based Complementary andAlternative Medicine

Volume 2018Hindawiwwwhindawicom

Submit your manuscripts atwwwhindawicom

and wash-out rate e wash-in rate was defined as themaximum slope of the NDE curve between two consecutivetime points comprised between the last baseline point andthe point of maximal enhancement [27] e wash-out ratewas defined as the slope of the line that best fits the last 40time points (ie scans 31 ndash 70) of the enhancement curve[21] Both wash-out and wash-in rates were normalized bythe maximal enhancement in each lymph node

Statistical differences in the semiquantitative curve pa-rameters (between clusters and between contrast agents)were assessed by two-way ANOVA and the results werecorrected for multiple comparisons with the Bonferronimethod

23 Histological Analysis For histological investigationlymph nodes were excised and fixed in 4 para-formaldehyde for four hours After fixation and embeddingin paraffin 7 μm thick sections were cut and stained withhematoxylin and eosin (HampE) e sections were observedusing an optical microscope (Olympus BX63 Life ScienceSolutions Centre Valley PA) at 4x and 10x magnifications

3 Results

Only superficial inguinal lymph nodes clearly visible onDCE-MRI were considered Due to motion induced bybreathing and bowel peristalsis during the MRI acquisitionthe registration procedure was applied in 9 nodes In 2 casesthe linear registration approach was not sufficient being theimages affected by bowel motion really close to the node and

they required nonlinear correction In one case motionproduced a very large shift that was not fully recovered bythe motion correction procedure and the lymph node wasexcluded from the successive analysis In total 15 nodes weresuccessfully identified and included in the analysis (9 by Gd-DTPA and 6 by Gd-BOPTA) Representative fat-suppressedDCE-MRI images of a healthy node are reported inFigures 1(a)ndash1(c) with the corresponding standard T1-weighted images (Figures 1(d)ndash1(f )) e node indicatedby the green arrow was the one excluded from the analysisbecause of a clear displacement of its position during thescan session Of note within our spatial resolution none ofthe observed lymph nodes showed a fatty hilum as exem-plarily shown in Figures 1(d)ndash1(f )

Cluster analysis revealed a heterogeneous structure inthe enhancement pattern of the lymph nodes PCA per-formed on the NDE curves demonstrated that two maincomponents were necessary and sufficient to explain at least90 of the variance in all the 15 nodes (Figure 2) Additionalcomponents negligibly increased variance explanationConsequently the successive k-means clustering was per-formed by using two clusters Of relevance these twoclusters were localized in the outer portion and in the innerportion of each lymph node in most of the investigatednodese spatial distribution and different enhancement ofthe identified clusters are shown in Figure 3 for a repre-sentative lymph node with the corresponding description ofthe segmentation performed by k-means clustering ecurves clearly show different shapes with the inner clusterbeing characterized by greater contrast uptake with respectto the outer cluster (Figure 3(d))

(a) (b) (c)

(d) (e) (f )

Figure 1 Precontrast (a) early (b) and late (c) enhancement of DCE-MRI images acquired respectively before 80 and 800 seconds after theadministration of Gd-BOPTA and after a motion correction procedure e lymph nodes are indicated by red arrows Unsaturated fat T1-weighted images (same slice as (a)ndash(c)) before (d) and about 50minutes after (e) the administration of the contrast agent ie after theacquisition of the DCE-MRI scan (f ) is the same as (e) after a nonlinear motion correction procedure Green arrows indicate a largedisplacement of the left node from (d) to (e) that was not fully recovered in (f) and consequently was excluded from the successive analysisFrames (d)ndash(f ) also show that a fatty hilum is not present e white strip indicated by the violet arrow is a vial filled by gadolinium solutionused as a standard signal in all DCE-MRI sequences

Contrast Media amp Molecular Imaging 3

e cluster-averaged NDE curves and the correspondingcoloured segmented maps of all the 15 examined lymphnodes are shown in Figure 4 conrming the peculiar het-erogeneous enhancement pattern

e parameters calculated on the cluster-averaged NDEcurves are reported in Table 1 and the corresponding meanvalues are shown in Figure 5

Two-way ANOVA was applied to compare the semi-quantitative perfusion parameters averaged over the twoclusters (signicant dierences are reported in Figure 5) Asapparent from Figure 5 AUCs and wash-in rates were sig-nicantly smaller in the outer cluster regardless of the ad-ministered contrast agent e size of the outer cluster wassignicantly greater than the size of the inner cluster witheither Gd-DTPA or Gd-BOPTA e wash-out rates weresignicantly dierent between the two clusters with Gd-BOPTA but close to be signicant (p 0056) with Gd-DTPA

Two-way ANOVA performed through contrast agentsrevealed no statistically signicant dierences in the en-hancement pattern of the two contrast agents tested here

Histological analysis performed with HampE stainingconrmed a heterogeneous structure of the normal node(Figures 6(a) and 6(b) (at 4x and 10x magnication)) ecortex (highlighted with blue dotted line in Figure 6) and themedulla of the node are clearly distinguishable

4 Discussion

In this study cluster analysis was applied on DCE-MRI dataacquired on normal nodes of healthy mice by two Gd-basedcontrast agents characterized by dierent albumin-bindingproperties k-Means clustering was applied to identify po-tential heterogeneities and the minimum number of clusterswas utilized in the algorithm Of note PCA suggested thatmost of the variability of the lymph node contrast enhance-ment could be accounted for by two main components withboth contrast agentse applied clustering method was basedonly on the enhancement pattern and not on the spatialposition of each pixel assigned to the cluster that is neigh-borhood connectivity was not considered by the algorithm

0 10 20 30 40 50 60 7006

065

07

075

08

085

09

095

1

123

456

789

101112

131415

1 2 3 4 506

065

07

075

08

085

09

095

1

Figure 2 Principal component analysis (PCA) demonstrates that two principal components are suumlcient to explain at least 90 of thevariance in all the 15 nodes Additional components negligibly increase variance explanation e percentage of variance is reported inordinate and the component number (equal to the number of dynamic scans) is reported in abscissa e whole range and a detailed range(in the inset) are shown

4 Contrast Media amp Molecular Imaging

Of relevance such a heterogeneous enhancement pat-tern arising from k-means evidenced a marked anatomicalstructure regardless of the contrast agent used In fact thetwo clusters identied in each node resulted clearly localizedin the outer portion and in the inner portion of the nodesrespectively e observed pattern seems to be compatiblewith the functional organization of a normal lymph nodecomposed of two main functional units the cortex and themedulla Since the lymphatic ordfow is directed from thecapsule and the cortex of the lymph node towards themedulla and the hilum in this latter portion the contrastagents might accumulate also because of interstitial diu-sion at least partially explaining the greater contrast uptakein the inner region of the lymph nodes

e observed spatial pattern characterized the heteroge-neous distribution of the enhancement in all the assessedlymph nodes Independently from the contrast agent usedAUC and wash-in rate were greater in the inner cluster whichalso showed a steeper wash-out rate than the outer cluster

both with Gd-BOPTA and by Gd-DTPA On the contrary theenhancement of Gd-DTPA was not signicantly dierentfrom the enhancement pattern of Gd-BOPTA

Many studies investigated the role of postcontrast T1imaging in assessing the lymph node status includingquantitative assessment on DCE-MRI but to ourknowledge the peculiar heterogeneity of contrast en-hancement in normal nodes has not been reported beforeTo the best of our knowledge only one study focused onnormal nodes analysing axillary lymph nodes in breastcancer patients [28] However that study focused on theenhancement curve of a single region of interest placedinside the cortex of the healthy nodes without covering thehilum to assess potential heterogeneity As shown in nativeprecontrast T1-weighted images in our study none of theassessed mice nodes showed a fatty hilum allowing toinclude the whole nodes in the analysis of the contrastenhancement heterogeneity and the subsequent segmen-tation procedure

5 m

m

(a)

5 m

m

(b)

5 m

m

(c)

0 10 20 30 40 50 60 70ndash05

0

05

1

15

2

25

3

35

4

45

Inner

Outer

(d)

5 m

m

(e)

Figure 3 Precontrast (a) early (b) and late (c) DCE-MRI images (the same slice reported in Figures 1(a)ndash1(c) is shown) of a representativelymph node (15) e region of interest (in yellow in (a)ndash(c)) was manually drawn to encompass the whole lymph node e long-axis sizeof this lymph node was around 25mm k-means clustering assigned each pixel-based NDE curve (thin dashed lines) to one of the twoclusters (d) cluster-averaged NDE curves are also shown (thick black continuous lines) e obtained segmentation map is shown with thecorresponding colours (e)

Contrast Media amp Molecular Imaging 5

Interestingly in a study aiming at classifying axillarylymph nodes in breast cancer patients [18] the best per-forming feature was a morphological feature described as thedegree to which the enhancement structure extends in aradial pattern originating from the centre of the node lesionIn our study which of course needs to be conrmed on

human subjects an intrinsic radial structure on normalnodes was revealed and it is reasonable to speculate thatsuch a structure might be altered in metastatic nodes

It is worth noting that the identication of a normalenhancement pattern might have a role in the detection ofpossible alterations induced by the metastatic transformation

0 20 40 600

2

4

0 20 40 600

1

2

3

2

0 20 40 600123

3

0 20 40 600

1

2

3

0 20 40 600

1

2

5

0 20 40 600

1

2

6

0 20 40 600

1

2

0 20 40 600

1

2

3

8

0 20 40 600

1

2

3

9

0 20 40 600

2

4

0 20 40 600

2

4

11

0 20 40 600

1

2

12

0 20 40 600

1

2

1

4

7

10

13

0 20 40 600

1

2

14

0 20 40 600

1

2

3

15

Figure 4 Enhancement pattern-based k-means clustering on 15 healthy nodes with Gd-DTPA (nodes 1ndash9) and with Gd-BOPTA (nodes10ndash15) e redgreen colours used to report the cluster-averaged NDE curves correspond to the colour used to localize them in thecorresponding segmentation maps (on the right of each plot)

Table 1 Semiquantitative parameters on segmented clusters

NodeAUC (au) Wash-in (aumin) Wash-out (aumin) Volume ()

Inner Outer Inner Outer Inner Outer Inner Outer

Gd-DTPA

1 217plusmn 41 100plusmn 25 13plusmn 03 08plusmn 03 minus38plusmn 08 minus15plusmn 06 25 752 124plusmn 16 71plusmn 12 19plusmn 03 12plusmn 05 minus30plusmn 05 minus16plusmn 04 19 813 101plusmn 14 58plusmn 13 26plusmn 04 12plusmn 03 minus19plusmn 02 minus12plusmn 03 21 794 143plusmn 23 74plusmn 17 16plusmn 05 09plusmn 04 minus06plusmn 06 minus05plusmn 04 26 745 100plusmn 9 69plusmn 9 11plusmn 07 11plusmn 04 minus07plusmn 03 minus04plusmn 03 49 516 91plusmn 9 63plusmn 6 17plusmn 05 12plusmn 05 minus05plusmn 03 minus03plusmn 02 32 687 98plusmn 11 66plusmn 9 14plusmn 04 12plusmn 05 minus07plusmn 04 minus04plusmn 02 33 678 178plusmn 26 99plusmn 22 11plusmn 03 10plusmn 03 minus11plusmn 06 minus05plusmn 04 29 719 149plusmn 27 91plusmn 18 15plusmn 05 10plusmn 05 minus04plusmn 07 minus06plusmn 03 25 75

Gd-BOPTA

10 211plusmn 33 109plusmn 29 14plusmn 03 12plusmn 02 minus27plusmn 05 minus12plusmn 04 47 5311 157plusmn 23 97plusmn 14 23plusmn 04 13plusmn 04 minus22plusmn 06 minus12plusmn 03 14 8612 88plusmn 14 51plusmn 12 13plusmn 03 10plusmn 03 minus23plusmn 12 minus12plusmn 07 40 6013 51plusmn 9 29plusmn 7 19plusmn 04 13plusmn 04 minus21plusmn 04 minus13plusmn 03 38 6214 61plusmn 7 36plusmn 8 15plusmn 05 13plusmn 07 minus14plusmn 02 minus09plusmn 03 43 5715 109plusmn 18 48plusmn 16 17plusmn 03 11plusmn 04 minus35plusmn 08 minus13plusmn 05 29 71

6 Contrast Media amp Molecular Imaging

For example the accuracy obtained by lymphotropic ironoxide nanoparticles for nodal staging [29 30] was based onthe negative enhancement observed in normal nodes which

was modied by the presence of a metastatic lesion in thenodes Similarly in gadofosveset-enhanced MRI the aspectof the chemical shift artefact encircling the lymph nodes

Gd-DTPA Gd-BOPTA0

20

40

60

80

Inner

Outer

lowastlowast

lowast

(a)

Gd-DTPA Gd-BOPTA0

50

100

150

Inner

Outer

lowastlowast

lowastlowast

(b)

Gd-DTPA Gd-BOPTA0

05

1

15

2

Inner

Outer

lowastlowast

lowast

(c)

Gd-DTPA Gd-BOPTAndash25

ndash2

ndash15

ndash1

ndash05

0

Inner

Outer

lowastlowast

(d)

Figure 5 Mean parameter values calculated averaging on the lymph nodes evaluated with the same contrast agent Statistical signicancelevels obtained comparing by two-way ANOVA the two segmented clusters are also shown (lowastlowastplt 001 and lowastplt 005) (a) Volume ()(b) AUC (au) (c) Wash-in rate (aumin) (d) Wash-out rate (aumin)

(a) (b)

Figure 6 HampE staining of normal lymph nodes (a) e lymphatic cell is clearly visible and the lymph node structure is preserved both inthe cortex (violet-surrounded area) and in the medulla (4x magnication) (b) 10x magnication of the boxed area shown in (a)

Contrast Media amp Molecular Imaging 7

(ldquothe chemical shift criterionrdquo) on enhanced images wasconsidered a sign of benign normal nodes [31 32] Par-ticularly the benign nodes fell into the category of ldquosharplydelineated and intact chemical shift artefactrdquo whereas anirregular or optically ldquointerruptedrdquo chemical shift artefact ora pronounced enhancing rim encircling the entire node wasconsidered as a malignant criterion

5 Conclusions

In conclusion the results obtained showed a heterogeneouspattern of enhancement in normal lymph nodes in-dependently of the contrast agent used Semiautomaticcluster analysis of signal intensity vs time data showed theexistence of two clusters characterized by different signalintensity dynamics belonging to the inner and outer regionsof lymph nodes

is heterogeneous pattern might be peculiar of normallymph nodes and if confirmed on human lymph nodesshould be deeply investigated to assess any alteration pos-sibly induced by the metastatic transformation and con-sequently its potential role for nodal staging

Data Availability

e MRI data used to support the findings of this study areavailable from the corresponding author upon request

Conflicts of Interest

e authors declare that they have no conflicts of interest

Acknowledgments

is work was supported by the University of Verona andAzienda Provinciale per i Servizi Sanitari Trento (JointProject JPVR17YEPM 2017)

References

[1] P Marzola A Degrassi L Calderan et al ldquoIn vivo assessmentof antiangiogenic activity of SU6668 in an experimental coloncarcinoma modelrdquo Clinical Cancer Research vol 10 no 2pp 739ndash750 2004

[2] P Marzola A Degrassi L Calderan et al ldquoEarly anti-angiogenic activity of SU11248 evaluated in vivo by dynamiccontrast-enhanced magnetic resonance imaging in an ex-perimental model of colon carcinomardquo Clinical Cancer Re-search vol 11 no 16 pp 5827ndash5832 2005

[3] H Degani V Gusis D Weinstein S Fields and S StranoldquoMapping pathophysiological features of breast tumors byMRI at high spatial resolutionrdquo Nature Medicine vol 3 no 7pp 780ndash782 1997

[4] J F Schaefer V Schneider J Vollmar et al ldquoSolitary pul-monary nodules association between signal characteristics indynamic contrast enhanced MRI and tumor angiogenesisrdquoLung Cancer vol 53 no 1 pp 39ndash49 2006

[5] X Wu P Reinikainen M Kapanen T Vierikko P Ryyminand P L Kellokumpu-Lehtinen ldquoDynamic contrast-enhanced imaging as a prognostic tool in early diagnosis ofprostate cancer correlation with PSA and clinical stagerdquo

Contrast Media Mol Imaging vol 2018 Article ID 31812587 pages 2018

[6] S J Hectors M Wagner C Besa W Huang and B TaoulildquoMultiparametric FDG-PETMRI of hepatocellular carci-noma initial experiencerdquo Contrast Media Mol Imagingvol 2018 Article ID 5638283 10 pages 2018

[7] S Yan Z Wang L Li et al ldquoCharacterization of cervicallymph nodes using DCE-MRI differentiation between me-tastases from SCC of head and neck and benign lymph nodesrdquoClinical Hemorheology and Microcirculation vol 64 no 2pp 213ndash222 2016

[8] C M Wendl S Muller J Meier et al ldquoHigh resolutioncontrast-enhanced ultrasound and 3-tesla dynamic contrast-enhanced magnetic resonance imaging for the preoperativecharacterization of cervical lymph nodes first resultsrdquoClinical Hemorheology and Microcirculation vol 52 no 2ndash4pp 153ndash166 2012

[9] N J Fischbein S M Noworolski R G Henry M J KaplanW P Dillon and S J Nelson ldquoAssessment of metastaticcervical adenopathy using dynamic contrast-enhanced MRimagingrdquo AJNR American Journal of Neuroradiology vol 24no 3 pp 301ndash311 2003

[10] W J Alberda H P N Dassen R S Dwarkasing et alldquoPrediction of tumor stage and lymph node involvement withdynamic contrast-enhancedMRI after chemoradiotherapy forlocally advanced rectal cancerrdquo International Journal of Co-lorectal Disease vol 28 no 4 pp 573ndash580 2013

[11] T Vag J Slotta-Huspenina R Rosenberg et al ldquoComput-erized analysis of enhancement kinetics for preoperativelymph node staging in rectal cancer using dynamic contrast-enhanced magnetic resonance imagingrdquo Clinical Imagingvol 38 no 6 pp 845ndash849 2014

[12] S M Noworolski N J Fischbein M J Kaplan et alldquoChallenges in dynamic contrast-enhanced MRI imaging ofcervical lymph nodes to detect metastatic diseaserdquo Journal ofMagnetic Resonance Imaging vol 17 no 4 pp 455ndash462 2003

[13] W T Yang W W M Lam M Y Yu T H Cheung andC Metreweli ldquoComparison of dynamic helical CT and dy-namic MR imaging in the evaluation of pelvic lymph nodes incervical carcinomardquo American Journal of Roentgenologyvol 175 no 3 pp 759ndash766 2000

[14] B Huang D L Kwong V Lai Q Chan B Whitcher andP L Khong ldquoDynamic contrast-enhanced magnetic reso-nance imaging of regional nodal metastasis in nasopharyngealcarcinoma correlation with nodal stagingrdquo Contrast Media ampMolecular Imaging vol 2017 Article ID 4519653 6 pages2017

[15] A D Murray R T Staff T W Redpath et al ldquoDynamiccontrast enhanced MRI of the axilla in women with breastcancer comparison with pathology of excised nodesrdquo eBritish Journal of Radiology vol 75 no 891 pp 220ndash2282002

[16] H Rahbar J L Conlin S Parsian et al ldquoSuspicious axillarylymph nodes identified on clinical breast MRI in patientsnewly diagnosed with breast cancerrdquo Academic Radiologyvol 22 no 4 pp 430ndash438 2015

[17] K A Kvistad J Rydland H-B Smethurst S LundgrenH E Fjoslashsne and O Haraldseth ldquoAxillary lymph node me-tastases in breast cancer preoperative detection with dynamiccontrast-enhanced MRIrdquo European Radiology vol 10 no 9pp 1464ndash1471 2000

[18] D V Schacht K Drukker I Pak H Abe and M L GigerldquoUsing quantitative image analysis to classify axillary lymphnodes on breast MRI a new application for the Z 0011 erardquo

8 Contrast Media amp Molecular Imaging

European Journal of Radiology vol 84 no 3 pp 392ndash3972015

[19] J Krammer K Wasser A Schnitzer T HenzlerS O Schoenberg and C G Kaiser ldquoAxillary lymph nodecharacterization in breast cancer patients using magneticresonance mammography a prospective comparative studywith FDG PET-CTand healthy womenrdquo European Journal ofRadiology vol 82 no 12 pp 2194ndash2198 2013

[20] V J L Kuijs M Moossdorff R J Schipper et al ldquoe role ofMRI in axillary lymph node imaging in breast cancer patientsa systematic reviewrdquo Insights into Imaging vol 6 no 2pp 203ndash215 2015

[21] P Farace F Merigo S Fiorini et al ldquoDCE-MRI using small-molecular and albumin-binding contrast agents in experi-mental carcinomas with different stromal contentrdquo EuropeanJournal of Radiology vol 78 no 1 pp 52ndash59 2011

[22] F Boschi P Marzola M Sandri et al ldquoTumor microvas-culature observed using different contrast agents a com-parison between Gd-DTPA-Albumin and B-229561 in anexperimental model of mammary carcinomardquo MagneticResonance Materials in Physics Biology and Medicine vol 21no 3 pp 169ndash176 2008

[23] C Corot X Violas P Robert and M Port ldquoPharmacoki-netics of three gadolinium chelates with different molecularsizes shortly after intravenous injection in rabbitsrdquo In-vestigative Radiology vol 35 no 4 pp 213ndash218 2000

[24] HW Lee and S H Kim ldquoBreast magnetic resonance imagingfor assessment of internal mammary lymph node status inbreast cancerrdquo Journal of Breast Cancer vol 19 no 2pp 191ndash198 2016

[25] E J Kim S H Kim B J Kang B G Choi B J Song andJ J Choi ldquoDiagnostic value of breast MRI for predictingmetastatic axillary lymph nodes in breast cancer patientsdiffusion-weighted MRI and conventional MRIrdquo MagneticResonance Imaging vol 32 no 10 pp 1230ndash1236 2014

[26] S M Smith M Jenkinson M W Woolrich et al ldquoAdvancesin functional and structural MR image analysis and imple-mentation as FSLrdquo NeuroImage vol 23 no 1 pp 208ndash2192004

[27] J K Kim S S Hong Y J Choi et al ldquoWash-in rate on thebasis of dynamic contrast-enhanced MRI usefulness forprostate cancer detection and localizationrdquo Journal of Mag-netic Resonance Imaging vol 22 no 5 pp 639ndash646 2005

[28] J Krammer D Engel J Nissen et al ldquoCharacteristics ofaxillary lymph nodes apparent on dynamic contrast-enhancedbreast MRI in healthy womenrdquo Clinical Imaging vol 36no 4 pp 249ndash254 2012

[29] M G Harisinghani J Barentsz P F Hahn et al ldquoNon-invasive detection of clinically occult lymph-node metastasesin prostate cancerrdquo New England Journal of Medicinevol 348 no 25 pp 2491ndash2499 2003

[30] O Will S Purkayastha C Chan et al ldquoDiagnostic precisionof nanoparticle-enhanced MRI for lymph-node metastases ameta-analysisrdquo e Lancet Oncology vol 7 no 1 pp 52ndash602006

[31] D M Lambregts L A Heijnen M Maas et alldquoGadofosveset-enhanced MRI for the assessment of rectalcancer lymph nodes predictive criteriardquo Abdominal Imagingvol 38 no 4 pp 720ndash727 2012

[32] R-J Schipper M L Smidt L M van Roozendaal et alldquoNoninvasive nodal staging in patients with breast cancerusing gadofosveset-enhanced magnetic resonance imagingrdquoInvestigative Radiology vol 48 no 3 pp 134ndash139 2013

Contrast Media amp Molecular Imaging 9

Stem Cells International

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

MEDIATORSINFLAMMATION

of

EndocrinologyInternational Journal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Disease Markers

Hindawiwwwhindawicom Volume 2018

BioMed Research International

OncologyJournal of

Hindawiwwwhindawicom Volume 2013

Hindawiwwwhindawicom Volume 2018

Oxidative Medicine and Cellular Longevity

Hindawiwwwhindawicom Volume 2018

PPAR Research

Hindawi Publishing Corporation httpwwwhindawicom Volume 2013Hindawiwwwhindawicom

The Scientific World Journal

Volume 2018

Immunology ResearchHindawiwwwhindawicom Volume 2018

Journal of

ObesityJournal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Computational and Mathematical Methods in Medicine

Hindawiwwwhindawicom Volume 2018

Behavioural Neurology

OphthalmologyJournal of

Hindawiwwwhindawicom Volume 2018

Diabetes ResearchJournal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Research and TreatmentAIDS

Hindawiwwwhindawicom Volume 2018

Gastroenterology Research and Practice

Hindawiwwwhindawicom Volume 2018

Parkinsonrsquos Disease

Evidence-Based Complementary andAlternative Medicine

Volume 2018Hindawiwwwhindawicom

Submit your manuscripts atwwwhindawicom

e cluster-averaged NDE curves and the correspondingcoloured segmented maps of all the 15 examined lymphnodes are shown in Figure 4 conrming the peculiar het-erogeneous enhancement pattern

e parameters calculated on the cluster-averaged NDEcurves are reported in Table 1 and the corresponding meanvalues are shown in Figure 5

Two-way ANOVA was applied to compare the semi-quantitative perfusion parameters averaged over the twoclusters (signicant dierences are reported in Figure 5) Asapparent from Figure 5 AUCs and wash-in rates were sig-nicantly smaller in the outer cluster regardless of the ad-ministered contrast agent e size of the outer cluster wassignicantly greater than the size of the inner cluster witheither Gd-DTPA or Gd-BOPTA e wash-out rates weresignicantly dierent between the two clusters with Gd-BOPTA but close to be signicant (p 0056) with Gd-DTPA

Two-way ANOVA performed through contrast agentsrevealed no statistically signicant dierences in the en-hancement pattern of the two contrast agents tested here

Histological analysis performed with HampE stainingconrmed a heterogeneous structure of the normal node(Figures 6(a) and 6(b) (at 4x and 10x magnication)) ecortex (highlighted with blue dotted line in Figure 6) and themedulla of the node are clearly distinguishable

4 Discussion

In this study cluster analysis was applied on DCE-MRI dataacquired on normal nodes of healthy mice by two Gd-basedcontrast agents characterized by dierent albumin-bindingproperties k-Means clustering was applied to identify po-tential heterogeneities and the minimum number of clusterswas utilized in the algorithm Of note PCA suggested thatmost of the variability of the lymph node contrast enhance-ment could be accounted for by two main components withboth contrast agentse applied clustering method was basedonly on the enhancement pattern and not on the spatialposition of each pixel assigned to the cluster that is neigh-borhood connectivity was not considered by the algorithm

0 10 20 30 40 50 60 7006

065

07

075

08

085

09

095

1

123

456

789

101112

131415

1 2 3 4 506

065

07

075

08

085

09

095

1

Figure 2 Principal component analysis (PCA) demonstrates that two principal components are suumlcient to explain at least 90 of thevariance in all the 15 nodes Additional components negligibly increase variance explanation e percentage of variance is reported inordinate and the component number (equal to the number of dynamic scans) is reported in abscissa e whole range and a detailed range(in the inset) are shown

4 Contrast Media amp Molecular Imaging

Of relevance such a heterogeneous enhancement pat-tern arising from k-means evidenced a marked anatomicalstructure regardless of the contrast agent used In fact thetwo clusters identied in each node resulted clearly localizedin the outer portion and in the inner portion of the nodesrespectively e observed pattern seems to be compatiblewith the functional organization of a normal lymph nodecomposed of two main functional units the cortex and themedulla Since the lymphatic ordfow is directed from thecapsule and the cortex of the lymph node towards themedulla and the hilum in this latter portion the contrastagents might accumulate also because of interstitial diu-sion at least partially explaining the greater contrast uptakein the inner region of the lymph nodes

e observed spatial pattern characterized the heteroge-neous distribution of the enhancement in all the assessedlymph nodes Independently from the contrast agent usedAUC and wash-in rate were greater in the inner cluster whichalso showed a steeper wash-out rate than the outer cluster

both with Gd-BOPTA and by Gd-DTPA On the contrary theenhancement of Gd-DTPA was not signicantly dierentfrom the enhancement pattern of Gd-BOPTA

Many studies investigated the role of postcontrast T1imaging in assessing the lymph node status includingquantitative assessment on DCE-MRI but to ourknowledge the peculiar heterogeneity of contrast en-hancement in normal nodes has not been reported beforeTo the best of our knowledge only one study focused onnormal nodes analysing axillary lymph nodes in breastcancer patients [28] However that study focused on theenhancement curve of a single region of interest placedinside the cortex of the healthy nodes without covering thehilum to assess potential heterogeneity As shown in nativeprecontrast T1-weighted images in our study none of theassessed mice nodes showed a fatty hilum allowing toinclude the whole nodes in the analysis of the contrastenhancement heterogeneity and the subsequent segmen-tation procedure

5 m

m

(a)

5 m

m

(b)

5 m

m

(c)

0 10 20 30 40 50 60 70ndash05

0

05

1

15

2

25

3

35

4

45

Inner

Outer

(d)

5 m

m

(e)

Figure 3 Precontrast (a) early (b) and late (c) DCE-MRI images (the same slice reported in Figures 1(a)ndash1(c) is shown) of a representativelymph node (15) e region of interest (in yellow in (a)ndash(c)) was manually drawn to encompass the whole lymph node e long-axis sizeof this lymph node was around 25mm k-means clustering assigned each pixel-based NDE curve (thin dashed lines) to one of the twoclusters (d) cluster-averaged NDE curves are also shown (thick black continuous lines) e obtained segmentation map is shown with thecorresponding colours (e)

Contrast Media amp Molecular Imaging 5

Interestingly in a study aiming at classifying axillarylymph nodes in breast cancer patients [18] the best per-forming feature was a morphological feature described as thedegree to which the enhancement structure extends in aradial pattern originating from the centre of the node lesionIn our study which of course needs to be conrmed on

human subjects an intrinsic radial structure on normalnodes was revealed and it is reasonable to speculate thatsuch a structure might be altered in metastatic nodes

It is worth noting that the identication of a normalenhancement pattern might have a role in the detection ofpossible alterations induced by the metastatic transformation

0 20 40 600

2

4

0 20 40 600

1

2

3

2

0 20 40 600123

3

0 20 40 600

1

2

3

0 20 40 600

1

2

5

0 20 40 600

1

2

6

0 20 40 600

1

2

0 20 40 600

1

2

3

8

0 20 40 600

1

2

3

9

0 20 40 600

2

4

0 20 40 600

2

4

11

0 20 40 600

1

2

12

0 20 40 600

1

2

1

4

7

10

13

0 20 40 600

1

2

14

0 20 40 600

1

2

3

15

Figure 4 Enhancement pattern-based k-means clustering on 15 healthy nodes with Gd-DTPA (nodes 1ndash9) and with Gd-BOPTA (nodes10ndash15) e redgreen colours used to report the cluster-averaged NDE curves correspond to the colour used to localize them in thecorresponding segmentation maps (on the right of each plot)

Table 1 Semiquantitative parameters on segmented clusters

NodeAUC (au) Wash-in (aumin) Wash-out (aumin) Volume ()

Inner Outer Inner Outer Inner Outer Inner Outer

Gd-DTPA

1 217plusmn 41 100plusmn 25 13plusmn 03 08plusmn 03 minus38plusmn 08 minus15plusmn 06 25 752 124plusmn 16 71plusmn 12 19plusmn 03 12plusmn 05 minus30plusmn 05 minus16plusmn 04 19 813 101plusmn 14 58plusmn 13 26plusmn 04 12plusmn 03 minus19plusmn 02 minus12plusmn 03 21 794 143plusmn 23 74plusmn 17 16plusmn 05 09plusmn 04 minus06plusmn 06 minus05plusmn 04 26 745 100plusmn 9 69plusmn 9 11plusmn 07 11plusmn 04 minus07plusmn 03 minus04plusmn 03 49 516 91plusmn 9 63plusmn 6 17plusmn 05 12plusmn 05 minus05plusmn 03 minus03plusmn 02 32 687 98plusmn 11 66plusmn 9 14plusmn 04 12plusmn 05 minus07plusmn 04 minus04plusmn 02 33 678 178plusmn 26 99plusmn 22 11plusmn 03 10plusmn 03 minus11plusmn 06 minus05plusmn 04 29 719 149plusmn 27 91plusmn 18 15plusmn 05 10plusmn 05 minus04plusmn 07 minus06plusmn 03 25 75

Gd-BOPTA

10 211plusmn 33 109plusmn 29 14plusmn 03 12plusmn 02 minus27plusmn 05 minus12plusmn 04 47 5311 157plusmn 23 97plusmn 14 23plusmn 04 13plusmn 04 minus22plusmn 06 minus12plusmn 03 14 8612 88plusmn 14 51plusmn 12 13plusmn 03 10plusmn 03 minus23plusmn 12 minus12plusmn 07 40 6013 51plusmn 9 29plusmn 7 19plusmn 04 13plusmn 04 minus21plusmn 04 minus13plusmn 03 38 6214 61plusmn 7 36plusmn 8 15plusmn 05 13plusmn 07 minus14plusmn 02 minus09plusmn 03 43 5715 109plusmn 18 48plusmn 16 17plusmn 03 11plusmn 04 minus35plusmn 08 minus13plusmn 05 29 71

6 Contrast Media amp Molecular Imaging

For example the accuracy obtained by lymphotropic ironoxide nanoparticles for nodal staging [29 30] was based onthe negative enhancement observed in normal nodes which

was modied by the presence of a metastatic lesion in thenodes Similarly in gadofosveset-enhanced MRI the aspectof the chemical shift artefact encircling the lymph nodes

Gd-DTPA Gd-BOPTA0

20

40

60

80

Inner

Outer

lowastlowast

lowast

(a)

Gd-DTPA Gd-BOPTA0

50

100

150

Inner

Outer

lowastlowast

lowastlowast

(b)

Gd-DTPA Gd-BOPTA0

05

1

15

2

Inner

Outer

lowastlowast

lowast

(c)

Gd-DTPA Gd-BOPTAndash25

ndash2

ndash15

ndash1

ndash05

0

Inner

Outer

lowastlowast

(d)

Figure 5 Mean parameter values calculated averaging on the lymph nodes evaluated with the same contrast agent Statistical signicancelevels obtained comparing by two-way ANOVA the two segmented clusters are also shown (lowastlowastplt 001 and lowastplt 005) (a) Volume ()(b) AUC (au) (c) Wash-in rate (aumin) (d) Wash-out rate (aumin)

(a) (b)

Figure 6 HampE staining of normal lymph nodes (a) e lymphatic cell is clearly visible and the lymph node structure is preserved both inthe cortex (violet-surrounded area) and in the medulla (4x magnication) (b) 10x magnication of the boxed area shown in (a)

Contrast Media amp Molecular Imaging 7

(ldquothe chemical shift criterionrdquo) on enhanced images wasconsidered a sign of benign normal nodes [31 32] Par-ticularly the benign nodes fell into the category of ldquosharplydelineated and intact chemical shift artefactrdquo whereas anirregular or optically ldquointerruptedrdquo chemical shift artefact ora pronounced enhancing rim encircling the entire node wasconsidered as a malignant criterion

5 Conclusions

In conclusion the results obtained showed a heterogeneouspattern of enhancement in normal lymph nodes in-dependently of the contrast agent used Semiautomaticcluster analysis of signal intensity vs time data showed theexistence of two clusters characterized by different signalintensity dynamics belonging to the inner and outer regionsof lymph nodes

is heterogeneous pattern might be peculiar of normallymph nodes and if confirmed on human lymph nodesshould be deeply investigated to assess any alteration pos-sibly induced by the metastatic transformation and con-sequently its potential role for nodal staging

Data Availability

e MRI data used to support the findings of this study areavailable from the corresponding author upon request

Conflicts of Interest

e authors declare that they have no conflicts of interest

Acknowledgments

is work was supported by the University of Verona andAzienda Provinciale per i Servizi Sanitari Trento (JointProject JPVR17YEPM 2017)

References

[1] P Marzola A Degrassi L Calderan et al ldquoIn vivo assessmentof antiangiogenic activity of SU6668 in an experimental coloncarcinoma modelrdquo Clinical Cancer Research vol 10 no 2pp 739ndash750 2004

[2] P Marzola A Degrassi L Calderan et al ldquoEarly anti-angiogenic activity of SU11248 evaluated in vivo by dynamiccontrast-enhanced magnetic resonance imaging in an ex-perimental model of colon carcinomardquo Clinical Cancer Re-search vol 11 no 16 pp 5827ndash5832 2005

[3] H Degani V Gusis D Weinstein S Fields and S StranoldquoMapping pathophysiological features of breast tumors byMRI at high spatial resolutionrdquo Nature Medicine vol 3 no 7pp 780ndash782 1997

[4] J F Schaefer V Schneider J Vollmar et al ldquoSolitary pul-monary nodules association between signal characteristics indynamic contrast enhanced MRI and tumor angiogenesisrdquoLung Cancer vol 53 no 1 pp 39ndash49 2006

[5] X Wu P Reinikainen M Kapanen T Vierikko P Ryyminand P L Kellokumpu-Lehtinen ldquoDynamic contrast-enhanced imaging as a prognostic tool in early diagnosis ofprostate cancer correlation with PSA and clinical stagerdquo

Contrast Media Mol Imaging vol 2018 Article ID 31812587 pages 2018

[6] S J Hectors M Wagner C Besa W Huang and B TaoulildquoMultiparametric FDG-PETMRI of hepatocellular carci-noma initial experiencerdquo Contrast Media Mol Imagingvol 2018 Article ID 5638283 10 pages 2018

[7] S Yan Z Wang L Li et al ldquoCharacterization of cervicallymph nodes using DCE-MRI differentiation between me-tastases from SCC of head and neck and benign lymph nodesrdquoClinical Hemorheology and Microcirculation vol 64 no 2pp 213ndash222 2016

[8] C M Wendl S Muller J Meier et al ldquoHigh resolutioncontrast-enhanced ultrasound and 3-tesla dynamic contrast-enhanced magnetic resonance imaging for the preoperativecharacterization of cervical lymph nodes first resultsrdquoClinical Hemorheology and Microcirculation vol 52 no 2ndash4pp 153ndash166 2012

[9] N J Fischbein S M Noworolski R G Henry M J KaplanW P Dillon and S J Nelson ldquoAssessment of metastaticcervical adenopathy using dynamic contrast-enhanced MRimagingrdquo AJNR American Journal of Neuroradiology vol 24no 3 pp 301ndash311 2003

[10] W J Alberda H P N Dassen R S Dwarkasing et alldquoPrediction of tumor stage and lymph node involvement withdynamic contrast-enhancedMRI after chemoradiotherapy forlocally advanced rectal cancerrdquo International Journal of Co-lorectal Disease vol 28 no 4 pp 573ndash580 2013

[11] T Vag J Slotta-Huspenina R Rosenberg et al ldquoComput-erized analysis of enhancement kinetics for preoperativelymph node staging in rectal cancer using dynamic contrast-enhanced magnetic resonance imagingrdquo Clinical Imagingvol 38 no 6 pp 845ndash849 2014

[12] S M Noworolski N J Fischbein M J Kaplan et alldquoChallenges in dynamic contrast-enhanced MRI imaging ofcervical lymph nodes to detect metastatic diseaserdquo Journal ofMagnetic Resonance Imaging vol 17 no 4 pp 455ndash462 2003

[13] W T Yang W W M Lam M Y Yu T H Cheung andC Metreweli ldquoComparison of dynamic helical CT and dy-namic MR imaging in the evaluation of pelvic lymph nodes incervical carcinomardquo American Journal of Roentgenologyvol 175 no 3 pp 759ndash766 2000

[14] B Huang D L Kwong V Lai Q Chan B Whitcher andP L Khong ldquoDynamic contrast-enhanced magnetic reso-nance imaging of regional nodal metastasis in nasopharyngealcarcinoma correlation with nodal stagingrdquo Contrast Media ampMolecular Imaging vol 2017 Article ID 4519653 6 pages2017

[15] A D Murray R T Staff T W Redpath et al ldquoDynamiccontrast enhanced MRI of the axilla in women with breastcancer comparison with pathology of excised nodesrdquo eBritish Journal of Radiology vol 75 no 891 pp 220ndash2282002

[16] H Rahbar J L Conlin S Parsian et al ldquoSuspicious axillarylymph nodes identified on clinical breast MRI in patientsnewly diagnosed with breast cancerrdquo Academic Radiologyvol 22 no 4 pp 430ndash438 2015

[17] K A Kvistad J Rydland H-B Smethurst S LundgrenH E Fjoslashsne and O Haraldseth ldquoAxillary lymph node me-tastases in breast cancer preoperative detection with dynamiccontrast-enhanced MRIrdquo European Radiology vol 10 no 9pp 1464ndash1471 2000

[18] D V Schacht K Drukker I Pak H Abe and M L GigerldquoUsing quantitative image analysis to classify axillary lymphnodes on breast MRI a new application for the Z 0011 erardquo

8 Contrast Media amp Molecular Imaging

European Journal of Radiology vol 84 no 3 pp 392ndash3972015

[19] J Krammer K Wasser A Schnitzer T HenzlerS O Schoenberg and C G Kaiser ldquoAxillary lymph nodecharacterization in breast cancer patients using magneticresonance mammography a prospective comparative studywith FDG PET-CTand healthy womenrdquo European Journal ofRadiology vol 82 no 12 pp 2194ndash2198 2013

[20] V J L Kuijs M Moossdorff R J Schipper et al ldquoe role ofMRI in axillary lymph node imaging in breast cancer patientsa systematic reviewrdquo Insights into Imaging vol 6 no 2pp 203ndash215 2015

[21] P Farace F Merigo S Fiorini et al ldquoDCE-MRI using small-molecular and albumin-binding contrast agents in experi-mental carcinomas with different stromal contentrdquo EuropeanJournal of Radiology vol 78 no 1 pp 52ndash59 2011

[22] F Boschi P Marzola M Sandri et al ldquoTumor microvas-culature observed using different contrast agents a com-parison between Gd-DTPA-Albumin and B-229561 in anexperimental model of mammary carcinomardquo MagneticResonance Materials in Physics Biology and Medicine vol 21no 3 pp 169ndash176 2008

[23] C Corot X Violas P Robert and M Port ldquoPharmacoki-netics of three gadolinium chelates with different molecularsizes shortly after intravenous injection in rabbitsrdquo In-vestigative Radiology vol 35 no 4 pp 213ndash218 2000

[24] HW Lee and S H Kim ldquoBreast magnetic resonance imagingfor assessment of internal mammary lymph node status inbreast cancerrdquo Journal of Breast Cancer vol 19 no 2pp 191ndash198 2016

[25] E J Kim S H Kim B J Kang B G Choi B J Song andJ J Choi ldquoDiagnostic value of breast MRI for predictingmetastatic axillary lymph nodes in breast cancer patientsdiffusion-weighted MRI and conventional MRIrdquo MagneticResonance Imaging vol 32 no 10 pp 1230ndash1236 2014

[26] S M Smith M Jenkinson M W Woolrich et al ldquoAdvancesin functional and structural MR image analysis and imple-mentation as FSLrdquo NeuroImage vol 23 no 1 pp 208ndash2192004

[27] J K Kim S S Hong Y J Choi et al ldquoWash-in rate on thebasis of dynamic contrast-enhanced MRI usefulness forprostate cancer detection and localizationrdquo Journal of Mag-netic Resonance Imaging vol 22 no 5 pp 639ndash646 2005

[28] J Krammer D Engel J Nissen et al ldquoCharacteristics ofaxillary lymph nodes apparent on dynamic contrast-enhancedbreast MRI in healthy womenrdquo Clinical Imaging vol 36no 4 pp 249ndash254 2012

[29] M G Harisinghani J Barentsz P F Hahn et al ldquoNon-invasive detection of clinically occult lymph-node metastasesin prostate cancerrdquo New England Journal of Medicinevol 348 no 25 pp 2491ndash2499 2003

[30] O Will S Purkayastha C Chan et al ldquoDiagnostic precisionof nanoparticle-enhanced MRI for lymph-node metastases ameta-analysisrdquo e Lancet Oncology vol 7 no 1 pp 52ndash602006

[31] D M Lambregts L A Heijnen M Maas et alldquoGadofosveset-enhanced MRI for the assessment of rectalcancer lymph nodes predictive criteriardquo Abdominal Imagingvol 38 no 4 pp 720ndash727 2012

[32] R-J Schipper M L Smidt L M van Roozendaal et alldquoNoninvasive nodal staging in patients with breast cancerusing gadofosveset-enhanced magnetic resonance imagingrdquoInvestigative Radiology vol 48 no 3 pp 134ndash139 2013

Contrast Media amp Molecular Imaging 9

Stem Cells International

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

MEDIATORSINFLAMMATION

of

EndocrinologyInternational Journal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Disease Markers

Hindawiwwwhindawicom Volume 2018

BioMed Research International

OncologyJournal of

Hindawiwwwhindawicom Volume 2013

Hindawiwwwhindawicom Volume 2018

Oxidative Medicine and Cellular Longevity

Hindawiwwwhindawicom Volume 2018

PPAR Research

Hindawi Publishing Corporation httpwwwhindawicom Volume 2013Hindawiwwwhindawicom

The Scientific World Journal

Volume 2018

Immunology ResearchHindawiwwwhindawicom Volume 2018

Journal of

ObesityJournal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Computational and Mathematical Methods in Medicine

Hindawiwwwhindawicom Volume 2018

Behavioural Neurology

OphthalmologyJournal of

Hindawiwwwhindawicom Volume 2018

Diabetes ResearchJournal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Research and TreatmentAIDS

Hindawiwwwhindawicom Volume 2018

Gastroenterology Research and Practice

Hindawiwwwhindawicom Volume 2018

Parkinsonrsquos Disease

Evidence-Based Complementary andAlternative Medicine

Volume 2018Hindawiwwwhindawicom

Submit your manuscripts atwwwhindawicom

Of relevance such a heterogeneous enhancement pat-tern arising from k-means evidenced a marked anatomicalstructure regardless of the contrast agent used In fact thetwo clusters identied in each node resulted clearly localizedin the outer portion and in the inner portion of the nodesrespectively e observed pattern seems to be compatiblewith the functional organization of a normal lymph nodecomposed of two main functional units the cortex and themedulla Since the lymphatic ordfow is directed from thecapsule and the cortex of the lymph node towards themedulla and the hilum in this latter portion the contrastagents might accumulate also because of interstitial diu-sion at least partially explaining the greater contrast uptakein the inner region of the lymph nodes

e observed spatial pattern characterized the heteroge-neous distribution of the enhancement in all the assessedlymph nodes Independently from the contrast agent usedAUC and wash-in rate were greater in the inner cluster whichalso showed a steeper wash-out rate than the outer cluster

both with Gd-BOPTA and by Gd-DTPA On the contrary theenhancement of Gd-DTPA was not signicantly dierentfrom the enhancement pattern of Gd-BOPTA

Many studies investigated the role of postcontrast T1imaging in assessing the lymph node status includingquantitative assessment on DCE-MRI but to ourknowledge the peculiar heterogeneity of contrast en-hancement in normal nodes has not been reported beforeTo the best of our knowledge only one study focused onnormal nodes analysing axillary lymph nodes in breastcancer patients [28] However that study focused on theenhancement curve of a single region of interest placedinside the cortex of the healthy nodes without covering thehilum to assess potential heterogeneity As shown in nativeprecontrast T1-weighted images in our study none of theassessed mice nodes showed a fatty hilum allowing toinclude the whole nodes in the analysis of the contrastenhancement heterogeneity and the subsequent segmen-tation procedure

5 m

m

(a)

5 m

m

(b)

5 m

m

(c)

0 10 20 30 40 50 60 70ndash05

0

05

1

15

2

25

3

35

4

45

Inner

Outer

(d)

5 m

m

(e)

Figure 3 Precontrast (a) early (b) and late (c) DCE-MRI images (the same slice reported in Figures 1(a)ndash1(c) is shown) of a representativelymph node (15) e region of interest (in yellow in (a)ndash(c)) was manually drawn to encompass the whole lymph node e long-axis sizeof this lymph node was around 25mm k-means clustering assigned each pixel-based NDE curve (thin dashed lines) to one of the twoclusters (d) cluster-averaged NDE curves are also shown (thick black continuous lines) e obtained segmentation map is shown with thecorresponding colours (e)

Contrast Media amp Molecular Imaging 5

Interestingly in a study aiming at classifying axillarylymph nodes in breast cancer patients [18] the best per-forming feature was a morphological feature described as thedegree to which the enhancement structure extends in aradial pattern originating from the centre of the node lesionIn our study which of course needs to be conrmed on

human subjects an intrinsic radial structure on normalnodes was revealed and it is reasonable to speculate thatsuch a structure might be altered in metastatic nodes

It is worth noting that the identication of a normalenhancement pattern might have a role in the detection ofpossible alterations induced by the metastatic transformation

0 20 40 600

2

4

0 20 40 600

1

2

3

2

0 20 40 600123

3

0 20 40 600

1

2

3

0 20 40 600

1

2

5

0 20 40 600

1

2

6

0 20 40 600

1

2

0 20 40 600

1

2

3

8

0 20 40 600

1

2

3

9

0 20 40 600

2

4

0 20 40 600

2

4

11

0 20 40 600

1

2

12

0 20 40 600

1

2

1

4

7

10

13

0 20 40 600

1

2

14

0 20 40 600

1

2

3

15

Figure 4 Enhancement pattern-based k-means clustering on 15 healthy nodes with Gd-DTPA (nodes 1ndash9) and with Gd-BOPTA (nodes10ndash15) e redgreen colours used to report the cluster-averaged NDE curves correspond to the colour used to localize them in thecorresponding segmentation maps (on the right of each plot)

Table 1 Semiquantitative parameters on segmented clusters

NodeAUC (au) Wash-in (aumin) Wash-out (aumin) Volume ()

Inner Outer Inner Outer Inner Outer Inner Outer

Gd-DTPA

1 217plusmn 41 100plusmn 25 13plusmn 03 08plusmn 03 minus38plusmn 08 minus15plusmn 06 25 752 124plusmn 16 71plusmn 12 19plusmn 03 12plusmn 05 minus30plusmn 05 minus16plusmn 04 19 813 101plusmn 14 58plusmn 13 26plusmn 04 12plusmn 03 minus19plusmn 02 minus12plusmn 03 21 794 143plusmn 23 74plusmn 17 16plusmn 05 09plusmn 04 minus06plusmn 06 minus05plusmn 04 26 745 100plusmn 9 69plusmn 9 11plusmn 07 11plusmn 04 minus07plusmn 03 minus04plusmn 03 49 516 91plusmn 9 63plusmn 6 17plusmn 05 12plusmn 05 minus05plusmn 03 minus03plusmn 02 32 687 98plusmn 11 66plusmn 9 14plusmn 04 12plusmn 05 minus07plusmn 04 minus04plusmn 02 33 678 178plusmn 26 99plusmn 22 11plusmn 03 10plusmn 03 minus11plusmn 06 minus05plusmn 04 29 719 149plusmn 27 91plusmn 18 15plusmn 05 10plusmn 05 minus04plusmn 07 minus06plusmn 03 25 75

Gd-BOPTA

10 211plusmn 33 109plusmn 29 14plusmn 03 12plusmn 02 minus27plusmn 05 minus12plusmn 04 47 5311 157plusmn 23 97plusmn 14 23plusmn 04 13plusmn 04 minus22plusmn 06 minus12plusmn 03 14 8612 88plusmn 14 51plusmn 12 13plusmn 03 10plusmn 03 minus23plusmn 12 minus12plusmn 07 40 6013 51plusmn 9 29plusmn 7 19plusmn 04 13plusmn 04 minus21plusmn 04 minus13plusmn 03 38 6214 61plusmn 7 36plusmn 8 15plusmn 05 13plusmn 07 minus14plusmn 02 minus09plusmn 03 43 5715 109plusmn 18 48plusmn 16 17plusmn 03 11plusmn 04 minus35plusmn 08 minus13plusmn 05 29 71

6 Contrast Media amp Molecular Imaging

For example the accuracy obtained by lymphotropic ironoxide nanoparticles for nodal staging [29 30] was based onthe negative enhancement observed in normal nodes which

was modied by the presence of a metastatic lesion in thenodes Similarly in gadofosveset-enhanced MRI the aspectof the chemical shift artefact encircling the lymph nodes

Gd-DTPA Gd-BOPTA0

20

40

60

80

Inner

Outer

lowastlowast

lowast

(a)

Gd-DTPA Gd-BOPTA0

50

100

150

Inner

Outer

lowastlowast

lowastlowast

(b)

Gd-DTPA Gd-BOPTA0

05

1

15

2

Inner

Outer

lowastlowast

lowast

(c)

Gd-DTPA Gd-BOPTAndash25

ndash2

ndash15

ndash1

ndash05

0

Inner

Outer

lowastlowast

(d)

Figure 5 Mean parameter values calculated averaging on the lymph nodes evaluated with the same contrast agent Statistical signicancelevels obtained comparing by two-way ANOVA the two segmented clusters are also shown (lowastlowastplt 001 and lowastplt 005) (a) Volume ()(b) AUC (au) (c) Wash-in rate (aumin) (d) Wash-out rate (aumin)

(a) (b)

Figure 6 HampE staining of normal lymph nodes (a) e lymphatic cell is clearly visible and the lymph node structure is preserved both inthe cortex (violet-surrounded area) and in the medulla (4x magnication) (b) 10x magnication of the boxed area shown in (a)

Contrast Media amp Molecular Imaging 7

(ldquothe chemical shift criterionrdquo) on enhanced images wasconsidered a sign of benign normal nodes [31 32] Par-ticularly the benign nodes fell into the category of ldquosharplydelineated and intact chemical shift artefactrdquo whereas anirregular or optically ldquointerruptedrdquo chemical shift artefact ora pronounced enhancing rim encircling the entire node wasconsidered as a malignant criterion

5 Conclusions

In conclusion the results obtained showed a heterogeneouspattern of enhancement in normal lymph nodes in-dependently of the contrast agent used Semiautomaticcluster analysis of signal intensity vs time data showed theexistence of two clusters characterized by different signalintensity dynamics belonging to the inner and outer regionsof lymph nodes

is heterogeneous pattern might be peculiar of normallymph nodes and if confirmed on human lymph nodesshould be deeply investigated to assess any alteration pos-sibly induced by the metastatic transformation and con-sequently its potential role for nodal staging

Data Availability

e MRI data used to support the findings of this study areavailable from the corresponding author upon request

Conflicts of Interest

e authors declare that they have no conflicts of interest

Acknowledgments

is work was supported by the University of Verona andAzienda Provinciale per i Servizi Sanitari Trento (JointProject JPVR17YEPM 2017)

References

[1] P Marzola A Degrassi L Calderan et al ldquoIn vivo assessmentof antiangiogenic activity of SU6668 in an experimental coloncarcinoma modelrdquo Clinical Cancer Research vol 10 no 2pp 739ndash750 2004

[2] P Marzola A Degrassi L Calderan et al ldquoEarly anti-angiogenic activity of SU11248 evaluated in vivo by dynamiccontrast-enhanced magnetic resonance imaging in an ex-perimental model of colon carcinomardquo Clinical Cancer Re-search vol 11 no 16 pp 5827ndash5832 2005

[3] H Degani V Gusis D Weinstein S Fields and S StranoldquoMapping pathophysiological features of breast tumors byMRI at high spatial resolutionrdquo Nature Medicine vol 3 no 7pp 780ndash782 1997

[4] J F Schaefer V Schneider J Vollmar et al ldquoSolitary pul-monary nodules association between signal characteristics indynamic contrast enhanced MRI and tumor angiogenesisrdquoLung Cancer vol 53 no 1 pp 39ndash49 2006

[5] X Wu P Reinikainen M Kapanen T Vierikko P Ryyminand P L Kellokumpu-Lehtinen ldquoDynamic contrast-enhanced imaging as a prognostic tool in early diagnosis ofprostate cancer correlation with PSA and clinical stagerdquo

Contrast Media Mol Imaging vol 2018 Article ID 31812587 pages 2018

[6] S J Hectors M Wagner C Besa W Huang and B TaoulildquoMultiparametric FDG-PETMRI of hepatocellular carci-noma initial experiencerdquo Contrast Media Mol Imagingvol 2018 Article ID 5638283 10 pages 2018

[7] S Yan Z Wang L Li et al ldquoCharacterization of cervicallymph nodes using DCE-MRI differentiation between me-tastases from SCC of head and neck and benign lymph nodesrdquoClinical Hemorheology and Microcirculation vol 64 no 2pp 213ndash222 2016

[8] C M Wendl S Muller J Meier et al ldquoHigh resolutioncontrast-enhanced ultrasound and 3-tesla dynamic contrast-enhanced magnetic resonance imaging for the preoperativecharacterization of cervical lymph nodes first resultsrdquoClinical Hemorheology and Microcirculation vol 52 no 2ndash4pp 153ndash166 2012

[9] N J Fischbein S M Noworolski R G Henry M J KaplanW P Dillon and S J Nelson ldquoAssessment of metastaticcervical adenopathy using dynamic contrast-enhanced MRimagingrdquo AJNR American Journal of Neuroradiology vol 24no 3 pp 301ndash311 2003

[10] W J Alberda H P N Dassen R S Dwarkasing et alldquoPrediction of tumor stage and lymph node involvement withdynamic contrast-enhancedMRI after chemoradiotherapy forlocally advanced rectal cancerrdquo International Journal of Co-lorectal Disease vol 28 no 4 pp 573ndash580 2013

[11] T Vag J Slotta-Huspenina R Rosenberg et al ldquoComput-erized analysis of enhancement kinetics for preoperativelymph node staging in rectal cancer using dynamic contrast-enhanced magnetic resonance imagingrdquo Clinical Imagingvol 38 no 6 pp 845ndash849 2014

[12] S M Noworolski N J Fischbein M J Kaplan et alldquoChallenges in dynamic contrast-enhanced MRI imaging ofcervical lymph nodes to detect metastatic diseaserdquo Journal ofMagnetic Resonance Imaging vol 17 no 4 pp 455ndash462 2003

[13] W T Yang W W M Lam M Y Yu T H Cheung andC Metreweli ldquoComparison of dynamic helical CT and dy-namic MR imaging in the evaluation of pelvic lymph nodes incervical carcinomardquo American Journal of Roentgenologyvol 175 no 3 pp 759ndash766 2000

[14] B Huang D L Kwong V Lai Q Chan B Whitcher andP L Khong ldquoDynamic contrast-enhanced magnetic reso-nance imaging of regional nodal metastasis in nasopharyngealcarcinoma correlation with nodal stagingrdquo Contrast Media ampMolecular Imaging vol 2017 Article ID 4519653 6 pages2017

[15] A D Murray R T Staff T W Redpath et al ldquoDynamiccontrast enhanced MRI of the axilla in women with breastcancer comparison with pathology of excised nodesrdquo eBritish Journal of Radiology vol 75 no 891 pp 220ndash2282002

[16] H Rahbar J L Conlin S Parsian et al ldquoSuspicious axillarylymph nodes identified on clinical breast MRI in patientsnewly diagnosed with breast cancerrdquo Academic Radiologyvol 22 no 4 pp 430ndash438 2015

[17] K A Kvistad J Rydland H-B Smethurst S LundgrenH E Fjoslashsne and O Haraldseth ldquoAxillary lymph node me-tastases in breast cancer preoperative detection with dynamiccontrast-enhanced MRIrdquo European Radiology vol 10 no 9pp 1464ndash1471 2000

[18] D V Schacht K Drukker I Pak H Abe and M L GigerldquoUsing quantitative image analysis to classify axillary lymphnodes on breast MRI a new application for the Z 0011 erardquo

8 Contrast Media amp Molecular Imaging

European Journal of Radiology vol 84 no 3 pp 392ndash3972015

[19] J Krammer K Wasser A Schnitzer T HenzlerS O Schoenberg and C G Kaiser ldquoAxillary lymph nodecharacterization in breast cancer patients using magneticresonance mammography a prospective comparative studywith FDG PET-CTand healthy womenrdquo European Journal ofRadiology vol 82 no 12 pp 2194ndash2198 2013

[20] V J L Kuijs M Moossdorff R J Schipper et al ldquoe role ofMRI in axillary lymph node imaging in breast cancer patientsa systematic reviewrdquo Insights into Imaging vol 6 no 2pp 203ndash215 2015

[21] P Farace F Merigo S Fiorini et al ldquoDCE-MRI using small-molecular and albumin-binding contrast agents in experi-mental carcinomas with different stromal contentrdquo EuropeanJournal of Radiology vol 78 no 1 pp 52ndash59 2011

[22] F Boschi P Marzola M Sandri et al ldquoTumor microvas-culature observed using different contrast agents a com-parison between Gd-DTPA-Albumin and B-229561 in anexperimental model of mammary carcinomardquo MagneticResonance Materials in Physics Biology and Medicine vol 21no 3 pp 169ndash176 2008

[23] C Corot X Violas P Robert and M Port ldquoPharmacoki-netics of three gadolinium chelates with different molecularsizes shortly after intravenous injection in rabbitsrdquo In-vestigative Radiology vol 35 no 4 pp 213ndash218 2000

[24] HW Lee and S H Kim ldquoBreast magnetic resonance imagingfor assessment of internal mammary lymph node status inbreast cancerrdquo Journal of Breast Cancer vol 19 no 2pp 191ndash198 2016

[25] E J Kim S H Kim B J Kang B G Choi B J Song andJ J Choi ldquoDiagnostic value of breast MRI for predictingmetastatic axillary lymph nodes in breast cancer patientsdiffusion-weighted MRI and conventional MRIrdquo MagneticResonance Imaging vol 32 no 10 pp 1230ndash1236 2014

[26] S M Smith M Jenkinson M W Woolrich et al ldquoAdvancesin functional and structural MR image analysis and imple-mentation as FSLrdquo NeuroImage vol 23 no 1 pp 208ndash2192004

[27] J K Kim S S Hong Y J Choi et al ldquoWash-in rate on thebasis of dynamic contrast-enhanced MRI usefulness forprostate cancer detection and localizationrdquo Journal of Mag-netic Resonance Imaging vol 22 no 5 pp 639ndash646 2005

[28] J Krammer D Engel J Nissen et al ldquoCharacteristics ofaxillary lymph nodes apparent on dynamic contrast-enhancedbreast MRI in healthy womenrdquo Clinical Imaging vol 36no 4 pp 249ndash254 2012

[29] M G Harisinghani J Barentsz P F Hahn et al ldquoNon-invasive detection of clinically occult lymph-node metastasesin prostate cancerrdquo New England Journal of Medicinevol 348 no 25 pp 2491ndash2499 2003

[30] O Will S Purkayastha C Chan et al ldquoDiagnostic precisionof nanoparticle-enhanced MRI for lymph-node metastases ameta-analysisrdquo e Lancet Oncology vol 7 no 1 pp 52ndash602006

[31] D M Lambregts L A Heijnen M Maas et alldquoGadofosveset-enhanced MRI for the assessment of rectalcancer lymph nodes predictive criteriardquo Abdominal Imagingvol 38 no 4 pp 720ndash727 2012

[32] R-J Schipper M L Smidt L M van Roozendaal et alldquoNoninvasive nodal staging in patients with breast cancerusing gadofosveset-enhanced magnetic resonance imagingrdquoInvestigative Radiology vol 48 no 3 pp 134ndash139 2013

Contrast Media amp Molecular Imaging 9

Stem Cells International

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

MEDIATORSINFLAMMATION

of

EndocrinologyInternational Journal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Disease Markers

Hindawiwwwhindawicom Volume 2018

BioMed Research International

OncologyJournal of

Hindawiwwwhindawicom Volume 2013

Hindawiwwwhindawicom Volume 2018

Oxidative Medicine and Cellular Longevity

Hindawiwwwhindawicom Volume 2018

PPAR Research

Hindawi Publishing Corporation httpwwwhindawicom Volume 2013Hindawiwwwhindawicom

The Scientific World Journal

Volume 2018

Immunology ResearchHindawiwwwhindawicom Volume 2018

Journal of

ObesityJournal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Computational and Mathematical Methods in Medicine

Hindawiwwwhindawicom Volume 2018

Behavioural Neurology

OphthalmologyJournal of

Hindawiwwwhindawicom Volume 2018

Diabetes ResearchJournal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Research and TreatmentAIDS

Hindawiwwwhindawicom Volume 2018

Gastroenterology Research and Practice

Hindawiwwwhindawicom Volume 2018

Parkinsonrsquos Disease

Evidence-Based Complementary andAlternative Medicine

Volume 2018Hindawiwwwhindawicom

Submit your manuscripts atwwwhindawicom

Interestingly in a study aiming at classifying axillarylymph nodes in breast cancer patients [18] the best per-forming feature was a morphological feature described as thedegree to which the enhancement structure extends in aradial pattern originating from the centre of the node lesionIn our study which of course needs to be conrmed on

human subjects an intrinsic radial structure on normalnodes was revealed and it is reasonable to speculate thatsuch a structure might be altered in metastatic nodes

It is worth noting that the identication of a normalenhancement pattern might have a role in the detection ofpossible alterations induced by the metastatic transformation

0 20 40 600

2

4

0 20 40 600

1

2

3

2

0 20 40 600123

3

0 20 40 600

1

2

3

0 20 40 600

1

2

5

0 20 40 600

1

2

6

0 20 40 600

1

2

0 20 40 600

1

2

3

8

0 20 40 600

1

2

3

9

0 20 40 600

2

4

0 20 40 600

2

4

11

0 20 40 600

1

2

12

0 20 40 600

1

2

1

4

7

10

13

0 20 40 600

1

2

14

0 20 40 600

1

2

3

15

Figure 4 Enhancement pattern-based k-means clustering on 15 healthy nodes with Gd-DTPA (nodes 1ndash9) and with Gd-BOPTA (nodes10ndash15) e redgreen colours used to report the cluster-averaged NDE curves correspond to the colour used to localize them in thecorresponding segmentation maps (on the right of each plot)

Table 1 Semiquantitative parameters on segmented clusters

NodeAUC (au) Wash-in (aumin) Wash-out (aumin) Volume ()

Inner Outer Inner Outer Inner Outer Inner Outer

Gd-DTPA

1 217plusmn 41 100plusmn 25 13plusmn 03 08plusmn 03 minus38plusmn 08 minus15plusmn 06 25 752 124plusmn 16 71plusmn 12 19plusmn 03 12plusmn 05 minus30plusmn 05 minus16plusmn 04 19 813 101plusmn 14 58plusmn 13 26plusmn 04 12plusmn 03 minus19plusmn 02 minus12plusmn 03 21 794 143plusmn 23 74plusmn 17 16plusmn 05 09plusmn 04 minus06plusmn 06 minus05plusmn 04 26 745 100plusmn 9 69plusmn 9 11plusmn 07 11plusmn 04 minus07plusmn 03 minus04plusmn 03 49 516 91plusmn 9 63plusmn 6 17plusmn 05 12plusmn 05 minus05plusmn 03 minus03plusmn 02 32 687 98plusmn 11 66plusmn 9 14plusmn 04 12plusmn 05 minus07plusmn 04 minus04plusmn 02 33 678 178plusmn 26 99plusmn 22 11plusmn 03 10plusmn 03 minus11plusmn 06 minus05plusmn 04 29 719 149plusmn 27 91plusmn 18 15plusmn 05 10plusmn 05 minus04plusmn 07 minus06plusmn 03 25 75

Gd-BOPTA

10 211plusmn 33 109plusmn 29 14plusmn 03 12plusmn 02 minus27plusmn 05 minus12plusmn 04 47 5311 157plusmn 23 97plusmn 14 23plusmn 04 13plusmn 04 minus22plusmn 06 minus12plusmn 03 14 8612 88plusmn 14 51plusmn 12 13plusmn 03 10plusmn 03 minus23plusmn 12 minus12plusmn 07 40 6013 51plusmn 9 29plusmn 7 19plusmn 04 13plusmn 04 minus21plusmn 04 minus13plusmn 03 38 6214 61plusmn 7 36plusmn 8 15plusmn 05 13plusmn 07 minus14plusmn 02 minus09plusmn 03 43 5715 109plusmn 18 48plusmn 16 17plusmn 03 11plusmn 04 minus35plusmn 08 minus13plusmn 05 29 71

6 Contrast Media amp Molecular Imaging

For example the accuracy obtained by lymphotropic ironoxide nanoparticles for nodal staging [29 30] was based onthe negative enhancement observed in normal nodes which

was modied by the presence of a metastatic lesion in thenodes Similarly in gadofosveset-enhanced MRI the aspectof the chemical shift artefact encircling the lymph nodes

Gd-DTPA Gd-BOPTA0

20

40

60

80

Inner

Outer

lowastlowast

lowast

(a)

Gd-DTPA Gd-BOPTA0

50

100

150

Inner

Outer

lowastlowast

lowastlowast

(b)

Gd-DTPA Gd-BOPTA0

05

1

15

2

Inner

Outer

lowastlowast

lowast

(c)

Gd-DTPA Gd-BOPTAndash25

ndash2

ndash15

ndash1

ndash05

0

Inner

Outer

lowastlowast

(d)

Figure 5 Mean parameter values calculated averaging on the lymph nodes evaluated with the same contrast agent Statistical signicancelevels obtained comparing by two-way ANOVA the two segmented clusters are also shown (lowastlowastplt 001 and lowastplt 005) (a) Volume ()(b) AUC (au) (c) Wash-in rate (aumin) (d) Wash-out rate (aumin)

(a) (b)

Figure 6 HampE staining of normal lymph nodes (a) e lymphatic cell is clearly visible and the lymph node structure is preserved both inthe cortex (violet-surrounded area) and in the medulla (4x magnication) (b) 10x magnication of the boxed area shown in (a)

Contrast Media amp Molecular Imaging 7

(ldquothe chemical shift criterionrdquo) on enhanced images wasconsidered a sign of benign normal nodes [31 32] Par-ticularly the benign nodes fell into the category of ldquosharplydelineated and intact chemical shift artefactrdquo whereas anirregular or optically ldquointerruptedrdquo chemical shift artefact ora pronounced enhancing rim encircling the entire node wasconsidered as a malignant criterion

5 Conclusions

In conclusion the results obtained showed a heterogeneouspattern of enhancement in normal lymph nodes in-dependently of the contrast agent used Semiautomaticcluster analysis of signal intensity vs time data showed theexistence of two clusters characterized by different signalintensity dynamics belonging to the inner and outer regionsof lymph nodes

is heterogeneous pattern might be peculiar of normallymph nodes and if confirmed on human lymph nodesshould be deeply investigated to assess any alteration pos-sibly induced by the metastatic transformation and con-sequently its potential role for nodal staging

Data Availability

e MRI data used to support the findings of this study areavailable from the corresponding author upon request

Conflicts of Interest

e authors declare that they have no conflicts of interest

Acknowledgments

is work was supported by the University of Verona andAzienda Provinciale per i Servizi Sanitari Trento (JointProject JPVR17YEPM 2017)

References

[1] P Marzola A Degrassi L Calderan et al ldquoIn vivo assessmentof antiangiogenic activity of SU6668 in an experimental coloncarcinoma modelrdquo Clinical Cancer Research vol 10 no 2pp 739ndash750 2004

[2] P Marzola A Degrassi L Calderan et al ldquoEarly anti-angiogenic activity of SU11248 evaluated in vivo by dynamiccontrast-enhanced magnetic resonance imaging in an ex-perimental model of colon carcinomardquo Clinical Cancer Re-search vol 11 no 16 pp 5827ndash5832 2005

[3] H Degani V Gusis D Weinstein S Fields and S StranoldquoMapping pathophysiological features of breast tumors byMRI at high spatial resolutionrdquo Nature Medicine vol 3 no 7pp 780ndash782 1997

[4] J F Schaefer V Schneider J Vollmar et al ldquoSolitary pul-monary nodules association between signal characteristics indynamic contrast enhanced MRI and tumor angiogenesisrdquoLung Cancer vol 53 no 1 pp 39ndash49 2006

[5] X Wu P Reinikainen M Kapanen T Vierikko P Ryyminand P L Kellokumpu-Lehtinen ldquoDynamic contrast-enhanced imaging as a prognostic tool in early diagnosis ofprostate cancer correlation with PSA and clinical stagerdquo

Contrast Media Mol Imaging vol 2018 Article ID 31812587 pages 2018

[6] S J Hectors M Wagner C Besa W Huang and B TaoulildquoMultiparametric FDG-PETMRI of hepatocellular carci-noma initial experiencerdquo Contrast Media Mol Imagingvol 2018 Article ID 5638283 10 pages 2018

[7] S Yan Z Wang L Li et al ldquoCharacterization of cervicallymph nodes using DCE-MRI differentiation between me-tastases from SCC of head and neck and benign lymph nodesrdquoClinical Hemorheology and Microcirculation vol 64 no 2pp 213ndash222 2016

[8] C M Wendl S Muller J Meier et al ldquoHigh resolutioncontrast-enhanced ultrasound and 3-tesla dynamic contrast-enhanced magnetic resonance imaging for the preoperativecharacterization of cervical lymph nodes first resultsrdquoClinical Hemorheology and Microcirculation vol 52 no 2ndash4pp 153ndash166 2012

[9] N J Fischbein S M Noworolski R G Henry M J KaplanW P Dillon and S J Nelson ldquoAssessment of metastaticcervical adenopathy using dynamic contrast-enhanced MRimagingrdquo AJNR American Journal of Neuroradiology vol 24no 3 pp 301ndash311 2003

[10] W J Alberda H P N Dassen R S Dwarkasing et alldquoPrediction of tumor stage and lymph node involvement withdynamic contrast-enhancedMRI after chemoradiotherapy forlocally advanced rectal cancerrdquo International Journal of Co-lorectal Disease vol 28 no 4 pp 573ndash580 2013

[11] T Vag J Slotta-Huspenina R Rosenberg et al ldquoComput-erized analysis of enhancement kinetics for preoperativelymph node staging in rectal cancer using dynamic contrast-enhanced magnetic resonance imagingrdquo Clinical Imagingvol 38 no 6 pp 845ndash849 2014

[12] S M Noworolski N J Fischbein M J Kaplan et alldquoChallenges in dynamic contrast-enhanced MRI imaging ofcervical lymph nodes to detect metastatic diseaserdquo Journal ofMagnetic Resonance Imaging vol 17 no 4 pp 455ndash462 2003

[13] W T Yang W W M Lam M Y Yu T H Cheung andC Metreweli ldquoComparison of dynamic helical CT and dy-namic MR imaging in the evaluation of pelvic lymph nodes incervical carcinomardquo American Journal of Roentgenologyvol 175 no 3 pp 759ndash766 2000

[14] B Huang D L Kwong V Lai Q Chan B Whitcher andP L Khong ldquoDynamic contrast-enhanced magnetic reso-nance imaging of regional nodal metastasis in nasopharyngealcarcinoma correlation with nodal stagingrdquo Contrast Media ampMolecular Imaging vol 2017 Article ID 4519653 6 pages2017

[15] A D Murray R T Staff T W Redpath et al ldquoDynamiccontrast enhanced MRI of the axilla in women with breastcancer comparison with pathology of excised nodesrdquo eBritish Journal of Radiology vol 75 no 891 pp 220ndash2282002

[16] H Rahbar J L Conlin S Parsian et al ldquoSuspicious axillarylymph nodes identified on clinical breast MRI in patientsnewly diagnosed with breast cancerrdquo Academic Radiologyvol 22 no 4 pp 430ndash438 2015

[17] K A Kvistad J Rydland H-B Smethurst S LundgrenH E Fjoslashsne and O Haraldseth ldquoAxillary lymph node me-tastases in breast cancer preoperative detection with dynamiccontrast-enhanced MRIrdquo European Radiology vol 10 no 9pp 1464ndash1471 2000

[18] D V Schacht K Drukker I Pak H Abe and M L GigerldquoUsing quantitative image analysis to classify axillary lymphnodes on breast MRI a new application for the Z 0011 erardquo

8 Contrast Media amp Molecular Imaging

European Journal of Radiology vol 84 no 3 pp 392ndash3972015

[19] J Krammer K Wasser A Schnitzer T HenzlerS O Schoenberg and C G Kaiser ldquoAxillary lymph nodecharacterization in breast cancer patients using magneticresonance mammography a prospective comparative studywith FDG PET-CTand healthy womenrdquo European Journal ofRadiology vol 82 no 12 pp 2194ndash2198 2013

[20] V J L Kuijs M Moossdorff R J Schipper et al ldquoe role ofMRI in axillary lymph node imaging in breast cancer patientsa systematic reviewrdquo Insights into Imaging vol 6 no 2pp 203ndash215 2015

[21] P Farace F Merigo S Fiorini et al ldquoDCE-MRI using small-molecular and albumin-binding contrast agents in experi-mental carcinomas with different stromal contentrdquo EuropeanJournal of Radiology vol 78 no 1 pp 52ndash59 2011

[22] F Boschi P Marzola M Sandri et al ldquoTumor microvas-culature observed using different contrast agents a com-parison between Gd-DTPA-Albumin and B-229561 in anexperimental model of mammary carcinomardquo MagneticResonance Materials in Physics Biology and Medicine vol 21no 3 pp 169ndash176 2008

[23] C Corot X Violas P Robert and M Port ldquoPharmacoki-netics of three gadolinium chelates with different molecularsizes shortly after intravenous injection in rabbitsrdquo In-vestigative Radiology vol 35 no 4 pp 213ndash218 2000

[24] HW Lee and S H Kim ldquoBreast magnetic resonance imagingfor assessment of internal mammary lymph node status inbreast cancerrdquo Journal of Breast Cancer vol 19 no 2pp 191ndash198 2016

[25] E J Kim S H Kim B J Kang B G Choi B J Song andJ J Choi ldquoDiagnostic value of breast MRI for predictingmetastatic axillary lymph nodes in breast cancer patientsdiffusion-weighted MRI and conventional MRIrdquo MagneticResonance Imaging vol 32 no 10 pp 1230ndash1236 2014

[26] S M Smith M Jenkinson M W Woolrich et al ldquoAdvancesin functional and structural MR image analysis and imple-mentation as FSLrdquo NeuroImage vol 23 no 1 pp 208ndash2192004

[27] J K Kim S S Hong Y J Choi et al ldquoWash-in rate on thebasis of dynamic contrast-enhanced MRI usefulness forprostate cancer detection and localizationrdquo Journal of Mag-netic Resonance Imaging vol 22 no 5 pp 639ndash646 2005

[28] J Krammer D Engel J Nissen et al ldquoCharacteristics ofaxillary lymph nodes apparent on dynamic contrast-enhancedbreast MRI in healthy womenrdquo Clinical Imaging vol 36no 4 pp 249ndash254 2012

[29] M G Harisinghani J Barentsz P F Hahn et al ldquoNon-invasive detection of clinically occult lymph-node metastasesin prostate cancerrdquo New England Journal of Medicinevol 348 no 25 pp 2491ndash2499 2003

[30] O Will S Purkayastha C Chan et al ldquoDiagnostic precisionof nanoparticle-enhanced MRI for lymph-node metastases ameta-analysisrdquo e Lancet Oncology vol 7 no 1 pp 52ndash602006

[31] D M Lambregts L A Heijnen M Maas et alldquoGadofosveset-enhanced MRI for the assessment of rectalcancer lymph nodes predictive criteriardquo Abdominal Imagingvol 38 no 4 pp 720ndash727 2012

[32] R-J Schipper M L Smidt L M van Roozendaal et alldquoNoninvasive nodal staging in patients with breast cancerusing gadofosveset-enhanced magnetic resonance imagingrdquoInvestigative Radiology vol 48 no 3 pp 134ndash139 2013

Contrast Media amp Molecular Imaging 9

Stem Cells International

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

MEDIATORSINFLAMMATION

of

EndocrinologyInternational Journal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Disease Markers

Hindawiwwwhindawicom Volume 2018

BioMed Research International

OncologyJournal of

Hindawiwwwhindawicom Volume 2013

Hindawiwwwhindawicom Volume 2018

Oxidative Medicine and Cellular Longevity

Hindawiwwwhindawicom Volume 2018

PPAR Research

Hindawi Publishing Corporation httpwwwhindawicom Volume 2013Hindawiwwwhindawicom

The Scientific World Journal

Volume 2018

Immunology ResearchHindawiwwwhindawicom Volume 2018

Journal of

ObesityJournal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Computational and Mathematical Methods in Medicine

Hindawiwwwhindawicom Volume 2018

Behavioural Neurology

OphthalmologyJournal of

Hindawiwwwhindawicom Volume 2018

Diabetes ResearchJournal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Research and TreatmentAIDS

Hindawiwwwhindawicom Volume 2018

Gastroenterology Research and Practice

Hindawiwwwhindawicom Volume 2018

Parkinsonrsquos Disease

Evidence-Based Complementary andAlternative Medicine

Volume 2018Hindawiwwwhindawicom

Submit your manuscripts atwwwhindawicom

For example the accuracy obtained by lymphotropic ironoxide nanoparticles for nodal staging [29 30] was based onthe negative enhancement observed in normal nodes which

was modied by the presence of a metastatic lesion in thenodes Similarly in gadofosveset-enhanced MRI the aspectof the chemical shift artefact encircling the lymph nodes

Gd-DTPA Gd-BOPTA0

20

40

60

80

Inner

Outer

lowastlowast

lowast

(a)

Gd-DTPA Gd-BOPTA0

50

100

150

Inner

Outer

lowastlowast

lowastlowast

(b)

Gd-DTPA Gd-BOPTA0

05

1

15

2

Inner

Outer

lowastlowast

lowast

(c)

Gd-DTPA Gd-BOPTAndash25

ndash2

ndash15

ndash1

ndash05

0

Inner

Outer

lowastlowast

(d)

Figure 5 Mean parameter values calculated averaging on the lymph nodes evaluated with the same contrast agent Statistical signicancelevels obtained comparing by two-way ANOVA the two segmented clusters are also shown (lowastlowastplt 001 and lowastplt 005) (a) Volume ()(b) AUC (au) (c) Wash-in rate (aumin) (d) Wash-out rate (aumin)

(a) (b)

Figure 6 HampE staining of normal lymph nodes (a) e lymphatic cell is clearly visible and the lymph node structure is preserved both inthe cortex (violet-surrounded area) and in the medulla (4x magnication) (b) 10x magnication of the boxed area shown in (a)

Contrast Media amp Molecular Imaging 7

(ldquothe chemical shift criterionrdquo) on enhanced images wasconsidered a sign of benign normal nodes [31 32] Par-ticularly the benign nodes fell into the category of ldquosharplydelineated and intact chemical shift artefactrdquo whereas anirregular or optically ldquointerruptedrdquo chemical shift artefact ora pronounced enhancing rim encircling the entire node wasconsidered as a malignant criterion

5 Conclusions

In conclusion the results obtained showed a heterogeneouspattern of enhancement in normal lymph nodes in-dependently of the contrast agent used Semiautomaticcluster analysis of signal intensity vs time data showed theexistence of two clusters characterized by different signalintensity dynamics belonging to the inner and outer regionsof lymph nodes

is heterogeneous pattern might be peculiar of normallymph nodes and if confirmed on human lymph nodesshould be deeply investigated to assess any alteration pos-sibly induced by the metastatic transformation and con-sequently its potential role for nodal staging

Data Availability

e MRI data used to support the findings of this study areavailable from the corresponding author upon request

Conflicts of Interest

e authors declare that they have no conflicts of interest

Acknowledgments

is work was supported by the University of Verona andAzienda Provinciale per i Servizi Sanitari Trento (JointProject JPVR17YEPM 2017)

References

[1] P Marzola A Degrassi L Calderan et al ldquoIn vivo assessmentof antiangiogenic activity of SU6668 in an experimental coloncarcinoma modelrdquo Clinical Cancer Research vol 10 no 2pp 739ndash750 2004

[2] P Marzola A Degrassi L Calderan et al ldquoEarly anti-angiogenic activity of SU11248 evaluated in vivo by dynamiccontrast-enhanced magnetic resonance imaging in an ex-perimental model of colon carcinomardquo Clinical Cancer Re-search vol 11 no 16 pp 5827ndash5832 2005

[3] H Degani V Gusis D Weinstein S Fields and S StranoldquoMapping pathophysiological features of breast tumors byMRI at high spatial resolutionrdquo Nature Medicine vol 3 no 7pp 780ndash782 1997

[4] J F Schaefer V Schneider J Vollmar et al ldquoSolitary pul-monary nodules association between signal characteristics indynamic contrast enhanced MRI and tumor angiogenesisrdquoLung Cancer vol 53 no 1 pp 39ndash49 2006

[5] X Wu P Reinikainen M Kapanen T Vierikko P Ryyminand P L Kellokumpu-Lehtinen ldquoDynamic contrast-enhanced imaging as a prognostic tool in early diagnosis ofprostate cancer correlation with PSA and clinical stagerdquo

Contrast Media Mol Imaging vol 2018 Article ID 31812587 pages 2018

[6] S J Hectors M Wagner C Besa W Huang and B TaoulildquoMultiparametric FDG-PETMRI of hepatocellular carci-noma initial experiencerdquo Contrast Media Mol Imagingvol 2018 Article ID 5638283 10 pages 2018

[7] S Yan Z Wang L Li et al ldquoCharacterization of cervicallymph nodes using DCE-MRI differentiation between me-tastases from SCC of head and neck and benign lymph nodesrdquoClinical Hemorheology and Microcirculation vol 64 no 2pp 213ndash222 2016

[8] C M Wendl S Muller J Meier et al ldquoHigh resolutioncontrast-enhanced ultrasound and 3-tesla dynamic contrast-enhanced magnetic resonance imaging for the preoperativecharacterization of cervical lymph nodes first resultsrdquoClinical Hemorheology and Microcirculation vol 52 no 2ndash4pp 153ndash166 2012

[9] N J Fischbein S M Noworolski R G Henry M J KaplanW P Dillon and S J Nelson ldquoAssessment of metastaticcervical adenopathy using dynamic contrast-enhanced MRimagingrdquo AJNR American Journal of Neuroradiology vol 24no 3 pp 301ndash311 2003

[10] W J Alberda H P N Dassen R S Dwarkasing et alldquoPrediction of tumor stage and lymph node involvement withdynamic contrast-enhancedMRI after chemoradiotherapy forlocally advanced rectal cancerrdquo International Journal of Co-lorectal Disease vol 28 no 4 pp 573ndash580 2013

[11] T Vag J Slotta-Huspenina R Rosenberg et al ldquoComput-erized analysis of enhancement kinetics for preoperativelymph node staging in rectal cancer using dynamic contrast-enhanced magnetic resonance imagingrdquo Clinical Imagingvol 38 no 6 pp 845ndash849 2014

[12] S M Noworolski N J Fischbein M J Kaplan et alldquoChallenges in dynamic contrast-enhanced MRI imaging ofcervical lymph nodes to detect metastatic diseaserdquo Journal ofMagnetic Resonance Imaging vol 17 no 4 pp 455ndash462 2003

[13] W T Yang W W M Lam M Y Yu T H Cheung andC Metreweli ldquoComparison of dynamic helical CT and dy-namic MR imaging in the evaluation of pelvic lymph nodes incervical carcinomardquo American Journal of Roentgenologyvol 175 no 3 pp 759ndash766 2000

[14] B Huang D L Kwong V Lai Q Chan B Whitcher andP L Khong ldquoDynamic contrast-enhanced magnetic reso-nance imaging of regional nodal metastasis in nasopharyngealcarcinoma correlation with nodal stagingrdquo Contrast Media ampMolecular Imaging vol 2017 Article ID 4519653 6 pages2017

[15] A D Murray R T Staff T W Redpath et al ldquoDynamiccontrast enhanced MRI of the axilla in women with breastcancer comparison with pathology of excised nodesrdquo eBritish Journal of Radiology vol 75 no 891 pp 220ndash2282002

[16] H Rahbar J L Conlin S Parsian et al ldquoSuspicious axillarylymph nodes identified on clinical breast MRI in patientsnewly diagnosed with breast cancerrdquo Academic Radiologyvol 22 no 4 pp 430ndash438 2015

[17] K A Kvistad J Rydland H-B Smethurst S LundgrenH E Fjoslashsne and O Haraldseth ldquoAxillary lymph node me-tastases in breast cancer preoperative detection with dynamiccontrast-enhanced MRIrdquo European Radiology vol 10 no 9pp 1464ndash1471 2000

[18] D V Schacht K Drukker I Pak H Abe and M L GigerldquoUsing quantitative image analysis to classify axillary lymphnodes on breast MRI a new application for the Z 0011 erardquo

8 Contrast Media amp Molecular Imaging

European Journal of Radiology vol 84 no 3 pp 392ndash3972015

[19] J Krammer K Wasser A Schnitzer T HenzlerS O Schoenberg and C G Kaiser ldquoAxillary lymph nodecharacterization in breast cancer patients using magneticresonance mammography a prospective comparative studywith FDG PET-CTand healthy womenrdquo European Journal ofRadiology vol 82 no 12 pp 2194ndash2198 2013

[20] V J L Kuijs M Moossdorff R J Schipper et al ldquoe role ofMRI in axillary lymph node imaging in breast cancer patientsa systematic reviewrdquo Insights into Imaging vol 6 no 2pp 203ndash215 2015

[21] P Farace F Merigo S Fiorini et al ldquoDCE-MRI using small-molecular and albumin-binding contrast agents in experi-mental carcinomas with different stromal contentrdquo EuropeanJournal of Radiology vol 78 no 1 pp 52ndash59 2011

[22] F Boschi P Marzola M Sandri et al ldquoTumor microvas-culature observed using different contrast agents a com-parison between Gd-DTPA-Albumin and B-229561 in anexperimental model of mammary carcinomardquo MagneticResonance Materials in Physics Biology and Medicine vol 21no 3 pp 169ndash176 2008

[23] C Corot X Violas P Robert and M Port ldquoPharmacoki-netics of three gadolinium chelates with different molecularsizes shortly after intravenous injection in rabbitsrdquo In-vestigative Radiology vol 35 no 4 pp 213ndash218 2000

[24] HW Lee and S H Kim ldquoBreast magnetic resonance imagingfor assessment of internal mammary lymph node status inbreast cancerrdquo Journal of Breast Cancer vol 19 no 2pp 191ndash198 2016

[25] E J Kim S H Kim B J Kang B G Choi B J Song andJ J Choi ldquoDiagnostic value of breast MRI for predictingmetastatic axillary lymph nodes in breast cancer patientsdiffusion-weighted MRI and conventional MRIrdquo MagneticResonance Imaging vol 32 no 10 pp 1230ndash1236 2014

[26] S M Smith M Jenkinson M W Woolrich et al ldquoAdvancesin functional and structural MR image analysis and imple-mentation as FSLrdquo NeuroImage vol 23 no 1 pp 208ndash2192004

[27] J K Kim S S Hong Y J Choi et al ldquoWash-in rate on thebasis of dynamic contrast-enhanced MRI usefulness forprostate cancer detection and localizationrdquo Journal of Mag-netic Resonance Imaging vol 22 no 5 pp 639ndash646 2005

[28] J Krammer D Engel J Nissen et al ldquoCharacteristics ofaxillary lymph nodes apparent on dynamic contrast-enhancedbreast MRI in healthy womenrdquo Clinical Imaging vol 36no 4 pp 249ndash254 2012

[29] M G Harisinghani J Barentsz P F Hahn et al ldquoNon-invasive detection of clinically occult lymph-node metastasesin prostate cancerrdquo New England Journal of Medicinevol 348 no 25 pp 2491ndash2499 2003

[30] O Will S Purkayastha C Chan et al ldquoDiagnostic precisionof nanoparticle-enhanced MRI for lymph-node metastases ameta-analysisrdquo e Lancet Oncology vol 7 no 1 pp 52ndash602006

[31] D M Lambregts L A Heijnen M Maas et alldquoGadofosveset-enhanced MRI for the assessment of rectalcancer lymph nodes predictive criteriardquo Abdominal Imagingvol 38 no 4 pp 720ndash727 2012

[32] R-J Schipper M L Smidt L M van Roozendaal et alldquoNoninvasive nodal staging in patients with breast cancerusing gadofosveset-enhanced magnetic resonance imagingrdquoInvestigative Radiology vol 48 no 3 pp 134ndash139 2013

Contrast Media amp Molecular Imaging 9

Stem Cells International

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

MEDIATORSINFLAMMATION

of

EndocrinologyInternational Journal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Disease Markers

Hindawiwwwhindawicom Volume 2018

BioMed Research International

OncologyJournal of

Hindawiwwwhindawicom Volume 2013

Hindawiwwwhindawicom Volume 2018

Oxidative Medicine and Cellular Longevity

Hindawiwwwhindawicom Volume 2018

PPAR Research

Hindawi Publishing Corporation httpwwwhindawicom Volume 2013Hindawiwwwhindawicom

The Scientific World Journal

Volume 2018

Immunology ResearchHindawiwwwhindawicom Volume 2018

Journal of

ObesityJournal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Computational and Mathematical Methods in Medicine

Hindawiwwwhindawicom Volume 2018

Behavioural Neurology

OphthalmologyJournal of

Hindawiwwwhindawicom Volume 2018

Diabetes ResearchJournal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Research and TreatmentAIDS

Hindawiwwwhindawicom Volume 2018

Gastroenterology Research and Practice

Hindawiwwwhindawicom Volume 2018

Parkinsonrsquos Disease

Evidence-Based Complementary andAlternative Medicine

Volume 2018Hindawiwwwhindawicom

Submit your manuscripts atwwwhindawicom

(ldquothe chemical shift criterionrdquo) on enhanced images wasconsidered a sign of benign normal nodes [31 32] Par-ticularly the benign nodes fell into the category of ldquosharplydelineated and intact chemical shift artefactrdquo whereas anirregular or optically ldquointerruptedrdquo chemical shift artefact ora pronounced enhancing rim encircling the entire node wasconsidered as a malignant criterion

5 Conclusions

In conclusion the results obtained showed a heterogeneouspattern of enhancement in normal lymph nodes in-dependently of the contrast agent used Semiautomaticcluster analysis of signal intensity vs time data showed theexistence of two clusters characterized by different signalintensity dynamics belonging to the inner and outer regionsof lymph nodes

is heterogeneous pattern might be peculiar of normallymph nodes and if confirmed on human lymph nodesshould be deeply investigated to assess any alteration pos-sibly induced by the metastatic transformation and con-sequently its potential role for nodal staging

Data Availability

e MRI data used to support the findings of this study areavailable from the corresponding author upon request

Conflicts of Interest

e authors declare that they have no conflicts of interest

Acknowledgments

is work was supported by the University of Verona andAzienda Provinciale per i Servizi Sanitari Trento (JointProject JPVR17YEPM 2017)

References

[1] P Marzola A Degrassi L Calderan et al ldquoIn vivo assessmentof antiangiogenic activity of SU6668 in an experimental coloncarcinoma modelrdquo Clinical Cancer Research vol 10 no 2pp 739ndash750 2004

[2] P Marzola A Degrassi L Calderan et al ldquoEarly anti-angiogenic activity of SU11248 evaluated in vivo by dynamiccontrast-enhanced magnetic resonance imaging in an ex-perimental model of colon carcinomardquo Clinical Cancer Re-search vol 11 no 16 pp 5827ndash5832 2005

[3] H Degani V Gusis D Weinstein S Fields and S StranoldquoMapping pathophysiological features of breast tumors byMRI at high spatial resolutionrdquo Nature Medicine vol 3 no 7pp 780ndash782 1997

[4] J F Schaefer V Schneider J Vollmar et al ldquoSolitary pul-monary nodules association between signal characteristics indynamic contrast enhanced MRI and tumor angiogenesisrdquoLung Cancer vol 53 no 1 pp 39ndash49 2006

[5] X Wu P Reinikainen M Kapanen T Vierikko P Ryyminand P L Kellokumpu-Lehtinen ldquoDynamic contrast-enhanced imaging as a prognostic tool in early diagnosis ofprostate cancer correlation with PSA and clinical stagerdquo

Contrast Media Mol Imaging vol 2018 Article ID 31812587 pages 2018

[6] S J Hectors M Wagner C Besa W Huang and B TaoulildquoMultiparametric FDG-PETMRI of hepatocellular carci-noma initial experiencerdquo Contrast Media Mol Imagingvol 2018 Article ID 5638283 10 pages 2018

[7] S Yan Z Wang L Li et al ldquoCharacterization of cervicallymph nodes using DCE-MRI differentiation between me-tastases from SCC of head and neck and benign lymph nodesrdquoClinical Hemorheology and Microcirculation vol 64 no 2pp 213ndash222 2016

[8] C M Wendl S Muller J Meier et al ldquoHigh resolutioncontrast-enhanced ultrasound and 3-tesla dynamic contrast-enhanced magnetic resonance imaging for the preoperativecharacterization of cervical lymph nodes first resultsrdquoClinical Hemorheology and Microcirculation vol 52 no 2ndash4pp 153ndash166 2012

[9] N J Fischbein S M Noworolski R G Henry M J KaplanW P Dillon and S J Nelson ldquoAssessment of metastaticcervical adenopathy using dynamic contrast-enhanced MRimagingrdquo AJNR American Journal of Neuroradiology vol 24no 3 pp 301ndash311 2003

[10] W J Alberda H P N Dassen R S Dwarkasing et alldquoPrediction of tumor stage and lymph node involvement withdynamic contrast-enhancedMRI after chemoradiotherapy forlocally advanced rectal cancerrdquo International Journal of Co-lorectal Disease vol 28 no 4 pp 573ndash580 2013

[11] T Vag J Slotta-Huspenina R Rosenberg et al ldquoComput-erized analysis of enhancement kinetics for preoperativelymph node staging in rectal cancer using dynamic contrast-enhanced magnetic resonance imagingrdquo Clinical Imagingvol 38 no 6 pp 845ndash849 2014

[12] S M Noworolski N J Fischbein M J Kaplan et alldquoChallenges in dynamic contrast-enhanced MRI imaging ofcervical lymph nodes to detect metastatic diseaserdquo Journal ofMagnetic Resonance Imaging vol 17 no 4 pp 455ndash462 2003

[13] W T Yang W W M Lam M Y Yu T H Cheung andC Metreweli ldquoComparison of dynamic helical CT and dy-namic MR imaging in the evaluation of pelvic lymph nodes incervical carcinomardquo American Journal of Roentgenologyvol 175 no 3 pp 759ndash766 2000

[14] B Huang D L Kwong V Lai Q Chan B Whitcher andP L Khong ldquoDynamic contrast-enhanced magnetic reso-nance imaging of regional nodal metastasis in nasopharyngealcarcinoma correlation with nodal stagingrdquo Contrast Media ampMolecular Imaging vol 2017 Article ID 4519653 6 pages2017

[15] A D Murray R T Staff T W Redpath et al ldquoDynamiccontrast enhanced MRI of the axilla in women with breastcancer comparison with pathology of excised nodesrdquo eBritish Journal of Radiology vol 75 no 891 pp 220ndash2282002

[16] H Rahbar J L Conlin S Parsian et al ldquoSuspicious axillarylymph nodes identified on clinical breast MRI in patientsnewly diagnosed with breast cancerrdquo Academic Radiologyvol 22 no 4 pp 430ndash438 2015

[17] K A Kvistad J Rydland H-B Smethurst S LundgrenH E Fjoslashsne and O Haraldseth ldquoAxillary lymph node me-tastases in breast cancer preoperative detection with dynamiccontrast-enhanced MRIrdquo European Radiology vol 10 no 9pp 1464ndash1471 2000

[18] D V Schacht K Drukker I Pak H Abe and M L GigerldquoUsing quantitative image analysis to classify axillary lymphnodes on breast MRI a new application for the Z 0011 erardquo

8 Contrast Media amp Molecular Imaging

European Journal of Radiology vol 84 no 3 pp 392ndash3972015

[19] J Krammer K Wasser A Schnitzer T HenzlerS O Schoenberg and C G Kaiser ldquoAxillary lymph nodecharacterization in breast cancer patients using magneticresonance mammography a prospective comparative studywith FDG PET-CTand healthy womenrdquo European Journal ofRadiology vol 82 no 12 pp 2194ndash2198 2013

[20] V J L Kuijs M Moossdorff R J Schipper et al ldquoe role ofMRI in axillary lymph node imaging in breast cancer patientsa systematic reviewrdquo Insights into Imaging vol 6 no 2pp 203ndash215 2015

[21] P Farace F Merigo S Fiorini et al ldquoDCE-MRI using small-molecular and albumin-binding contrast agents in experi-mental carcinomas with different stromal contentrdquo EuropeanJournal of Radiology vol 78 no 1 pp 52ndash59 2011

[22] F Boschi P Marzola M Sandri et al ldquoTumor microvas-culature observed using different contrast agents a com-parison between Gd-DTPA-Albumin and B-229561 in anexperimental model of mammary carcinomardquo MagneticResonance Materials in Physics Biology and Medicine vol 21no 3 pp 169ndash176 2008

[23] C Corot X Violas P Robert and M Port ldquoPharmacoki-netics of three gadolinium chelates with different molecularsizes shortly after intravenous injection in rabbitsrdquo In-vestigative Radiology vol 35 no 4 pp 213ndash218 2000

[24] HW Lee and S H Kim ldquoBreast magnetic resonance imagingfor assessment of internal mammary lymph node status inbreast cancerrdquo Journal of Breast Cancer vol 19 no 2pp 191ndash198 2016

[25] E J Kim S H Kim B J Kang B G Choi B J Song andJ J Choi ldquoDiagnostic value of breast MRI for predictingmetastatic axillary lymph nodes in breast cancer patientsdiffusion-weighted MRI and conventional MRIrdquo MagneticResonance Imaging vol 32 no 10 pp 1230ndash1236 2014

[26] S M Smith M Jenkinson M W Woolrich et al ldquoAdvancesin functional and structural MR image analysis and imple-mentation as FSLrdquo NeuroImage vol 23 no 1 pp 208ndash2192004

[27] J K Kim S S Hong Y J Choi et al ldquoWash-in rate on thebasis of dynamic contrast-enhanced MRI usefulness forprostate cancer detection and localizationrdquo Journal of Mag-netic Resonance Imaging vol 22 no 5 pp 639ndash646 2005

[28] J Krammer D Engel J Nissen et al ldquoCharacteristics ofaxillary lymph nodes apparent on dynamic contrast-enhancedbreast MRI in healthy womenrdquo Clinical Imaging vol 36no 4 pp 249ndash254 2012

[29] M G Harisinghani J Barentsz P F Hahn et al ldquoNon-invasive detection of clinically occult lymph-node metastasesin prostate cancerrdquo New England Journal of Medicinevol 348 no 25 pp 2491ndash2499 2003

[30] O Will S Purkayastha C Chan et al ldquoDiagnostic precisionof nanoparticle-enhanced MRI for lymph-node metastases ameta-analysisrdquo e Lancet Oncology vol 7 no 1 pp 52ndash602006

[31] D M Lambregts L A Heijnen M Maas et alldquoGadofosveset-enhanced MRI for the assessment of rectalcancer lymph nodes predictive criteriardquo Abdominal Imagingvol 38 no 4 pp 720ndash727 2012

[32] R-J Schipper M L Smidt L M van Roozendaal et alldquoNoninvasive nodal staging in patients with breast cancerusing gadofosveset-enhanced magnetic resonance imagingrdquoInvestigative Radiology vol 48 no 3 pp 134ndash139 2013

Contrast Media amp Molecular Imaging 9

Stem Cells International

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

MEDIATORSINFLAMMATION

of

EndocrinologyInternational Journal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Disease Markers

Hindawiwwwhindawicom Volume 2018

BioMed Research International

OncologyJournal of

Hindawiwwwhindawicom Volume 2013

Hindawiwwwhindawicom Volume 2018

Oxidative Medicine and Cellular Longevity

Hindawiwwwhindawicom Volume 2018

PPAR Research

Hindawi Publishing Corporation httpwwwhindawicom Volume 2013Hindawiwwwhindawicom

The Scientific World Journal

Volume 2018

Immunology ResearchHindawiwwwhindawicom Volume 2018

Journal of

ObesityJournal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Computational and Mathematical Methods in Medicine

Hindawiwwwhindawicom Volume 2018

Behavioural Neurology

OphthalmologyJournal of

Hindawiwwwhindawicom Volume 2018

Diabetes ResearchJournal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Research and TreatmentAIDS

Hindawiwwwhindawicom Volume 2018

Gastroenterology Research and Practice

Hindawiwwwhindawicom Volume 2018

Parkinsonrsquos Disease

Evidence-Based Complementary andAlternative Medicine

Volume 2018Hindawiwwwhindawicom

Submit your manuscripts atwwwhindawicom

European Journal of Radiology vol 84 no 3 pp 392ndash3972015

[19] J Krammer K Wasser A Schnitzer T HenzlerS O Schoenberg and C G Kaiser ldquoAxillary lymph nodecharacterization in breast cancer patients using magneticresonance mammography a prospective comparative studywith FDG PET-CTand healthy womenrdquo European Journal ofRadiology vol 82 no 12 pp 2194ndash2198 2013

[20] V J L Kuijs M Moossdorff R J Schipper et al ldquoe role ofMRI in axillary lymph node imaging in breast cancer patientsa systematic reviewrdquo Insights into Imaging vol 6 no 2pp 203ndash215 2015

[21] P Farace F Merigo S Fiorini et al ldquoDCE-MRI using small-molecular and albumin-binding contrast agents in experi-mental carcinomas with different stromal contentrdquo EuropeanJournal of Radiology vol 78 no 1 pp 52ndash59 2011

[22] F Boschi P Marzola M Sandri et al ldquoTumor microvas-culature observed using different contrast agents a com-parison between Gd-DTPA-Albumin and B-229561 in anexperimental model of mammary carcinomardquo MagneticResonance Materials in Physics Biology and Medicine vol 21no 3 pp 169ndash176 2008

[23] C Corot X Violas P Robert and M Port ldquoPharmacoki-netics of three gadolinium chelates with different molecularsizes shortly after intravenous injection in rabbitsrdquo In-vestigative Radiology vol 35 no 4 pp 213ndash218 2000

[24] HW Lee and S H Kim ldquoBreast magnetic resonance imagingfor assessment of internal mammary lymph node status inbreast cancerrdquo Journal of Breast Cancer vol 19 no 2pp 191ndash198 2016

[25] E J Kim S H Kim B J Kang B G Choi B J Song andJ J Choi ldquoDiagnostic value of breast MRI for predictingmetastatic axillary lymph nodes in breast cancer patientsdiffusion-weighted MRI and conventional MRIrdquo MagneticResonance Imaging vol 32 no 10 pp 1230ndash1236 2014

[26] S M Smith M Jenkinson M W Woolrich et al ldquoAdvancesin functional and structural MR image analysis and imple-mentation as FSLrdquo NeuroImage vol 23 no 1 pp 208ndash2192004

[27] J K Kim S S Hong Y J Choi et al ldquoWash-in rate on thebasis of dynamic contrast-enhanced MRI usefulness forprostate cancer detection and localizationrdquo Journal of Mag-netic Resonance Imaging vol 22 no 5 pp 639ndash646 2005

[28] J Krammer D Engel J Nissen et al ldquoCharacteristics ofaxillary lymph nodes apparent on dynamic contrast-enhancedbreast MRI in healthy womenrdquo Clinical Imaging vol 36no 4 pp 249ndash254 2012

[29] M G Harisinghani J Barentsz P F Hahn et al ldquoNon-invasive detection of clinically occult lymph-node metastasesin prostate cancerrdquo New England Journal of Medicinevol 348 no 25 pp 2491ndash2499 2003

[30] O Will S Purkayastha C Chan et al ldquoDiagnostic precisionof nanoparticle-enhanced MRI for lymph-node metastases ameta-analysisrdquo e Lancet Oncology vol 7 no 1 pp 52ndash602006

[31] D M Lambregts L A Heijnen M Maas et alldquoGadofosveset-enhanced MRI for the assessment of rectalcancer lymph nodes predictive criteriardquo Abdominal Imagingvol 38 no 4 pp 720ndash727 2012

[32] R-J Schipper M L Smidt L M van Roozendaal et alldquoNoninvasive nodal staging in patients with breast cancerusing gadofosveset-enhanced magnetic resonance imagingrdquoInvestigative Radiology vol 48 no 3 pp 134ndash139 2013

Contrast Media amp Molecular Imaging 9

Stem Cells International

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

MEDIATORSINFLAMMATION

of

EndocrinologyInternational Journal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Disease Markers

Hindawiwwwhindawicom Volume 2018

BioMed Research International

OncologyJournal of

Hindawiwwwhindawicom Volume 2013

Hindawiwwwhindawicom Volume 2018

Oxidative Medicine and Cellular Longevity

Hindawiwwwhindawicom Volume 2018

PPAR Research

Hindawi Publishing Corporation httpwwwhindawicom Volume 2013Hindawiwwwhindawicom

The Scientific World Journal

Volume 2018

Immunology ResearchHindawiwwwhindawicom Volume 2018

Journal of

ObesityJournal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Computational and Mathematical Methods in Medicine

Hindawiwwwhindawicom Volume 2018

Behavioural Neurology

OphthalmologyJournal of

Hindawiwwwhindawicom Volume 2018

Diabetes ResearchJournal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Research and TreatmentAIDS

Hindawiwwwhindawicom Volume 2018

Gastroenterology Research and Practice

Hindawiwwwhindawicom Volume 2018

Parkinsonrsquos Disease

Evidence-Based Complementary andAlternative Medicine

Volume 2018Hindawiwwwhindawicom

Submit your manuscripts atwwwhindawicom

Stem Cells International

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

MEDIATORSINFLAMMATION

of

EndocrinologyInternational Journal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Disease Markers

Hindawiwwwhindawicom Volume 2018

BioMed Research International

OncologyJournal of

Hindawiwwwhindawicom Volume 2013

Hindawiwwwhindawicom Volume 2018

Oxidative Medicine and Cellular Longevity

Hindawiwwwhindawicom Volume 2018

PPAR Research

Hindawi Publishing Corporation httpwwwhindawicom Volume 2013Hindawiwwwhindawicom

The Scientific World Journal

Volume 2018

Immunology ResearchHindawiwwwhindawicom Volume 2018

Journal of

ObesityJournal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Computational and Mathematical Methods in Medicine

Hindawiwwwhindawicom Volume 2018

Behavioural Neurology

OphthalmologyJournal of

Hindawiwwwhindawicom Volume 2018

Diabetes ResearchJournal of

Hindawiwwwhindawicom Volume 2018

Hindawiwwwhindawicom Volume 2018

Research and TreatmentAIDS

Hindawiwwwhindawicom Volume 2018

Gastroenterology Research and Practice

Hindawiwwwhindawicom Volume 2018

Parkinsonrsquos Disease

Evidence-Based Complementary andAlternative Medicine

Volume 2018Hindawiwwwhindawicom

Submit your manuscripts atwwwhindawicom