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Year: 2019
Assessing lesion malignancy by scanning small-angle X-ray scattering ofbreast tissue with microcalcifications
Arboleda, Carolina ; Lütz-Bueno, Viviane ; Wang, Zhentian ; Villanueva-Perez, Pablo ; Guizar-Sicairos,Manuel ; Liebi, Marianne ; Varga, Zsuzsanna ; Stampanoni, Marco
Abstract: Scanning small-angle X-ray scattering (SAXS) measurements were performed on 36 formalin-fixed breast tissue biopsies, obtained from two patients. All samples contained microcalcifications oftype II, i.e. formed by hydroxyapatite. We demonstrate the feasibility of classifying breast lesions byscanning SAXS of tissues containing microcalcifications with a resolution of 35 m × 30 m. We report acharacteristic Bragg peak found around q=1.725 nmamp;lt;supamp;gt;-1amp;lt;/supamp;gt; that occursprimarily for malignant lesions. Such a clear SAXS fingerprint is potentially linked to structural changesof the breast tissue and correspond to dimensions of about 3.7 nm. Such a material property could be usedas an early indicator of malignancy development, as it is readily assessed by SAXS. If this fingerprintis combined with other known SAXS features, which also indicate the level of malignancy, such aslipid spacing and collagen periodicity, it could complement traditional pathology-based analyses. Toconfirm the SAXS-based classification, a histopathological workup and a gold standard histopathologicaldiagnosis were conducted to determine the malignancy level of the lesions. Our aim is to report thisSAXS fingerprint, which is clearly related to malignant breast lesions. However, any further conclusionbased on our dataset is limited by the low number of patients and samples. Running a broad study toincrease the number of samples and patients is of great importance and relevance for the breast-imagingcommunity.
DOI: https://doi.org/10.1088/1361-6560/ab2c36
Posted at the Zurich Open Repository and Archive, University of ZurichZORA URL: https://doi.org/10.5167/uzh-171695Journal ArticlePublished Version
Originally published at:Arboleda, Carolina; Lütz-Bueno, Viviane; Wang, Zhentian; Villanueva-Perez, Pablo; Guizar-Sicairos,Manuel; Liebi, Marianne; Varga, Zsuzsanna; Stampanoni, Marco (2019). Assessing lesion malignancy byscanning small-angle X-ray scattering of breast tissue with microcalcifications. Physics in Medicine andBiology, 64(15):155010.DOI: https://doi.org/10.1088/1361-6560/ab2c36
Physics in Medicine & Biology
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Assessing lesion malignancy by scanning small-angle X-ray scattering ofbreast tissue with microcalcificationsTo cite this article before publication: Carolina Arboleda et al 2019 Phys. Med. Biol. in press https://doi.org/10.1088/1361-6560/ab2c36
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Assessing lesion malignancy by scanning small-angle X-ray scattering of breast tissues with microcalcifications
Assessing lesion malignancy by scanning small-angle X-ray scattering of1
breast tissue with microcalcifications2
C. Arboleda,1, 2, a) V. Lutz-Bueno,1, b) Z. Wang,1, 2 P. Villanueva-Perez,1 M. Guizar-Sicairos,1 M. Liebi,3, 4 Z.3
Varga,5 and M. Stampanoni6, 24
1)Swiss Light Source, Paul Scherrer Institute, 5232 Villigen, Switzerland5
2)ETH Zurich, 8092 Zurich, Switzerland6
3)MAX IV Laboratory, 225 92 Lund, Sweden7
4)Chalmers University of Technology, 412 58 Goeteborg, Sweden8
5)Institute of Pathology and Molecular Pathology, University Hospital Zurich, 8091 Zurich,9
Switzerland10
6)PSI, 5232 Villigen, Switzerland11
(Dated: 24 June 2019)12
Scanning small-angle X-ray scattering (SAXS) measurements were performed on 36 formalin-fixed breast13
tissue biopsies, obtained from two patients. All samples contained microcalcifications of type II, i.e. formed14
by hydroxyapatite. We demonstrate the feasibility of classifying breast lesions by scanning SAXS of tissues15
containing microcalcifications with a resolution of 35 µm × 30 µm. We report a characteristic Bragg peak16
found around q = 1.725 nm−1 that occurs primarily for malignant lesions. Such a clear SAXS fingerprint is17
potentially linked to structural changes of the breast tissue and correspond to dimensions of about 3.7 nm.18
Such a material property could be used as an early indicator of malignancy development, as it is readily19
assessed by SAXS. If this fingerprint is combined with other known SAXS features, which also indicate the20
level of malignancy, such as lipid spacing and collagen periodicity, it could complement traditional pathology-21
based analyses. To confirm the SAXS-based classification, a histopathological workup and a gold standard22
histopathological diagnosis were conducted to determine the malignancy level of the lesions. Our aim is23
to report this SAXS fingerprint, which is clearly related to malignant breast lesions. However, any further24
conclusion based on our dataset is limited by the low number of patients and samples. Running a broad study25
to increase the number of samples and patients is of great importance and relevance for the breast-imaging26
community.27
Keywords: Small-angle X-ray scattering, breast cancer, breast microcalcifications, breast lesion diagnosis28
I. INTRODUCTION29
Breast cancer is the second most commonly diagnosed30
cancer among women after skin cancer1. Even though31
several in situ and in vivo imaging methods are com-32
bined to increase the confidence of cancer malignancy33
level assessment, the accurate diagnosis of cancer remains34
a challenge and biopsy extraction is often required to35
confirm whether a breast tissue lesion is benign or ma-36
lignant. Cancer diagnosis and treatment require a multi-37
disciplinary team composed of surgeons, pathologists and38
technicians, to have full access to the clinical history of39
the patient as well as the biological and structural char-40
acteristics of the biopsy sample.41
One important predictor of breast cancer is the pres-42
ence of microcalcifications, which are usually benign de-43
posits of calcium. Orsi et al.2 suggested that the mor-44
phology and distribution of microcalcifications may indi-45
cate the malignancy level of breast tissue lesions. Grating46
interferometry (GI) has been tested on its ability to pro-47
vide a non-invasive malignancy level assessment based on48
the microcalcifications type and structure3–5. The results49
a)Electronic mail: [email protected])Electronic mail: [email protected]
of those investigations suggest that measuring scattering50
interactions can potentially discriminate morphological51
characteristics that are associated to cancer4–6.52
Insights into the structural organization of biological53
tissues provide ways to understand how their processes,54
diseases and functionality develop. Small-angle X-ray55
scattering (SAXS) is able to provide structural informa-56
tion of noncrystalline materials in the range of tens of57
micrometers down to a few nanometers7,8. If a scanning-58
based SAXS setup is combined with a focused X-ray59
beam, two-dimensional maps of the structural changes60
can be obtained for heterogeneous samples9–14. For in-61
stance, Siu et al.15 evaluated the diagnostic potential of62
SAXS for brain tumors and concluded that this tech-63
nique can be an effective classifier of malignancy. Gian-64
nini et al.16 evaluated the SAXS and wide-angle X-ray65
scattering (WAXS) patterns of bone biopsies collected66
from osteoarthritis-affected patients. After performing67
principal component and canonical correlation analyses68
on the SAXS and WAXS data, the nanostructural prop-69
erties of collagen over extended areas of bone were char-70
acterized and quantified. They concluded based on struc-71
tural changes that there is correlation between age and72
cross-linking-induced rigidity of collagen fibers.73
Among the numerous diseases that provoke structural74
changes in tissues, the understanding of the formation75
and the classification of breast cancer with high accuracy76
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Assessing lesion malignancy by scanning small-angle X-ray scattering of breast tissues with microcalcifications 2
is of fundamental importance. Fernandez et al.10 em-77
ployed SAXS to investigate 28 human breast tumor spec-78
imens. Differences between the scattering signals from79
invasive malignant lesions and healthy regions were ob-80
served. Ryan and Farquharson17 measured Compton and81
coherent scattering interactions, using an X-ray tube and82
a high-purity Germanium (HPGe) detector, to classify83
malignant and benign breast tissue lesions. The scatter-84
ing spectra were analyzed with a peak-fitting routine and85
a subsequent multivariate analysis. A sensitivity of 54%86
and a specificity of 100% were obtained for the dataset.87
Despite valuable outcomes in breast cancer diagnosis by88
SAXS, to our knowledge none of them focused specifically89
on tissue containing microcalcifications, whose presence90
is known to constitute one of the most important diag-91
nostic markers of breast cancer18–2192
Here we focus on 36 formalin-fixed human breast tis-93
sue samples from two different patients, all containing94
microcalcifications. Scanning SAXS measurements were95
performed using a focused X-ray beam with a resolution96
of 35 µm × 30 µm. The SAXS patterns distributed over97
millimetric areas of tissue containing embedded microcal-98
cifications served as a base for malignancy level assess-99
ment. Thanks to the spatial resolution and coverage pro-100
vided by scanning SAXS, different sample regions can be101
resolved. The possibility of distinguishing different types102
and structures of tissues in regions of a single sample en-103
ables a detailed analysis and makes easier to establish a104
link between malignancy and structural changes of the105
healthy tissue. Such reliable method could be a valu-106
able candidate to increase the precision of cancer diag-107
nosis and classification. The outcomes of our SAXS data108
analysis indicate that a diagnosis based on the structural109
changes of a tissue that contains a microcalcification is110
promising in the examined range of scattering vectors111
q = 0.5 - 4 nm−1, especially around q = 1.725 nm−1112
where a fingerprint was observed. However, it is neces-113
sary to increase the number of samples and patients to114
verify the relevance of the aforementioned findings.115
II. MATERIALS AND METHODS116
A. Sample preparation117
Formalin-fixed human breast tissue samples from two118
patients were attained from the Institute of Pathol-119
ogy and Molecular Pathology at the University Hospital120
Zurich. Ethical consent was obtained from both patients.121
Radiographic measurements were performed to verify if122
microcalcifications were present. Thin 1 - 2 mm slices123
were cut in the regions of interest (ROI) where micro-124
calcifications were observed. These slices were further125
imaged on a setup with a field of view of 10 cm × 5 cm126
to select smaller ROIs. In total, 36 slices containing mi-127
crocalcifications were obtained. For scanning SAXS mea-128
surements, these slices were fixed on a sample holder us-129
ing Kapton foil and tape and keeping them embedded in130
formalin.131
B. Scanning SAXS measurements132
Scanning SAXS9 was performed at the cSAXS beam-133
line of the Paul Scherrer Institute. A monochromatic134
beam of 11.2 keV (λ = 1.107A) was focused to about135
35 µm × 30 µm. For every point in the raster scan, a136
SAXS pattern was recorded; at the same time, the sam-137
ple transmission was measured by a diode at the beam138
stop. Scattering patterns were acquired using a PILA-139
TUS 2M22 detector placed 2.16 m away from the sam-140
ple. An evacuated flight tube was placed between the141
sample and detector to reduce absorption and parasitic142
scattering from air. For fast acquisition, SAXS patterns143
were recorded in a continuous line scan mode with the144
sample moving at constant speed along y, while the de-145
tector continuously records data (Fig. 1a). The detector146
was operated with 35 ms exposure time and 5 ms readout147
time, i.e. with a frame rate of 25 Hz. The total scan time148
was 19.6 hours for all 36 samples (1.5 cm × 1.5 cm in area149
each), with an X-ray flux of 1.81 ×1014 photons/s/mm2.150
After these measurements, samples underwent a patho-151
logical workup with eosin/hematoxylin to assess their152
malignancy level23. Additionally, the microcalcification153
chemical type was evaluated based on its birefringence154
properties24–26.155
C. Scanning SAXS data analysis156
The analysis of the data set composed of 36 samples157
was based on the presence of characteristic peaks, here158
called fingerprints, in the integrated scattering curves for159
the accessed experimental q-range of 0.5 - 4 nm−1, as160
shown in Fig. 1b. Our goal is to classify the samples in161
the data set in malignant and benign lesions. We name162
the samples as bipj and mipj, where b stands for be-163
nign and m for malignant lesions, while i is the sample164
number and j is the patient number. As an example,165
we select sample m9p1. Figure 1b shows four selected166
scattering curves covering the whole measured q-range,167
while Fig. 1c zooms in the q-range = 1.67 - 1.75 nm−1168
where fingerprints were observed. The location of the169
microcalcifications is clear from the transmission map in170
Fig. 1d, as the X-ray beam is less transmitted when hit-171
ting a microcalcification. Points S1-S4 indicate the posi-172
tions where the scattering patterns in Fig. 1b and c were173
measured. Points S1 and S4 are similar as they lay in tis-174
sue. As expected from breast tissue27, a prominent lipid175
Bragg peak is measured at q = 1.5 nm−1 in all samples176
(see Figs. 1c)28. Point S2 hits the microcalcification and177
higher scattering intensities are measured over the whole178
q-range. The SAXS fingerprint discussed in this work is179
observed in S2 and S3, indicating that it occurs not only180
in regions near, but also in regions far away from the181
microcalcification. In this example, we compare the az-182
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Assessing lesion malignancy by scanning small-angle X-ray scattering of breast tissues with microcalcifications 3
imuthally integrated SAXS patterns in regions near the183
calcification, from which the scattering curve S3 origi-184
nates displaying a clear peak around 1.725 nm−1. Note185
that S2 also contains a peak around 1.725 nm−1, but it186
has a higher baseline due to the high scattering origi-187
nated by the microcalcification. We restricted our peak188
finding routine to the q-range = 1.67 - 1.75 nm−1, as189
shown in Fig. 1c, to avoid lipid and collagen peaks. In190
this range, we search for the position in q and amplitude191
A of peaks in the selected q-range by fitting a one-term192
Gaussian function after baseline subtraction. We search193
for such peaks in all collected scattering patterns, there-194
with obtaining a map of their amplitude in each pixel195
and sample, as shown in Fig. 1e.196
The measured breast tissue lesions were classified197
based on the histopathological diagnosis. From the 36198
measured samples, 21 were diagnosed as benign and 15 as199
malignant lesions. Regarding the chemical composition200
of the microcalcification, all were classified as hydroxya-201
patite or type II24. The histogram in Fig. 1f shows the202
distribution of peaks in the selected q-range for the 21203
benign samples, while Fig. 1g shows the same for the 15204
malignant lesions. Each pixel is assigned a value of 1205
if there is a peak, and 0 if there is none. These pixel206
labels are summed up for all benign or malignant sam-207
ples for each q-range shown in the histograms. It is clear208
that the large majority of pixels with such signature peak209
occurs for malignant samples in the searched q-range.210
Even though q has a distribution of peak positions in211
Fig. 1g, the maximum number of peaks is found around212
1.725 nm−1, and this is the value we refer to as the fin-213
gerprint.214
III. RESULTS AND DISCUSSION215
For further discussion, the samples were separated216
into two groups, benign and malignant, according to the217
histopathological diagnosis. They were not further cate-218
gorized according to the cancer type or malignancy level,219
due to the reduced number of samples and patients. The220
main goal of this study is to test the ability of scan-221
ning SAXS to discriminate between benign and malig-222
nant lesions. The transmission maps, as well as the223
peak amplitude maps, as previously discussed in Fig. 1,224
are shown for benign and malignant lesions in Figs. 2225
and 3, respectively. We confirmed that all samples con-226
tain microcalcifications, based on the transmission maps227
shown in Figs. 2a and 3a. Clear microcalcifications228
are observed in the benign samples shown in Fig. 2a,229
although the amplitude of peaks in the q-range = 1.67 -230
1.75 nm−1 do not form clear regions, neither near nor231
far from the microcalcifications, Fig. 2b, except for sam-232
ple b21p2. An obvious difference is seen in Fig. 3. By233
comparing Figs. 3a and 3b, a feature emerges as a Bragg234
peak around q = 1.725 nm−1 with large amplitude. Such235
features are spatially distributed near and far from the236
microcalcifications. This fingerprint is associated to most237
of the malignant samples, except for m1p1, m2p2, m3p2,238
m4p2 and m5p2. Such a clear spatially-resolved feature,239
which was revealed without any staining or human inter-240
pretation, since it is originated directly from structural241
changes of the tissue, can be potentially used as a finger-242
print for cancer diagnosis. The amplitude maps of the243
Bragg peaks around q = 1.725 nm−1 indicate that struc-244
tural changes occur to the tissue near and far from the245
microcalcifications. However, whether the microcalcifica-246
tions lead to the tissue structural changes or vice versa,247
remains unclear. Additionally, the fingerprint was absent248
in 5 out of the 15 malignant samples, which might be re-249
lated to the corresponding malignancy level (BI-RADS)2.250
Although this fingerprint appeared in samples from both251
patients, which suggests that it may be patient indepen-252
dent, it is important to recall that the majority of benign253
specimens belonged to patient 2, whereas most of the ma-254
lignant samples originated from patient 1. This consti-255
tutes a major limitation of this study and more patients256
are definitely needed to be able to reach a significant257
conclusion concerning the relevance of this fingerprint.258
It can be observed in Fig. 3b that, whereas the top row259
samples m1-m5 do not display any clear peak amplitude260
in that q-range, all the other samples exhibit increased261
peak amplitudes located close to the microcalcifications.262
Samples m6p1 and m7p1 present peak amplitudes mostly263
located around the microcalcifications and nowhere else264
in the tissue, whereas the remaining eight samples dis-265
play peaks even where no microcalcifications are found.266
One hypothesis is that the Bragg peak at q = 1.725 nm−1267
is a consequence of tissue structural remodeling induced268
by cancer and that the microcalcifications are somewhat269
responsible for this process. The reason why some mi-270
crocalcifications do not generate such structural change271
in the tissue, as it is the case for samples m1-m5 as well272
as for the benign ones, is a potential study that could273
correlate this fingerprint with microcalcification nanos-274
tructure and morphology.275
Two receiver-operating characteristic (ROC) curves29276
were calculated, shown in Fig. 4, to find the best thresh-277
old to classify benign and malignant lesions using either278
the presence of peaks or the sum of peak amplitudes per279
sample (Fig. 2d and 2e) in the q = 1.67-1.75 nm−1 range280
as metric. In the former case, the pixel value was set to281
1 where a peak was found and 0 otherwise. Afterwards,282
the sensitivity, also known as true positive rate (TPR),283
and specificity, also known as true negative rate (TNR),284
were calculated as follows:285
TPR =TP
P, (1)
TNR =TN
N, (2)
where TP, P, TN and N, are the true positives, positives,286
true negatives and negatives, respectively. The Youden287
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Assessing lesion malignancy by scanning small-angle X-ray scattering of breast tissues with microcalcifications 4
(f) (g)
(b) (c)
S1
S2
S3S4
(d) (e)
X-RAYS
SAMPLE
DETECTOR
BEAMSTOP
y
x
(a)
+
+
+
+
S1
S2
S3S4
+
+
+
+
FIG. 1. (a) Experimental setup: The sample is scanned across an X-ray beam along x and y. Scattering patterns aremeasured by a 2D detector at each scan point. The beamstop is equipped with a diode to simultaneously measure the sample’stransmission. (b) Azimuthal integration of points S1-S4 covering the experimental q-range. (c) Zoom in the q-range = 1.3 -1.8 nm−1, where the amplitudes A of the peaks were extracted in the indicated q-range = 1.67 - 1.75 nm−1, after baselinesubtraction. (d) Transmission map of sample m9p1. (e) Map of the amplitude of the peaks in the q-range = 1.67 - 1.75 nm−1
of sample m9p1. Points S1-S4 indicate the location of the scattering patterns shown in (b). (f) Histogram of all occurrencesof peaks in the q-range = 1.67 - 1.75 nm−1 for the 21 benign lesion samples. (g) Histogram of all occurrences of peaks in theq-range = 1.67 - 1.75 nm−1 for the 15 malignant lesion samples. The scale bar corresponds to 1 mm.
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Assessing lesion malignancy by scanning small-angle X-ray scattering of breast tissues with microcalcifications 5
index (sensitivity+specificity-1)29 was used to define the288
optimal cutoff values in both cases and the outcomes are289
summarized in table I.290
TABLE I. Sensitivity and specificity at the optimal cutoffvalue (Youden index)
Method Sensitivity Specificity
Peak presence 60% 100%Sum of peak amplitudes 67% 100%
The specificity of 100% generated by the presence of291
a peak at q = 1.725 nm−1 indicates a high potential for292
breast cancer diagnosis for samples containing microcal-293
cifications. The obtained specificity value bespeaks that294
there is no risk of false positives, while the sensitivity295
one indicates that up to 40 % of the cancerous cases will296
be missed if only the peak-presence detection criterion is297
employed. If the sum of peak amplitudes is considered298
instead, a 7 % increase in sensitivity can be obtained.299300
The structural changes related to this SAXS finger-301
print could be related to the formation of fibrous tissue.302
It is known that healthy breast tissue is formed either303
by evenly dispersed or well-ordered cells. In either case,304
there are no extraneous proliferation or foreign materials305
present. A cancerous tumour is formed when excessive306
accumulation of abnormal cells occur. In vivo Magnetic307
Resonance Spectroscopy (MRS) studies31–33 showed that308
the water-to-fat ratio was higher in invasive ductal car-309
cinomas compared to benign lesions or normal breast310
parenchyma31,33,34. An ex-vivo Nuclear Magnetic Reso-311
nance (NMR) investigation further confirmed this finding312
by demonstrating that malignant carcinosarcoma tissue313
has higher amounts of water content, which is directly314
related to fibrous tissue, compared to normal healthy315
tissue30. Since cancerous regions have the tendency to316
contain more fibrous tissue and water, the peak around317
q = 1.725 nm−1 could correspond to such a structural318
change17, and it might explain why this peak is only pre-319
dominant in malignant lesions.320
The diagnosis based on the fingerprint at321
q = 1.725 nm−1 is only known for samples containing322
microcalcifications, and it could be complementary of323
other SAXS fingerprints previously reported. Most324
SAXS studies of human tissues relate abnormalities on325
collagen structure to the level of malignancy of tumors.326
For example, the degradation of collagen is associated327
with invasive carcinoma in breast tissue. This exhibits328
itself as disperse collagen bundles that break the order of329
normal tissue. Collagen fibril degradation is associated330
to the presence of an acidic collagen component that331
causes collagen chain modifications35–37. The collagen332
degradation is seen in SAXS signals as the axial peaks333
of collagen become less intense and broader, due to the334
decrease of ordering with malignancy38. Another known335
SAXS fingerprint is the longitudinal arrangement of336
collagen fibrils, which gives rise to axial d-spacing peaks337
that can be used to classify breast tissue types39–43.338
Small displacements of the position of the lipid Bragg339
peak along q was indicated as a possible SAXS fin-340
gerprint for breast cancer diagnosis by Castro et al.28.341
Combining collagen, lipids and fibrous tissue SAXS342
fingerprints could expand the reliable tools available343
for cancer diagnosis, as well as level of malignancy344
assessment (BI-RADS)2. If scanning SAXS could345
be employed not only for classification, but also for346
BI-RADS categorization, it could become an excellent347
complement to histo-pathological workups.348
IV. CONCLUSION349
We analyzed a set of 36 formalin-fixed human breast350
tissue samples from two different patients by scanning351
SAXS. The search and classification of fingerprints in-352
dicate that it might be possible to classify benign and353
malignant lesions based on the scattering signals from354
tissues containing microcalcifications. The presence of a355
Bragg peak around q = 1.725 nm−1 generated a speci-356
ficity of 100% and a sensitivity of up to 67% when the357
sum of peak amplitudes is considered per sample, to358
classify between benign and malignant lesions. Notwith-359
standing, it is important to recall that a limited number360
of samples from only two different patients were mea-361
sured and that the majority of the malignant samples362
originated from one of the patients, which implies that363
more samples and patients are definitely required to reach364
more solid conclusions, including malignant lesions with-365
out microcalcifications. It is important to emphasize366
the added benefit of the spatial-resolution from scanning367
SAXS for the differentiation of the structural changes of368
tissue upon the growth of a tumor around a microcalcifi-369
cation. The fact that the scattering is not integrated over370
the whole sample volume allows discrimination between371
different sample regions. After this report, deeper inves-372
tigations to link such a fingerprint to structural changes373
in breast tissue, as well as the BI-RADS level of can-374
cer, would be essential to understand the development of375
cancer and its dependency on microcalcifications. Never-376
theless, a potential SAXS fingerprint has been identified377
in malignant breast tissue lesions, which might offer po-378
tential in diagnostics as well as in the understanding of379
structural changes leading to breast cancer.380
It is still not certain whether the microcalcifications381
themselves induce or are related to the structural tissue382
changes that lead to the peak at q = 1.725 nm−1, ob-383
served in malignant lesions. Whether the calcium de-384
posits lead to tissue structural changes, or the tissue385
structural changes lead to calcium deposits, remains un-386
certain.387
An important limitation of this study is the use of for-388
malin for sample preparation, which can affect the colla-389
gen structure in the tissue and cause further degradation390
and dehydration, influencing SAXS structural analysis44.391
As future work, we plan to measure fresh tissue sam-392
ples, with and without microcalcifications, to remove the393
influence of formalin on collagen and combine all known394
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Assessing lesion malignancy by scanning small-angle X-ray scattering of breast tissues with microcalcifications 6
(a) Transmitted photons
(b) Peak amplitude for q = 1.67 - 1.75 nm-1
0
100
Am
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FIG. 2. Benign lesions measured by scanning SAXS: (a) Sample transmission maps. (b) Maps of the intensity of thepeaks in the q-range = 1.67 - 1.75 nm−1. The scale bars corresponds to 1 mm.
SAXS fingerprints, collagen, lipid, and the possible fi-395
brous tissue, for malignancy level assessment. Addition-396
ally, measurements of samples with type I microcalcifi-397
cations, formed by calcium oxalate, in the q-range cov-398
ered in this work, are essential to include the scattering399
of their crystalline configuration as an additional poten-400
tial fingerprint for breast cancer classification. An in-401
teresting next step would be to measure the scattering402
signals of microcalcification-containing samples with GI,403
which does not require a synchrotron and can be car-404
ried out with a regular X-ray tube, to test whether the405
information in the q ranges accessible by this technique406
also allows a benign-malignant lesion discrimination and407
potentially a BI-RADS categorization4,5.408
V. ACKNOWLEDGMENT409
The authors acknowledge the European Research410
Council (ERC) (ERC-2012-StG 310005-PhaseX) and411
the Swiss National Foundation (SNF)-Sinergia CRSII2-412
154472 MedXPhase and CRSII5-183568 for funding this413
work. They also thank Dr. Andreas Menzel from the the414
cSAXS beamline at the Swiss Light Source for his critical415
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Assessing lesion malignancy by scanning small-angle X-ray scattering of breast tissues with microcalcifications 7
(a) Transmitted photons
(b) Peak amplitude for q = 1.67 - 1.75 nm-1
0
100
Am
plitu
de
(photo
ns/s
)
0
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Tra
nsm
issio
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FIG. 3. Malignant lesions measured by scanning SAXS: (a) Maps of the relative transmitted photons. (b) Maps of theintensity of the peaks in the q-range = 1.67 - 1.75 nm−1. The scale bars corresponds to 1 mm.
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FIG. 4. Receiver operating characteristic (ROC) curves usingthe presence of peaks (dotted line) or the amplitude of thepeaks (solid line) as a criterion to classify benign and malig-nant breast tissue lesions.
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