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Radiology of Infectious Diseases 3 (2016) 84e91

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Review

Imaging spinal infection

Jay Acharya a, Wende N. Gibbs b,*a University of Southern California, Department of Radiology, 1500 San Pablo Street, 2nd Floor, Los Angeles, CA 90033, USA

b Keck Medical Center of USC, Healthcare Consultation Center II, 1520 San Pablo Street, Suite L1600, Los Angeles, CA 90033-5310, USA

Received 6 March 2016; revised 14 March 2016; accepted 15 March 2016

Available online 29 March 2016

Abstract

Infection involving the vertebral column, including the bone, intervertebral disk, and paravertebral soft tissues is critical and early diagnosisand directed treatment is paramount. Different infectious organisms present with variable imaging characteristics, which when examined inconjunction with the clinical history, can facilitate early diagnosis and treatment and ultimately prevent patient morbidity and mortality. Thisarticle discusses the pathophysiology of infection of the vertebral column, as well as the imaging findings of bacterial, tuberculous, and fungalspondylitis/spondylodiskitis. We review the imaging findings utilizing plain radiography, computed tomography, and magnetic resonance im-aging, as well as a discussion regarding advanced imaging techniques.© 2016 Beijing You’an Hospital affiliated to Capital Medical University. Production and hosting by Elsevier B.V. This is an open access articleunder the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Keywords: Spondylitis; Spondylodiskitis; Spine Infection; Tuberculosis

1. Introduction

Infection of the vertebral column may lead to profound neuro-logic deficits, structural deformity, and may lead to significantmorbidity and mortality. Infection of the vertebral columnmay have a variety of different clinical presentations, which in turn,may present with differing imaging characteristics. Furthermore,directed treatment options of these infections are critical in orderto optimize patient recovery. The proximity of the spinal columnto critical structures including the spinal cord, mediastinum, andaortamake accurate and early diagnosis integral in patient recovery.Less than 2e4% of all cases of osteomyelitis are secondary toinfection involving thevertebral column; however, its importance iskey given the critical adjacent structures [1,2]. This article will

* Corresponding author. Tel.: þ1 323 442 9140.

E-mail address: Wende.Gibbs@med.usc.edu (W.N. Gibbs).

Peer review under responsibility of Beijing You'an Hospital affiliated to

Capital Medical University.

http://dx.doi.org/10.1016/j.jrid.2016.03.001

2352-6211/© 2016 Beijing You’an Hospital affiliated to Capital Medical University

the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

review the salient imaging characteristics of vertebral columninfection with focus on discitis/osteomyelitis and adjacentstructures.

1.1. Spondylitis and spondylodiskitis

A variety of organisms may result in infection of thevertebral column, including bacteria, mycobacteria, and fun-gus. Patients with infection of the spine may have variableclinical presentations, which can make diagnosis difficult.Typically, patients present with back pain, tenderness, andfocal rigidity in the site of the infection. Fever may also be apresenting factor although is reported in less than 20% ofpatients. Neurological symptoms are rare and usually areassociated with infection resulting in regional mass effect[3,4]. Patients can have radicular nerve pain if there isinflammation affecting adjacent nerve roots. Additionally,epidural extension can lead to more severe neurologic deficits.If untreated, infection may involve adjacent structures bydirect extension, including involvement of the aorta,

. Production and hosting by Elsevier B.V. This is an open access article under

85J. Acharya, W.N. Gibbs / Radiology of Infectious Diseases 3 (2016) 84e91

esophagus, and paravertebral musculature. A recent literaturereview by Buensalido et al. discussed the utility of biomarkersfor assessment of spinal infection. Their literature reviewconcluded that patients with spondylodiskitis and a positiveculture was associated with significantly higher C-ReactiveProtein (CRP) levels (range: 22e400 mg/L), and correlatedbetter than elevated ESR levels (range: 30e127 mm/h). Pro-calcitonin (PCT) has also been used as a biomarker for oste-omyelitis. A serum PCT level of >0.4 ng/mL was reported tobe 100% specific for diagnosis of acute osteomyelitis; how-ever, PCT levels may decrease once antibiotics have beenimplemented and limited studies have been performed toassess the utility of PCT as a biomarker in chronic osteomy-elitis [5].

1.2. Pathophysiology

The most common hypothesis of infectious involvement ofthe vertebral column is secondary to hematogenous spreadwith deposition of an infected micro-embolus lodging into ametaphyseal artery in the vertebra, which causes infarction atthis site and secondary infection results. The endplates aremost frequently involved because of the vascular supply ismost abundant at this site, in the adult population. The met-aphyseal artery in adults is an end artery, which results ininfarction, then adjacent extension to the adjacent same levelendplate through primary periosteal arteries. Extension toadjacent level endplates occurs via extension through inter-metaphyseal arteries [6]. The adult disc is nearly avascular,which precludes blood borne immune defense mechanisms atthis site [7,8].

A second route of hematogenous spread is via venousinvolvement. The Batson plexus, which forms the epidural

Fig. 1. Pyogenic Spondylodiskitis: 71 year old male with prior spinal Tuberculous in

pain, fever, and lower extremity weakness 4 weeks after surgery. Staphylococcus

change of the endplates at the L4eL5 level with intervertebral disk height loss an

shows hypointense signal in the L3, L4, and L5 vertebral bodies with edema in

demonstrates ill defined hyperintense signal in the L3, L4, and L5 vertebral bodies

paraspinal soft tissues. D) Sagittal T2/STIR sequence better demonstrates the edem

and L4eL5 intervertebral disks, and paraspinal musculature. The suppression of the

sensitivity to detect edema when compared to the T2-weighted sequence (C).

venous plexus and serves as a conduit of spread of infection.Venous spread has been discussed in patients with inflamma-tory bowel disease and urinary tract infection, with propaga-tion of the infection through the Batson plexus and into thevertebral column, usually involving the lumbar spine [9].

Direct extension may also lead to infection, which can beseen in patients in the setting of penetrating trauma and openwounds. Infection may also occur from direct involvementfrom surgical intervention, from both spine surgery or surgicalintervention of adjacent structures. Procedures includingepidural spinal injections, lumbar puncture, vertebroplasty,kyphoplasty, facet block, and the use of indwelling catheters,such as lumbar drain, spinal pain pump catheters, and spinalcord stimulator leads may also result in infection [10,11].Other risk factors that predispose spinal infection include,malnutrition, substance abuse, HIV infection, malignancy,chronic renal failure, septicemia, liver failure, and diabetesmellitus [4,12].

2. Bacterial spondylitis/spondylodiskitis

The lumbar spine is the most common location for pyo-genic spondylodiskitis, accounting for 48% of cases. Thethoracic spine is involved in approximately 35% of cases, withcervical spine involvement comprising 6.5% of cases of pyo-genic spondylodiskitis [13] Fig. 1.

Pyogenic spondylitis is usually caused by hematogenousspread of infection. Sources of septic embolism are mostcommonly from the genitourinary tract, followed by skin andrespiratory infections. Bacterial spondylitis may also becaused by direct extension from penetrating trauma, surgicalintervention, or from adjacent infected structures. Theseinclude invasion from the oropharynx, lung pleura, or from

fection with subsequent spinal decompression presenting with worsening back

aureus was the causative organism. A) Sagittal CT demonstrates destructive

d destruction with retrolisthesis of L4 on L5. B) Sagittal T1-weighted image

filtrating the expected fatty marrow signal. C) Sagittal T2-weighted image

with hyperintense signal in the L4eL5 intervertebral disk space and surround

a and inflammatory change within the L3, L4, and L5 vertebral bodies, L3eL4

fatty marrow in the more normal L1 and L2 vertebral bodies allows for better

Fig. 4. Pyogenic Spondylodiskitis with posterior mediastinal abscess: 35 year

old male intravenous drug user presenting with right arm weakness, back pain,

and chest pain. Methicillin-resistant Staphylococcus aureus (MRSA) was the

causative organism. A) Axial CT demonstrates destructive changes involving

the T2 vertebral body. B) Axial T2-weighted image demonstrates prevertebral

phlegmon with abscess formation within the posterior mediastinum, which

anteriorly displaces the esophagus and the aorta. C) Axial T1-weighted image

demonstrates prevertebral phlegmon with abscess formation within the pos-

terior mediastinum, which anteriorly displaces the esophagus and the aorta. D)

Axial T1-weighted fat-saturated post contrast image demonstrates prevertebral

phlegmon with abscess formation within the posterior mediastinum, which

anteriorly displaces the esophagus and the aorta.

Fig. 2. Pyogenic Spondylodiskitis: 71 year old male with prior spinal Tuber-

culous infection with subsequent spinal decompression presenting with

worsening back pain, fever, and lower extremity weakness 4 weeks after

surgery. Staphylococcus aureus was the causative organism. A) and (B) Axial

T1-weighted and axial T1-weighted fat suppressed contrast-enhanced (B)

images demonstrate extensive phlegmonous tissue with enhancement in the

bone, epidural space, prevertebral region, and paraspinal musculature.

86 J. Acharya, W.N. Gibbs / Radiology of Infectious Diseases 3 (2016) 84e91

infection involving the thoracic or abdominal wall. Thecausative organisms are predominantly gram-positive, withStaphylococcus aureus as the most common bacterium Fig. 2.Enterobacteriaceae comprise approximately 30% of cases,with other less common causative organisms includingStaphylococcus epidermidis, Haemophilus influenzae, andStreptococcal species [14]. Escherichia coli is the most com-mon gram-negative source Fig. 3. Pseudomonas is commonlyseen in intravenous drug abusers. Salmonella is relativelymore commonly encountered in patients with Sickle cell dis-ease [15]. Salmonella spondylodiskitis has also been impli-cated in disease spread to the aorta and mycotic aneurysmformation [16]. There is a similar predilection for males andfemales [17] Fig. 4.

Patient presentation is variable in patients with pyogenicinfections, but typically involve focal back pain, myalgia, andmuscle spasm, which are reported in more than 90% of cases[18]. Fever and elevated white blood cell counts are reportedin approximately 40e50% of patients [6]. Additionally,erythrocyte sedimentation rate and CRP are almost alwayselevated [19].

While plain radiography is often the primary imaging ex-amination performed due to its availability and cost efficiency,

Fig. 3. Pyogenic Spondylodiskitis with posterior mediastinal abscess: 35 year old m

chest pain. Methicillin-resistant Staphylococcus aureus (MRSA) was the causative

the T2eT3 level with reactive sclerosis of the adjacent vertebral bodies. B) an

enhancement of the intervertebral disk space and adjacent vertebral bodies at the

the findings are often not evident until later in disease course.Radiographic evidence of osseous demineralization requires30%e40% loss of the osseous matrix, which may occur twoweeks after onset of clinical symptomology [20]. Evaluation

ale intravenous drug user presenting with right arm weakness, back pain, and

organism. A) Sagittal CT demonstrates osseous destruction of the endplates at

d (C) Sagittal T1-weighted fat-saturated post contrast images demonstrate

T2eT3 level.

Fig. 5. Pyogenic Spondylodiskitis with massive mycotic aortic aneurysm: 71 year old male presenting with fever and back pain. Salmonella enteritidis was the

causative organism. A) and (B) Lateral radiographs demonstrate minimal loss of the osseous matrix involving the anterior aspect of the L3 and L4 vertebral bodies.

Prospective diagnosis of osteomyelitis is very difficult on this example and exemplifies the poor sensitivity of radiographs for early osteomyelitis. Small foci of gas,

however, can be seen which may clue in the Radiologist to a site of infection at these levels. (arrow). C) Sagittal T2/STIR image demonstrates the edema involving

the L2, L3, and L4 vertebral bodies. Edema involving the L2eL3, L3eL4, and L4eL5 intervertebral disk spaces is also present. D) Sagittal T1-weighted fat-

saturated post contrast image of the lumbar spine demonstrates enhancement of the anterior margins of the L3 and L4 vertebral bodies. An abscess in the pre-

vertebral soft tissues at the L5 level is also noted.

Fig. 6. Pyogenic Spondylodiskitis with massive mycotic aortic aneurysm: 71

year old male presenting with fever and back pain. Salmonella enteritidis was

the causative organism. A) Sagittal contrast-enhanced CT demonstrates a

large aneurysm of the aorta just above its bifurcation into the common iliac

arteries. Foci of gas within the anterior aspect of the L4 vertebral body and in

the prevertebral tissue are present. B) Axial contrast-enhanced CT demon-

strates a large aneurysm of the aorta just above its bifurcation into the com-

mon iliac arteries. Foci of gas within the anterior aspect of the L4 vertebral

body and in the prevertebral tissue are present. C) Axial T1-weighted fat-

saturated contrast-enhanced CT demonstrates a large aneurysm of the aorta

just above its bifurcation into the common iliac arteries. Foci of gas within the

anterior aspect of the L4 vertebral body and in the prevertebral tissue are

present.

87J. Acharya, W.N. Gibbs / Radiology of Infectious Diseases 3 (2016) 84e91

of soft tissue structures on plain radiographic imaging can alsoprovide a secondary sign of infection and may clue theRadiologist and clinician to a suspicious area. Computed to-mography is not considered to be of much utility for diagnosisof intervertebral disk infection [21,22]. However, CT is oftenutilized in image guidance to obtain samples of infectedspecimens, for both osseous and non-osseous tissue Fig. 5.

The mainstay to diagnose and assess the extent of diseaseinvolvement is with MR imaging. MR is the most sensitiveimaging modality to assess for early osteomyelitis [23]. Theearliest imaging finding (across all imaging modalities) isosseous bone marrow edema [24]. Marrow edema manifests asill-defined hypointense signal on T1-weighted imaging. Thereis often loss of endplate definition in the vertebral body end-plates adjacent to the level of the infected intervertebral disk.Bone marrow edema demonstrates hyperintense signal on T2-weighted imaging. With T2-weighted imaging, the interverte-bral disk space may show increased signal intensity, as well asan abnormal configuration of the infected disk. The use of fatsuppression techniques, specifically short tau inversion recov-ery (STIR), provides the highest sensitivity for increased watercontent within the infected tissue. It is important, however, tonote that MR imaging findings of osseous infection may lagbehind the clinical symptoms. Follow-up MR imaging maydemonstrate imaging findings of diskitis/osteomyelitis in caseswith persistent clinical suspicion and a negative initial MRimaging examination. Furthermore, MR imaging findings maylag behind the healing phase of spinal diskitis/osteomyelitis; sofollow-up imaging should be performed judiciously. TheRadiologist should maintain careful consideration of the clin-ical status of the patient when evaluating follow up studies. Astudy conducted by Layton et al. demonstrated no specific

Fig. 7. Tuberculous spondylitis: 64 year old female with history of low back pain. Image D is the same patient 19 month later, presenting with severe lower

extremity weakness and cauda equina like symptoms. A) Sagittal T1-weighted image demonstrates hypointense signal in the L1, L2, and L3 vertebral bodies with

collapse of the L3 vertebral body with osseous retropulsion and a mild gibbus deformity. B) Sagittal T2-weighted image demonstrates mild ill defined hyperintense

signal in the L1, L2, and L3 vertebral bodies with collapse of the L3 vertebral body with osseous retropulsion and a mild gibbous deformity. Note the relative lack

of abnormal signal within the intervertebral disk spaces in the lumbar spine due to the lack of proteolytic enzymes in the Tuberculosis mycobacterium. C) Sagittal

T1-weighted fat-saturated contrast-enhanced image demonstrates enhancement of the L1, L2, and L3 vertebral bodies without abnormal enhancement of the

intervertebral disks. D) Sagittal T2-weighted image demonstrates destruction and collapse of the L1 vertebral body with osseous retropulsion and compression of

the distal spinal cord/conus medullaris in the same patient 19 months later. There is a resultant gibbus deformity.

88 J. Acharya, W.N. Gibbs / Radiology of Infectious Diseases 3 (2016) 84e91

associations on 4e8 week follow up MR imaging and theclinical status in their population cohort involving patients withspinal infection [25]. As can be seen in healing infection inother parts of the body, decreased inflammatory changes in theadjacent soft tissue correlates as one of the earliest imagingfindings of improvement in the infection [26]. Healing can alsobe demonstrated by a return to the expected fatty marrow signalwithin the involved vertebral bodies. This finding is demon-strated with hyperintense signal in the bone marrow on T1-weighted imaging, which signifies an underlying decrease inthe edema and inflammation in these areas Fig. 6.

3. Tuberculous spondylitis/spondylodiskitis

The prevalence of tuberculosis has declined across theworld secondary to disease recognition and antibiotic use.

Fig. 8. Tuberculous spondylitis with intravertebral and psoas major abscesses:

57 year old male with low back pain. A) Sagittal T1-weighted fat-saturated

contrast-enhanced image demonstrates intraosseous abscess formation with a

well defined border of enhancement around the abscess. B) Axial T1-weighted

fat-saturated contrast-enhanced image demonstrates intramuscular abscess

involving the right psoas major.

However, tuberculosis is still commonly encountered inimmunocompromised patients, the homeless population, andthird world countries. The initially low-grade and ofteninsidious onset and presentation of symptoms allow for a delayin diagnosis. Many patients also often do not have readilyavailable primary health care services. Tuberculosis is causedby Mycobacterium tuberculosis and generally affects the res-piratory system, but any organ system can be affected Fig. 7.

The thoracolumbar junction is the most commonly affectedsegment of the spine involved in tuberculous infection Fig. 8.Cervical and sacral spine involvement is less common [27].Spinal tuberculosis usually begins in the anterior aspect of thevertebral body, either at its superior or inferior margin. Theinfection typically spreads in a sub-ligamentous fashion, usu-ally deep to the anterior longitudinal ligament and may traversemultiple vertebral levels. The route of disease spread generallyoccurs anterolaterally. In contradistinction to pyogenic diskitis,tuberculous disease spares the intervertebral disk, as Myco-bacterium tuberculosis lacks the proteolytic enzymes to breakdown the disk. Due to the lack of intervertebral disk involve-ment, there may be no abnormal T2-weighted signal within thedisk space. However, as vertebral body disease progresses andresults in collapse, destruction of the disk space may occur as afinding seen in a late stage of disease [4]. Vertebral bodymarrow demonstrates T1-weighted hypointense signal and T2-weighted hyperintense signal in the involved levels. T2-weighted hyperintense signal is also noted within the affectedvertebrae and adjacent soft tissues. Peripheral enhancementsurrounding osseous and paraspinal abscesses is more commonin tuberculous infection, in comparison to other organismscausing spinal infections and paraspinal phlegmonous changes[28]. Paravertebral phlegmonous change is associated withthick enhancement on contrast-enhanced imaging. Para-vertebral involvement may be secondary to direct spread or via

Fig. 9. Tuberculous spondylitis: 56 year old female with neck pain, difficulty swallowing and arm weakness bilaterally. A) Sagittal T2/STIR image demonstrates

edema in the C3, C4, and C5 vertebral bodies with infected prevertebral and ventral epidural fluid. B) Sagittal T1-weighted fat-saturated contrast-enhanced image

demonstrates enhancement of the C3, C4 and C5 vertebral bodies with enhancement of the prevertebral and ventral epidural phlegmon. C) Sagittal T2 image

demonstrates prevertebral abscess and ventral epidural abscess resulting in spinal cord compression.

89J. Acharya, W.N. Gibbs / Radiology of Infectious Diseases 3 (2016) 84e91

paravertebral veins. Paravertebral soft tissue and muscular ab-scesses are more commonly seen in tuberculous infectioncompared to other spinal infectious organisms [29]. Fistuloustracts to adjacent structures, such as the aorta and pleural space,may also be present [30] Fig. 9.

4. Fungal infection

Fungal infection of the spine is most commonly encounteredin immunocompromised patients. These include patients with

Fig. 10. Coccidioidomycosis: 15 year old female with 2 month history of back

pain. A) Lateral radiograph demonstrates destructive change involving the L4

vertebral body and pedicles. Increased density involving the anterior and

inferior aspect of the L3 vertebral body is compatible with spondylitis as well.

B) Sagittal T1-weighted fat-saturated contrast-enhanced image demonstrates

enhancement multiple lower thoracic and lumbar vertebral bodies. Note the

enhancement of the anterior and inferior aspect of the L3 vertebral body,

which corresponds to the abnormal density on the corresponding radiograph.

the human immunodeficiency virus (HIV), diabetes mellitus,patients on certain chemotherapeutic agents, or post transplantpatients on immunosuppressive therapy. The incidence offungal infections has increased in the past decade [31]. Candidaand Aspergillus are the most common causes of opportunisticfungal infection [7]. Similarly to bacterial and mycobacterialinfection, fungal infections may lead to diskitis/osteomyelitis.The imaging findings are similar to that of pyogenic infection,with hypointense T1-weighted signal in the infected endplates.

Fig. 11. Coccidioidomycosis, diffuse hematogenous spread: 16 year old female

with progression of fungal disease after stopping anti fungal medication. A)

Sagittal T2-weighted image demonstrates multiple foci of hyperintense signal in

the lower thoracic and lumbar vertebral bodieswith collapseofmultiple levels and

spinal malalignment. Collapse of lower thoracic/upper lumbar vertebral bodies

result in osseous retropulsion and severe spinal stenosis. B) Sagittal T1-weighted

fat-saturated contrast-enhanced image demonstrates multiple foci of abnormal

enhancement in the lower thoracic and lumbar vertebral bodies with collapse of

multiple levels and spinal malalignement. Note the multiple intraosseous ab-

scesses and the abscess in the presacral soft tissues. C) Axial T1-weighted fat-

saturated contrast-enhanced image demonstrates multiple foci of intraosseous

abscesses and the abscesses in the right multifidus and longissimus muscles.

Fig. 12. Pyogenic paraspinal musculature abscess: 6 year old female with rapidly progressive fever and back pain. Axial DWI (A), Axial ADC (B), and Axial T2-

weighted images demonstrate restricted diffusion and edema within an intramuscular left psoas major abscess, as well as phlegmonous tissue and edema in the right

paraspinal musculature.

90 J. Acharya, W.N. Gibbs / Radiology of Infectious Diseases 3 (2016) 84e91

However, the abnormal T2-weighted signal is relatively lesscommonly identified in patients with fungal diskitis/osteomye-litis [31]. The imaging findings in patients with fungal diskitis/osteomyelitis may be attributed to the relatively blunted im-mune response in affected patients [6].

Various fungi may lead to spondylitis/spondylodiskitis, anddepend on the area in which the fungus is endemic. Coccidioi-domycosis immitis is endemic to the San Joaquin Valley in theSouthwestern United States, as well as in Mexico, Central andSouth America Fig. 10. Histoplasmosis is most commonly

Fig. 13. Pyogenic diskitis/osteomyelitis: 40 year old male presenting with fever

and ataxia. Staphylocccus aureus was the causative organism. Axial DWI (A),

Axial ADC (B) demonstrates restricted diffusion within the T5eT6 interverte-

bral disk. (C) Sagittal T1-weighted fat-saturated contrast-enhanced image

demonstrates enhancement of the T5 and T6 vertebral bodies with endplate

destructive and enhancement of the intervertebral disk at this level. (D) Axial

T1-weighted fat-saturated contrast-enhanced image demonstrates enhancement

of the T5eT6 intervertebral disk with paravertebral enhancement.

encountered in the Ohio River Valley in the United States, but isalso endemic to Central and South America, Africa, Asia, andAustralia [32]. Mucormycosis and aspergillosis infections havean increased incidence in patients with diabetes mellitus.Candida infections have also demonstrated an increased inci-dence in immunocompromised patients. Coccidioidomycosisinfection typically affects the disk space and demonstrates diskspace narrowing and often is associated with paraspinal softtissue infection. Although osseous manifestations are uncom-mon, the spine is the most often involved osseous structure.Osseous destruction is less commonly seen in coccidioidomyo-cosis in comparison to pyogenic infections [33]. Even thoughfungal spinal infection is less common than pyogenic or tuber-culous involvement, it is important to consider fungal disease inthe differential diagnosis and use clinical history and the patientpresentation to make the imaging diagnosis more accurateFig. 11.

5. Advanced imaging

Diffusion weighted imaging (DWI), which is commonlyused in the evaluation of intracranial pathology, has increas-ingly been applied to imaging of spine pathology, includingevaluation of the spinal cord, extra-axial space, in a hetero-geneous magnetic environment, and physiologic motion in andaround the spinal cord. Technical advances including parallelimaging and more powerful gradient systems, as well astechniques including multi-shot echo planar imaging (EPI) andrestricted field of view DWI are practical and more resistant toartifact, which facilitates diffusion weighted imaging of thespine [34,35] Fig. 12.

In the setting of infection, DWI can highlight epidural ab-scess, osteomyelitis, and paravertebral abscess. Patel et al.demonstrated that DWI of the spine can be used to distinguishType 1 degenerative endplate signal changes from discitis/osteomyelitis; a common diagnostic dilemma in the setting ofa T2 hyperintense disc. The “claw sign” is described as pairedregions of well-marginated, linear, increased diffusionweighted signal within the adjacent endplates, which reflectsdegenerative change, while diffusely increased signal in thevertebral bodies adjacent to the disk suggests diskitis/osteo-myelitis [36] Fig. 13.

91J. Acharya, W.N. Gibbs / Radiology of Infectious Diseases 3 (2016) 84e91

6. Summary

Infection involving the vertebral column, including the bone,intervertebral disk, and paravertebral soft tissues is of criticalimportance and early detection and diagnosis is paramount.Utilizing the clinical information in conjunction with the im-aging findings is necessary to optimize treatment and ultimatelyimprove patient care and prevent mortality and morbidity.

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