Magnetic Resonance Imaging Findings of Early Spondylodiscitis: Interpretive Challenges and Atypical Findings

MR findings of early infectious spondylodiscitis are non-specific and may be confused with those of other conditions. Therefore, it is important to recognize early MR signs of conditions, such as inappreciable cortical changes in endplates, confusing marrow signal intensities of vertebral bodies, and inflammatory changes in paraspinal soft tissues, and subligamentous and epidural spaces. In addition, appreciation of direct inoculation, such as in iatrogenic spondylodiscitis may be important, because the proportion of patients who have undergone recent spine surgery or a spinal procedure is increasing. In this review, the authors focus on the MR findings of early spondylodiscitis, atypical findings of iatrogenic infection, and the differentiation between spondylodiscitis and other disease entities mimicking infection.

Association between Asymptomatic Urinary Tract Infection and Postoperative Spine Infection in Elderly Women : A Retrospective Analysis Study

OBJECTIVE: The purpose of this study is to identify the relationship between asymptomatic urinary tract infection (aUTI) and postoperative spine infection. METHODS: A retrospective review was done in 355 women more than 65 years old who had undergone laminectomy and/or discectomy, and spinal fusion, between January 2004 and December 2008. Previously postulated risk factors (i.e., instrumentation, diabetes, prior corticosteroid therapy, previous spinal surgery, and smoking) were investigated. Furthermore, we added aUTI that was not previously considered. RESULTS: Among 355 patients, 42 met the criteria for aUTI (Bacteriuria > or = 10(5) CFU/mL and no associated symptoms). A postoperative spine infection was evident in 15 of 355 patients. Of the previously described risk factors, multi-levels (p 0.05) was not statistically significant. However, aUTI with Foley catheterization was statistically significant when Foley catheterization was added as a variable to the all existing risk factors. CONCLUSION: aUTI is not rare in elderly women admitted to the hospital for lumbar spine surgery. The results of this study suggest that aUTI with Foley catheterization may be considered a risk factor for postoperative spine infection in elderly women. Therefore, we would consider treating aUTI before operating on elderly women who will need Foley catheterization.

Aspergillus Spondylitis involving the Cervico-Thoraco-Lumbar Spine in an Immunocompromised Patient: a Case Report

Aspergillosis is a rare cause of spondylitis. Moreover, early diagnosis by MR imaging and adequate treatment can prevent the serious complications of fungal infection. To our knowledge, the MR findings of multilevel aspergillus spondylitis in the cervico-thoraco-lumbar spine have not been previously described. Here, we report the MR findings of aspergillus spondylitis involving the cervical, thoracic, and lumbar spine in a liver transplant recipient.

Tuberculous Spondylitis vs Pyogenic Spondylitis: Focusing on the Discriminative MR Findings for Differentiation

PURPOSE: The purpose of this study is to analyze the most discriminative MR findings for making the differential diagnosis of tuberculous and pyogenic spondylitis. MATERIALS AND METHODS: Sixty MR scans of 18 pyogenic spondylitis patients and 42 tuberculous spondylitis patients were retrospectively reviewed. The statistical analysis was performed using stepwise discriminant analysis and Student's T-test. RESULTS: The patients with tuberculous spondylitis had a significantly higher incidence of MRI findings as follows (p <0.05): smooth margin of a paraspinal mass/abscess in 67% [28/42] of the tuberculous spondylitis patients vs 6% [1/18] in the pyogenic spondylitis patients, mild endplate erosion in 52% [22/42] vs 38% [7/18], respectively, the presence of paraspinal mass/abscess in 100% [42/42] vs 6% [1/18], respectively, central dark signal intensity of the abscess in 86% [36/42] vs 39% [7/18]), respectively, subligamentous spread in 81% [34/42] vs 50% [9/18]), respectively, severe vertebral collapse in 20% [8/42] vs 11% [2/18]), respectively, and posterior extension in 62% [26/42] vs 33% [6/18]), respectively. Among of them, the significant discriminative MR findings were the margin of a paraspinal mass, the grade of endplate erosion and the presence or absence of a paraspinal mass in that order. CONCLUSION: In the differentiation of tuberculous and pyogenic spondylitis, the margin of the paraspinal mass, the grade of endplate erosion and the presence or absence of a paraspinal mass are the most three discriminating MR findings in that order.

The Diagnostic Usefulness of CT-guided Needle Biopsy or Aspiration in Infectious Spondylitis

PURPOSE: To determine the diagnostic value of CT-guided biopsy or aspiration of the spine and paraspinal soft tissue in infectious spondylitis. MATERIALS AND METHODS: Between January 2000 and June 2002, 58 patients underwent 67 biopsies and/or aspirations under CT guidance to identify the organism causing infectious spondylitis, and were included in this study. Nine underwent rebiopsy. In all patients, MR images were available before biopsy and/or aspiration. In 63 of 67 procedures, the specimens or aspirates obtained were prepared for culture and smear, and for histological examination, four procedures involved aspiration only. In ten patients with suspected tuberculosis, a polymerase chain reaction test was performed. For all procedures, the transpedicular, transcostovertebral or paravertebral route was involved, according to the level and shape of the lesions, and 14-, 16-, or 18-gauge core biopsy needles and/or 20-gauge aspiration needles were employed. Lesions invloved a paravertebral (n=17), psoas (n=8) or epidural (n=1) abscess; an intervertebral disc (n=20); or a vertebral body (n=21). The levels at the mid-thoracic spine were T4-T10 (n=11); at the thoracolumbar junction, T11-L1 (n=14); at the lumbar spine, L1-L4 (n=25); and at the lumbo-sacral junction, L5-S1 (n=17). In nine of 58 patients, rebiopsy was performed. RESULTS: Diagnosis was confirmed in 22 of 58 patients (38%), and was as follows: tuberculous spondylitis (n=17), pyogenic spondylitis (n=4), and fungal spondylitis (n=1). Thirty-six unconfirmed cases were diagnosed as nonspecific inflammation (n=21), fibrosis involving cortical bone (n=1), necrotic material (n=5) and inadequate specimen without evidence of malignancy (n=9). Only one of the nine cases in which biopsy was repeated was confirmed as tuberculous spondylitis. Diagnosis was confirmed in 7 of 17 paravertebral abscesses (41%), 8 of 21 vertebral bodies (38%), 6 of 20 intervertebral discs (30%) and 1 of 8 psoas abscesses (13%). CONCLUSION: In infectious spondylitis, the overall diagnostic yield of CT-guided needle biopsy and/or aspiration is relatively low, but the procedure seems to be effective for excluding malignancy. In identifying the organisms involved in infectious spondylitis, a paravertebral lesion is in a more favoured location than a psoas lesion.

The Usefulness of Diffusion-weighted MR Imaging for Differentiation between Degenerative Spines and Infectious Spondylitis

PURPOSE: The differential diagnosis between Modic type I degenerative spine and infectious spondylitis sometimes is difficult, because the affected bone marrows in both disease show similar signal intensity on conventional MR imaging. We evaluate the usefulness of diffusion-wighted MR imaging for differential diagnosis between Modic type I degenerative spine and infectious spondylitis. MATERIALS AND METHODS: The spin-echo and diffusion-weighted MR images of eight patients with Modic type I degenerative spines and 14 patients with infectious spondylitis diagnosed by clinical findings or CTguided biopsies were analyzed. The diffusion-weighted imaging sequence was based on reversed fast imaging with steady-state precession (PSIF). Signal intensity changes of the vertebral bone marrow on conventional spin-echo and diffusion-weighted MR imaging were compared between degenerative spine and infectious spondylitis. RESULTS: On T1-weighted images, the affeted bone marrow in both disease showed hypointense signals. On T2-weighted images, all of type I degenerative spine and 11 of infectious spondylitis showed hyperintensity, and three of infectious spondylitis showed heterogeneous mixed signal intensity. On diffusionweighted MR images, all of type I degenerative spine were hypointense with peripheral high signal intensity to normal vertebral body, but infectious spondylitis was hyperintense (n=11) and hypointense (n=3). CONCLUSION: Diffusion-weighted MR imaging is useful to differentiate Modic type I degenerative spine from infectious spondylitis. On diffusion-weighted images, the high singal intensity of bone marrow suggests infectious spondylitis, whereas the low signal intensity of bone marrow with peripheral focal high signal intensity suggests type I degenerative spine.

Differentiation between Tuberculous and Pyogenic Spondylitis on Gd-enhanced MR Imaging: Focus on the Patterns of Disc Enhancement

PURPOSE: The purpose of this study was to analyze the patterns of intervertebral disc enhancement seen in tuberculous and pyogenic spondylitis, and to evaluate their utility in differentiating between the two groups. MATERIALS AND METHODS: Magnetic resonance images obtained in 31 consecutive infectious spondylitis patients (43 discs) in whom intervention occurred due to infected vertebral bodies, were retrospectively analysed. Nineteen of the patients had tuberculosis and 12 were infected by pyogenic organisms. After analysis, the patterns of disc enhancement revealed by contrast-enhanced T1-weighted axial and sagittal MR imaging were classified as of four types: Type I, non-enhancing; Type II, enhancement of the peripheral margin of the disc; Type III, enhancement of the peripheral margin and central area adjacent to the cortical vertebral endplate; Type IV, general enhancement and/or destruction of the disc. RESULTS: There were 19 cases of tuberculous spondylitis involving 28 intervertebral discs, and the enhancement patterns observed were as follows: Type I: n=4, 14%, Type II: n=17, 61%, Type III: n=1, 4%, Type IV: n=6, 21%. Twelve cases of pyogenic spondylitis involved 15 intervertebral discs; the enhancement patterns observed in these cases were as follows: Type I: n=1, 7%, Type II: n=2, 13%, Type III: n=10, 67%, Type IV: n=2, 13%. CONCLUSION: Careful analysis of the patterns of disc enhancement occurring in infectious spondylitis can be useful for differentiating between the tuberculous and pyogenic varieties of this condition.

Pyogenic Spondylitis: MR Imaging Findings

PURPOSE: To prevent permanent neurologic deficit and/or spinal deformity in pyogenic spondylitis earlydiagnosis and prompt treatment are essential. The purpose of this study is to determine the MR imaging findings ofpyogenic spondylitis. MATERIALS AND METHODS: In 31 patients with pathologically or clinically proven pyogenicspondylitis, MR images(31, T1-weighted ; 30, T2-weighted ; 31, Gd-enhanced T1-weighted) were retrospectivelyanalyzed. Analysis focused on the signal intensity and enhancement pattern of involved vertebral bodies andintervertebral discs, as well as paravertebral soft tissue abnormality. RESULTS: A total of 77 vertebral bodies(mean, 2.5 per patient) were involved. Signal intensity was low in 58 of 77 T1-weighted images, high in 63 of 75T2-weighted images and in 72 of 77 contrast-enhanced T1-weighted images, enhancement was diffuse. A total of 47intervertebral discs were involved. Signal intensity was low or intermediate in all 47 T1-weighted images, andhigh or intermediate in 38/46 T2-weighted images ; in 24 of 38 contrast-enhanced T1-weighted images, signalintensity was peripheral, and in 14, enhancement was diffuse. Twenty-six patients showed diffusely enhancedparavertebral soft tissue abnormality and in 14, the largest diameter was less than 1cm. CONCLUSION: With regardto vertebral bodies, MR imaging findings of pyogenic spondylitis are low signal intensity on T1-weighted images,and high or intermediate signal intensity on T2-weighted images, together with diffuse enhancement. Forintervertebral discs, signal intensity was low on T1-weighted images, high on T2-weighted images, and peripheralor diffuse enhancement was seen. Diffusely enhanced small paravertebral soft tissue abnormality was also present.

Differential Diagnosis of Vertebral Lesions with paraspinal Mass with MRI

PURPOSE: To assess the characteristic features of MR findings which would be useful for the differentiation of various spinal diseases involving paraspinal soft tissue mass. MATERIALS AND METHODS: We retrospectively reviewed MR findings in 31 cases(M:F=20:11) of spinal disease in which paraspinal mass was involved. The breakdown of cases was as follows : spinal tuberculosis, 12; spinal metastasis, 13; multiple myeloma, 3; pyogenic spondylitis, 2; spinal aspergillosis; 1. RESULTS: The pattern of bone marrow invasion in spinal metastasis, multiple myeloma, spinal tuberculosis and aspergillosis was mixed ; focal, homogeneously diffuse and inhomogeneously patterns were seen. Pyogenic spondylitis showed inhomogeneously diffuse invasion; an intravertebral abscess was seen in the only five cases of spinal tuberculosis. Vertebral posterior compartment invasion was observed in seven cases of spinal tuberculosis, two of multiple myeloma, the one case of spinal aspergillosis and in all 13 cases of spinal metastasis. This and multiple myeloma showed no disc space invasion, in any case, but all cases of infectious spondylitis showed such invasion. Peripheral rim-enhancement in the paravertebral mass was seen in 11 cases of spinal tuberculosis, one case of pyogenic spondylitis and the case of aspergillosis. Bilobate anterior epidural mass was noted in 60% of spinal tuberculosis cases, 36% of spinal metastasis and one case of pyogenic spondylitis. CONCLUSION: MR findings of spinal disease involving a paraspinal soft tissue mass were useful for differentiation.

Differentiation between Tuberculous and Pyogenic Spondylitis: MR Imaging Characteristics of Paraspinal Mass

PURPOSE: To determine the MR imaging findings for the differentiation of tuberculous spondylitis(TS) and pyogenic spondylitis(PS) with emphasis on the shape and MR signal characteristics of paraspinal mass. MATERIALS AND METHODS: We obtained spin-echo T1- and T2-weighted MR images of 63 surgically proved cases of TS and 15 casesof PS. Gadopentetate dimeglumine(Gd)-enhanced T1-weighted MR images in 37 cases of TS and in all 15 cases of PS were also obtained. Paraspinal mass formation, the size, shape and Gd-enhancing pattern of this mass and penetration of paraspinal ligaments by inflammatory tissue were analyzed. RESULTS: Paraspinal mass was found inboth TS(63/63) and PS(9/15). The mean longitudinal dimension of this mass was 4.3 vertebral body heights in TS and1.8 in PS. The margin of the mass was smooth in TS due to subligamentous spread of inflammation, while PS showedan irregular margin and invaded the para-aortic or para-caval space(9/15) due to penetration of inflammatory tissue through the paraspinal ligament. In the lumbar spine, however, TS showed focal penetration of the paraspinal ligament and formed psoas abscesses. After Gd enhancement, TS showed irregular thick or uniformly thinrim enhancement(35/37), suggesting caseation necrosis and cold abscess, while PS showed diffuse enhancement, suggesting abundant granulation tissue. CONCLUSION: MR imaging findings helpful for the differentiation of TS andPS were size, shape and enhancing pattern of paraspinal mass and penetration of paraspinal ligament by inflammatory tissue.