Clinical significance of the intranuclear cleft of the lumbar intervertebral disk on MRI

MR studies of the lumbar spine in 111 patients were analyzed at 469 disks to assess the prevalence of intranuclear cleft (INC) in the lumbar intervertebral disk. MR studies were performed on either 0.1-tesla (T) magnet (69 patients) or 0.22-T magnet (42 patients). The pulse sequences reviewed were saturation recovery (SR; TR = 0.5 sec), short TR, TE spin echo (S-SE; TR = 0.5 sec, TE = 34 msec) and long TR, TE spin echo (L-SE; TR = 1.5 sec, TE = 68,80 msec). All study were done in a sagittal plane with 10 mm slice thickness. The conclusions were as follows: 1) On a 80 msec TE, 1.5 sec TR image, INCs were detected in more than 80% of disks in patients over 30 years old but in only 13.3% of disks in patients under 20 years old. 2) In both imaging system, L-SE showed INCs more frequently than SR and S-SE. 3) INCs were less frequently demonstrated in the disk with decreased signal intensity on 0.1-T magnet as compared with 0.22-T magnet. 4) On SR and S-SE, there is an increase in the prevalence of INC in the disk with decreased signal intensity. We suggest that the INC will be a good landmark of the pathological process of the lumbar disk, such as degeneration.     

MR imaging of marrow changes adjacent to end plates in degenerative lumbar disk disease

MR studies of the lumbar spine in 41 patients were analyzed at 203 disk interspaces to assess the appearance and frequency of bone marrow signal changes in the vertebral bodies adjacent to normal and degenerated disks. Degenerative changes were found at 58 interspaces; an abnormal bone marrow signal was identified in 29 (50%) of these. On spin-echo pulse sequences with short and long repetition times (TRs) and echo times (TEs), an area of relative increased signal intensity was seen in the vertebral body adjacent to the disk in 24 cases (17 were bandlike on both sides of the disk, four were focal on one side of the disk, and three were bandlike and focal on one or both sides of the disk). In one patient decreased signal was noted on both short and long TR/TE imaging. In the other four patients decreased signal was noted on short TR/TE pulse sequences and increased signal was evident on long TR/TE. These marrow changes were not present adjacent to normal disks. The relatively high signal intensity on both short and long TR/TE pulse sequences suggests that the increased signal resulted from the conversion of normal hemopoietic bone marrow to fatty marrow. We conclude that bandlike or focal areas of high signal intensity in the bone marrow adjacent to degenerated intervertebral disks occur commonly on MR images of the spine and must not be confused with signal changes from tumors or infections involving the disk space and adjacent vertebral end plates.     

The role of magnetic resonance imaging in the diagnosis of postoperative spondylodiscitis

BACKGROUND: Spondylodiscitis, discitis associated with vertebral osteomyelitis may follow disc-removal surgery. A targeted successful treatment of spinal infections requires clinical and laboratory data that are completed by the contribution of imaging procedures. Neuroimaging provides precise information on correct topography, localization, propagation, and differential diagnosis of spinal infectious lesions. The aim of this study was to present magnetic resonance imaging (MRI) findings in patients with postoperative spondylodiscitis. METHODS: MRI was performed in 6 patients aged 29-50, with clinically suspected postoperative spondylodiscitis. Initial examination was performed 3-8 weeks after surgery and 3, 6, or 12 months after the treatment by antibiotics. Patients underwent MRI on a IT imaging unit (Siemens, Magnetom-Impact), including sagittal T1W and T2W images and axial T1W images before and after the administration of gadolinium contrast medium. RESULTS: MRI findings included: significantly decreased signal intensity with the loss of distinction between vertebral body and intervertebral disc space on T1W, increased signal intensity in the adjacent vertebral body and end-plates on T2W, contrast enhancement of vertebral body and disc space and paravertebral soft tissue changes. Follow-up examinations performed 3, 6, or 12 months after the treatment showed less abnormal signal intensities on both T1- and T2-weighted images. CONCLUSION: Postoperative spondylodiscitis is a rare but severe complication of lumbar disc surgery. Since conventional imaging techniques are not reliable for detecting spondylodiscitis in its early stages, MRI is of great significance in the diagnosis of postoperative spondylodiscitis.     

Chronic spondylodiscitis. Clinical aspects and imaging features]

INTRODUCTION: The diagnosis of a chronic inflammatory process involving the vertebral body and disk is often very difficult because patient's history, subjective symptoms and physical findings are often unconclusive. Thus imaging techniques play a decisive role. Radiography, tomography, CT and MR have different capabilities and limitations and provide different findings in spondylodiscitis. MATERIAL AND METHODS: We observed 18 cases of spondylodiscitis in the last three years. The responsible microbe, a Staphylococcus aureus from extraosseous sites, was found in two cases at blood culture. Small cell inflammatory infiltration was confirmed with CT-guided biopsy in one case, while the other cases were diagnosed based on constant chronic back pain, feveret, moderate neutrophile leukocytosis or increased erythrosedimentation speed, plus changes in radiographic patterns following antibiotic therapy. RESULTS: Plain radiography and tomography are the techniques of choice to detect or suspect the lesion, which is then studied with CT or MRI. Clear-cut irregularities and erosions on opposing vertebral bodies, reactive bone sclerosis and reduced disk space were typical signs in our series; nine patients presented irregular cavitations(s), like bone caries, surrounded by reactive sclerosis in the body near the frontal vertebral plate. CONCLUSIONS: Together with the imaging patterns of all cases, we studied in detail three cases, relative to physical findings and diagnostic techniques. We also compared the changes in chronic spondylodiscitis with those in intraspongious herniation, intervertebral osteochondritis and severe degenerative arthritis. Bone erosions on the anterior cortical surface of the vertebral body were seen in 50% of our cases and may represent a specific sign of chronic spondylodiscitis if the finding is confirmed in further studies.     

MR imaging of infectious spondylitis

MR images of 14 patients with pyogenic and three patients with tuberculous infectious spondylitis were studied to develop criteria for diagnosis. T1-weighted scans, 800/20 (TR/TE), were obtained in 17 patients and T2-weighted scans, greater than 2000/30,80, were obtained in 14. In seven patients, T2*-weighted scans (gradient-recalled acquisition into steady state, 25/15/5-7 degrees [TR/TE/flip angle]) and short-T1 inversion-recovery scans (STIR), 1400/150/40 (TR/TI/TE), as well as fat and water images (using a suppression technique), were obtained. Unenhanced and gadopentetate-dimeglumine-enhanced scans were obtained in four patients. In all but two patients with pyogenic infectious spondylitis, the T1-weighted sagittal scan showed characteristic findings: narrowed disk space, low signal intensity in the marrow of at least two adjacent vertebrae, subligamentous or epidural soft-tissue masses, and erosion of cortical bone. In one patient the T1-weighted scan was normal and abnormalities could be detected only on the T2-weighted scan. The remaining patient had abnormal marrow signal on the T1-weighted scan but only in one vertebral body. On T2-weighted images the major findings were a narrowed disk space with variable signal changes, abnormal high signal in marrow of at least two adjacent vertebrae, high-signal subligamentous or epidural masses, and cortical bone erosion. The findings in the three patients with tuberculous spondylitis included areas of increased and decreased signal intensity in vertebrae on T1-weighted images. Disk spaces were relatively spared given the extent of disease. Extraosseous soft-tissue components could be large. Bone erosion was best seen on the first echo of a T2-weighted sequence and on a water image; the latter was most reliable since it had no chemical-shift artifact. The use of gadopentetate dimeglumine could obscure or clarify MR findings, depending on the situation. T1- and T2-weighted MR images should be obtained for assessment of infectious spondylitis. STIR scans are particularly helpful. Fat images can be useful in subtle presentations, since they are very sensitive to marrow replacement, and gadopentetate dimeglumine may be helpful for epidural delineation of disease.     

Magnetic resonance imaging of multiple sclerosis: a study of pulse-technique efficacy

Forty-two patients with the clinical diagnosis of multiple sclerosis were examined by proton magnetic resonance imaging (MRI) at 0.5 T. An extensive protocol was used to facilitate a comparison of the efficacy of different pulse techniques. Results were also compared in 39 cases with high-resolution x-ray computed tomography (CT). MRI revealed characteristic abnormalities in each case, whereas CT was positive in only 15 of 33 patients. Milder grades 1 and 2 disease were usually undetected by CT, and in all cases, the abnormalities noted on MRI were much more extensive than on CT. Cerebral abnormalities were best shown with the T2-weighted spin-echo sequence (TE/TR = 120/1000); brainstem lesions were best defined on the inversion-recovery sequence (TE/TI/TR = 30/400/1250). Increasing TE to 120 msec and TR to 2000 msec heightened the contrast between normal and abnormal white matter. However, the signal intensity of cerebrospinal fluid with this pulse technique obscured some abnormalities.     

Intervertebral disk: normal age-related changes in MR signal intensity

The effect of age on the signal intensity of normal lumbar intervertebral disks was studied. Twenty-seven cadavers ranging in age from newborn to 79 years were studied with use of a 1.5-T magnetic resonance (MR) imager within 48 hours of death. The signal intensity in the central area of the disk was measured on a sagittal image obtained with a long repetition time (TR) and a long echo time (TE) and correlated to the age. A significant correlation between the decrease in signal intensity and age was found, although signal intensity changed less than 6% in 80 years. The decrease in signal intensity is concomitant with decreases in water and glycosaminoglycans and increases in collagen in the disk.     

Magnetic resonance imaging of the metastatic vertebral tumor

Fourty two patients underwent MR studies for a variety of lesions in the vertebral body. A 0.15-T MR system was employed. Twenty five patients were found to have malignant metastatic lesions (group 1); 16 had non-neoplastic lesions (group 2). The ability to discriminate between group 1 and group 2 with MR imaging was evaluated. All malignant metastatic lesions appeared as low intensity areas on both T1-weighted spin echo image and inversion recovery image, but 44 to 53% of the non-neoplastic lesions appeared as low intensity areas, respectively. The diagnostic ability with signal intensity of the vertebral column was evaluated on various pulse sequences; sensitivity of inversion recovery and T1-weighted spin echo image was 100%, in contrast specificity of these pulse sequences was 47 to 56%, overall accuracy was the highest on T1-weighted spin echo image (86%). The signal intensity of intervertebral disk was also evaluated in both groups. The intervertebral disks adjacent to the all malignant metastatic lesions showed normal intensity on both T1-weighted spin echo image and inversion recovery image, but non-neoplastic lesions showed variable intensities on images with all pulse sequences. The diagnostic ability with the signal intensities of the vertebral column and intervertebral disk was higher than that of the vertebral columns alone. Consequently accuracy was the highest in that case of both intervertebral disk and bone marrow which were imaged on T1-weighted spin echo (93%). We concluded that this diagnostic method was useful in distinguishing malignant metastatic from non-neoplastic lesions.     

腰椎椎间盘MRI T2加权信号强度变化的探讨

目的：探讨腰椎间盘Ｔ２加权ＭＲＩ信号变化与年龄、椎间隙位置和椎间盘突出的关系。材料和方法：本文收集了１６５例患者（８２５只腰椎间盘），其中正常６１９只，突出２０６只，２０１只手术证实。患者分为正常和突出两组，每组分６个年龄段；信号强度分为三型：强、不规则和低三型。检查方法均采用ＳＥ程序（ＴＲ２０００ｍｓ，ＴＥ４０，８０ｍｓ）。全部资料经统计学处理。结果：在正常椎间盘，年龄影响主要在２０岁组与３０岁至７０岁以上组，３０岁组与５０至７０岁以上组之间；椎间隙位置影响主要在腰（４－５）与腰（１－２，２－３，３－４），腰５骶１与腰１－２，２－３，３－４之间。在伴有突出的椎间盘，年龄影响主要在２０岁组与３０，６０及７０岁以上组之间：椎间隙位置影响主要在腰（４－５）与腰５骶１之间。结论：两组椎间盘信号变化均与年龄和椎间隙位置有关，各型信号的椎间盘均可发生突出。     

Diskogenic vertebral sclerosis: MR imaging

Magnetic resonance imaging findings in three patients with diskogenic vertebral sclerosis of the lumbar spine are presented. Increased signal intensity within the vertebral bodies was observed on T2-weighted images that corresponded to areas of bony sclerosis on plain radiography. Decreased signal intensity within the disk space on T2-weighted images serves to differentiate diskogenic sclerosis from infectious spondylitis.     

MR imaging of the dilated biliary tract

The magnetic resonance (MR) examinations of 18 patients with dilated bile ducts were reviewed retrospectively to determine the capability of MR to demonstrate biliary dilatation, assess MR appearance of the dilated biliary tract using spin-echo techniques, and define the optimal MR imaging parameters (repetition time [TR] and echo time [TE]) for its demonstration. On images with short TR (0.5 sec) and TE (28 msec), the dilated intrahepatic and intrapancreatic bile ducts usually had lower signal intensity compared with the surrounding liver or pancreas; on images with long TR (2.0 sec) and TE (56 msec), they had higher signal intensity. Because of the observed variation in percentage of contrast between dilated bile ducts and surrounding liver and pancreas, two imaging sequences are recommended to obtain reliable demonstration of dilated intrahepatic and intrapancreatic bile ducts. The dilated common bile duct at the level of the hepatic hilus is best seen with a short TR and TE.     

MR imaging of the female pelvis at 3 Tesla: evaluation of image homogeneity using different dielectric pads

PURPOSE: To evaluate improvements in image homogeneity in pelvic MR imaging at 3 Tesla (T) using two different dielectric pads. MATERIALS AND METHODS: A total of eight healthy females were scanned using a 3T MR scanner equipped with a body-array coil. Axial and sagittal fast spin-echo T2-weighted images (T2WI) (TR/TE = 3200 msec/94 msec), axial fast spin-echo T1-weighted images (T1WI) (TR/TE = 700 msec/11 msec), and sagittal half-Fourier acquisition single-shot turbo spin-echo (HASTE) images (TR/TE = 3000 msec/100 msec) were performed for pelvic imaging. Sequences were repeated with dielectric pads (consisting of either ultrasound [US] gel or water), and without pads. Three or four regions of interest (ROIs) were placed on fatty tissues and the ratio of minimum to maximum signal intensity (RSI) was calculated as a marker of image homogeneity. RESULTS: RSI was significantly higher on T2WI and T1WI when using dielectric pads than when no pad was used. A similar tendency was observed in RSI on HASTE. No significant difference was found between images with US gel pads and those with water pads. CONCLUSION: Dielectric pads consisting of either US gel or water are effective in improving image homogeneity of the pelvis on 3T MRI.     

Radiologic diagnosis of spondylodiscitis: role of magnetic resonance

PURPOSE: To report the Magnetic Resonance Imaging (MRI) features of acute and chronic spontaneous spondylodiscitis as well as any typical patterns which can be useful for the differential diagnosis between pyogenic and tuberculous forms. MATERIAL AND METHODS: Eleven patients affected with spontaneous spondylodiscitis were selected for the study; they were 7 men and 4 women ranging in age 33-87 years (mean: 64). We excluded the patients with iatrogenic spondylodiscitis. MR images were acquired with a superconductive magnet at 1.5, with the following sequences: sagittal PD and T2-weighted TSE, sagittal T1-weighted SE, axial PD and T2-weighted TSE for the lumbar spine, axial T2-weighted GRE for the cervical and dorsal spine and axial and sagittal T1-weighted SE after contrast agent (gadolinium DTPA) injection. MR images were reviewed by three experienced radiologists and morphological and signal intensity changes of vertebral body and disk were recorded on a standard form. In 9 patients it was possible to compare MR to CT findings. RESULTS: At the time of our observation all patients reported pain at the spine level, associated with fever and weight loss in 50% of cases and with increased values of the inflammatory markers. Three patients had infectious diseases in other organs and 2 were diabetics. Biopsy was performed in two cases only and demonstrated Staphylococcus aureus in one and Mycobacterium tuberculosis in the other patient. MRI allowed the correct diagnosis to be made in all cases, demonstrating the pathological involvement of the paravertebral structures and into the spinal canal earlier and more accurately than CT. A common finding in pyogenic and tuberculous spondylodiscitis was the low signal of the subcortical bone marrow on T1-weighted sagittal images, which enhanced after Gd-DTPA administration and became intermediate or high on T2-weighted images. Moreover, the steady high signal intensity of the disk on T2-weighted images and its contrast enhancement on T1-weighted images is typical for an acute inflammatory process. CONCLUSIONS: Based on our personal experience and literature data, we believe MRI to be the most sensitive technique for the diagnosis of spondylodiscitis in the acute phase, whereas it is comparable to CT in the chronic stage of the disease. At present MRI does not allow to differentiate pyogenic from tuberculous forms.     

The postoperative lumbar spine: enhanced MR evaluation of the intervertebral disk.

PURPOSETo document the pattern of enhancement and morphologic changes on MR images that occur in the intervertebral disk and adjacent vertebral bodies after diskectomy and to correlate the presence of intervertebral disk enhancement with the preoperative and postoperative clinical findings.METHODSPreoperatively, and at 3 months and 6 months after surgery, 94 adults who had first-time surgery for a herniated lumbar intervertebral disk that was associated with radiculopathy, expressed as leg symptoms or signs (with or without lower back pain), were asked to respond to a questionnaire regarding pain, were given serial physical examinations, and were examined with contrast-enhanced MR imaging. The measures of clinical outcome that were evaluated included the straight leg raise sign, radicular pain, and lower back pain. Type of disk herniation, intervertebral disk enhancement, disk space height, and degenerative end-plate changes were also assessed.RESULTSOf the 94 patients evaluated, 19 (20%) had postoperative intervertebral disk enhancement that was not present on the preoperative study. The pattern of enhancement was remarkably consistent, with 18 of the cases showing linear enhancement within the intervertebral disk, manifested as two thin bands paralleling the end plates. End-plate enhancement was present in 7 (37%) of the 19 patients with disk enhancement. There were no significant associations between disk enhancement and specific clinical symptoms before or after surgery.CONCLUSIONOur group of asymptomatic postoperative patients had anular enhancement (curette site), disk enhancement, and vertebral end-plate enhancement on MR images without evidence of disk space infection. This finding points out the need to understand asymptomatic postoperative changes that are sequelae of surgery and not necessarily indicators of infection.     

MRI in acute transverse myelopathy

Summary The MRI examinations of seven patients with acute transverse myelopathy (ATM) were analysed. The patients were examined 2–5 times during the course of their disease with short and long TR/TE spin-echo sequences in the sagittal projection. A previous history of autoimmune disorder and/or signs of infection at the onset of ATM were present in all cases. Cerebrospinal fluid analysis showed local synthesis of immunoglobulin in the nervous system in three cases and signs of infectious myelitis in one. During the acute phase four patients had local enlargement of the cord and all had increased signal on long TR/TE sequences. The outcome was grave in the majority of patients and there seemed to be a correlation between the degree of cord enlargement, persistence of increased signal intensity and limited recovery. Atrophy and remaining high signal intensity were noted on late MRI in patients with poor outcome. In one patient with probable anterior spinal artery occlusion, cavitation of the cord was seen.     

Brucellar spondylodiscitis: magnetic resonance imaging features with conventional sequences and diffusion-weighted imaging

Purpose

In this retrospective study, we evaluated the contribution and role of diffusion-weighted imaging (DWI) in differentiating acute and chronic forms of brucellar spondylodiscitis. We also describe the characteristics and some indistinguishable features of brucellar spondylodiscitis on magnetic resonance imaging (MRI) to emphasise the importance and limitations of MRI.

Materials and methods

MRI examinations of 25 patients with brucellar spondylodiscitis were retrospectively reviewed and analysed by two experienced radiologists. Signal and morphological changes were assessed. The imaging characteristics of acute and chronic forms of spondylodiscitis were compared. Both discriminative imaging findings of brucellar spondylodiscitis and some uncommon findings were interpreted.

Results

Of 25 patients with spinal brucellosis, eight had thoracic, ten had lumbar, five had both thoracic and lumbar and two had both lumbar and sacral vertebral involvement. We detected posterior longitudinal ligament elevation in 11 patients, epidural abscess formation in 11 and paravertebral abscess formation in nine. Ten patients had cord compression and eight had root compression. Three patients had facet-joint involvement, and one had erector spinae muscle involvement. Eight patients (32%) were in the acute stage, six (24%) in the subacute stage and 11 (44%) in the chronic stage. Vertebral bodies, vertebral end plates and intervertebral disc spaces were hypointense and hyperintense in the acute stage, whereas they were hypointense and heterogeneous in the subacute and chronic stages on T1- and T2-weighted images, respectively. In the acute stage on the DWI series, vertebral bodies, end plates and discs were all hyperintense but hypointense in the chronic stage.

Conclusions

Although conventional MRI has several advantages over other imaging modalities and is very useful in the differential diagnosis between brucellar spondylodiscitis and other spinal pathologies, it has some difficulties in discriminating acute and chronic forms of spondylodiscitis. DWI is a sensitive, fast sequence that has the potential for differentiating acute and chronic forms of spondylodiscitis, which makes it crucial in spinal imaging.     

Central nervous system magnetic resonance imaging findings in neuro-Beh?et syndrome

In a patient with neuro-Beh?et (N-B) syndrome, MRI images obtained with TR 2000 msec, and TE 80 msec showed an increased signal intensity in the brain stem corresponding to the neurological symptoms. In N-B syndrome, the brain stem has been documented as a main site of the lesion, and MRI shows promise as a useful technique in the diagnosis of this disease.     

The value of MRI in the diagnosis of postoperative spondylodiscitis

We evaluated the role of MRI in the diagnosis of postoperative spondylodiscitis. Spondylodiscitis is a serious complication of surgery, and the diagnosis frequently depends on a combination of clinical, laboratory and imaging findings. We compared the MRI findings in six patients with biopsy- or surgery-proven spondylodiscitis with those in 38 asymptomatic postoperative patients. Contrast enhancement and signal changes in the intervertebral disc or the vertebral endplates are not specific for spondylodiscitis, being also seen in the asymptomatic patients. However, absence of Modic type 1 changes, of contrast enhancement of the disc or of enhancing paravertebral soft tissues suggests that the patient does not have spondylodiscitis. MRI appears more useful for exclusion than for confirmation of postoperative spondylodiscitis. Received: 3 September 1999 Accepted: 25 November 1999     

Cervical spine: MR imaging with a partial flip angle, gradient- refocused pulse sequence. Part II. Spinal cord disease

A magnetic resonance imaging pulse sequence (GRASS) with a short repetition time (TR), short echo time (TE), partial flip angle, and gradient refocused echo was prospectively evaluated for the detection of cervical cord disease that caused minimal or no cord enlargement in eight patients. Sagittal T2-weighted, cerebrospinal fluid (CSF)-gated images and sagittal and axial GRASS images were obtained in all patients. The following GRASS parameters were manipulated to determine their effect on signal-to-noise ratio (S/N) and contrast: flip angle (4 degrees-18 degrees), TR (22-50 msec), and TE (12.5-25 msec). Flip angle had the greatest effect on S/N and contrast. There were no differences between axial and sagittal imaging for the spinal cord or lesion. However, because the signal intensity of CSF did differ on sagittal and axial images and because this influenced the conspicuity of lesions, there was a difference in the useful flip angle range for axial and sagittal imaging. No one set of imaging parameters was clearly superior, and in all patients, the gated image was superior to the sagittal GRASS image in lesion detection. GRASS images should be used in the axial plane primarily to confirm spinal cord disease detected on sagittal CSF-gated images. For this, a balanced approach is suggested (TR = 40 msec, TE = 20 msec, with flip angles of 4 degrees-6 degrees for sagittal and 6 degrees-8 degrees for axial imaging).     

MR signal intensity of parathyroid adenomas: correlation with histopathology

Recent experience has shown that parathyroid adenomas vary in their MR signal intensity, which raises the question of whether the signal intensity is related to different histologic characteristics. In order to address this question, 10 patients who had MR imaging studies (four at 0.35 T, six at 1.5 T) showing large- to medium-sized parathyroid adenomas and who subsequently underwent surgery with histologic proof of the lesion were evaluated. The MR appearance was compared with histologic characteristics. The adenomas were classified into three groups according to the MR appearance: group I, low signal intensity on short TR/TE images, high signal intensity on long TR/TE images (n = 5); group II, low signal intensity on short and long TR/TE images (n = 3); group III, high signal intensity on short and long TR/TE images (n = 2). Histologic analysis revealed that the major features of each group were different. High cellularity without degeneration or fibrosis was observed for all five adenomas from group I. In group II, all three adenomas showed cellular degenerative changes, old hemorrhage with hemosiderin-loaded macrophages, and/or fibrosis. In group III, both adenomas showed evidence of acute hemorrhage without significant degenerative or fibrotic changes. These data suggest that the signal intensity of parathyroid adenomas on T1- and T2-weighted images corresponds at least in part to differences in histologic composition.