The Use of Magnetic Resonance Imaging to Predict the Clinical Outcome of Non-Surgical Treatment for Lumbar Interverterbal Disc Herniation

OBJECTIVE: We wanted to investigate the relationship between the magnetic resonance (MR) findings and the clinical outcome after treatment with non-surgical transforaminal epidural steroid injections (ESI) for lumbar herniated intervertebral disc (HIVD) patients. MATERIALS AND METHODS: Transforaminal ESI were performed in 91 patients (50 males and 41 females, age range: 13-78 yrs) because of lumbosacral HIVD from March 2001 to August 2002. Sixty eight patients whose MRIs and clinical follow-ups were available were included in this study. The medical charts were retrospectively reviewed and the patients were divided into two groups; the successful (responders, n = 41) and unsatisfactory (non-responders, n = 27) outcome groups. A successful outcome required a patient satisfaction score greater than two and a pain reduction score greater than 50%. The MR findings were retrospectively analyzed and compared between the two groups with regard to the type (protrusion, extrusion or sequestration), hydration (the T2 signal intensity), location (central, right/left central, subarticular, foraminal or extraforaminal), and size (volume) of the HIVD, the grade of nerve root compression (grade 1 abutment, 2 displacement and 3 entrapment), and an association with spinal stenosis. RESULTS: There was no significant difference between the responders and non-responders in terms of the type, hydration and size of the HIVD, or an association with spinal stenosis (p > 0.05). However, the location of the HIVD and the grade of nerve root compression were different between the two groups (p < 0.05). CONCLUSION: MRI could play an important role in predicting the clinical outcome of non-surgical transforaminal ESI treatment for patients with lumbar HIVD.

Radiological Evaluation of Percutaneous Endoscopic Lumbar Discectomy: A Three-Year Follow-Up Study

PURPOSE: We wanted to analyze the radiological changes of the patients who underwent percutaneous endoscopic lumbar discectomy (PELD) for treating soft disc herniation. MATERIALS AND METHODS: We retrospectively reviewed 30 patients (32 cases) who were observed for a minimum of 3 years after they underwent PELD. The authors investigated the postoperative radiological changes after PELD and the related clinical outcomes. All the patients received plain X-rays, CT and MRI both preoperatively and at the final follow-up. The radiological parameters were evaluated, including the disc height, the disc signal intensity, the subchondral marrow signal intensity, the sagittal plane instability and the facet joint osteoarthritis. RESULTS: The average amount of removed disc was 1.363 g and a significant correlation was detected between the narrowing of disc height and the amount of removed disc. Although the disc height and the disc height ratio were significantly decreased (-0.97 mm and 86.9%, respectively), the angle of sagittal rotation was well maintained. There were 18 (56.3%) cases of disc signal changes, six cases (18.8%) of subchondral marrow signal changes, and three cases (9.4%) of facet joint osteoarthritis. The success rate was 90.6%. CONCLUSION: Although disc height narrowing was observed, there was no postoperative instability and the overall clinical outcome was satisfactory. Our results show that PELD is a useful and minimal invasive procedure for the selected patients who are suffering with lumbar disc herniation.

Lumbar Internal Disc Derangement in Patients with Chronic Low Back Pain: Diagnostic Value of the MR Imaging Findings as Compared with Provoked Discography as the Standard

PURPOSE: The aim of this study was to evaluate the diagnostic value of the MR Imaging findings with provoked discography used as the standard for painful lumbar disc derangement. MATERIALS AND METHODS: Two hundred patients (412 discs), (age range: 21-77 years), with chronic low back pain underwent MRI and provoked discography. We evaluated the MRI T2-WI findings such as disc degeneration, high-Intensity zones and endplate abnormalities. Subsequently, provocative discography was independently performed with using MR imaging, and a painful disc was defined when moderate to severe and concordant pain was provoked. We calculated the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of the MRI findings with using provoked discography as the standard. RESULTS: 400 discs showed abnormal findings such as disc degeneration, HIZ and endplate abnormalities on the T2-WI images. 12 discs showed normal findings. HIZ or endplate abnormalities were always combined with disc degeneration. The prevalence of each findings were disc degeneration (400 discs: 97.1%), HIZ (111 discs: 26.9%), type I endplate abnormalities (34 discs: 8.3%), type II endplate abnormalities (75 discs: 18.2%), the combined findings of HIZ and type I endplate abnormalities (2 discs: 0.5%) and the combined findings of HIZ and type II endplate abnormalities (7 discs: 1.7%). The disc degeneration showed high sensitivity (99.5%) and low specificity (5.0%), so only the NPV (91.7%) was significant, and not the PPV (47.8%). Each findings of HIZ (sensitivity, 36.5%; specificity, 81.4%; PPV, 63.18%; NPV, 59.5%), type I endplate abnormalities (11.0%, 94.1%, 61.8% and 54.8%, respectively), type II endplate abnormalities (19.8%, 83.2%, 50.7% and 54.3%, respectively), the combined findings of HIZ and type I endplate abnormalities (0.5%, 99.6%, 50.0% and 53.4%, respectively) and the combined findings of HIZ and type II endplate abnormalities (26.0%, 99.1%, 71.4% and 53.8%, respectively) show high specificity, but low sensitivity, so the PPV and NPV were also not significant. CONCLUSION: For diagnosing painful lumbar disc derangement, the MR imaging findings seem to be inadequate as predictive factors when provoked discography was used as the standard.

Value of Preoperative Cervical Discography

PURPOSE: The aim of this study was to describe the method and the value of cervical discography as correlated with the MR findings. MATERIALS AND METHODS: Twenty-one discs in 11 consecutive patients who underwent cervical discography were analyzed. MR and CT discography (CTD) were performed in all patients. Discography was performed after swallowing barium for visualizing the pharynx and the esophagus to prevent penetration. We also analyzed the preceding causes of the subjects' cervical pain. The results of the pain provocation test were classified into concordant pain, discordant pain and a negative test. MRI was analyzed according to the T2-signal intensity (SI) of the disc, disc height, annular bulging and disc herniation. The CTD was analyzed for degeneration or radial tear of the disc, epidural leakage of the contrast agent and pooling of the contrast agent at the periphery of the disc. The pain provocation tests were correlated with the MR and CTD findings. We used the chi-square test to analyze the results. RESULTS: Concordant pain was observed in 14 cases, discordant pain in 3 cases and there were negative tests in 4 cases. There were no complications related to the procedure. Four patients had undergone anterior cervical fusion and four patients had pain that developed after traffic injuries. The decreased T2-SI and annular bulging on MRI, disc degeneration and peripheral pooling of the contrast agent on CT were significantly correlated with pain provocation. CONCLUSION: When the diagnosis of disc disease is difficult with performing MRI, cervical discography with using swallowed barium solution to reduce the penetration of the esophagus or hypopharynx may play be helpful. The decreased T2-SI and annular bulging on MRI correlated significantly with a positive result on the pain provocation test.

Intradural Cervical Disc Herniation: A Case Report

Intradural cervical disc herniation is an extremely rare condition and its pathogenesis is not certain. We experienced a case of intradural cervical disc herniation at the C4-5 level in a 56-year-old man. The preoperative sagittal T1- and T2- weighted images revealed an intradural iso-intensity lesion, with the spinal cord behind the posterior longitudinal ligament at the C4-5 disc level. The post-contrast T1-weighted image revealed a peripheral enhanced intradural lesion. We report here on a case of an intradural cervical disc herniation that was diagnosed by radiological examination, and we include a review of the related literature.

Internal Disc Derangement in Patients with Low Back Pain: Correlation of MR Imaging and Provocative Discography and CT Discography

PURPOSE: The aim of this study was to correlate the MR imaging abnormalities of the lumbar intervertebral discs, with emphasis being placed on the high intensity zone (HIZ) with the use of discography for pain provocation and disc morphologic evaluation of the disc. MATERIALS AND METHODS: Consecutive patients with low back pain unresponsive to conservative treatment, and who were being considered for spinal fusion had MRI performed, and this was followed by lumbar discography. The MR imaging, discography and CT discography (CTD) were evaluated for all of the 19 patients. Forty-three lumbar discs in 19 patients were included in this study. The findings of MR and CTD images were evaluated retrospectively with the professional opinion and agreement of two radiologists. MR images were assessed for the presence or absence of decreased T2-wighted signal intensity, decreased disc height, annular bulging, HIZ on T2-weighted images and disc herniation. The results of pain provocation were graded as 0, nonconcordant pain; 1, definite pain, but only as part of the symptom complex; 2, concordant pain. The morphology of CTD was analyzed for presence or absence of disc degeneration, radial tearing and extravasation of the contrast agent. The presence of radial tearing was defined as contrast extension to the outer third of the annulus. The prevalence of all MR abnormalities was calculated, and the data were compared with disc morphologic characteristics and the pain response on provocative discography. We used the chi-square test to analyze the results. RESULTS:Grade 1 and 2 discogenic pain was observed in 8 (19%) and 12 disc levels (28%), respectively. All of the seven non-degenerated discs on MR had no pain response. The decreased SI on T2-weighted image, annular bulging and HIZ were significantly correlated with discogenic pain. Extravasation of contrast media had good correlation with annular bulging and disc herniation on MRI. Radial tearing on CT discography correlated significantly with HIZ. The HIZ was detected in 14 levels (32.6%). The HIZ on MRI correlated significantly with the pain provocation and radial tearing noted on the discograms. CONCLUSION: Several MR imaging findings correlated significantly with the severity of pain provocation to discography. For patients with symptomatic low back pain, the HIZ observed on MR may represent a painful outer annular disruption.

Comparison of MRI and Discography in Disc Extrusion: Low Signal Intensity Change in the Anterior Epidural Space at Sagittal T1-weighted Imaging

PURPOSE: To determine the significance of low signal intensity change in the anterior epidural space at sagittal T1-weighted (ST1WI) magnetic resonance imaging (MRI) of patients in whom discography revealed disc extrusion, and to correlate interruption of the solid dark line seen at sagittal T2-weighted imaging (ST2WI) with discographic findings of extrusion. MATERIALS AND METHODS: One hundred and forty-two patients (159 cases) with lumbar disc disease proven at MRI underwent discography. Disc extrusion was diagnosed in cases in which contrast media leaked into the anterior epidural space. The findings of ST1WI were used to determine whether low signal intensity change had occurred in the anterior epidural space between the posterior aspect of the vertebral body and the posterior longitudinal ligament, and whether ST2WI depicted interruption of the solid dark line at the posterior aspect of the disc was also assessed. RESULTS: At discography, disc extrusion was diagnosed in 134 of 159 cases. At ST1WI, low signal intensity change was noted in 75 (56%) of the 134 cases, and at ST2WI interruption of the solid dark line was observed in 63 (47%). In the remaining 25 cases, there was no evidence of disc extrusion, and at ST2WI the solid dark line was well-preserved. At ST1WI, 22 (88%) of 25 cases showed normal signal intensity in the anterior epidural space, but in the remaining three, low signal intensity change was evident. Correlation between the findings of MRI and discography was statistically significant. CONCLUSION: In disc disease, low signal intensity change at ST1WI, as well as interruption of the solid dark line seen at ST2WI, are useful indicators of disc extrusion.

The Influence of Changes in Cervical Lordosis on Bulging Disk and Spinal Stenosis: Functional MR Imaging

PURPOSE: To assess the effect of lordotic curve change of the cervical spine on disk bulging and spinal stenosis by means of functional cervical MR imaging at the flexion and extension position. MATERIALS AND METHODS: Using a 1.5T imager, kinematic MR examinations of 25 patients with degenerative spondylosis (average age, 41 years) were performed at the neutral, flexed and extended position of the cervical spine. Sagittal T2-weighted turbo spin-echo images were obtained during each of the three phases. Lordotic an-gle, bulging thickness of the disk, AP diameter of the spinal canal, and distance between the disk and spinal cord were measured on the workstation at each disk level. After qualitative independent observation of disk bulging, one of four grades(0, normal; 1, mild; 2, moderate; 3, marked) was assigned at each phase, and after further comparative observation, one of five scores (-2, prominent decrease; -1, mild decrease; 0, no change; 1, notable increase; 2 prominent increase) was also assigned. In addition, bulging thickness of the disk was measured and compared at the neutral, flexed, and extended positions. RESULTS: Average angles of the cervical spine were 160.5+/-5.9 degrees (neutral position, lordotic angle); 185.4+/-8.5 degrees (flexion, kyphotic angle); and 143.7+/-6.7 degrees (extension, lordotic angle). Average grades of disk bulging were 0.55 at the neutral position, 0.16 at flexion, and 0.7 at extension. Comparative observation showed that average scores of disk bulging were -0.39 at flexion and 0.31 at extension. The bulging thickness of the disk decreased by 24.2% at flexion and increased by 30.3% at extension, while the diameter of the spinal canal increased by 4.5% at flexion and decreased by 3.6% at extension. The distance from the posterior margin of the disk to the anterior margin of the spinal cord decreased at both flexion(6.6%) and extension(19.1%). CONCLUSION: Functional MRI showed that compared with the neutral position, disk bulging and spinal stenosis are less prominent at flexion and accentuated at extension. The results demonstrate the need to consider the extent to which changes in the cervical lordotic curve affect the degree of disk bulging and spinal stenosis.

Regional Disc Change in Segmental Hypoplasia of the Lumbosacral Vertebral Bodies: MR Findings

PURPOSE: To classify types of vertebral hypoplasia and to investigate the prevalence and patterns of associated disc degeneration. MATERIALS AND METHODS: Defining vertebral hypoplasia as occurring when the AP diameter of a lower vertebral body is smaller than that of an upper ones, we retrospectively reviewed the MR images obtained in 34 cases of this condition invloving young adults. Two major types and two subtypes, a total of four different entities were classified as follows; type I: hypoplasia involving a single vertebral body; type II: hypoplasia in-volving serial lower segmental vertebral bodies; subtype a: hypoplastic body located anteriorly along the anterior spinal line; subtype b: hypoplastic body located posteriorly along the posterior spinal line. We also investigated each type of vertebral hypopla-sia and patterns of associated disc changes. RESULTS: Three different types were observed. In type IIa(n= 29), posterior disc occurred in 8/29 cases, diffuse degeneration in 21/29 patients, and posterior disc herniation in all. All type Ia cases(3/3) showed diffuse disc degeneration at both upper and lower disc levels, with posterior disc herniation, while both type IIb cases(2/2) showed diffuse disc degeneration, with bidirectional disc herniation. CONCLUSION: By identifying the exact patterns of vertebral hypoplasia, we were able to predict which portion of the disc was likely to degenerate.

High Signal Intensity on T1-Weighted MR Image Related to Vacuum Cleft in the Intervertebral Disk: Clinical and Phantom Study

PURPOSE: To determine the possible mechanism by which an area of high signal intensity appears on T1-weighted MR images adjacent to a vacuum cleft in intervertebral disks. MATERIALS AND METHODS: We analyzed a total of 14 disks in nine patients in whom a vacuum cleft with T1-signal hyperintensity was observed. Lesions were present from T11-12 to L5-S1 using a 1.5-T whole-body imager, sagittal spine-echo T1-weighted and gradient-echo images (flip angle, 20 'and 60 ) were obtained. In order to identify the vacuum cleft, using plain radiographs in all patients and CT scans in two were also obtained. A 3% agar-gel block containing empty slits to form a magnetic susceptibility difference, a phantom was designed. The air spaces were 1.6 mm in thickness, 25 mm in width, and 20 to 25 mm in depth with 1.6-mm spacing. RESULTS: In all patients, vacuum clefts were confirmed by plain radiographs and CT scans. At the level containing air, T1-weighted images (both spin-echo and gradient-echo) showed a signal void resulting from the intervertebral disk vacuum cleft. A hyperintense band adjacent to the vacuum cleft was, however, observed. A gradient-echo image with a 60 'flip angle showed a brighter signal intensity than one with a 20 'angle. Our phantom study gave the same results. CONCLUSION: The magnetic susceptibility artifact may be responsible for the T1-signal hyperintensity observed adjacent to the vacuum cleft in intervertebral disks. In addition, in order to generate signal hyperintensity, the desiccating disk material must contain a certain amount of water molecules.

High Signal Intensity on T1-Weighted MR Image Related to Vacuum Cleft in the Intervertebral Disk: Clinical and Phantom Study

PURPOSE: To determine the possible mechanism by which an area of high signal intensity appears on T1-weighted MR images adjacent to a vacuum cleft in intervertebral disks. MATERIALS AND METHODS: We analyzed a total of 14 disks in nine patients in whom a vacuum cleft with T1-signal hyperintensity was observed. Lesions were present from T11-12 to L5-S1 using a 1.5-T whole-body imager, sagittal spine-echo T1-weighted and gradient-echo images (flip angle, 20 'and 60 ) were obtained. In order to identify the vacuum cleft, using plain radiographs in all patients and CT scans in two were also obtained. A 3% agar-gel block containing empty slits to form a magnetic susceptibility difference, a phantom was designed. The air spaces were 1.6 mm in thickness, 25 mm in width, and 20 to 25 mm in depth with 1.6-mm spacing. RESULTS: In all patients, vacuum clefts were confirmed by plain radiographs and CT scans. At the level containing air, T1-weighted images (both spin-echo and gradient-echo) showed a signal void resulting from the intervertebral disk vacuum cleft. A hyperintense band adjacent to the vacuum cleft was, however, observed. A gradient-echo image with a 60 'flip angle showed a brighter signal intensity than one with a 20 'angle. Our phantom study gave the same results. CONCLUSION: The magnetic susceptibility artifact may be responsible for the T1-signal hyperintensity observed adjacent to the vacuum cleft in intervertebral disks. In addition, in order to generate signal hyperintensity, the desiccating disk material must contain a certain amount of water molecules.

Usefulness of Dynamic Contrast Enhanced Lumbar Spine MR Imaging in Postoperative Herniated Lumbar Disc

PURPOSE: To compare the usefulness of dynamic contrast enhanced lumber spine MR Imaging with that ofconventional delayed contrast enhanced MR imaging in the assessment of postoperative herniated lumbar disc. MATERIALS AND METHODS: Forty-one postoperative herniated lumbar disc (HLD) lesions of 32 patients with back painwere examined with MR imaging(1.5T, Vision, Siemens, Germany). Five-phase dynamic 2D FLASH sagittalimages(TR/TE=118.1 msec) was obtained every 19 seconds with a 4 minutes delayed image after contrast injection. Asseen on delayed images, the discs were assessed as recurred, fibrosis, or no change. On dynamic images, thepattern of enhancement was evaluated as follows : Type I(no change in peripheral disc enhancement between theearly and late phase);or Type II(minimal internal extension of marginal smooth enhancement during the latephase);or Type III(marked internal extension f peripheral irregular enhancement). Dynamic and delayed imaging werecompared, and early epidural space enhancement with rapid wash-out was also evaluated. RESULTS: of 41postoperative HLDs, 39 lesions showed peripheral contrast enhancement. Evaluation depended on delayed imaging, andwas as follows:recurred HLD(n=27);fibrosis(n=5);no change in postoperative disc(n=7). On dynamic contrast-enhancedimaging, enhancement patterns were Type I(n=29), Type II(n=7), and Type III(n=3). In 29 Type-I lesions, there wereno significant differences in image findings between dynamic and delayed images. However, in the lesions(typeII:n=7, type III:n=3), findings additional to those revealed by delayed images were demonstrated by dynamiccontrast-enhanced MR imaging. Nine of the ten Type-II and III lesions were diagnosed as recurred HLD. On dynamicOn dynamic images, five lesions showed early epidural space enhancement. CONCLUSION: dymamic contrast-enhancedlumbar spine MR imaging provided additional findings such as increased peripheral disc enhancement, and epiduralspace enhancement, which cannot be detected on conventional delayed images. Inrecurred postoperative herniatedlumbar discs, these findings are frequent.

MR Imaging Findings of Lumbar Scheuermann's Disease: Correlation with Disk Pathologies

PURPOSE: To describe the MR imaging findings of lumbar Scheuermann's disease and to determine therelationship between various MR imaging findings of this disease and disk pathologies. MATERIALS AND METHODS: Weretrospectively evaluated the MR imaging findings of 13 patients under the age of 20 with lumbar Scheuermann'sdisease. One hundred and four vertebral bodies and 91 intervertebral disks were included in the study. The imagingfindings were analyzed with particular emphasis on the wedging of vertebral bodies, Schmorl's nodes, and theheight of intervertebral disks. The relationship between these findings and disk degeneration or herniation wasevaluated. RESULTS: Lumbar Scheuermann's disease was classified into two types according to Blumenthal'sclassification. Seven patients were type I and six were type II. Disk degeneration and herniation were identifiedin 28.6% (26/91) and 20.9% (19/91), respectively, of intervertebral disks. In type I, wedging of the vertebralbodies was noted in 48.2% of cases(27/56) and degeneration and herniation of adjacent disks were identified in24.1% (7/29) and 13.8% (4/29), respectively. Central Schmorl's nodes were identified in 29.5% (33/112) ofend-plates and degeneration and herniation of adjacent disks in 34.8% (8/23) and 17.4% (4/23), respectively. Intype II, anterior Schmorl's nodes were found in 11.5% (11/96) of end-plates and degeneration and herniation ofadjacent disks in 100% (10/10) and 70% (7/10), respectively. Decreased height of intervertebral disks was notedadjacent to the anterior Schmorl's nodes ; all were related to disk degeneration and 70% (7/10) to diskherniation. There was statistically significant correlation between anterior Schmorl's node, decreased height ofintervertebral disk and adjacent disk pathologies (p0.05). CONCLUSION: In lumbar Scheuermann's disease, anterior Schmorl's nodeand decreased height of an intervertebral disk are related to disk degeneration and herniation. MR is useful forthe evaluation of disk pathologies as well as changes in vertebral bodies.

Lumbar Disc Herniation at High Levels: MRI and Clinical Findings

PURPOSE: To assess the frequency, location, associated MR findings, and clinical symptoms of the high levellumbar disc herniation(HLDH). MATERIALS AND METHODS: A total of 1076 patients with lumbar disc herniation wereretrospectively reviewed. MR images of 41 of these with HLDH(T12-L1, L1-2, L2-3) were analysed in terms offrequency, location, and associated MR findings, and correlated with clinical symptoms of HLDH. RESULTS: Theprevalence of HLDH was 3.8%(41/1076). HLDH was located at T12-L1 level in four patients(10%), at L1-2 level in14(34%), at L2-3 level in 21(51%), and at both L1-2 and L2-3 levels in two. The age of patients ranged from 20 to72 years (mean, 44), and there were 26 men and 16 women. In 11(27%), whose mean age was 32 years, isolated discherniation was limited to these high lumbar segments. The remaining 30 patients had HLDH associated with variableinvolvement of the lower lumbar segments. Associated lesions were as follow : lower level disc herniation(14patients, 34%); apophyseal ring fracture(8 patients, 19%); Schmorl's node and spondylolisthesis (each 6patients, each 14%); spondylolysis(3 patients, 7%); and retrolisthesis(2 patients, 5%). In 20 patients(49%) withHLDH(n=41), there was a previous history. CONCLUSION: Patients with HLDH showed a relatively high incidence ofassociated coexisting abnormalities such as lower lumbar disc herniation, apophyseal ring fracture, Schmorl'snode, spondylolysis, and retrolisthesis. In about half of all patients with HLDH there was a previous history oftrauma. The mean age of patients with isolated HLDH was lower; clinical symptoms of the condition were relativelynonspecific and their incidence was low.

MR Findings of Large Schmorl's Nodes

PURPOSE: To demonstrate the MR findings of large Schmorl's nodes(>1 cm). Method and Materials: Six hundredpatients underwent MRI and the results were retrospectively analysed. Eleven patients(1.83%) had 12 largeSchmorl's nodes. We analyzed the size, contour, location, signal changes and enhancement of these, as well asmarrow changes in adjacent vertebral bodies. RESULTS: Twelve large Schmorl's nodes were found in eleven of 600patients(1.83%) with a mean age of 46.1 years and a female : male ratio of 4 : 7. Their mean size was 1.35 cm(AP)x 0.99 cm(height) x 1.23 cm(transverse), and they were observed at various sites, namely lower(n=7) and upperend-plate locations(n=5). Central locations(n=8) on end-plates were most common. A semi-lunar appearance was notedin seven cases, and in most, a well-demarcated irregular margin was seen. All large Schmorl's nodes were enhanced; peripheral forms(n=8) were more common than diffuse(n=4). Adjacent discs showed no intranuclear enhancement butin seven cases there was flat-contoured enhancements in the annulus fibrosus. In disks with large Schmorl's nodes,degeneration was noted on T2WI regardless of the degree of diskal herniation. In nearly all cases, signalintensity on T1WI was low, but on T2WI, this was variable. Large Schmorl's nodes showed characteristic marrowchange in adjacent vertebral bodies ; the most common pattern was fatty and sclerotic(n=8). Especially onT1-weighted axial images, target appearances were visible in ten cases. CONCLUSION: MR findings of Schmorl'snodes will be very useful for differentiating nodes from other vertebral or diskal lesions, especially spondylitiscombined with diskitis or vertebral body tumor.

Schmorl's Nodes of the Lumbar Spine: Are They Simply Normal

PURPOSE: To evaluate the accompanying abnormal findings of Schmorl's nodes(SN), a normal variants of thelumbar spine. MATERIALS AND METHODS: Seventy-five patients with one or more SN, as seen on lumbar spine MRI werestudied. Using a 1.5T MR unit, the number and location of SN, their site of the end plate, adjacent disc changesand lesion associated and not associated with SN, and accompanying associated bony spinal stenosis wereretrospectively investigated. RESULTS: Among the 75 patients, 230 SN were noted in 375 vertebral bodies; theywere relatively frequently located on the second(65, 28.2%) and third(65, 28.2%) lumbar vertebrae. The most commonend-plate site of SN was the posterior one-third portion(160;69.6%). In 450 discs of these 75 patients, 172lesions were noted;those associated with SN(76/167, 45.5%) was more common than those not thus associated (96/283,33.9%)(p <0.05), and those associated with SN were relative frequently located on intervertebral disc L2-3 orL3-4(p <0.05). Thirty-seven SN (16.1%) were associated with bony spinal stenosis. CONCLUSION: Because it isfrequently associated with disc lesions and bony spinal stenosis, SN of the lumbar spine may be a pathologiccondition rather than a normal variant.

MR Imaging of Herniated Lumbar Disc: Morphologic Change between Supine and Flexed-Prone Position

PURPOSE: To determine morphologic change in a herniated lumbar disc, as seen on MR imaging, according to position change (supine and flexed-prone positions). MATERIALS AND METHODS: A hundred and twenty-two patients with herniated lumbar discs , as seen on supine MR imaging, underwent repeat MR imaging in the flexed-prone position; 100 patients, who showed more than 2 degrees of flexion angle difference, were included in this study. Sixty-two were men and thirty-eight were women, and their ages ranged from 13 to 59 (mean, 30) years. Disc degeneration was graded as 1, 2, or 3, depending on the area of decreased signal intensity seen on a T2-weighted MR image. Difference in the angle of flexion is defined as the angle difference of lumbar curvature, calculated by the Begg-Falconer method in supine and flexed-prone positions. Morphologic changes in herniated discs in different positions were analysed on the basis of shape change of anterior epidural spaces, thecal sacs and posterior margins of herniated discs, and classified as either A (not changed) or B (changed). Group B was subtyped as type I (decreased herniation without change of shape), type II (decreased herniation with change of shape) or type III(increased disc herniation). We statistically analysed correlation between a patient's age, morphologic change in a herniated disc in different positions, and degree of degeneration in such a disc, as well as the correlation between morphologic change in a herniated disc in different positions and the degree of the flexion angle. RESULTS: Disc degeneration was apparent in 99 of 100 patients. Grades 1, 2, and 3 were seen in 32 (32.3%), 49 (49.5%), and 18 (18.2%) patients, respectively; the difference in the angle of flexion ranged from 2 to 24 degrees (mean 7.97; SD=6.20). Group A consisted of 37 (37.4%) patients, and group B of 62 (62.6%) (type I in 29 (29.3%), type II in 27 (27.3%), and type III in 6 (6.0%)). There was no significant statistical correlation between a patient's age and morphologic change in a herniated disc in different positions (correlation coefficient=0.0183; p=0.086), and between the degree of degeneration of a herniated disc and morphologic change in such a disc in different positions (correlation coefficient=0.1736; p=0.249). The mean angle of flexion was 5.15 degrees (SD=4.94) in group A and 10.06 degrees (SD=6.28) in group B; there was significant statistical correlation between this and morphologic change in a herniated disc (p=0.0017). CONCLUSION: In the flexion-prone position, which is similar to that used during surgery, MRI can reveal various morphologic changes in a herniated lumbar disc, mainly decreased herniation, and is helpful in making decisions related to surgery.

The Analysis of MR Findings of the Postoperative Diskitis

PURPOSE: To evaluate MR findings of postoperative diskitis following operation for intervertebral disk herniation. MATERIALS AND METHODS: Twelve cases with postoperative diskitis following operation for intervertebral disk herniation were included in this study. MR findings of postoperative diskitis were analysed to determine 1) the extent and pattern of alteration of the involved disks, 2) the pattern of destruction of endplates and vertebral bodies, and 3) the pattern of inflammatory extension into the surrounding soft tissue. RESULTS: 1) Disk alteration developed mainly at the middle and posterior portions of the disk, and was characterized by loss of intranuclear cleft at the involved portion of the disk and intranuclear abscess formation 2) Vertebral bodies involved ware symmetrically adjacent to involved disks and in three cases, bone abscesses within the endplates were detected. 3) The extension of inflammation yielded prevertebral or pre-/paravertebral masses (7 cases), epidural abscesses (5 cases), arachnoiditis (6 cases), and inflammatory masses (2 cases) beneath the posterior longitudinal ligament. CONCLUSION: Disk involvement was mainly at the middle and posterior portions of the disks, and there was accompanying intranuclear cleft loss. Symmetric involvement of the vertebral bodies adjacent to the involved disks was noted.

CT-Discography: Diagnostic Accuracy in Lumbar Disc Herniation and Significance of Induced Pain During Procedure

PURPOSE: To evaluate the usefulness and the accuracy of CT-discography in lumbar disc disease by analyzing the findings of CT-discogram and types of evoked pain during the procedure. MATERIALS AND METHODS: CT-discograms were retrospectively evaluated in 47 intervertebral discs of 20 patients with multilevel involvement of lumbardisc diseases. In 28 herniated discs confirmed at surgery, the findings of CT-discogram (28 disc levels/20 patients), MRI(23/16) and CT(21/15) were comparatively analysed. The type of pain after infusion of contrast mediaduring CT-discography was compared with that prior to the procedure. RESULTS: The accuracy for determining typesof the herniated lumbar disc when compared with postoperative results was 96.4%(27 discs/28 discs) in the CT-discogram, 82.6%(19 discs/23 discs) in MRI and 71.4%(15 discs/21 discs) in the CT scan. Pains encountered during discography were radiating pain in 12 discs and back pain in 24 discs. CT-discography was especially helpful in 10 patients with multilevel involvement of the lumbar disc diseases to evaluate the exact location of diseased disc(s) that provoked the pain. CONCLUSION: CT-discography is a highly accurate method in diagnosis ofthe herniated lumbar intervertebral discs and is very useful in determining the precise location related to the development of pain in such cases.

Gd-DTPA Enhancement of Lumbar Discs on MRI: Frequency and Pattern

PURPOSE: To assess the frequency and pattern of disc enhancement of lumbar spine on enhanced MR images and to determine whether enhanced MR images are useful for locating internal disc lesions. MATERIALS AND METHODS: MR images of a total of 225 discs from 45 patients were reviewed. Fifteen discs from 15 patients who had previously undergone an operation were excluded and 210 discs were therefore studied. T1-, T2-, and gadolinium-enhanced T1-weighted images were obtained after intravenous injection of Gd-DTPA(0.2 ml/kg). Findings were analyzed retrospectively. RESULTS: Sixty-nine(32.6%) of 210 discs showed enhancement. The pattern of enhancement was intradiscal(linear or nodular) or extradiscal. Of 165 morphologically normal discs, 34(20.6%) discs were enhanced; 32 showed linear and two showed nodular enhancement. All of six ruptured discs were enhanced. Six patients were operated on after MRI study ; one case of intradiscal linear enhancement revealed a bulging disc, three of five patients were confirmed on surgery as having ruptured discs in view of the extradiscal enhancement and the other two patients were confirmed having protruded discs. CONCLUSION: The pattern of disc enhancement is classifiedinto intradiscal and extradiscal. The former is further classified into linear and nodular. Gd-DTPA enhanced MRimages may be helpful in diagnosing ruptured discs and in detecting pathologic conditions in those patients whose discs appear to be morphologically normal before enhancement.