Observer variation in MRI evaluation of patients suspected of lumbar disk herniation

OBJECTIVE: Our objective was to assess observer variation in MRI evaluation in patients suspected of lumbar disk herniation. SUBJECTS AND METHODS: Two experienced neuroradiologists independently evaluated 59 consecutive patients with lumbosacral radicular pain. Per patient, three levels (L3-L4 through L5-S1) and the accompanying roots were evaluated on both sides. For each segment, the presence of a bulging disk or a herniation and compression of the root was reported. Images were interpreted twice: once before and once after disclosure of clinical information. Interobserver agreement was expressed as unweighted kappa values. RESULTS: Without clinical information, interobserver agreement for the presence of herniation or bulging disk was moderate (full agreement, 84%; kappa = 0.63; 95% confidence interval [CI], 0.53-0.72). Of a total of 352 segments evaluated, there was disagreement on 58 segments (17%): bulging disk versus no defect in 26 (7.4%), bulging disk versus herniation in five (1.4%), and hernia versus no defect in 27 (7.7%). With clinical information, twice as many bulging disks were reported but no new herniations were detected. Agreement slightly decreased, but not significantly (full agreement, 77%; kappa = 0.59; 95% CI, 0.49-0.69; p = 0.12). CONCLUSION: On average, more than 50% of interobserver variation in MRI evaluation of patients with lumbosacral radicular pain is caused by disagreement on bulging disks. Knowledge of clinical information does not influence the detection of herniations but lowers the threshold for reporting bulging disks.     

Unusual osseous changes in lumbar herniated disks: CT features

Osseous changes in cases of lumbar herniated disks including erosion of the posterior vertebral body cortex near the herniated disk, spinal canal and intervertebral foramen enlargement, and focal sclerosis of the adjacent body are described. The changes were observed in four patients with large and old herniated disks.     

CT evaluation of the lumbosacral spine

The biologic cost-effectiveness of computed tomography (CT) versus myelography is so favorable to CT that it is now the method of choice for evaluating patients with less clear-cut clinical findings. CT is now used to detect lesions formerly difficult to diagnose, such as subluxation, arthrosis, facet osteophytes, and stenosis of the vertebral canal, as well as herniated disks and lateral disks. The findings in over 1,000 patients examined by CT for lumbosacral spinal pathology are documented. Associated or multiple abnormalities were present in about 60% of cases, with bulging or herniated disks occurring in 45% and 44%, respectively. Postsurgical arachnoiditis was seen in 43% of 64 patients studied for recurrence of symptoms after surgery.     

Lumbar disk herniation and canal stenosis: value of intraoperative sonography in diagnosis and surgical management

One-hundred-four patients with preoperative diagnoses of lumbar canal stenosis, disk herniation, or a combination of both were evaluated with intraoperative sonography with the intent of (1) describing the sonographic characteristics of herniated disks and distinguishing these from bulging anuli, epidural fat, scar tissue, and spondylolisthesis; (2) establishing criteria for adequate decompression of canal stenosis; and (3) determining the usefulness of sonography in monitoring disk removal. Disk material demonstrates medium echogenicity, different in its sonographic features from bone, epidural fat, scar tissue, and epidural veins. A sonographic diagnosis of disk herniation was made in 43 cases, 41 of which were confirmed during surgery. Sonography established the presence or absence of disk herniation (confirmed by surgery) in 14 of 19 patients who had equivocal preoperative findings. After routine diskectomy, residual disk material was found in 17 (41%) of 41 patients, which led to further surgery in 16 patients with removal of the additional disk fragments. In 84 patients undergoing decompressive surgery for canal stenosis, sonography detected residual canal compression in 19 (23%), which led to a widened decompression in 15 of these patients. Sonography can differentiate disk material from other normal or abnormal structures in the canal; therefore, sonographic monitoring helps to ensure adequate bony decompression and complete diskectomy. We conclude that intraoperative sonography is an important tool in the surgical management of lumbar disk disease and stenosis.     

Lumbar disk herniation and canal stenosis: value of intraoperative sonography in diagnosis and surgical management

One hundred four patients with preoperative diagnoses of lumbar canal stenosis, disk herniation, or a combination of both were evaluated with intraoperative sonography with the intent of (1) describing the sonographic characteristics of herniated disks and distinguishing these from bulging anuli, epidural fat, scar tissue, and spondylolisthesis; (2) establishing criteria for adequate decompression of canal stenosis; and (3) determining the usefulness of sonography in monitoring disk removal. Disk material demonstrates medium echogenicity, different in its sonographic features from bone, epidural fat, scar tissue, and epidural veins. A sonographic diagnosis of disk herniation was made in 43 cases, 41 of which were confirmed during surgery. Sonography established the presence or absence of disk herniation (confirmed by surgery) in 14 of 19 patients who had equivocal preoperative findings. After routine diskectomy, residual disk material was found in 17 (41%) of 41 patients, which led to further surgery in 16 patients with removal of the additional disk fragments. In 84 patients undergoing decompressive surgery for canal stenosis, sonography detected residual canal compression in 19 (23%), which led to a widened decompression in 15 of these patients. Sonography can differentiate disk material from other normal or abnormal structures in the canal; therefore, sonographic monitoring helps to ensure adequate bony decompression and complete diskectomy. We conclude that intraoperative sonography is an important tool in the surgical management of lumbar disk disease and stenosis.     

Nuclear magnetic resonance imaging of the spine

Forty subjects were examined to determine the accuracy and clinical usefulness of nuclear magnetic resonance (NMR) examination of the spine. The NMR images were compared with plain radiographs, high-resolution computed tomograms, and myelograms. The study included 15 patients with normal spinal cord anatomy and 25 patients whose pathological conditions included canal stenosis, herniated discs, metastatic tumors, primary cord tumor, trauma, Chiari malformations, syringomyelia, and developmental disorders. Saturation recovery images were best in differentiating between soft tissue and cerebrospinal fluid. NMR was excellent for the evaluation of the foramen magnum region and is presently the modality of choice for the diagnosis of syringomyelia and Chiari malformation. NMR was accurate in diagnosing spinal cord trauma and spinal canal block. The normal disc was seen, but with rare exceptions bulging of the annulus and herniation of the nucleus pulposus were not visualized.     

Conjoined lumbosacral nerve roots compromised by disk herniation: sagittal shoulder sign for the preoperative diagnosis

Objective The objective was to determine the importance of the “sagittal shoulder sign” on magnetic resonance (MR) images for the diagnosis of conjoined lumbosacral nerve roots (CLNR) that are compromised by herniated disks. Materials and methods Magnetic resonance images of 11 patients (6 men and 5 women; age range, 25–71 years; average age, 48.7 years) with surgically proven CLNR, which was compromised by herniated disks, were retrospectively evaluated by two musculoskeletal radiologists. MR images were evaluated for the presence or absence of the sagittal shoulder sign—a vertical structure connecting two consecutive nerve roots and overlying disk on the sagittal MR images. The radiologists noted the type of accompanying disk herniation and bony spinal canal changes, as well as other characteristic MR features of CLNR, the common passage of two consecutive nerve roots through the neural foramen on axial MR images. Results The sagittal shoulder sign was identified with a mean frequency of 90.9% by the two observers (in 10 of 11 patients). The common passage of two consecutive nerve roots through the neural foramen on axial MR images was identified with a mean frequency of 59.1% (in 7 and 6 out of 11 patients, by observers 1 and 2, respectively). Good interobserver agreement for the sagittal shoulder sign was present (k = 0.621, p < 0.05). Conclusion Observation of the sagittal shoulder sign may prove helpful for diagnosing CLNR in patients with disk herniation. In particular, this sign appears to be useful when there is no evidence of CLNR on axial MR images.     

Classification, diagnostic imaging, and imaging characterization of a lumbar herniated disk

The absence of universal nomenclature standardization with respect to the definition of a disk herniation and its different categories, especially regarding type and location, is still a major problem that will only be overcome when major national or international scientific societies join efforts to support a particular scheme. Meanwhile, it is important to realize that the two models that are currently most used are based on a different [figure: see text] perspective. Trying to straddle the two by opposing, for instance, bulging disk and herniation is doomed to failure because this exercise defies formal logic. MR imaging is currently the most accurate noninvasive imaging modality to diagnose a disk herniation and to determine its exact location. The determination of some pathoanatomic characteristics of herniated disks (type and composition) may require the use of CT, diskography, or CT diskography.     

Utility of high-dose contrast enhancement for detecting recurrent herniated intervertebral disks.

PURPOSETo study the utility of high-dose contrast enhancement in the detection of recurrent herniated disk fragments.METHODSRecurrent herniated disks were modeled in nine dogs by placing a fragment of normal autologous disk tissue in the epidural space at laminectomy. MR was performed at 30, 60, and 90 days with 0.3 mmol/kg of gadoteridol and repeated 24 hours later with 0.1 mmol/kg of gadopentetate dimeglumine. Contrast enhancement in the disk and scar tissue was measured and conspicuousness of the disk fragments assessed.RESULTSIn 70% of the animals, disk fragments were more conspicuous with the larger dose of contrast medium than with the smaller dose. In 30% of animals the conspicuousness was approximately equal. Contrast between disk fragment and scar decreased with time elapsed since surgery, with time elapsed since contrast-medium injection, and with decreasing dose of contrast medium.CONCLUSIONIn the experimental model, increased conspicuousness of disk fragments was achieved with the larger dose of contrast medium. A clinical study is needed to confirm that a contrast-medium dose of 0.3 mmol/kg improves detection of recurrent herniated disks over a dose of 0.1 mmol/kg.     

Percutaneous discectomy on lumbar radiculopathy related to disk herniation: Why under CT guidance? An open study of 100 consecutive patients

The primary objective of this study conducted on 100 patients is to demonstrate that performing CT-guided percutaneous discectomy for herniated disks results in a significant improvement in pain symptoms at several times (D1, D2, D7, 1 month, 3 months, 6 months). This objective assesses the effectiveness and feasibility of this technique under CT guidance in patients presenting documented lower back pain related to disk herniation that has not improved with appropriate medical treatment. The impact of various factors on the effectiveness of discectomy will also be evaluated. At 1 week, we notes a decrease in average VAS respectively of 71% and 67% in patients treated for posterolateral and foraminal herniated disks; the result for posteromedian herniated disks is only 45% in average decrease. At 6 months post op, 79% of lateralized herniated disks have a satisfactory result (≥ 70% decrease in pain as compared to initial pain), whereas post median herniated disks had a satisfactory result in only 50% of cases. Percutaneous fine needle discectomy probe under combined CT and fluoroscopic guidance is a minimally invasive spine surgery which should be considered as an alternative to surgery. This technique presents several advantages: the small diameter of the probe used (maximum 16 G or 1.5mm) allows a cutaneous incision of only a few millimeters, and a trans-canal approach can be possible; it also decreases the risk of ligamentary lesion and does not cause an osseous lesion of the posterior arc or of the adjacent muscular structures.     

采用Kappa统计量评价腰椎间盘突出的MRI诊断

目的 应用Kappa统计量评价MRI诊断腰椎间盘突出的一致性.方法 检查100例腰腿痛患者的300个椎体.采用3.0 T MR扫描仪,脊柱表而线圈,应用快速自旋回波序列行腰椎矢状面T1WI及T2WI、横轴面T2WI.由2名放射科医师分别在有及无临床资料的情况下对其中50例患者的L3～4、L4～5、I5～S1椎间盘的膨出、突出进行2次评价;再由此2名医师在无临床资料的情况下共同对其中52例患者的156个腰椎间盘进行评价.应用Kappa统计量评价2名医师前后2次的诊断结果及其对相同病例诊断结果的一敛性.结果 甲乙2名放射科医师前后2次诊断结果相符合的椎间盘数量分别为114和109个,不相符合的椎间盘数量分别为36和41个,诊断结果的一致性为中度,Kappa值分别为0.60±O.06和0.57±0.06.在有临床资料的情况下,腰椎间盘膨出的诊断较前明显增加,分别增加了10个和31个.在没有临床资料的情况下,2名放射科医师之间的诊断结果相符合的椎间盘数量为77个,不相符合者为79个,诊断结果的一致性为弱(Kappa=0.24±0.06).在有无临床资料的情况下,最大的诊断差异出现在对正常和膨出的腰椎间盘的鉴别上,2名医师2次诊断膨出的差异分别达20和30个,分别占各自总不符合率的55.6%(20/36)和73.2%(30/41);2名医师对156个椎间盘诊断膨出与正常的差异达56个,为总不符合率的70.9%(56/79).结论对腰椎间盘膨出判断的不一致是造成同一医师2次诊断结果和2名医师之间诊断结果Kappa值低的最主要原因.     

Lumbar disk herniation: correlation of histologic findings with marrow signal intensity changes in vertebral endplates at MR imaging

PURPOSE: To compare findings at preoperative magnetic resonance (MR) imaging with data for tissue composition of herniated disks in patients after microsurgical removal of herniated material. MATERIALS AND METHODS: Fifty-one patients underwent MR imaging before microsurgical removal of extruded lumbar disk herniation material. Marrow signal intensity changes along the cartilaginous endplates were classified according to Modic types 1-3. Severity of changes was evaluated with respect to extension along the endplate in the anteroposterior diameter (0%, <33%, 33%-66%, >66%). The existence of a dorsal vertebral corner defect was evaluated in relation to the existence of hyaline cartilage in the disk extrusion material. RESULTS: Mean tissue composition of herniated material in all patients was 63% anulus fibrosus, 30% nucleus pulposus, and 8% cartilaginous endplate. Twenty-five of the 51 patients had hyaline cartilaginous material in the extrusion (range, 5%-50%). Patients without marrow signal intensity changes along the cartilaginous endplate showed significantly less cartilaginous material in the extruded disk (P =.023, Fisher exact test). Mean percentage hyaline cartilage in patients without changes was 2% +/- 4 (SD) (Modic type 1, 16% +/- 15; type 2, 10% +/- 12). When the changes extended 33% of the vertebral endplate, there was cartilaginous endplate material in the extruded disk (P =.006). Cartilage from the endplate was present in the extruded disk material in 40% (16 of 40) of patients without a vertebral corner defect and in 82% (nine of 11) of patients with a vertebral corner defect (P =.019). CONCLUSION: Avulsion-type disk herniation seems to be common, and vertebral endplate marrow signal intensity changes on MR images are indicative of cartilaginous material in the extruded disk herniation material.     

Cervical nerve root blocks: indications and role of MR imaging

PURPOSE: To examine whether magnetic resonance (MR) imaging findings of the cervical spine can predict pain relief after selective computed tomography (CT)-guided nerve root block and thus assist in the appropriate selection of patients who are suitable for this procedure. MATERIALS AND METHODS: Sixty consecutive patients with cervical radicular pain were examined with MR imaging and then treated with CT-guided cervical nerve root blocks (CNRBs). Various MR imaging findings were assessed and compared in terms of associated pain relief after CNRB. Pain relief was graded (0%-100%) by using a visual analogue scale (VAS). The relationship between MR imaging findings and level of pain relief was tested by using Mann-Whitney U and Kruskal-Wallis tests. RESULTS: The mean percentage of pain reduction at VAS grading was 46%. There was a significant relationship between pain relief level and both location of disk herniation (mean pain reductions of 41% at median or mediolateral locations and 64% at foraminal locations, P =.034) and location of nerve root compromise (mean pain reductions of 19% at intraspinal, 45% at foraminal entrance, and 58% at foraminal locations; P =.019). There was an inverse relationship between pain relief level and absence or presence of spinal canal stenosis (mean pain reductions of 29% when stenosis present and 53% when stenosis absent, P =.013). Other parameters were not significantly related to pain relief. CONCLUSION: MR imaging of the cervical spine assists in the appropriate selection of patients suitable for CNRB. Patients with foraminal disk herniation, foraminal nerve root compromise, and no spinal canal stenosis appear to have the greatest pain relief after this procedure.     

经皮穿刺腰椎间盘切吸术治疗腰椎间盘突出症的远期疗效

目的 观察X线电视引导下经皮穿刺腰椎间盘切吸术治疗腰椎间盘突出症的远期疗效。方法 32例经CT扫描证实的腰椎间盘突出症患者，其中，膨出型29例，游离型2例，以及突出型1例，均经X线电视引导下经皮穿刺腰椎间盘切吸术治疗，术后均经随访0.5～11.0a。结果 术后1周～3个月，32例中的24例临床症状与体征得到有效控制或明显减轻，随访5～11a观察表明，症状完全消失和明显减轻者分别见于23例和6例，总有效率90.6%，预后极好和较好者均见于膨出型腰椎间盘突出症患者。结论 游离型和突出型腰椎间盘突出症的疗效均不理想，因此，术前认真选择适应证是获得理想疗效的关键性因素。     

Magnetic resonance imaging of the lumbar spine with CT correlation

The results of magnetic resonance (MR) imaging and computed tomography (CT) in 18 patients with known degenerative disk disease of the lumbar spine were compared. In 60 intervertebral disk levels studied, there were 17 disks with degeneration and disk bulge, and 15 herniated disks. Final diagnoses were based on several factors, with surgical confirmation in five patients. There was good correlation between the two methods at 51 of the 60 levels studied. However, there were major discrepancies in interpretation at nine intervertebral disk levels. These included three false-positive MR imaging interpretations of a herniated disk and one false-negative herniated disk on MR imaging. MR imaging detected one case of disk herniation that was missed prospectively on CT. There were also four presumed degenerated disks seen on MR scans that appeared normal on CT. The conus medullaris was imaged in 16 of 18 patients. The sagittal view proved best for demonstrating both disk abnormality and the conus medullaris. The transaxial view was sometimes helpful in localizing a disk herniation, but partial-volume averaging in the 7-mm slice thickness limited its usefulness. There were five disk herniations that could not be accurately localized on the MR scan. MR imaging proved more sensitive than CT in detecting early disk disease, which appeared as decreased signal intensity within the disk. In three postoperative cases, MR imaging was better able to distinguish between recurrent disk herniation and postoperative scar formation. CT, on the other hand, was more specific in distinguishing herniated disk from disk bulge and proved far superior to MR imaging in localizing disk herniation.(ABSTRACT TRUNCATED AT 250 WORDS)     

Can MRI signal characteristics of lumbar disk herniations predict disk regression?

PURPOSE: To assess whether or not MRI signal characteristics of lumbar disk herniations can predict subsequent disk regression. MATERIALS AND METHODS: Medical and radiology records from 1999-2003 were reviewed, and 123 patients who had more than one lumbar MRI during the study interval were identified. Of these, 42 patients had a disk herniation (protrusion, extrusion, or free fragment) identified on their first examination. Six of the 42 patients were not included because of prior lumbar surgery, or inadequate examinations. The remaining 36 patients had a total of 77 examinations to evaluate 44 disk herniations. The herniated disks were evaluated by two CAQ neuroradiologists for size, morphology and a qualitative assessment of the T2 signal. RESULTS: Between the first and last examination, 25 of 44 (57%) herniated disks decreased, 17 (39%) were unchanged, and two increased in size. 9 of 11 (82%) of disk extrusions improved. The mean size of the disks that regressed was significantly larger than those that were unchanged (8.6 mm vs. 6 mm, p=.001). On average, the disks decreased 3.2 mm (37%). Of the disks that decreased in size, 15 (63%) had an area of increased signal on T2-weighted images (T2WI) compared to the parent disk on the initial study. Of the disks that were unchanged, 6 (35%) had increased signal on the T2WI's. CONCLUSION: 57% of herniated disks in this study group decreased in size over time. Larger herniations and extrusions were more likely to regress than smaller herniations. Disks that regressed were more likely to have high signal on T2WI's than those that were stable.     

Computed tomography and myelography of the postoperative lumbar spine

Postoperative myelographic changes in the thecal sac, epidural tissues, and bony canal, as well as nerve roots, may be difficult to interpret. A series of 32 postoperative patients, all of whom had a metrizamide myelogram and subsequent lumbar computed tomogram, was reviewed to examine the ability of computed tomography to recognize abnormalities when the myelogram is equivocal or uninterpretable. Criteria to distinguish recurrent herniated disk from postoperative changes are presented, including the demonstration of mass densities similar to and in continuity with the intervertebral disk. In 12 reoperated cases, five recurrent herniated disks and two new herniated disks were diagnosed and confirmed. In 20 nonreoperated cases, no recurrent herniated disks were identified, although two new herniated disks were found at levels not believed clinically significant. Computed tomography after metrizamide myelography appears to be a reliable technique for distinguishing abnormalities in the postoperative spine.     

Correlation between image noise and body weight in coronary CTA with 16-row MDCT

RATIONALE AND OBJECTIVES: To evaluate the correlation between image noise and body weight (BW) or body mass index (BMI) in coronary computed tomography angiography (CTA) as a potential parameter for reducing radiation dose in coronary CTA. MATERIALS AND METHODS: Thirty-six patients who underwent electrocardiogram-gated cardiac CT were analyzed in this study. The patients included 26 men and 10 women with a mean age of 60 years (range 43-79 years). All patients were imaged on a 16-row multidetector CT scanner. Mean value of BW and BMI was 83.5 kg and 28.1, respectively. Image noise was defined as standard deviation (SD) of the attenuation values measured by using 1 cm2 circular region of interest in the ascending aorta at the level of the right main pulmonary artery. The SD values were plotted against BW and BMI. The correlations were examined using a linear regression method. A P value of less than .05 was considered significant. RESULTS: The r value of linear regression between noise and BW was 0.90 (P < .001). The r value of linear regression between noise and BMI was 0.74 (P = .015). CONCLUSIONS: Excellent correlation was observed between noise and BW in coronary CTA. These data may be used as potential parameters for customized radiation dose modification to reduce radiation dose in coronary CT examinations.     

CT myelographic findings in degenerative disorders of the cervical spine: clinical significance

CT myelographic data in 80 patients with clinical evidence of nerve-root involvement or long tract signs attributed to degenerative disorders of the cervical spine were classed into five diagnostic groups, and their clinical significance was assessed. Unilateral flattening of the cord by a spondylotic mass or bulging disk in a normally wide canal (group 1) was considered nonspecific because nerve-root signs were nearly as often contralateral as unilateral to the radiologic findings, and none of the patients had long tract signs. As a rule, conventional myelography showed only minor root-sleeve deformity. Concentric compression of the cord in a narrow (stenotic) canal (group 2) proved to produce long tract signs only after the cross-sectional area of the cord had been reduced by about 30% to a value of about 60 mm2 or less. In most cases, nerve-root swelling (group 3) coincided with the side of nerve-root symptoms. A 100% correlation was found between the side of disk herniation with occlusion of the corresponding foramen (group 4) and the side of nerve-root symptoms. In 24 patients, cord and nerve roots showed no abnormalities (group 5). If stenosis of the spinal canal, nerve root swelling, and disk herniation are considered specific CT myelographic signs in nerve-root symptomatology, a specific diagnosis could be made in about 40% of the cases.     

Observer variation in the evaluation of lumbar herniated discs and root compression: spiral CT compared with MRI

Spiral CT is considered the best alternative for MRI in the evaluation of herniated discs. The purpose of this study was to compare radiological evaluation of spiral CT with MRI in patients suspected of herniated discs. 57 patients with lumbosacral radicular syndrome underwent spiral CT and 1.5 T MRI. Two neuroradiologists independently evaluated 171 intervertebral discs for herniation or "bulge" and 456 nerve roots for root compression, once after CT and once after MRI. We compared interobserver agreement using the kappa statistic and we performed a paired comparison between CT and MRI. For detection of herniated or bulging discs, we observed no significant difference in interobserver agreement (CT kappa 0.66 vs MRI kappa 0.71; p = 0.40). For root compression, we observed significantly better interobserver agreement at MRI evaluation (CT kappa 0.59 vs MRI kappa 0.78; p = 0.01). In 30 of 171 lumbar discs (18%) and in 54 of 456 nerve roots (12%), the observers disagreed on whether CT results were similar to MRI. In the cases without disagreement, CT differed from MRI in 6 discs (3.5%) and in 3 nerve roots (0.7%). For radiological evaluation of lumbar herniated discs, we found no evidence that spiral CT is inferior to MRI. For evaluating lumbar nerve root compression, spiral CT is less reliable than MRI.