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.     

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.     

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.     

Clinical manifestations and MRI findings of patients with hydrated and dehydrated lumbar disc herniation

RATIONALE AND OBJECTIVES: In addition to the expected appearance of degenerated discs that become dehydrated, hydrated intervertebral disc herniations are sometimes encountered in radiologic practice. This study was undertaken to evaluate the clinical manifestations and MRI findings of hydrated and dehydrated herniated intervertebral discs. MATERIALS AND METHODS: This cross-sectional single-institution study included 73 patients with dehydrated (group I) and hydrated (group II) lumbar disk herniation. The criteria for hydrated and dehydrated disc herniation were subjective criteria compared to the normal signal of intervertebral discs. A herniated disc has been regarded to be hydrated if more than two thirds of it was hypersignal in T2-weighted images, while more than two thirds of a dehydrated disc was hyposignal on T2-weighted images. RESULTS: The mean weight of patients in group I was greater than that of patients in group II (69.3 versus 64.2 kg, P < 0.05). Also, patients in group I tended to be older than those in group II (35.2 versus 28.9 years). Regarding physical activity, a greater number of patients in group II had intense physical activity compared to group I patients (25% versus 13.2%, respectively; P < 0.05). The duration of radicular pain and back pain was significantly greater in group I than in group II (485 versus 202 and 1346 versus 242 days, respectively; P < 0.05). CONCLUSION: Hydrated intervertebral disc herniation tends to be associated with younger age, lighter body weight, shorter duration of radicular pain, and more intense physical activity compared to dehydrated intervertebral disc herniation. These findings may suggest other mechanisms rather than degenerative changes for hydrated disc herniation.     

Interobserver agreement for the interpretation of contrast-enhanced 3D MR angiography and MDCT angiography in peripheral arterial disease

OBJECTIVE: The objective of our study was to compare interobserver agreement for interpretations of contrast-enhanced 3D MR angiography and MDCT angiography in patients with peripheral arterial disease. SUBJECTS AND METHODS: Of 226 eligible patients, 69 were excluded. The remaining 157 consecutive patients were prospectively randomized to either MR angiography (n = 78) or MDCT angiography (n = 79). Two observers independently evaluated for arterial stenosis or occlusion on MR angiography (2,157 segments) and MDCT angiography (2,419 segments) using a 5-point ordinal scale. Vessel wall calcifications were noted. Interobserver agreement for each technique was evaluated with a weighted kappa (kappa(w)) statistic. RESULTS: Although interobserver agreement for both was excellent, the interobserver agreement for MR angiography (kappa(w) = 0.90; 95% confidence interval [CI], 0.89-0.92) was higher than that for MDCT angiography (kappa(w) = 0.85; 95% CI, 0.83-0.86) for reporting the degree of arterial stenosis or occlusion in all segments. For the different anatomic locations, the interobserver agreement for MR angiography versus MDCT angiography was as follows: aortoiliac (kappa(w) =0.91 vs 0.84, respectively), femoropopliteal (kappa(w) = 0.91 vs 0.87), and crural (kappa(w) = 0.90 vs 0.83) segments. The interobserver agreement of MDCT angiography significantly decreased in the presence of calcifications but was still good for all anatomic locations. The lowest agreement was found for crural segments in the presence of calcifications (kappa(w) = 0.67). With MR angiography, there were 12 times more nondiagnostic segments than with MDCT angiography (81 vs 7, respectively). CONCLUSION: Interpretations of MR angiography and MDCT angiography for peripheral arterial disease have an excellent interobserver agreement. MR angiography has a higher interobserver agreement than MDCT angiography, and the presence of calcified segments significantly decreases interobserver agreement for MDCT angiography.     

Spontaneous resolution of lumbar disk herniation: predictive signs for prognostic evaluation

Spontaneous regression of lumbar disk herniation in patients who did not undergo surgery nor interventional therapy is reported in up to 70% of cases; however, no perspective study has clarified the possible predictive signs of a positive evolution. Aim of our study was to search for plan and contrast enhancement MRI signs able to define disk-herniation resolution. We enrolled 64 patients, affected by 72 lumbar disk herniations as per the classification proposed by the American Society of Neuroradiology (Nomenclature and Classification of Lumbar Disk Pathology 2001). MRI examinations were performed by 1.5-T magnet, using T1w SE sequences on sagittal and axial planes, before and after contrast, and T2w FSE ones on the same planes. The following parameters were considered: age, sex, level and size of disk herniation, its relationship to the spinal canal, clinical onset interval, type of disk herniation, herniated-material signal intensity on T2w sequences and its pattern of contrast enhancement. All the patients, conservatively treated, underwent clinical and MRI follow-up examination after 6 months. At MRI follow-up exams spontaneous regression of disk herniation was observed in 34.72% of cases. Among these, free fragments regressed in 100% of cases, herniations with high signal intensity on T2w sequences in 85.18%, herniations with peripheral contrast-enhancement in 83% of cases. Disk-herniation evolution did not show any relationship with location, size and level. Our study demonstrates that MRI, in addition to its high diagnostic value, offers predictive information about disk-herniation evolution.     

Multidetector CT in patients suspected of having lumbar disk herniation: comparison of standard-dose and simulated low-dose techniques

PURPOSE: To compare standard-dose and simulated low-dose multidetector computed tomography (CT) in patients suspected of having lumbar disk herniation. MATERIALS AND METHODS: The institutional review board approved the research protocol with a waiver of patient informed consent. Sixty consecutive patients underwent multidetector CT with four detector rows at 1 mm collimation at 140 kVp, with tube current-time product adapted to body mass index (BMI): 200 (BMI< 22 kg/m(2)), 300 (BMI > or =22 to <30 kg/m(2)), and 400 effective mAs (BMI > or =30 kg/m(2)). Simulated doses at 65%, 50%, 35%, and 20% of the dose were used for acquisition. During two separate sessions, three independent radiologists coded each of three caudal disks as normal, bulging, or herniated and graded canal and foramen compromise. Median numbers of discrepancies between the standard and reduced doses were compared with Friedman and Wilcoxon tests. Agreements within and between readers were evaluated through kappa statistics. RESULTS: Dose reduction had no effect on a reader's ability to identify bulging disks (P = .128) and left and right foramen compromises (P = .413 and .665, respectively). However, for normal disks (P = .002), herniated disks (P = .004), and canal compromise (P = .002), dose reduction did have a significant effect. For normal disks and canal compromise, a reduction dose effect was not detected at 65% (P = .121 and .250, respectively) but appeared at 50% (P = .004 and .008, respectively). For herniation, a dose reduction effect was detected at 35% (P = .031). Agreements within and between readers ranged from poor to excellent and tended to decrease with dose reduction. CONCLUSION: For patients suspected of having lumbar disk herniation, tube charge settings could be reduced to 65% of the standard dose adapted to the BMI.     

腰骶椎椎间盘突出的影像诊断

目的：通过回顾性分析，探讨腰骶椎椎间盘突出的非创性影像诊断及相关问题。材料与方法；报告200例腰骶椎椎间盘突出者的影像学表现，其中67例经手术证实。全部病例摄有X线平片及CT扫描，21例做了MRI检查。结果：对腰骶椎椎间盘突出的诊断，MRI和CT显示优于传统X线检查。但MRI在鉴别诊断方面又比CT稍胜一筹。结论：MRI虽然敏感性高，但检查费用昂贵，故对本症的诊断，应首选CT检查。     

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.     

Evaluation of intervertebral disc herniation and hypermobile intersegmental instability in symptomatic adult patients undergoing recumbent and upright MRI of the cervical or lumbosacral spines

PURPOSE: The purpose of the study was to determine the difference in findings between recumbent and upright-sitting MRI of the cervical and lumbosacral spine in patients with related sign and symptoms. MATERIALS AND METHODS: A total of 89 patients were studied (lumbosacral spine: 45 patients; cervical: 44 patients). T1-weighted (TR: 350, TE: 20) fast spin echo and T2-weighted (TR: 2500, TE: 160) fast spin echo images were acquired in the sagittal and axial planes in both the recumbent and sitting-neutral positions. The images were acquired on the Upright MRI unit (Fonar Corporation, Melville, NY). Differences were sought between the recumbent and upright-sitting positions at all levels imaged, in both planes. RESULTS: The total number of cases of pathology was 68, including instances of posterior disc herniation and anterior and posterior spondylolisthesis. Focal posterior disc herniations were noted in 55 patients (cervical: 31, lumbosacral: 24) [62% of patients]. Six of these herniations (cervical: 4, lumbosacral: 2) [11%] were seen only on the upright-sitting study. Focal posterior disc herniations were seen to comparatively enlarge in size in 35 patients on the upright-seated examination (cervical: 21, lumbosacral: 14) [72%], and reduce in size in 9 patients (cervical: 5, lumbosacral: 4) [18%]. Degenerative anterior (n: 11) and posterior (n: 2) spondylolisthesis was seen in 13 patients (cervical: 0, lumbosacral: 13) [15% of patient total]. Anterior spondylolisthesis was only seen on the upright-seated examination in 4 patients (cervical: 0, lumbosacral: 4) [31%]. Anterior spondylolisthesis was comparatively greater in degree on the upright-seated study in 7 patients (cervical: 0, lumbosacral: 7) [54%]. Posterior spondylolisthesis was comparatively greater in degree on the recumbent examination in 2 patients (cervical: 0, lumbosacral: 2) [15%]. The overall combined recumbent miss rate in cases of pathology was 15% (10/68). The overall combined recumbent underestimation rate in cases of pathology was 62% (42/68). The overall combined upright-seated underestimation in cases of pathology was 16% (11/69). CONCLUSIONS: Overall, upright-seated MRI was found to be superior to recumbent MRI of the spine in 52 patents (recumbent missed pathology [n: 10]+recumbent underestimated pathology [n: 42]=52/89 total patients: 58%) in cases of posterior disc herniation and anterior spondylolisthesis. This seems to validate the importance of weight-bearing imaging in the spine that might be expected to unmask positional enlarging disc herniations and worsening spondylolisthesis. Overall, recumbent MRI was found to be superior to upright-seated MRI in 11 cases (11/89: 12%). The latter finding was possibly due to the fact that upright seated position is actually partial flexion that might be expected to reduce some cases of hypermobile posterior spondylolisthesis.     

MR imaging of foraminal and extraforaminal lumbar disk herniations

Foraminal and extraforaminal disk herniations are less frequent than intraspinal herniations at the lumbar level and more difficult to diagnose. They are undetected by myelography and distinction between them and an enlarged nerve root may be difficult with CT. Thirty-three patients presenting with persistent radiculopathy and showing an image suggesting a far lateral disk herniation on CT at 34 disk levels were prospectively imaged with magnetic resonance (MR). In all cases the disk fragment was identified and its separation from the nerve root was possible. This separation was more readily visible on sagittal or angled coronal views. The exact location of the herniation in relation to the facet joints and the pedicles was best assessed with MR: Ten were purely intraforaminal, 8 extraforaminal, and 15 both. Cephalad migration was noted on the sagittal lateral facet plane in 71% of cases. Surgical correlations were available for 25 disks. Three were falsely positive for disk herniation. Enlarged foraminal veins were responsible for this appearance as confirmed by surgery in two of these. When a prediction of disruption of the lateral extension of the posterior longitudinal ligament was made, it was confirmed at surgery in 52% of cases because of extreme lateralization of the herniations.     

The value of MR in differentiating subligamentous from supraligamentous lumbar disk herniations.

PURPOSETo determine the value of MR criteria in differentiating subligamentous from supraligamentous lumbar disk herniations.METHODSA retrospective review of surgical reports and MR images of 50 patients undergoing first-time lumbar surgery was performed. Three MR imaging criteria were assessed: the presence and integrity of a low-signal-intensity line posterior to the disk herniation, the size of the disk herniation in comparison with the size of the spinal canal, and the presence of disk fragments. Correlation was made with surgical findings to determine the value of these MR criteria in differentiating subligamentous from supraligamentous disk herniations.RESULTSFor determining subligamentous disk herniations: the presence of a continuous low-signal-intensity line posterior to the disk herniation was 29% sensitive, 65% specific, and 42% accurate; disk herniation size less than 50% of the size of the spinal canal was 64% sensitive, 47% specific, and 58% accurate; and the absence of disk fragments was 88% sensitive, 12% specific, and 62% accurate. Combinations of individual MR criteria did not improve diagnostic accuracy.CONCLUSIONSFor differentiating subligamentous from supraligamentous lumbar disk herniations, none of the MR imaging criteria assessed was reliable.     

MRI of knee osteonecrosis in children with leukemia and lymphoma: Part 1, observer agreement

OBJECTIVE: The aim of this study was to determine whether a new MRI-based staging system for osteonecrosis of the knee in pediatric patients could be used with an acceptable level of intra- and interobserver agreement. MATERIALS AND METHODS: We conducted a retrospective analysis of MRI studies of the knee performed in a single institution between April 1994 and July 2003. Knee osteonecrosis was identified in 168 children with a primary diagnosis of hematologic malignancy. This substantial number prompted us to design a staging system for use with pediatric patients. To assess interobserver reliability of two primary observers in using the system, they reviewed and interpreted the same 36 imaging studies of randomly chosen patients. For the assessment of intraobserver reproducibility, each observer rereviewed 16 studies. A senior observer coded potential causes of disagreement between the primary observers. RESULTS: Interobserver agreement was substantial: the kappa value was 0.66 (95% confidence interval [CI], 0.58-0.75) in locations where the observers had to record only the presence or absence of a lesion, and the weighted kappa value was 0.65 (95% CI, 0.59-0.72) in locations where they had to classify the extent of involvement. The presence of marrow edema, punctate foci of altered signal, and mottled marrow changes was associated with a higher level of disagreement between the primary observers. CONCLUSION: Our proposed classification system, developed specifically for use with MRI, was used with substantial intra- and interobserver agreement. We think its use can contribute to a standardized approach to the interpretation of MRI findings in pediatric osteonecrosis of the knee.     

Lumbar disk herniation: MR imaging assessment of natural history in patients treated without surgery.

The aim of this study was to evaluate the evolution of lumbar disk herniation in patients treated without surgery. Sixty-nine patients with a lumbar disk herniation proved at magnetic resonance (MR) imaging underwent a follow-up MR imaging study. The disk herniations evaluated during both MR imaging examinations were measured and classified into four categories according to the change in size that occurred. The patients were also divided into three clinical classes on the basis of the clinical outcome. Sixty-three percent of the patients showed a reduction of disk herniation of more than 30% (48% had a reduction of more than 70%), while only 8% demonstrated worsening of the clinical picture. These findings suggest that lumbar disk herniation may be primarily a medical (nonsurgical) disease and that MR imaging could play an important role in management of and research into the disorder.     

The value of magnetic resonance imaging in the diagnosis of orbital floor fractures

The value of MRI in the diagnosis of acute orbital floor fractures has not been clearly defined. We therefore compared MR findings with CT findings in patients with orbital trauma. In 30 patients with isolated orbital trauma both coronal CT and coronal MRI were used to examine the orbits and the adjacent paranasal sinuses. Visualization of anatomical landmarks, the kind and extent of traumatic lesions, as well as artifacts were scored. The scores were compared using the Wilcoxon matched-pairs signed-rank test. Interexamination agreement between the two methods was calculated using a kappa analysis. All examinations had diagnostic quality: 30 fractures of the orbital floor (9 right and 21 left orbital floor fractures) were identified. In addition, CT showed fractures of the medial orbital wall in 19 patients (63.3%), of the lateral wall in 10 patients (33.3%), of the zygomatic arch in 2 patients (6.7%), and of the maxillary sinus in 4 patients (13.3%). Soft tissue herniation was shown in 13 patients (inferior rectus muscle twice, orbital fat in 11 cases). Magnetic resonance imaging demonstrated soft tissue herniation in 21 patients: muscle in 4, orbital fat in 17 cases. Magnetic resonance imaging is able to demonstrate orbital floor fractures as sensitively as CT, but CT is superior to MRI in showing small and associated fractures; therefore, CT remains in orbital fractures the imaging modality of choice. Magnetic resonance imaging is superior to CT in showing soft tissue herniations; therefore, MRI may have a role as an adjunct to CT if soft tissue entrapment remains unclear.     

Lumbosacral epidural lipomatosis: MRI grading

Lumbosacral epidural lipomatosis (LEL) is characterized by excessive deposition of epidural fat (EF). The purpose of our retrospective study was to quantify normal and pathologic amounts of EF in order to develop a reproducible MRI grading of LEL. In this study of 2528 patients (1095 men and 1433 women; age range 18–84 years, mean age 47.3 years) we performed a retrospective analysis of MRI exams. We obtained four linear measurements at the axial plane parallel and tangent to the superior end plate of S1 vertebral body: antero-posterior diameter of dural sac (A-Pd DuS), A-Pd of EF, located ventrally and dorsally to the DuS, and A-Pd of the spinal canal (Spi C). We calculated (a) DuS/EF index and (b) EF/Spi C index. We developed the following MRI grading of LEL: normal, grade 0: DuS/EF index ≥1.5, EF/Spi C index ≤40%; LEL grade I: DuS/EF index 1.49–1, EF/Spi C index 41–50% (mild EF overgrowth); LEL grade II: DuS/EF index 0.99–0.34, EF/Spi C index 51–74% (moderate EF overgrowth); LEL grade III: DuS/EF index ≤0.33, EF/Spi C index ≥75% (severe EF overgrowth). The MRI exams were evaluated independently by three readers. Intra- and interobserver reliabilities were obtained by calculating Kappa statistics. The MRI grading showed the following distribution: grade 0, 2003 patients (79.2%); LEL grade I, 308 patients (12.2%); LEL grade II, 165 patients (6.5%); and LEL grade III, 52 patients (2.1%). The kappa coefficients for intra- and interobserver agreement in a four-grade classification system were substantial to excellent: intraobserver, kappa range 0.79 [95% confidence interval (CI), 0.65–0.93] to 0.82 (95% CI, 0.70–0.95); interobserver, kappa range 0.76 (95% CI, 0.62–0.91) to 0.85 (95% CI, 0.73–0.97). In LEL grade I, there were no symptomatic cases due to fat hypertrophy. LEL grade II was symptomatic in only 24 cases (14.5%). In LEL grade III, all cases were symptomatic. A subgroup of 22 patients (42.3%) showed other substantial spinal pathologies (e.g., disk herniation). By means of simple reproducible measurements and indexes MRI grading enables a distinction between mild, moderate, and severe EF hypertrophy. Kappa statistics indicate that LEL can be reliably classified into a four-grade system by experienced observers.     

Radicular pain avoidance during needle placement in lumbar diskography

OBJECTIVE: The objective of our study was to determine whether a method could be found to reduce iatrogenic radicular pain during needle placement in lumbar diskography. MATERIALS AND METHODS: After obtaining permission from the institutional review board at the University of Pittsburgh Medical Center, we conducted a study using medical records and existing data that were recorded for quality control during lumbar diskography. A coaxial technique was being used for lumbar diskography. We evaluated data for 71 intervertebral disks in 26 patients in which the needle placement was randomly high (superior) or low (inferior), and the associated pain response during needle placement was recorded. In an attempt to minimize iatrogenic pain during needle placement, we identified a potentially "safe window" for needle placement on MRI of the lumbar spine. On oblique fluoroscopy of the lumbar spine, the safe window is a triangle formed by the superior articular facet medially, the superior endplate of the lower vertebra inferiorly, and an imaginary line joining the tip of the superior articular facet and the superolateral tip of the vertebral body. This safe window was then used for needle placement in another 73 intervertebral disks in 27 patients. Pain response to needle placement was recorded for quality control, and the medical records were retrospectively compared with the initial 71 intervertebral disks in which needle placement was random. RESULTS: In the initial group with random needle placement, lower extremity radicular pain occurred in 13 (18.3%) of 71 intervertebral disks with superior needle placement and in 23 (32.4%) of 71 intervertebral disks with inferior needle placement (total, 50.7%). The pain responses of the superior and inferior groups were not significantly different (p = 0.27). On MRI, the average distances between the nerve ganglion-fascicle-rami and the superior articular facets at the superior disk level were 1.1, 1.4, and 2.5 mm at L3-L4, L4-L5, and L5-S1, respectively. The average distances between the nerve ganglion-fascicle-rami and the superior articular facets at the inferior disk level were 3.0, 3.6, and 6.6 mm at L3-L4, L4-L5, and L5-S1, respectively. When the safe window was used, only five (6.8%) of 73 patients reported radicular pain. The decrease in radicular pain between the two groups was significant (p < 0.001). CONCLUSION: Iatrogenic lower extremity radicular pain is common during random needle placement at lumbar diskography. High or low needle placement in the intervertebral disk could not predict whether radicular pain would be averted. We identified a safe window that can be used for needle placement during lumbar diskography to minimize iatrogenic lower extremity radicular pain and thereby improve the reliability of the test.     

Lumbar intradural disk herniation. X-ray computed tomographic diagnosis

Intradural disk herniation is a rare condition. Most of reported cases involve the lumbar spine and have histories of chronic low back pain followed by an acute episode of radicular pain with neurologic deficit. The authors report the myelographic and lopamidol-CT findings in a case of a L4-5 intradural disk herniation. These two examinations demonstrated an intradural multilobular mass associated with an extradural component at the level of the disk space and with a same density as it. Anatomic adherences between dura-mater and posterior longitudinal ligament could explain the primary mechanism of these intradural disk herniations; but operative or traumatic antecedents are often noted. Most often operation discloses only the intradural component with a small anterior dural cleft, without extradural abnormalities. Postoperative follow up is usually good.     

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.     

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)