A cadaveric study comparing discography, magnetic resonance imaging, histology, and mechanical behavior of the human lumbar disc.

The aims of this study were 1) to compare discography and magnetic resonance imaging scanning on cadaver specimens and to correlate these imaging procedures by examining all the discs histologically; and 2) to study the extent to which the amplitude of rotational movement in the neutral and flexed position at a certain level correlates with the morphologic appearance of that disc. Twenty-four human lumbar spines were harvested from cadavers between the ages of 19 and 75 years. Each specimen underwent standard radiography, magnetic resonance imaging scanning, discography, histologic examination, and measurement of axial rotation in a torsion apparatus. For practical reasons, all specimens did not undergo all of the examinations. Not all peripheral anular lesions were detected by discography. Histology showed rim lesions of the anterior anulus in 18% of discs with normal discography. The overall incidence of anterior and posterior anular tears was greater in discs where larger amplitudes of rotation were observed. To which extent the one is a consequence of the other or vice versa is not clear. Magnetic resonance imaging was found to be less specific than discography. However, it must be emphasized that no axial magnetic resonance imaging scans were taken in this study. Discs with significantly decreased amounts of nuclear material (observed at histology) can still produce normal magnetic resonance imaging images. Infolding of the inner layers of the anulus fibrosus (33% anterior, 4% posterior) was a frequently observed feature.     

In vitro measurement of pressure in intervertebral discs and annulus fibrosus with and without annular tears during discography

BACKGROUND CONTEXT: Discogram studies have shown that pain reproduction correlates with the extent of annular disruption. However, it has not been assessed if pressure changes in the annulus fibrosus vary incrementally with intradiscal pressure. PURPOSE: To determine the relationship between intradiscal pressure and outer annular pressure during discography in intervertebral discs with and without annular tears. STUDY DESIGN: Intradiscal and periannular pressures were measured simultaneously in vitro during intradiscal injection in porcine cadaver spines. METHODS: Twenty fresh porcine cadaver lumbar spines with intervening discs were tested. Intradiscal and periannular pressures were measured simultaneously using two pressure sensors during intradiscal contrast injection. The tip of a 25-gauge needle connected with a pressure manometer was placed in the center of the nucleus pulposus. A second pressure transducer was located at the outer third of the annulus fibrosus. Needle and transducer locations were confirmed by fluoroscopy. To compare the intact and torn annulus fibrosus, annular disruptions were created with a 20-gauge needle and confirmed by fluoroscopy. RESULTS: During intradiscal injections of discs with an intact annulus, annulus fibrosus pressure remained low and a sharp increase in intradiscal pressure was observed. Significantly higher pressures were noted in the outer annulus in discs with annular tears (p<.01). Mean pressures at the central nucleus pulposus, the outer third of intact annuli and torn annuli were 93.4+/-40.9 psi, 14.8+/-1.9 psi and 85.7+/-24.8 psi, respectively. CONCLUSIONS: Volumetric injection of intervertebral discs with a torn annulus fibrosis during discography may increase intra-annular pressure similar to the increase in pressure that may occur during spinal loading activities. This effect may not occur in discs with an intact annulus fibrosus.     

腰椎间盘MRI高信号区在诊断椎间盘源性下腰痛中的意义

目的:探讨腰椎间盘MRI高信号区(HIZ)在诊断椎间盘源性下腰痛中的作用。方法:对52例经保守治疗无效、CT影像上无腰椎间盘突出的下腰痛患者行腰椎MRI检查和腰椎间盘造影术,分析腰椎间盘MRI高信号区与腰椎间盘造影诱发的下腰痛之间的关系。结果:在行腰椎间盘造影的142个椎间盘中,共有38个椎间盘呈现疼痛复制反应,其中17个椎间盘显示高信号区。这17个有高信号区的椎间盘在椎间盘造影过程中全部呈现2～3级的纤维环破裂和疼痛复制反应。结论:无椎间盘突出的下腰痛患者在腰椎MRI上存在椎间盘内高信号区,可表明该椎间盘是产生腰痛的破裂椎间盘。     

Diagnosis of symptomatic disc by magnetic resonance imaging: T2-weighted and gadolinium-DTPA-enhanced T1-weighted magnetic resonance imaging

Although radial tear of the annulus fibrosus can be detected on T2-weighted and Gd-DTPA-enhanced magnetic resonance (MR) images, the association between the annular tear on MR images and the symptomatic discs is unclear. The purpose of this study was to investigate the relationship between T2-weighted, gadolinium-DTPA-enhanced MR images and pain response through discography in patients with chronic low back pain. A total of 56 lumbar discs from 23 patients with chronic low back pain (13 to 47 years old) underwent MR imaging (T2-weighted, gadolinium-DTPA-enhanced MR images) followed by provocative discography. The sensitivity, specificity, positive predictive value, and negative predictive value of T2-weighted and gadolinium-DTPA-enhanced MR images in detecting the symptomatic discs were calculated. The sensitivity, specificity, positive predictive value, and negative predictive value of T2-weighted images in detecting the symptomatic disc were 94%, 71%, 59%, and 97%, respectively. The sensitivity, specificity, positive predictive value, and negative predictive value of gadolinium-DTPA-enhanced images were 71%, 75%, 56%, and 86%, respectively. The high sensitivity and the high negative predictive value of T2-weighted MR imaging in detecting the symptomatic disc indicated that MR imaging can be a useful screening tool in avoiding unnecessary discography in patients with chronic low back pain.     

The pathogenesis and clinical significance of a high-intensity zone (HIZ) of lumbar intervertebral disc on MR imaging in the patient with discogenic low back pain

Recently, the presence of a high-intensity zone (HIZ) within the posterior annulus seen on T2-weighted MRI has aroused great interest and even controversy among many investigators, particularly on whether the HIZ was closely associated with a concordant pain response on awake discography. The study attempted to interpret the correlation between the presence of the HIZ on MRI and awake discography, as well as its characteristic pathology. Fifty two patients with low back pain without disc herniation underwent MRI and discography successively. Each disc with HIZ was correlated for an association between the presence of a HIZ and the grading of annular disruption and a concordant pain response. Eleven specimens of lumbar intervertebral discs which contain HIZ in the posterior annulus from 11 patients with discogenic low back pain were harvested for histologic examination to interpret the histologic basis of a nociceptive response during posterior lumbar interbody fusion (PLIF). The study found that in all of 142 discograms in 52 patients, 17 presented HIZ. All 17 discs with HIZ showed painful reproduction and abnormal morphology with annular tears extending either well into or through the outer third of the annulus fibrosus. The consecutive sagittal slices through the HIZ lesion showed that a notable histologic feature of the formation of vascularized granulation tissue in the outer region of the annulus fibrosus. The current study suggests that the HIZ of the lumbar disc on MRI in the patient with low back pain could be considered as a reliable marker of painful outer anular disruption.     

腰椎间盘MRI高信号区的组织病理学特点和临床意义

目的研究椎间盘源性下腰痛患者腰椎间盘纤维环后方MRI高信号区的组织病理学特征及其临床意义。方法对52例经保守治疗无效、CT片显示无腰椎间盘突出的下腰痛患者行腰椎MR检查及腰椎间盘造影术。男39例,女13例;平均年龄38.8岁。选择纤维环后方出现高信号区的部分病例行腰椎后路椎间盘切除、椎体间融合、椎弓根螺钉内固定术,术中收集包括高信号区部位的椎间盘。对标本行矢状面连续组织学切片,光镜下观察高信号区椎间盘组织的组织病理学结构,并分析其临床意义。结果在行腰椎间盘造影的52例142个椎间盘中,17例17个椎间盘显示高信号区,且在椎间盘造影过程中全部呈现2或3级的纤维环破裂和疼痛复制反应。敏感性和特异性均为100%。高信号区与纤维环破裂程度分级呈正相关,说明纤维环破裂程度分级越高,越易出现高信号区(R=0.462,P<0.01)。共收集11例患者11个椎间盘,组织学研究发现对应高信号区的椎间盘组织表现为沿纤维环裂隙形成的不同程度的血管化肉芽组织,有成熟的瘢痕化胶原组织。结论症状性下腰痛患者的腰椎MRI上有椎间盘高信号区,可以作为椎间盘源性下腰痛诊断的重要征象。     

Radiofrequency heating of painful annular disruptions: one-year outcomes

OBJECTIVE: Although several studies have reported on outcomes following heating of annular tears with a thermoresistive catheter (SpineCATH), no data are available on the efficacy of thermal treatment with a flexible radiofrequency electrode (discTRODE). A prospective case-control study was conducted to determine the efficacy of radiofrequency heating of painful annular tears in the lumbar spine. METHODS: After at least 6 months of conservative treatment, 46 patients were studied for the presence of single-level painful annular tears with magnetic resonance imaging and provocative discography. Thirty-one patients underwent heating of their annular tears with a flexible radiofrequency electrode placed across the posterior annulus. The remaining 15 patients, who mostly could not obtain funding for the procedure, continued with conservative management and acted as a control group. The Visual Analogue Scale (VAS), Oswestry Disability Index (ODI), and Medication Quantification Score (MQS) were obtained before and at 3-monthly intervals after treatment. RESULTS: The VAS decreased significantly after the radiofrequency treatment, and this decrease persisted at 12 months of follow-up. The VAS did not change over 12 months in untreated control subjects. The decrease in VAS was significantly greater in the treated patients than the control subjects. The ODI also decreased in treated patients but not in control subjects. The MQS did not change in either group over the 12-month follow-up period. CONCLUSIONS: Radiofrequency heating of annular tears can lead to an improvement in the pain of internal disc disruption. The improvement gained by this treatment method is significantly better than that obtained from conservative management.     

MRI对腰椎纤维环后部破裂的诊断价值

目的明确腰椎MRI对诊断疼痛性纤维环破裂的敏感性。方法收集近 2年因腰椎间盘退变伴下肢放射痛而手术的患者47例,所有患者腰椎 MRI均有高信号区 (high-intensity zone, HIZ)表现。通过比较手术结果与 MRI影像学资料,对 MRI诊断纤维环后部破裂的敏感性作出评价。结果共研究 47例,手术探查 105个椎间盘。其中 HIZ椎间盘 56个,手术证实阳性率 85.7％,假阳性率 14.3％;无 HIZ椎间盘 49个,手术证实阴性率 87.8％,假阴性率 12.2％。结果表明 MRI诊断纤维环后部破裂的敏感性为 88.9％,特异性为 84.3％。结论 HIZ是诊断疼痛性腰椎纤维环后部破裂的特异性和敏感性较高的影像学标准。     

Intervertebral disc degeneration

Summary Disc degeneration in the human spine is a complex phenomenon characterised by biochemical change in the nucleus pulposus and inner annulus and the formation of clefts and fissures radiating from the central area of the disc towards the periphery. In addition, and probably independent of these phenomena, discrete defects in the outer annular attachement are seen which are likely to be due to mechanical stress and failure. The presence of stress tears in disc tissue and their failure to heal can initiate or accelerate the degeneration of the central component of the intervertebral disc. We postulate that discogenic pain may be linked to damage to the outer portion of the annulus fibrosus. Although it would seem logical to assume that discs with sustained high intradiscal pressure would be more prone to pain referred in the outer annular layers because of higher tensile strain, analysis of prospective studies has failed to confirm a relationship between typical pain reproduction at discography and high pressure values. It is concluded that, at present, the only consistent morphological changes present in patients with pain reproduction at discography are the presence of various annular defects involving the outer layers. Whether nerve ingrowth during attempts at repair of these defects is a consistent feature remains to be established.     

Lumbar discography followed by computed tomography. Refining the diagnosis of low-back pain

Two hundred fifty patients with low-back pain who underwent lumbar discography followed by computed tomography (CT) are the subject of this prospective study. In 93% of the patients, these combined imaging techniques provided additional useful diagnostic information that affected patient management and the selection of treatment alternatives. Lumbar discography followed by CT proved valuable in determining the significance of equivocal or multiple level abnormalities, determining the type of disc herniation, defining surgical options, and evaluating the previously operated spine. In 94% of patients who had surgery, CT-discography correctly predicted the type of disc herniation as protruded, extruded, sequestrated, or internally disrupted. Computed tomography-discography may be more sensitive that magnetic resonance imaging (MRI) in the early stages of disc degeneration because 18 of 177 discs with a normal T2-weighted image were discographically abnormal and the CT-discogram revealed annular tears or radial fissuring. The radiographic morphology of the normal herniated and degenerative lumbar discs shown by CT-discography gives unique insight into the pathogenesis of disc degeneration. The complications that followed the 750 discograms were one case of urticaria and one disc space infection. Even with the availability of high resolution CT and MRI, lumbar discography remains the only pain provocation challenge to the lumbar disc.     

An observation of ruptured annulus fibrosus in lumbar discs.

To observe anatomical or pathological changes in lumbar intervertebral discs, discography and computed tomography-discography (CTD) were performed on fresh human cadavers. The results of discograms and CTD were compared with histological findings of cross sections of discs. Preoperative CTD of lumbar disc herniation was investigated based on these results. Ruptures of the annulus fibrosus were divided into two categories: circumferential rupture and radial rupture. In CTD images of fresh human cadavers, most images of rupture of the annulus fibrosus showed anterior to lateral circumferential rupture. As disc degeneration progressed, circumferential rupture tended to coexist with radial rupture in many cases. In CTD cases of lumbar disc herniation, most images of ruptures of the annulus fibrosus showed a posterior radial rupture, which was the route for herniated nucleus. The greater the degree of degeneration, the more the images tended to show radial ruptures coexisting with circumferential ruptures.     

A porcine model of intervertebral disc degeneration induced by annular injury characterized with magnetic resonance imaging and histopathological findings. Laboratory investigation

OBJECT: Appropriate animal models of disc degeneration are critical for the study of proposed interventions as well as to further delineate the degenerative process. The purpose of this study was to characterize a porcine model for disc degeneration confirmed on magnetic resonance (MR) imaging studies and histological analysis. METHODS: Twelve miniature pigs were used (weight 48-65 kg) to study degeneration in the lumbar spine. Under fluoroscopic guidance, the disc was percutaneously punctured with a 3.2-mm-diameter trephine to a 5-mm depth into the annulus fibrosus. Control and experimental levels were randomized among 6 levels in the lumbar spine. The unlesioned spinal levels were used as controls and were compared with lesioned levels. Magnetic resonance imaging grading and disc height were serially recorded preoperatively, and at 5, 8, 19, 32, and 39 weeks postoperatively. The animals were killed in groups of 3 at 7, 18, 32, and 41 weeks postinjury, and the discs were examined histopathologically. RESULTS: Consistent, sequential, and progressive degeneration of the annular injury was observed on MR imaging and histopathological studies from the time of injury to the final time point. The disc height and the disc height index also sequentially decreased from the time of the injury in a consistent manner. The uninjured control levels did not show any progressive degeneration and maintained their normal state. CONCLUSIONS: Based on MR imaging and histopathological findings, the authors demonstrated and characterized a reliable model of sequential disc degeneration in miniature pigs with percutaneous injury to the annulus fibrosus. In the early stages, as soon as 5 weeks after injury, significant disc degeneration was seen on MR imaging grading with decreases in disc height. This degeneration did not improve by the final time point of 39 weeks.     

The pathogenesis of discogenic low back pain

Discogenic low back pain is a common cause of disability, but its pathogenesis is poorly understood. We collected 19 specimens of lumbar intervertebral discs from 17 patients with discogenic low back pain during posterior lumbar interbody fusion, 12 from physiologically ageing discs and ten from normal control discs. We investigated the histological features and assessed the immunoreactive activity of neurofilament (NF200) and neuropeptides such as substance P (SP) and vasoactive-intestinal peptide (VIP) in the nerve fibres. The distinct histological characteristic of the painful disc was the formation of a zone of vascularised granulation tissue from the nucleus pulposus to the outer part of the annulus fibrosus along the edges of the fissures. SP-, NF- and VIP-immunoreactive nerve fibres in the painful discs were more extensive than in the control discs. Growth of nerves deep into the annulus fibrosus and nucleus pulposus was observed mainly along the zone of granulation tissue in the painful discs. This suggests that the zone of granulation tissue with extensive innervation along the tears in the posterior part of the painful disc may be responsible for causing the pain of discography and of discogenic low back pain.     

Magnetic resonance imaging evaluation of recipient for cryopreserved aortic allograft.

Aortic valve replacement with a cryopreserved aortic allograft is the procedure of choice for many patients with aortic valvular heart disease. We have used magnetic resonance imaging preoperatively to determine annular size and coronary artery orientation in the recipient, which not only has enabled us to select an allograft of appropriate size from a distant tissue bank, but also has helped us to identify preoperatively the recipient with a truly bicuspid valve in which the coronary arteries are oriented 180 degrees apart. Sixteen consecutive patients were evaluated preoperatively, the aortic annulus being measured with both magnetic resonance imaging and echocardiography. Cryopreserved aortic allografts were ordered on the basis of the magnetic resonance imaging measurement. Annular size was then measured intraoperatively with calibrated sizers. Magnetic resonance imaging annular measurements correlated highly with those found at operation (r = 0.92), whereas echocardiographic measurements correlated less well (r = 0.69). Coronary orientation was accurately predicted in every case (r = 1.0). Therefore, we have found magnetic resonance imaging to be useful in the preoperative evaluation of patients for aortic valve replacement with a cryopreserved aortic allograft.     

Thoracic discography in healthy individuals. A controlled prospective study of magnetic resonance imaging and discography in asymptomatic and symptomatic individuals.

STUDY DESIGN: A prospective case-control investigation. OBJECTIVES: To determine the responses to thoracic discography of asymptomatic individuals. SUMMARY OF BACKGROUND DATA: Literature regarding lumbar and cervical discography reveals that even morphologically abnormal discs often are not painful, whereas painful discs typically exhibit anular or endplate disruption. METHODS: Ten adult lifelong asymptomatic volunteers, ages 23 to 45 years, underwent magnetic resonance imaging of the thoracic spine, followed by four-level discography. Provocative responses were graded on a scale of 0 (no sensation) to 10 (extreme pain or pressure), and filmed discs were graded using a modified Dallas scheme. Concomitantly, 10 nonlitigious adults (6 men and 4 women, ages 31 to 55 years) experiencing chronic thoracic pain were similarly studied as a control group. RESULTS: The mean pain response in the asymptomatic volunteers was 2.4/10. Three discs were intensely painful (scores of 7/10, 8/10, 10/10), with all three exhibiting prominent endplate irregularities and anular tears typical of thoracolumbar Scheuermann's disease. On discography, 27 of 40 discs were abnormal, with endplate irregularities, anular tears, and/or herniations. Ten discs read as normal on magnetic resonance imaging showed anular pathology on discography. In the group with chronic thoracic pain, the average pain response was 6.3/10 (P < 0.05). Of the 48 discs studied, 24 were concordantly painful, with a pain response of 8.5/10 (P < 0.05); 17 had nonconcordant pain/pressure, with an average pain of 4.8/10 (P < 0.05); and 5 had no response. On magnetic resonance imaging 21 of the 48 discs appeared normal. However, on discography, only 10 were judged as normal. CONCLUSIONS: On discography, thoracic discs with prominent Schmorl's nodes may be intensely painful, even in lifelong asymptomatic individuals, but the pain is unfamiliar or nonconcordant. Thoracic discography may-demonstrate disc pathology not seen on magnetic resonance imaging.     

Disc degeneration: a human cadaveric study correlating magnetic resonance imaging and quantitative discomanometry

STUDY DESIGN: This human cadaveric study evaluated disc degeneration of the lumbar spine using magnetic resonance imaging and quantitative discomanometry. OBJECTIVE: To determine if a correlation exists between magnetic resonance imaging and quantitative discomanometry in determining disc degeneration of the lumbar spine. SUMMARY OF BACKGROUND DATA: Several studies analyzing disc degeneration of the lumbar spine have compared magnetic resonance imaging with discography and discomanometry. The reported results are conflicting. No studies exist that compare magnetic resonance imaging and quantitative discomanometry in assessing the disc degeneration of the lumbar spine. METHODS: Three fresh human cadaveric thoracolumbar spine specimens (two T11-S1 and one L1-S1) that included a total of 19 discs were used. Spines were scanned with magnetic resonance imaging, and the scans were read by a neuroradiologist. Using the quantitative discomanometry technique, discs were injected with normal saline, and pressure-volume curves were collected and quantified with six parameters: intrinsic pressure, leakage pressure, initial slope, slope from 0.0 to 0.1 mL, maximum pressure, and volume at maximum pressure. Data analysis was performed using Spearman's Rank Correlation (Rho) statistic. RESULTS: Based on the results from 19 discs, an overall good correlation between magnetic resonance imaging scores and the six quantitative discomanometry parameters was demonstrated. With exception of the volume at maximum pressure, correlation coefficients ranged between 0.61 to 0.78 with a P < 0.05. CONCLUSIONS: Magnetic resonance imaging scores and quantitative discomanometry parameters correlated well in the assessment of disc degeneration of the lumbar spine. Quantitative discomanometry may be an important technique for evaluating early disc degeneration, especially tears of the anular fibers, which may be missed on magnetic resonance imaging.     

Metastatic disease involving the discovertebral junction of the spine

ObjectiveTo investigate the use of magnetic resonance imaging in the detection of metastatic tumors involving the discovertebral junction of the spine in cadaveric specimens and patients, with histologic findings as the reference standard.MethodsMagnetic resonance imaging studies were performed on 30 DVJs in 10 cadavers with documented metastatic bone disease. Anatomic sectioning and histologic evaluations were performed, and anatomic slices were correlated with the magnetic resonance images. For clinical study, magnetic resonance imaging examinations in three patients with vertebral metastasis were reviewed.ResultsOn magnetic resonance imaging, the signal intensity characteristics of vertebral body metastases were variable. Magnetic resonance imaging failed to detect metastatic foci invading the cartilaginous endplates. On microscopic examination, infiltration of the discovertebral junction by tumorous tissue was found in 11 (69%) of the 16 discovertebral junctions that had an irregular contour, and in 5 (31%) disrupted discovertebral junctions. In three specimens and three patients, microscopic examination revealed tumor metastasis to the intervertebral disc. In no specimen magnetic resonance imaging afforded depiction of discal invasion by tumor.ConclusionsOur results lend further support to the theory that metastatic tumors can invade the cartilaginous endplate through defects in its substance, allowing direct contact of tumor and disc. Minimal tumor invasion of the discovertebral junction may not be identified at magnetic resonance imaging or gross anatomic inspection, or both, because small metastatic foci may be obscured by abnormalities in the morphology of the cartilaginous endplate.     

Magnetic resonance arthrography in children with developmental hip dysplasia

Conventional and gadolinium enhanced magnetic resonance arthrograms were done on 14 hips in 10 children ages 7 to 24 months. The contralateral normal hips in those with unilateral disease were studied with unenhanced magnetic resonance imaging for comparison. By conventional arthrography, there were no well visualized structures. Visualized structures seen as filling defects were the labrum, ligamentum teres, and transverse acetabular ligament. By magnetic resonance arthrography, well visualized structures were the labrum, ligamentum teres, transverse acetabular ligament, and pulvinar. By unenhanced magnetic resonance imaging, well visualized structures were the labrum, ligamentum teres, and transverse acetabular ligament. The difference in visualization by magnetic resonance arthrography versus conventional arthrography was statistically significant with respect to all five structures: labrum, ligamentum teres, transverse acetabular ligament, pulvinar, and psoas tendon. The difference in visualization by magnetic resonance arthrography versus unenhanced magnetic resonance imaging was statistically significant with respect to the labrum and pulvinar. Magnetic resonance arthrography is indicated for assessing complete concentric reduction when it does not appear to be achieved by conventional arthrography, for confirming closed reduction immediately after manipulation, and potentially for preoperative planning for an open reduction.     

Innervation of pathologies in the lumbar vertebral end plate and intervertebral disc

Background contextMagnetic resonance imaging (MRI) has limited diagnostic value for chronic low back pain because of the unclear relationship between any anatomic abnormalities on MRI and pain reported by the patient. Assessing the innervation of end plate and disc pathologies—and determining the relationship between these pathologies and any abnormalities seen on MRI—could clarify the sources of back pain and help identify abnormalities with enhanced diagnostic value.PurposeTo quantify innervation in the vertebral end plate and intervertebral disc and to relate variation in innervation to the presence of pathologic features observed by histology and conventional MRI.Study design/settingA cross-sectional histology and imaging study of vertebral end plates and intervertebral discs harvested from human cadaver spines.MethodsWe collected 92 end plates and 46 intervertebral discs from seven cadaver spines (ages 51–67 years). Before dissection, the spines were scanned with MRI to grade for Modic changes and high-intensity zones (HIZ). Standard immunohistochemical techniques were used to localize the general nerve marker protein gene product 9.5. We quantified innervation in the following pathologies: fibrovascular end-plate marrow, fatty end-plate marrow, end-plate defects, and annular tears.ResultsNerves were present in the majority of end plates with fibrovascular marrow, fatty marrow, and defects. Nerve density was significantly higher in fibrovascular end-plate marrow than in normal end-plate marrow (p<.001). Of the end plates with fibrovascular and fatty marrow, less than 40% were Modic on MRI. Innervated marrow pathologies collocated with more than 75% of the end plate defects; hence, innervation was significantly higher in end plate defects than in normal end plates (p<.0001). In the disc, nerves were observed in only 35% of the annular tears; in particular, innervation in radial tears tended to be higher than in normal discs (p=.07). Of the discs with radial tears, less than 13% had HIZ on T2 MRI. Innervation was significantly less in radial tears than in fibrovascular end-plate marrow (p=.05) and end-plate defects (p=.02).ConclusionsThese findings indicate that vertebral end-plate pathologies are more innervated than intervertebral disc pathologies and that many innervated end-plate pathologies are not detectable on MRI. Taken together, these findings suggest that improved visualization of end-plate pathologies could enhance the diagnostic value of MRI for chronic low back pain.     

Acromial shapes and extension of rotator cuff tears: magnetic resonance imaging evaluation

Magnetic resonance imaging makes it possible to inspect the status of the rotator cuff and the shape of the acromion. To clarify the relationship between acromial shapes and rotator cuff tears, we evaluated magnetic resonance images obtained in 192 shoulders. We classified the acromial shapes into 3 types: type I (flat), type II (curved), and type III (hooked). Among a group of 91 shoulders with rotator cuff tears, 33 (36.3%) were type I, 22 (24.2%) type II, and 36 (39.6%) type III. The size of rotator cuff tears in type III acromions was significantly larger than in type I or II acromions. Comparison of the incidence of each acromial shape between groups of specimens with and without rotator cuff tears revealed no significant differences. We suggest that whereas acromial shapes have a bearing on the extent of rotator cuff tears, the correlation between rotator cuff tears and a type III acromion is not as strong as has been suggested in the literature.