Johnson D W, Farnum G N, Latchaw R E, Erba S M
Department of Radiology, Univesity Health Center of Pittsburgh, PA 15213.
AJR Am J Roentgenol. 1989 Feb;152(2):327-32. doi: 10.2214/ajr.152.2.327.
MR imaging of the lumbar spine has become a useful method for the noninvasive evaluation of low back pain. However, bone abnormalities are more difficult to detect than soft-tissue lesions, such as herniated disk. We reviewed 14 MR images of the lumbar spine in adults with spondylolisthesis. These were correlated with CT scans and plain films in all cases. From the CT scans and plain films we found that seven patients had spondylolysis and that seven had other causes for their spondylolisthesis. It was our opinion that the MR images suggested an abnormality of the pars interarticularis in all seven of the cases confirmed to have spondylolysis and in six of the seven patients that did not have spondylolysis. We also studied four cadaver lumbar spine, obtained as blocks of tissue, and scanned in the coronal, sagittal, and axial planes with MR and in the sagittal and axial planes with CT. The tissue blocks were then sectioned in the sagittal plane. Spondylolysis is suggested on sagittal MR images when there is an inability to resolve the marrow signal in the pars as uninterrupted from the superior to the inferior facet. This is caused by a dark signal on all pulsing sequences in the pars resulting from marginal sclerosis at the site of the break. If there is also a gap at the site of the break then there will also be an increased signal in the gap resulting from the presence of soft tissue. We found four situations in which the pars can simulate spondylolysis on sagittal MR images: (1) sclerosis of the neck of the pars: (2) partial volume imaging of the degenerative spur of the superior facet slightly lateral to the pars; (3) partial facetectomy; and (4) osteoblastic metastatic replacement of the marrow of the pars.
腰椎的磁共振成像已成为评估下腰痛的一种有用的无创方法。然而，与软组织病变（如椎间盘突出）相比，骨异常更难检测。我们回顾了14例成人腰椎滑脱患者的磁共振图像。所有病例均将这些图像与CT扫描及平片进行了对比。通过CT扫描和平片，我们发现7例患者有椎弓根峡部裂，7例患者的腰椎滑脱有其他病因。我们认为，在所有确诊为椎弓根峡部裂的7例病例以及7例未患椎弓根峡部裂的患者中的6例中，磁共振图像均显示关节突间部存在异常。我们还研究了4个尸体腰椎，将其制成组织块，分别进行了磁共振冠状面、矢状面和横断面扫描以及CT矢状面和横断面扫描。然后将组织块沿矢状面切开。当矢状面磁共振图像上无法分辨关节突间部的骨髓信号从上方小关节到下方小关节连续时，提示存在椎弓根峡部裂。这是由于断裂部位边缘硬化导致关节突间部在所有脉冲序列上均呈低信号。如果断裂部位也存在间隙，那么由于软组织的存在，间隙内信号也会增加。我们发现有四种情况可在矢状面磁共振图像上模拟椎弓根峡部裂：（1）关节突间部颈部硬化；（2）关节突间部稍外侧的上关节突退变骨刺的部分容积成像；（3）部分关节突切除术；（4）关节突间部骨髓的成骨性转移替代。
