MRI versus CT for the diagnosis of lumbar spinal stenosis

Summary Objective The purpose of the study was to compare the effectiveness of CT and MRI in visualizing soft tissues in lumbar spinal stenosis (LSS), and to correlate the images with preoperative symptoms. Materials and methods A total of 163 patients who had undergone unilateral laminotomy for bilateral decompression to treat LSS at L4–5 were retrospectively analyzed. The narrowed spinal canal area was measured on axial images with CT and MRI, and compared with the acquired dimensions from preoperative Visual Analog Scale (VAS) and Oswestry Disability Index (ODI) scores. Results The mean compromised spinal canal areas were 75.08 mm 2 on MRI and 63.13 mm 2 on CT, which were significantly different. Mean VAS for back pain was 5.37, and 7.94 for leg pain. Mean ODI was 55.17%. There was no significant correlation noted between clinical parameters and narrowed spinal canal area. Conclusion Spinal canal area was more narrowed on CT than on MRI in axial cuts. This finding can be explained by the superior ability of multidetector CT to discriminate cortical bone from soft tissue such as the ligamentum flavum . Our study highlights the value of CT examination in combination with MRI prior to LSS surgery.