Computed tomography in degenerative lumbar spinal stenosis: The value of multiplanar reconstruction

Computed tomography is superior to other radiologic modalities for evaluating degenerative lumbar spinal stenosis, because it directly images both bone and soft tissue. CT multiplanar reconstruction provides precise three dimensional analysis. Correlation of CT with myelography and clinical information leads to the following conclusions. 1. Severe central canal stenosis on CT corresponds to high grade or complete block on myelography. 2. Lateral recess encroachment is best identified on transaxial CT images and is the most common type of persistent stenosis in this series of postoperative patients. 3. Narrowing of the neural foramina is best demonstrated on CT sagittal reconstruction images. 4. Intraarachnoidal adhesions require intrathecal contrast agents (e.g., metrizamide) for radiographic demonstration. 5. Multiplanar reconstruction images are very helpful for accurately describing the spatial relationships involved in spinal disease. 6. Degenerative spondylolisthesis can be reliably characterized by CT and distinguished from spondylolytic forms of spondylolisthesis. The "double margin" sign is a reliable transaxial CT finding in all forms of spondylolisthesis. 7. A close correlation exists between CT-demonstrated moderate to severe postoperative stenosis and poor surgical results. Improved diagnostic imaging and interpretation leads to better preoperative planning and higher surgical success rates. Radiographic abnormalities do not necessarily produce clinically significant patient symptoms. Careful clinical correlation is required for successful treatment planning and patient management.