MR of the cauda equina.

To define the anatomy of the cauda equina nerve roots by MR imaging, the lower spine of 14 normal volunteers was imaged using a high-field surface-coil technique. A total of 56 sagittal and 56 axial MR sections (eight selected slices from each case) were correlated with undistorted anatomic sections from cadaver spine specimens, and the visualization of the nerve roots was assessed. In addition, MR images of three patients with infiltrating or seeding tumors affecting the cauda equina were analyzed. Seventy-eight percent of the MR sections from normal cases clearly showed the anatomy of the cauda equina nerve roots. The nerve roots were fairly shown in 17% of the sections; and false findings (presumably caused by CSF pulsation) were observed in the remaining 5%. Coronal imaging provided excellent anatomic views of the nerve roots within the intervertebral foramina. Morphologic alterations in the pathologic cases were correctly shown when both T1- and T2-weighted imaging were used. In conclusion, MR proved efficient in viewing the cauda equina region.