Fig 3.

Images of a 66-year-old man with left leg pain and weakness.

A−C, Contiguous axial view T2-weighted MR images obtained at the L4–L5 level. Canal distortion is present on the right at the disk margin. Narrowing of the left lateral recess was judged to be root compression by one observer but only canal distortion by the other observer because of visualization of the roots free within the canal in the left lateral recess region (arrows).

D, Conventional myelogram shows left lateral recess root compression at L4–L5 (curved arrow). Root compression was confirmed at surgery. The patient achieved complete recovery from leg pain after decompression.

E−G, Contiguous axial view post-myelogram CT images obtained at the L4–L5 level show slight canal distortion on the right but a normal appearing left lateral recess (arrows), similar to the findings of the MR imaging study. Both observers labeled this left lateral recess as noncompressive (grade 1).