Fig 3. MPR images from a 75-year-old woman with persistent back pain after multisegmental laminectomy. In the sagittal sections (A, ACT; B, MSCT), the relevant degenerative changes can be depicted equally well: ligamental hyperplasia in the segment L1/2, ventral osteochondrosis in the segment L2/3, and the slight listhesis in the segment L4/5. A, Note the loss of detail and the enhanced image noise in the ACT section at the level from L5 to S2 due to the high attenuation of contrast media in the thecal sac. The transverse sections through the vertebral body of L4 (C, ACT; D, MSCT) show the hypertrophic facet joints and the thecal sac herniating into the laminectomy site. Both techniques show a well-defined L4 nerve root of the right side and an increase of tissue around the L4 nerve root of the contralateral side.