Recurrent lumbar disc extrusion (herniation). A, Sagittal T1-weighted image demonstrates intermediate signal intensity in L4-L5 disc material (arrow) surrounded by hypointense cerebrospinal fluid. B, Sagittal T2-weighted image shows displaced disc material contiguous with intervertebral disc. Hyperintense cerebrospinal fluid provides improved contrast. C, Sagittal T1-weighted image after gadolinium administration demonstrates enhancement of epidural venous plexus (arrow) and overlying granulation tissue but no enhancement of disc material.