Section Editor: Sandy Cheng-Yu Chen, M.D.
Taipei Medical University Hospital, Taipei, Taiwan
Iophendylate (Pantopaque or Myodil), introduced in 1941, is an oil-based positive-contrast medium used in myelography. Due to the extremely slow clearance rate (0.5-3cc per year) of Pantopaque, the sequelae of this once widely-used contrast material can present decades later. Pantopaque has high attenuation (1000-3000 HU) on CT due to its iodine moiety (arrows in Figures A, B, and C). Retained Pantopaque in the subarachnoid space after myelography is usually an incidental finding, as it does not typically cause significant symptoms or neurologic deficits. Awareness of this infrequently encountered sequela is important, as it may mimic other intraspinal pathology and, when diagnosed, can obviate surgical intervention.