5,5'-[malonylbis(methylimino)]bis[N, N'-bis[2,3-dihydroxy-1-(hydroxymethyl)propyl]-2,4,6-triiodoisophthalamide]; a dimeric, nonionic, water-soluble, low osmolar radiographic contrast medium, used for myelography and other nonvascular applications. SYN: iotrol.