Our study focused on the evaluation of magnetic resonance imaging (MRI) with a contrast agent to living fishes.
Images were collected with a spin-echo pulse sequence using 1.5 and 2 tesla systems. Normal carps, eels and cold-injury induced carps, which could be kept alive for about two hours in the air, were examined in vivo. The enhancement study was performed by using Gd-DOTMA. The blood flow and renal excretion in a carp and an eel were clearly visualized by administering Gd-DOTMA. Normal brain parenchyma in rodentia is known not to be enhanced by Gd-DOTMA because of exis-tence of blood-brain-barrier (BBB). The normal carp brain wasn't enhanced by Gd-DOTMA, also. This fact indicates that the BBB exists in the carp. On the other hand, the disturbed region of BBB in-duced by cold-injury was enhanced by Gd-DOTMA. In addition, the existence of an unknown cavity tissue azound the brain in the carp was recognized by accumulation of Gd-DOTMA.