EXERCISE-INDUCED CHANGES IN MAGNETIZATION-TRANSFER CONTRAST OF MUSCLES

Magnetization transfer contrast (MTC) technique provides a new type of contrast in MR imaging. The MTC method is based on the interaction be tween the spins of free protons and those with restricted motion. Exer cise-induced changes in signal intensity and MTC were measured in the forearm muscles of 10 volunteers at 0.1 T. There was 26% increase in s ignal intensity of active flexor muscles after exercise when imaged wi th ordinary gradient echo sequence. Despite this marked intensity incr ease, the postexercise values of MTC did not differ from the preexerci se ones.