Characterization in vivo of Muscle Fiber Types by Magnetic Resonance Imaging

Abstract

Magnetic resonance imaging has been used to characterize muscle fiber types. Here, T 1 and T 2 values were determined in pure slow-twitch and fast-twitch rabbit muscles and in rabbit muscles with mixed fiber types. The muscles with high proportions of oxidative slow-twitch fibers had higher T 2 values than the others. Echo time, orientation of muscle fibers in B 0, and moving spins had no effect on relaxation parameters. The results are discussed in terms of slow myosin isoform content and oxidative metabolism.