There has been
longstanding interest in the anisotropic magnetic properties of muscle tissue,
but to date there has been little examination of these properties using MRI.
Here we describe an initial examination of muscle via field mapping
measurements carried out at 7T on phantoms containing small pieces of muscle
embedded in agar. The results indicate that the susceptibility of this
muscle is diamagnetic (~-100ppb) with respect to agar and only weakly
anisotropic (<5 ppb). There was a significant uniform and
orientation-independent positive frequency offset inside the muscle of 30 ppb
most likely due to chemical exchange effects.