Water Proton Relaxation Times Exhibit Muscle Fibre Orientation Dependence, While Water to Creatine Magnetization Transfer Rates Do Not

Erin L. MacMillan¹, Christine Sandra Bolliger¹, Chris Boesch¹, Roland Kreis¹

Magnetization transfer rates from water to creatine were previously demonstrated to be different between the soleus and tibialis anterior muscles. To elucidate whether this difference arises from the muscle fibre angle to the external magnetic field, a series of spectra with increasing water inversion delay times were acquired from human tibialis anterior muscles aligned both at the magic angle and parallel to the magnetic field. Water spectra were also acquired with increasing TE times. While water T₁ and T₂ times were significantly longer at the magic angle, water-creatine MT rates did not exhibit an orientation effect.