Quantitative Magnetization Transfer and Relaxation in Tissues at 3T
Stanisz G, Odrobina E, Graham S, Bronskill M, Pun J, Henkelman R
Sunnybrook & Womens' CHSC
T1, T2 and magnetization transfer (MT) measurements were performed in vitro at 3 T and 37oC on a variety of tissues: mouse liver, muscle and heart; rat spinal cord and kidney; bovine optic nerve, cartilage, white and gray matter; and human blood. The MR parameters were compared to those at 1.5 T. As expected, the T2 relaxation time constants and quantitative MT parameters (MT exchange rate, R, macromolecular pool fraction, M0B and macromolecular T2 relaxation time, T2B) at 3 T were similar to those at 1.5 T. The T1 relaxation time values however, for all measured tissues increased significantly with field strength. Consequently, the phenomenological MT parameter, magnetization transfer ratio, MTR was lower by approximately 2 to 10%. Collectively, these results provide a useful reference for optimization of pulse sequence parameters for MRI at 3 T.