T1, T2 relaxation and magnetization transfer in tissue at 3T

Abstract

T₁, T₂, and magnetization transfer (MT) measurements were performed in vitro at 3 T and 37°C on a variety of tissues: mouse liver, muscle, and heart; rat spinal cord and kidney; bovine optic nerve, cartilage, and 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, M_0B, and macromolecular T₂ relaxation time, T_2B) 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. Magn Reson Med, 2005.