Understanding Transverse Relaxation in Human Brain Through Its Field Dependence from 1.5 to 7T

Fumiyuki Mitsumori¹, Hidehiro Watanabe¹, Nobuhiro Takaya¹, Michael Garwood², Edward Auerbach², Shalom Michaeli², Silvia Mangia²

We conducted measurements of apparent transverse relaxation rate at 1.5, 1.9, 3, 4.7, and 7T using a MASE sequence. The regional distribution of the relaxation rate was well described by a linear combination of the regional iron concentration [Fe], and the macromolecular mass fraction f_M defined as 1 - water fraction. The B₀-dependence of the [Fe] and f_M terms was linear and quadratic, respectively. The linear dependence of the [Fe] term was similar to that reported for ferritin solution. The quadratic dependence of the macromolecular term was well explained with an exchange model of water protons with those in macromolecules.