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Abstract #4976

Transverse Relaxation of Tissue Water in Human Brain: Relative Contributions of Iron and Macromolecules

Fumiyuki Mitsumori1, Hidehiro Watanabe1, Nobuhiro Takaya1, Michael Garwood2, Edward Auerbach2

1National Inst. Environmental Studies, Tsukuba, Ibaraki, Japan; 2University of Minnesota, United States

Apparent transverse relaxation rate (R2) of the tissue water was measured in various regions of healthy human brain at four different fields of 1.9, 3, 4.7, and 7T using a multi-echo adiabatic spin echo (MASE) sequence. The R2 increased with field strength (B0). Distribution of R2 in various regions is well explained by contributions from regional non-hemin iron concentration ([Fe]) and macromolecular mass fraction defined by 1 water fraction. Assuming an equation of R2 = α[Fe] + βfM + γ, the coefficient α increased linearly with B0, as previously observed in ferritin solution.