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Abstract #1571

Signal Source in Heavily Diffusion-Weighted Functional MRI

Daigo Kuroiwa1, Hiroshi Kawaguchi1, Jeff Kershaw1, Atsumichi Tachibana1, Joonas Autio1, Masaya Hirano2, Ichio Aoki1, Iwao Kanno1, Takayuki Obata1

1Department of Biophysics, Molecular Imaging Center, National Institute of Radiological Sciences, Chiba, Japan; 2Japan Applied Science Laboratory, GE Yokogawa Medical Systems, Hino, Tokyo, Japan

The contribution of the BOLD effect in heavily diffusion-weighted fMRI is still unclear. In this study, a multiple spin-echo echo-planar-imaging sequence after motion probing gradients was used to measure the transverse relaxation rate at different b-values. The results suggest that the contribution of BOLD to DW fMRI signal changes is independent of the b-value. It is speculated that the main contribution to heavily diffusion-weighted functional MRI signal is not the BOLD effect.