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.