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; 2Advanced Application Center, GE Healthcare Japan, Hino, Tokyo, Japan
It has been suggested that the BOLD effect contributes to heavily diffusion-weighted (DW) fMRI signal changes. The BOLD effect is usually interpreted as a change in transverse relaxation rate (δR2). In this study, δR2 during visual stimulation (VS) and hypercapnia (HC) DW fMRI experiments was estimated using a multiple spin-echo EPI acquisitions after motion-probing gradients. δR2 showed dependence on b-value during VS, but not during HC. The results suggest that δR2 at high b-value may demonstrate a higher sensitivity to neuronal activation than at lower b-values.