Abstract #0121

Time-Course of δR2 During Visual Stimulation and Hypercapnia Diffusion-Weighted FMRI Experiments

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.