Diffusion-weighted resting-state functional MRI at 3T

Abstract

Resting-state functional MRI (rsfMRI) has emerged as a valuable become an increasingly important tool for mapping inter and intra-hemispheric connectivity in normal and diseased brains. To date, most rsfMRI studies have used T2*-weighted gradient-echo (GE) for the benefit of sensitivity. Theoretically, spin-echo (SE) provides better spatial specificity due to the elimination of static dephasing around macro-vessels. At 3T, the benefit however is limited because of a nearly equal share of undesired intravascular (IV) and well-localized extravascular (EV) contribution from microvasculature. Diffusion gradients induce velocity-dependent phase shifts and thus reduce signal from blood due to inhomogeneous velocities within vessel and presence of vessels with different orientations in a pixel. In this study, we aimed to investigate rsfMRI connectivity at 3T using diffusion-weighted (DW) SE to eliminate IV effect from large vessels. By using interleaving non-DW and DW acquisition, we identified default mode networks with similar but different pattern, spatially and spectrally. (Abstract by ISMRM)