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Abstract #3273

Diffusion-Weighted Resting-State Functional MRI at 3T

Joe S. Cheng1, 2, Iris Y. Zhou1, 2, Hua Guo3, Patrick P. Gao1, 2, Russell W. Chan1, 2, Queenie Chan4, Henry Ka Fung Mak5, Pek Lan Khong5, Ed X. Wu1, 2

1Laboratory of Biomedical Imaging and Signal Processing, The University of Hong Kong, Hong Kong, Hong Kong; 2Department of Electrical and Electronic Engineering, Hong Kong, Hong Kong; 3Biomedical Engineering & Center for Biomedical Imaging Research, Tsinghua University, Beijing, China; 4Philips Healthcare, Hong Kong, Hong Kong; 5Diagnostic Radiology, The University of Hong Kong, Hong Kong, Hong Kong

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.