Abstract #3398

Biophysical simulations of the BOLD fMRI signal using realistic imaging gradients: Understanding macrovascular contamination in Spin-Echo EPI

Avery JL Berman^1,2, Avery JL Berman^1,2, Fuyixue Wang^1,3, Kawin Setsompop^4,5, J. Jean Chen^6,7, and Jonathan R Polimeni^1,2,3

¹Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, United States, ²Department of Radiology, Harvard Medical School, Boston, MA, United States, ³Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, MA, United States, ⁴Department of Radiology, Stanford University, Palo Alto, CA, United States, ⁵Department of Electrical Engineering, Stanford University, Palo Alto, CA, United States, ⁶Rotman Research Institute, Baycrest Health Sciences, Toronto, ON, Canada, ⁷Department of Medical Biophysics, University of Toronto, Toronto, ON, Canada

We introduce simulations of the BOLD signal that incorporate realistic image encoding gradients to help better understand the role the acquisition window plays on BOLD contrast. We applied this framework to examine the well-known macrovascular R₂' contamination in spin-echo EPI BOLD signals as a function of readout duration, vessel diameter, and voxel size using randomly oriented cylinders. To understand large-vessel effects, more realistic anatomy is needed; therefore, we added a large pial vein to random microvascular networks to systematically investigate macrovascular contamination along cortical depths and across columns. This framework reproduced experimentally established results related to the acquisition window duration.

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