Effects of Diffusion on MR Signal Under Various Microvasculature

Cihat Eldeniz¹, Weili Lin², Hongyu An²

Paramagnetic deoxyhemoglobin within capillaries and veins can induce magnetic field variations around these vessels. MR signal decay is governed by both static and diffusion induced dephasing effects. It has been suggested that diffusion effects highly depends on MR pulse sequence, echo time, and vessel size. Previous studies have proposed models with simplistic assumptions such as uniform vessel radii within a voxel, or explore the morphology of cerebral cortex microvasculature that might help modeling; however, a realistic mathematical model that can embrace the vast variety of microvasculature in various regions of the human brain has not been established to date. This also complicates the quantification of diffusion effects on the measurement of hemodynamic parameters. In this study, we aimed to shed light on how diffusion affects the MR signal under different vascular configurations pertaining to distinct regions.