Oscillating Gradient Spin Echo Shows Elevated Diffusion Dispersion Rate in Human Acute Ischemic Stroke

Motivation: The diffusion dispersion rate (DDR, slope of diffusion with frequency of oscillating-gradient-spin-echo - OGSE) has been probed in animal stroke models and healthy human brain, but has not been explored in human acute ischemic stroke. Goal(s): Our goal is to map DDR in human stroke and explore its insight on the biophysical mechanisms related to reduced diffusion in stroke. Approach: DDR maps using OGSE 25/40/50Hz were acquired in 12 acute ischemic stroke patients. Results: DDR is significantly higher in ischemic lesions relative to contralateral white matter, and is highest in brain regions with presumably larger axons. Impact: The application of oscillating-gradient-spin-echo diffusion MRI with different oscillating frequencies highlights greater diffusion time effects in acute stroke than healthy tissue, which agrees with earlier preclinical ischemia models, and implicates changes of short range microstructural disorder (e.g. beading).