Exploring the oscillating gradient waveform frequency dependence of diffusivity changes in human acute ischemic stroke

Two previous oscillating-gradient-spin-echo (OGSE) studies of human acute ischemic stroke using different diffusion waveforms (40 Hz, one-period; 50 Hz, two-period) have reported considerably different mean diffusivity (MD) changes in lesion white matter relative to long diffusion time (“0 Hz”) pulsed-gradient-spin-echo (PGSE). Here both OGSE waveforms were acquired in 8 stroke patients. Lesions showed marked diffusion time dependencies with lesion MD reduction of 40% for PGSE compared to 25% for OGSE 40Hz, and yet OGSE 50Hz was only a bit less (21%). Large heterogeneity between patients (+6% to -43% of OGSE 50Hz MD lesion changes) may explain earlier study differences.