Dmitry S. Novikov1, Jens H. Jensen2, Joseph A. Helpern2
1Radiology, NYU School of Medicine, New York, NY, United States; 2Radiology and Radiological Science, Medical University of South Carolina, Charleston, SC, United States
The types of microstructural architecture in any media (including living tissues) are classified in terms of the long-time tail exponent in the molecular velocity autocorrelation function. The specific value of the power-law exponent obtained from the oscillating gradient spin echo measurement in rat cerebral gray matter characterizes the relevant tissue anatomy that restricts water diffusion. It is argued that short-range disorder, likely due to spines and varicosities, provides the chief hindrance to diffusion along dendrites and axons and that the increase in this structural disorder is a primary cause of the diffusivity drop in ischemic stroke.