Kevin D. Harkins1, Jean-Phillipe Galons2, Timothy W. Secomb3, Theodore P. Trouard1,2
1Biomedical Engineering, University of Arizona, Tucson, AZ, USA; 2Radiology, University of Arizona, Tucson, AZ, USA; 3Physiology, University of Arizona, Tucson, AZ, USA
The biophysical mechanisms which affect the apparent diffusion coefficient (ADC) have been debated since the initial observation of a drop in ADC following ischemic stroke. A computational model of water diffusion is used to assess the role of intracellular volume fraction (IVF), intracellular diffusion coefficient (Dint), membrane permeability and T2 relaxation on the calculated ADC. Simulations indicate that a 30-50% drop in ADC can be achieved by swelling cells from 80% to 90% IVF when the intracellular T2 was allowed to be lower than extracellular T2. Furthermore, at diffusion times greater than 20 ms, the ADC was virtually independent of Dint.