The DWI experiment simulated within the model revealed that intracellular ADC decreased by 79% in beaded neurites compared with the unbeaded form. We first derived a biophysical model of neurite beading, and we show that the beaded morphology allows a larger volume to be encompassed within an equivalent surface area and is, therefore, a consequence of osmotic imbalance after ischemia. We show that focal enlargement and constriction, or beading, in axons and dendrites are sufficient to substantially decrease ADC. However, although the change is related to cell swelling, the precise pathological mechanism remains elusive. Within minutes of an ischemic event in the brain, the microscopic motion of water molecules measured with DWI, termed the apparent diffusion coefficient (ADC), decreases within the infarcted region. Diffusion-weighted MRI (DWI) is a sensitive and reliable marker of cerebral ischemia.