RT Journal Article SR Electronic T1 Time course of the apparent diffusion coefficient (ADC) abnormality in human stroke JF Neurology JO Neurology FD Lippincott Williams & Wilkins SP 113 OP 119 DO 10.1212/WNL.49.1.113 VO 49 IS 1 A1 Schlaug, G. A1 Siewert, B. A1 Benfield, A. A1 Edelman, R. R. A1 Warach, S. YR 1997 UL http://n.neurology.org/content/49/1/113.abstract AB Diffusion-weighted MRI can rapidly detect acute cerebral ischemic injury as hyperintense signal changes, reflecting a decline in the apparent diffusion coefficient (ADC) of water through brain parenchyma, whereas ADC is elevated in the chronic stage because of increased extracellular water content. To determine the time course of these ADC changes, we analyzed 157 diffusion-weighted MRI studies performed at varying time points from the initial ischemic event from 101 patients. Data were expressed as the relative ADC (rADC), the ratio of lesion to control regions of interest. We observed two phases in the time course of rADC changes in acute human stroke: a significant (p < 0.005) reduction in rADC lasting for at least 96 hours from stroke onset (mean, 58.3% of control; SEM, 1.47) and an increasing trend from reduction to pseudonormalization to elevation of rADC values at later subacute to chronic time points (≥7 days). We suggest that the persistent reduction of rADC within the first four days may reflect ongoing or progressive cytotoxic edema to a greater degree than extracellular edema and cell lysis.