On the precision of diffusion/perfusion imaging by gradient sensitization

Computer simulation is used to assess the precision and accuracy of diffusion and perfusion parameters derived from a set of gradient‐sensitized images. Under ideal experimental conditions, a moderate signal‐to‐noise level (ca. 40) suffices to estimate diffusion coefficients to within 20% relative precision. However, estimation of a typical cerebral perfusion fraction of 5% to within 20% relative precision requires signal‐to‐noise levels of ca. 400. Simulations also show that systematic errors in perfusion fraction estimation, as well as understimation of the uncertainties in perfusion parameters (by X‐squared analysis), will be found at moderate signal‐to‐noise levels. © 1992 Academic Press, Inc.