Estimating the arterial input function using two reference tissues in dynamic contrast-enhanced MRI studies: fundamental concepts and simulations.

In dynamic contrast-enhanced MRI (DCE-MRI) studies, an accurate knowledge of the arterial contrast agent concentration as a function of time is crucial for the estimation of kinetic parameters. In this work, a novel method for estimating the arterial input function (AIF) based on the contrast agent concentration-vs.-time curves in two different reference tissues is described. It is assumed that the AIFs of the two tissues have the same shape, and that simple models with two or more compartments, and unknown kinetic parameters, can describe their tracer concentration-vs.-time curves. Based on the principle of self-consistency, one can relate the two tracer concentration-vs.-time curves to estimate their common underlining AIF, together with the kinetic parameters of the two tissues. In practice, the measured concentration-vs.-time curves have noise, and the AIFs of the two tissues are not exactly the same due to different dispersion effects. These factors will produce errors in the AIF estimate. Simulation studies show that despite the two error sources, the double-reference-tissue method provides reliable estimates of the AIF. (c) 2004 Wiley-Liss, Inc.