[T2*-contrast perfusion study--principles, theory and clinical utility in evaluating cerebral hemodynamics].

Contrast-enhanced dynamic study is easily feasible with a clinical MR system, for evaluating cerebral perfusion. A bolus of the paramagnetic contrast agents such as Gd-DTPA produces inhomogenity of the regional magnetic field between the capillaries and extravascular proton, and causes a decrease of signal intensity in the perfused region with T2*-weighted sequences. Echo planar imaging (EPI) is suitable for contrast-enhanced dynamic study, because it is markedly susceptible and provides high temporal-resolution. Tracer kinetic approaches are used for analysis of the dynamic data to acquire various perfusion parameters such as time delta R2* curve, rCBF, rCBV and MTT. T2*-weighted contrast-enhanced perfusion imaging is useful, especially, for detecting hyperacute ischemia and its therapeutic window, and depicting vasculature and ability of the brain tumors.