Dynamic Contrast Enhancement MRI Studies Using Low-Dose Gadolinium-Based Contrast Agents |Biomedgrid

The theory for the use of paramagnetic agents to measure tissue perfusion is based on two primary mechanisms of image contrast, relaxivity and susceptibility effects [1,2]. Relaxivity effects result from dipolar enhancement of T1 and T2 rates. Because tissue T1 relaxation rates are intrinsically smaller, the dominant effect is shortening of T1 relaxation times. The second mechanism of image contrast is the variation in tissue magnetic field produced by heterogeneous distribution of high magnetic susceptibility agents. Quantitation of tissue perfusion requires a detailed understanding of the relation between contrast agent concentration and associated MR signal changes. If this relationship is known, tracer kinetic modeling can be used to calculate regional cerebral blood flow (rCBF) and blood volume (rCBV).