Magnetic resonance angiography of the rat cerebrovascular system without the use of contrast agents.

We describe and discuss the application of three-dimensional (3D) time-of-flight (TOF) magnetic resonance angiography (MRA) to visualize non-invasively the cerebral vasculature of the rat. MR angiograms of healthy spontaneously hypertensive rats were obtained without the use of contrast agents. Total imaging time ranged from 1 to 50 min for a 3D data set. The influences of the data matrix and the inflow delay on the image quality and the total imaging time are assessed and discussed. Varying the inflow delay yielded in addition semiquantitative information on hemodynamics. The method was applied to obtain angiograms in rat models of permanent and temporal middle cerebral artery occlusion. Occlusion and reopening of the vessel could easily be verified by MRA. However, after reperfusion a slight reduction in blood flow was observed.