Contrast-enhanced MRA of the brain

Most sequences for MR angiography (MRA) used today exploit the macroscopic motion of the blood to differentiate vessels from the stationary tissues. An alternative approach to inflow based MRA is contrast enhanced MRA, in which relaxation agents are used to selectively shorten the T1 of the blood below the T1 value of the stationary tissues. We have evaluated cerebral Gd enhanced MRA, comparing it with conventional angiography and noncontrast inflow based MRA. Contrast/enhanced MRAs were obtained at 1.0 T with a 3D FISP sequence with TR/TE/alpha: 35-40 ms, 7-11 ms/TE/25 degrees. Contrast enhancement was obtained by a biphasic injection of a double dose of Gd-DOTA (0.2 mmol/kg) during image acquisition. With the described technique the conspicuity of both cerebral arteries and veins is improved compared to nonenhanced inflow MRA.