Middle cerebral artery: determination of flow velocities with MR angiography.

A magnetic resonance (MR) angiographic technique for noninvasive measurement of flow velocities in the intracranial cerebral arteries was studied. Velocity measurements were made in a phantom and in the middle cerebral artery of six volunteers. Velocities were assessed in the volunteers before, during, and after finger movement. Average values for mean maximal velocities determined with MR angiography were 69.8 cm/sec before, 77.2 cm/sec during, and 69.6 cm/sec after finger movement. Correlations between values obtained with MR angiography and transcranial Doppler (TCD) sonography were r = .86 and P = .0001 for values obtained at rest and r = .84 and P = .0001 for values obtained during finger movement. The velocity increase during finger movement compared with that at rest was 11% for MR angiography and 11.3% for TCD sonography. Values measured with TCD sonography, however, were less than those measured with MR angiography (P = .001). The results show the feasibility of measuring flow velocities in intracranial arteries with MR angiography.