Evaluation of subclavian steal with two-dimensional phase-contrast and two-dimensional time-of-flight MR angiography.

We describe two MR angiographic methods of diagnosing subclavian steal in each of three patients. By using phase-directional information from a single two-dimensional phase-contrast sequence, we were able to show that the direction of flow in the affected vertebral artery was reversed. The same vertebral artery showed no signal on a 2-D time-of-flight sequence with a concatenated presaturation pulse applied above each section.