Peripheral vascular and abdominal applications of MR flow imaging techniques

Many MR flow imaging techniques that have been successfully applied in the carotid arteries and intracranial circulation have been tested in the peripheral and abdominal vasculature. The results have been variable. The lack of success can be attributed to different imaging requirements as well as different patterns of blood flow. These requirements include a large field of view, sensitivity to a wide range of blood flow velocities and complex flow directions, and suppression of overlapping vascular structures and stationary tissue. We have designed strategies using phase contrast MR angiography (MRA) for imaging the arteries and veins of the lower extremity and the abdominal vasculature in normal subjects. This strategy takes advantage of the pulsatile flow pattern present in normal arteries. Overlapping blood flow and stationary tissue were suppressed by a combination of spatial presaturation, optimization of the amplitude and duration of the velocity sensitive gradients, and postprocessing techniques.