Fresh blood imaging of the peripheral vasculature: an emerging unenhanced MR technique.

OBJECTIVE There is an increasing demand for MR angiography (MRA) techniques that do not require the administration of exogenous contrast material. Fresh blood imaging utilizes an ECG-gated fast spin-echo sequence to acquire images in both the systolic and diastolic phases of the cardiac cycle. Fast systolic arterial flow is differentiated from slower diastolic flow and a subtraction technique is used to produce angiographic images. We describe the technical aspects of performing lower extremity MRA and illustrate some sample cases. CONCLUSION Fresh blood imaging is an emerging unenhanced MRA technique that has recently become commercially available. Early clinical trials appear promising and it is anticipated that fresh blood imaging will become invaluable, particularly in patients with impaired renal function. Technical refinements are still required to perfect this novel MR application, particularly for the assessment of distal calf and pedal vessels and for the evaluation of patients with arrhythmias and those with impaired cardiac function