Patient-specific timing for bolus-chase peripheral MR angiography

PURPOSE: To develop a timing algorithm for three-station moving-table MR angiography of the peripheral arteries (pMRA) based on individual patient hemodynamics that optimizes arterial opacification and minimizes venous enhancement. METHODS: Two separate patient cohorts were identified for this retrospective study. The first consisted of 71 patients for development of a patient specific timing algorithm to calculate multiple contrast agent bolus transit times at 1.5 Tesla using a spoiled gradient echo sequence. This timing data was applied to a separate group of 59 patients in which one of four predetermined pMRA protocols was performed based on a time-resolved MRA of the calves. Image quality was evaluated by two blinded readers grading venous enhancement and arterial opacification. RESULTS: Transit time from abdominal aorta to foot (Ao-F) ranged from 5-46 s, with a mean of 17.8 ± 8.2 s. Arteriovenous window (AVW) transit time ranged from -5 to 65 s, with a mean of 18.3 ± 16.0 s. Ischemic patients had longer injection site-to-arterial transit times (25.6 versus 20.7 s; P < 0.01). Of the 59 patients who underwent diagnostic pMRA, 81 and 83% (two readers, respectively) showed no or minimal venous enhancement, and all of the exams were diagnostic. Venous enhancement grades were significantly greater (P < 0.04) for ischemic versus nonischemic patients. CONCLUSION: Performing pMRA using a timing algorithm based on each patient's unique hemodynamics can minimize lower station venous enhancement.