Improved MR flow mapping in coronary artery bypass grafts during adenosine-induced stress

PURPOSE: To validate a recently developed fast high-temporal-resolution mag netic resonance (MR) flow sequence and use it to assess coronary artery byp ass graft function during pharmacologic stress. MATERIALS AND METHODS: Aortic and internal mammary artery flow was measured in 11 healthy volunteers by using conventional cine gradient-echo imaging as a reference standard method and turbo-field echo-planar imaging (TFEPI). By using TFEPI, breath-hold flow mapping with a spatial and temporal resol ution of 0.8 mm(2) and 23 msec, respectively, can be performed. This sequen ce was applied in 20 angiographically normal grafts, and total blood flow a t rest and during adenosine infusion (140 mug/kg/min) was measured. RESULTS: Good agreement in aortic and internal mammary artery flow values b etween conventional fast-field echo and TFEPI techniques was found. The mea n bypass graft total flow (+/- SD), as assessed with TFEPI, increased from 30.8 mL/ min +/- 13.5 to 76.7 mL/min +/- 36.5 (P < .05) to yield a flow res erve of 2.7. Furthermore, this sequence revealed a difference in total flow between single and sequential grafts at rest (25.4 mL/min vs 40.9 mL/min; P < .05) and during stress (65.2 mL/min vs 98.3 mL/min; P < .05). CONCLUSION: Breath-hold TFEPI provides fast accurate flow measurements with high temporal resolution and allows motion-compensated flow quantification in multiple coronary artery bypass grafts during one 6-minute adenosine in fusion.