2D-Phase contrast flow evaluation and contrast-enhanced MR angiography forperioperative assessment of Internal mammary artery grafts.

Purpose: To evaluate LV functional parameters, graft flow and patency in pa tients with IMA grafts using a combined MR protocol with phase-contrast tec hnique and contrast enhanced MR angiography. Material and Methods: Using a 1.5 T MR system 27 patients with 27 left internal mammary artery (LIMA) and 41 venous grafts were examined before and 6 months after CABG surgery. A T (1)w-TSE sequence (slice thickness 5 mm) was applied for morphological imag ing. LV function (EF, CO) was evaluated on cine images (segmented FLASH 2D, TReff 11 ms, TE 4.8 ms, flip angle 25 degrees). A phase-contrast FLASH 2D (TR 24 ms, TE 5 ms, flip angle 20 degrees) sequence was applied for aortic and IMA flow measurements. Postoperatively, a contrast enhanced FLASH 3D MR angiography (TR 3.8 ms, TE 1.4 ms, flip angle 30 degrees) with 25 ml Gd-DT PA was performed to assess bypass patency. Results: In patients with reduce d IV function (ejection fraction < 50 %) an improvement of the ejection fra ction from 38.4+/-10.3% to 49.8+/-15.3% (p < 0.05) was found postoperativel y. LIMA grafts were occluded in 1/27 patients, while 6/41 venous grafts wer e occluded. Distal LIMA anastomoses were demonstrated in 33% by MRA. Flow o f LIMA decreased from 21.2+/-11 ml/min/m(2) preoperatively to 14.4+/-9.6 ml /min/m(2) postoperatively (p < 0.01). Conclusion: MR imaging allows accurat e combined assessment of IV function, bypass patency and flow. The protocol of this study may be applicable for perioperative follow-up studies in pat ients after CABG surgery.