Perioperative monitoring of flow and patency in native and grafted internal mammary arteries using a combined MR protocol

The objective of this study was to evaluate graft flow (f) and patency (p) in patients with internal mammary artery (f,p) and venous (p only) grafts using a combined MR protocol with phase-contrast technique and MR angiography. 42 patients with 42 left internal mammary artery (LIMA) and 63 venous grafts were examined pre and 6 months post coronary artery bypass graft (CABG) surgery. Phase-contrast flow measurements were applied to the IMA. Post-operatively, a contrast enhanced MR angiogram was performed to assess bypass patency. LIMA/venous grafts were occluded in 3/42 and 13/63, respectively. Flow in LIMA decreased from 19.4±10.4 ml min−1 m−2 pre-operatively to 13.4±9.7 ml min−1 m−2 post-operatively (p<0.002). In contrast, flow in the native right IMA increased from 17.6±8.7 ml min−1 m−2 pre-operatively to 24.8±9.0 ml min−1 m−2 post-operatively (p<0.001). MRI allows a combined assessment of bypass patency and flow. This study protocol may be applicable to perioperative follow-up studies in patients after...