ASSESSMENT OF COMPLICATED ARTERIAL BYPASS GRAFTS - VALUE OF CONTRAST-ENHANCED SUBTRACTION MAGNETIC-RESONANCE ANGIOGRAPHY

Purpose: To evaluate complicated aortoiliac and lower extremity arteri al bypass grafts with contrast-enhanced subtraction magnetic resonance angiography (MRA). Methods: Twenty-three patients with 40 vascular gr afts with either clinical symptoms or abnormal duplex findings were se lected. They were examined using a fast T1-weighted gradient-echo sequ ence. Twelve to 19 coronal sections of 5 to 8 mm were acquired before and after an intravenous bolus injection of gadolinium (0.1 mmol/kg) i n 25 to 40 seconds, Final images were created by subtracting each prec ontrast section from its corresponding postcontrast section. The MRA w as obtained after subtraction and maximum intensity projection. Result s: MRA detected 38 grafts (95%) with 28 abnormalities. Two stenoses we re overestimated. MRA had a sensitivity of 91% and a specificity of 92 % for diagnosis of graft stenoses and occlusions. MRA brought out more information in five cases by demonstrating four nonthrombotic ectasia s that were unseen by duplex sonography and one thrombotic ectasia tha t was unseen by x-ray angiography.Conclusions: MRA seems to compare fa vorably with x-ray angiography for the diagnosis of arterial bypass gr aft complications. A multicenter trial will be necessary to validate t hese preliminary results and to assess the exact role of MRA, compared with the other established techniques.