MULTICENTER TRIAL TO EVALUATE VASCULAR MAGNETIC-RESONANCE ANGIOGRAPHY OF THE LOWER-EXTREMITY

Objectives.-To assess the value of magnetic resonance angiography (MRA) in presurgical evaluation of patients with severe lower limb atherosclerotic occlusive disease and to assess the feasibility of rapidly conducting rigorous technology assessment. Design.-Blinded, prospective study of consecutive patients with signs or symptoms of severe infrainguinal peripheral vascular disease who were candidates for percutaneous or surgical intervention, Using both descriptive statistics and multivariate logistic analyses, MRA was compared with contrast arteriography (CA) (the current technique) for imaging 15 arterial segments of the leg and foot. Intraoperative contrast angiography was the ''gold'' standard. Also studied was the effect of adding MRA to the information used in planning treatment. Setting.-Six US hospitals, one a community hospital. Patients.-A total of 155; 84% with either rest pain or tissue loss. Results.-Sensitivity in distinguishing patent segments from completely occluded segments was 83% for CA and 85% for MRA; both had 81% specificity, For distinguishing near-normal segments (suitable as bypass graft termini), CA was less sensitive than MRA (77% vs 82%), but more specific (92% vs 84%). After adjusting for same-reader effects, odds of correctly distinguishing patent segments were 1.6 times as great for MRA as for CA (P<.01); for distinguishing near-normal segments, the odds for CA were 1.5 times as great as for MRA (P<.05). The addition of MRA changed the treatment plan in 13% of patients; in 86% of these cases, the surgery actually performed indicated that the MRA-inclusive plan was superior. Conclusions.-Individually, MRA and CA are approximately equivalent in diagnostic accuracy, The addition of MRA to treatment plans based only on CA and other diagnostic information clearly improves the plans. Completed in 15 months (as planned), our study demonstrates the feasibility of conducting rigorous technology assessment rapidly enough to be timely even in fields in which diagnostic and treatment techniques are rapidly changing.