Magnetic resonance angiography in the management of lower extremity arterial occlusive disease: a prospective study.

PURPOSE

We conducted a prospective study to clarify the clinical utility of magnetic resonance angiography (MRA) in the treatment of patients with lower extremity arterial occlusive disease.

METHODS

During the interval of September 1993 through March 1995, 79 patients (43% claudicants, 57% limb-threatening ischemia) were studied with both MRA and contrast arteriography (ANGIO) and underwent intervention with either balloon angioplasty (9%), surgical inflow (28%), or outflow (63%) procedures. MRA and ANGIO were interpreted by separate blinded vascular radiologists, and arterial segments from the pelvis to the foot were graded as normal or with increasing degrees of mild (25% to 50%), moderate (51% to 75%), or severe (75% to 99%) stenosis or occlusion. Treatment plans were formulated by the attending surgeon and were based initially on hemodynamic, clinical, and MRA data and thereafter with ANGIO. Additional study surgeons formulated independent and specific treatment plans based on MRA or ANGIO alone. Indexes of agreement (beyond chance) for arterial segments depicted by MRA and ANGIO were assessed (kappa value), and treatment plans formulated were compared (chi-square).

RESULTS

Precise agreement (%) and the percent of major discrepancies (segment classified as normal/mild stenosis on one study and severe stenosis/occlusion on the other) between MRA and ANGIO for respective arterial segments was as follows: common and external iliacs (n = 256) 77/3.5; superficial femoral and above-knee popliteal (n = 255) 73/6.7; below-knee popliteal (n = 131) 84/3.8; infrapopliteal runoff vessels (n = 864) 74/12.4; pedal vessels (n = 111) 69/19.8 Kappa values indicated moderate agreement (between MRA and ANGIO) beyond chance for all arterial segments. Treatment plans formulated by the attending surgeon, the MRA surgeon, and the ANGIO surgeon agreed in more than 85% of cases. Inability of MRA to assess the significance of inflow disease and inadequate detail of tibial/pedal vessels were the principal deficiencies of MRA in those cases where it was considered an inadequate examination.

CONCLUSION

These findings suggest MRA and ANGIO are nearly equivalent examinations in the demonstration of infrainguinal vascular anatomy. MRA is an adequate preoperative imaging study (and may replace ANGIO), particularly in those circumstances when the risk of ANGIO is increased or when clinical and hemodynamic evaluation predict the likelihood of straightforward aortofemoral or femoral-popliteal reconstruction.