Videodensitometric quantitation of mean blood flow

Standard angiography demonstrates the anatomy of arterial occlusive disease but does not define its physiological significance. However, measurement of flow in a compromised vessel at rest and following peripheral dilatation provides important physiological information. Using digital subtraction angiography, femoral arterial flows determined by the cross-correlation transit time technique were compared to measurements by electromagnetic flowmeter. Thirty-five femoral arterial flow measurements were obtained in nine dogs instrumented with an electromagnetic flow probe and balloon occluder. Renografin 76 (7 cc) was power-injected at 14 cc/sec into the distal abdominal aorta. Angiographic flow measurements correlated well with electromagnetic flowmeter measurements (r = 0.94, standard deviation of the difference (SDD) = 15 ml/min). Intravenous studies provided somewhat poorer correlation due to difficulties in defining dimensions (r = 0.72, SDD = 36). Paired contrast injections (2 injections in succession) in 11 studies increased flow from an average of 80 to 250 ml/min (a 210 +/- 100% increase), providing an estimate of a vessel's capacity to provide increased flow during peripheral dilatation. Thus, reliable angiographic flow determinations may be obtained by arterial and intravenous contrast injections, adding physiological information to anatomical definition.