Factors affecting accuracy of quantitative blood flow measurements by duplex ultrasound

The effect of both physiologic variables and hardware variables on the accuracy of duplex ultrasound volume flow measurements was investigated with an in vivo model under controlled laboratory conditions. Changes in physiologic variables such as heart rate, cardiac output, vessel compliance and fluid volume consistently caused <10% error in measurements: similar results were seen for hardware variables such as sample volume size or angle of orientation. Small errors in vessel diameter measurement, however, were magnified in flow calculations and produced errors >25% in small vessels. The presence of flow turbulence caused underestimation of total flow, often by as much as 50%