Correction of intrinsic spectral broadening errors in Doppler peak velocity measurements made with phased sector and...

Commercial duplex ultrasound systems primarily measure peak velocity of blood flow to provide important information in diagnosing vascular disease. However, due to errors caused by intrinsic spectral broadening (ISB), the accuracy decreases as the Doppler angle increases. In general, vascular technologists and surgeons keep the Doppler angle under 60 degrees. Even at 60 degrees, ISB can produce an overestimation of peak velocity as high as 40%. This would indicate the necessity of reducing the Doppler angle even lower than 60 degrees. Since most vessels in the body run parallel with the skin surface any criteria requiring a Doppler angle of say 45 degrees or less would be difficult to achieve. Using the transverse Doppler equation as a correction for ISB, in conjunction with the classical Doppler equation, accurate peak velocity measurements were obtained at Doppler angles as high as 80 degrees. Corrections were made using both phased sector and linear array transducers for steered and unsteered beams. However, for beams steered at large angles, 20 degrees or more, corresponding to Doppler angles of < 70 degrees, the transverse Doppler equation failed to correct ISB errors in measurements made. This may be due to the experimental setup and not due to limitations in the transverse Doppler equation.