Winkler A J, Wu J
Department of Physics, University of Vermont, Burlington 04505, USA.
Ultrasound Med Biol. 1995;21(8):1029-35. doi: 10.1016/0301-5629(95)00047-u.
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.
商用双功超声系统主要通过测量血流峰值速度来为血管疾病的诊断提供重要信息。然而，由于固有频谱展宽（ISB）导致的误差，随着多普勒角度的增加，测量准确性会降低。一般来说，血管技术人员和外科医生会将多普勒角度保持在60度以下。即使在60度时，ISB也可能导致高达40%的峰值速度高估。这表明有必要将多普勒角度降低到60度以下。由于体内大多数血管与皮肤表面平行，任何要求多普勒角度为45度或更小的标准都很难实现。使用横向多普勒方程对ISB进行校正，并结合经典多普勒方程，在高达80度的多普勒角度下也能获得准确的峰值速度测量结果。使用相控扇形和线性阵列换能器对转向和未转向波束进行了校正。然而，对于大角度转向的波束，即20度或更大角度，对应于小于70度的多普勒角度，横向多普勒方程未能校正测量中的ISB误差。这可能是由于实验设置，而非横向多普勒方程的局限性所致。
