Effect of quantitated stenoses on arterial sound spectrum analysis

Area of Science:

• Vascular Ultrasound
• Medical Imaging
• Hemodynamics

Background:

• Carotid Doppler spectral analysis is a validated method for assessing carotid artery stenosis severity.
• Doppler angle and signal gain are potential confounding factors in spectral analysis accuracy.

Purpose of the Study:

• To evaluate the impact of Doppler angle and signal gain on spectral analysis parameters.
• To determine the reliability of peak frequency, mode frequency, and percent window in quantifying carotid stenosis.

Main Methods:

• An in vitro model using a cadaver artery with varying degrees of artificial stenosis (0-100%) was employed.
• Spectral analysis parameters (peak frequency, mode frequency, percent window) were measured at different Doppler angles (45°, 60°, 75°) and gain settings (low, medium, high).
• Correlation between stenosis percentage and spectral parameters was analyzed.

Main Results:

• Excellent correlation was observed between stenosis percentage and peak frequency (r=0.9520) and percent window (r=-0.9861) at 60° Doppler angle and medium gain.
• Peak frequency and mode frequency decreased at stenoses >82%, mimicking lower stenosis levels.
• Percent window demonstrated minimal overlap across all stenosis degrees and was unaffected by Doppler angle or gain.

Conclusions:

• Percent window is a robust spectral parameter for quantifying carotid artery stenosis, unaffected by Doppler angle or gain.
• Peak frequency is sensitive to Doppler angle and cannot reliably differentiate critical from subcritical stenoses.
• Spectral analysis, particularly percent window, offers a reliable method for stenosis assessment in carotid Doppler studies.