Quantification of Blood Flow Complexity from Carotid Doppler Ultrasonography: Perspectives for Atherosclerotic Risk
Andrea Cerminati1,2, María Teresa Politi1,2,3, Daniela Sabrina Andrés1,2
1Laboratory of Neuroengineering, Institute for Emergent Technologies and Applied Science (ITECA), San Martín, Argentina.
Insights
A new method quantifies carotid artery blood flow complexity using fractal dimension analysis of Doppler ultrasound signals. This technique aids in differentiating normal flow from conditions like atherosclerosis plaques.
Area of Science:
- Cardiovascular Imaging
- Biomedical Engineering
- Fluid Dynamics
Background:
- Turbulence is critical in atherosclerosis but unquantified in carotid ultrasound.
- A validated method is needed for assessing blood flow complexity.
- This study addresses the need for quantitative analysis of carotid Doppler signals.
Purpose of the Study:
- To develop a robust method for quantifying blood flow complexity in carotid Doppler ultrasound.
- To utilize fractal dimension of color Doppler signals for this quantification.
- To establish a novel approach for assessing internal carotid artery blood flow.
Main Methods:
- Observational study of adult outpatients undergoing carotid Doppler ultrasound.
- Extraction and analysis of color Doppler signals from the internal carotid artery.
- Calculation of Hausdorff fractal dimension using box-counting on green pixels indicating turbulent flow.
Main Results:
- The method successfully differentiated patients with plaques (stenosis <50%) from normal studies and increased intima-media thickness.
- Key parameters included a specific hue range (7.2°–208.8°) and pixel occupancy threshold (0.0025%).
- The amplitude of temporal oscillation of the Hausdorff dimension was the chosen metric.
Conclusions:
- An innovative method for assessing internal carotid artery blood flow complexity has been introduced.
- This technique offers a new tool for quantitative analysis in carotid ultrasound.
- The fractal dimension shows potential for improved diagnostic capabilities.
Introduction:
Turbulence plays a crucial role in atherosclerosis. However, it is not currently quantified in carotid ultrasound studies due to the lack of a validated method. This study aims to develop a robust method for quantifying blood flow complexity in carotid Doppler ultrasound studies using the fractal dimension of the color Doppler signal.
Methods:
This is an observational study of adult outpatients with a clinical indication for carotid Doppler ultrasound. Exclusion criteria were technical difficulties in image analysis and refusal to participate. Color Doppler signal from the internal carotid artery was extracted and analyzed. Green pixels, with high Doppler-frequency variance suggestive of turbulent-like blood flow, were identified in hue-saturation-value color space. The Hausdorff fractal dimension was calculated using the box-counting method to quantify flow complexity. On each image, the goodness of fit of the linear regressions was calculated through the coefficient of determination (R2).
Results:
Fifty-four patients were enrolled between August 2020 and March 2022. Critical parameters for the method were a hue range from 7.2° to 208.8° and a minimum pixel occupancy threshold of 0.0025%. The chosen metric was the amplitude of the temporal oscillation of the Hausdorff dimension. This method successfully differentiated patients with plaques with stenosis under 50% (0.24 [0.21-0.31]) from those with normal Doppler ultrasound studies (0.30 [0.24-0.35]; p = 0.0143) and those with increased intima-media thickness (0.31 [0.24-0.35]; p = 0.0405).
Conclusions:
This study introduces an innovative method for assessing internal carotid artery blood flow complexity.
