Assessment of Carotid Artery Vibrations by Using Optical Flow Methods on Ultrasound Images and Optical Flow

Saba  Rabiee; Parisa  Rangraz; Ahmad  Shalbaf

doi:10.18502/fbt.v11i4.16512

Saba Rabiee Department of Biomedical Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran
Parisa Rangraz Department of Biomedical Engineering and Medical Physics, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
Ahmad Shalbaf Department of Biomedical Engineering and Medical Physics, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran

DOI: https://doi.org/10.18502/fbt.v11i4.16512

Keywords: Optical Flow; Ultrasound; Image Tracking; Age; Body Mass Index; Radio Frequency Signal.

Abstract

Purpose: This study aims to extract carotid wall vibrations non-invasively and evaluate changes in the carotid artery caused by age, BMI, and sex. Such evaluation can increase the possibility of detecting wall stiffness and atherosclerosis in the early stages and prevent heart attack and death.

Materials and Methods: To extract small vibrations of the carotid wall, the image-tracking method, and optical flow with four different methods were used. The study involved twenty participants, comprising six females and fourteen males, with a mean age of 36.25 years, mean weight of 75.2 Kg, and mean BMI of 25. The posterior wall motion and vibration were extracted using ultrasound RF signals.

Results: 4 optical flow methods, Gunnar-Farneback, Horn- Schunk, Lucas-Kanade, and Lucas-Kanade derivative were used for all samples, and covariance, correlation, P-value, and R-squared were estimated. Results showed the differences in parameters such as age and BMI with carotid wall vibration. These values for age are (Cov = -0.1891, Corr = -0.6770, P-value < 0.001, r²= -0.4590) and for BMI are (Cov = -0.0564, Corr = -0.6510, P-value < 0.001, r²= 0.4238), respectively. For gender as a new parameter, a comparison between men’s and women’s vibrations was estimated. The range of measured vibrations by optical flow methods is about 0.0002 µm to 0.1µm, and the mean standard deviation is 0.04967 µm.

Conclusion: The results presented that gender affects the vibration of the vessel wall, which in men is more than in women. In addition, increasing age and BMI may increase the stiffness of the carotid wall and reduce vibrations that were evaluated previously. Using the Gunner-Farneback method as image tracking for small vibrations is the best way with the highest accuracy.