Quantitative Ultrasound and Optical Technology for Vascular Occlusion Assessment

  • 巫 建興

Student thesis: Doctoral Thesis

Abstract

Vascular occlusions have become the major causes of death in Taiwan Among them peripheral vascular disease (PVD) is a widespread vascular disease and chronic disease in patients with diabetics and long-term dialysis patients and is also associated with increased risk of cardiovascular disease and nerve damage Inadequate control or treatment of PVD usually causes ischemic chest pain poor wound healing and arteriovenous shunt stenosis and the symptoms become severer with age Therefore achieving accurate diagnosis and monitoring of PVD via assessing blood vessels are important issues This research combines Doppler ultrasound with optical technology to develop a PVD diagnosis system for clinical uses which provides not only the degrees of stenosis (DOS) but also anatomical locations and blood flow physiology information for clinical physicians lowing the risk arising from treatment The first part of this study is to real-time evaluate arteriovenous access occlusion using Doppler ultrasound based on multiple-site hemodynamic analysis and an adaptive color relation classifier In this study we proposed a method based on hemodynamic analysis with dimensionless numbers to capture and further quantify the feature values of Doppler ultrasound extracted from intraluminal blood flow The ratio of the supracritical Reynolds (Resupra) number and the resistive (Res) index were calculated via the peak-systolic and peak-diastolic velocities of blood flow from the arterial anastomosis sites (A) to the venous anastomosis sites (V) to quantitate the DOS at multiple measurement sites After that the results were mapped with an adaptive color relation classifier to real-time display the DOS The examination results from thirty long-term dialysis patients showed that this proposed method performed well in DOS and occlusion site detection with >95% of accuracy The second part of this study is to evaluate PVD using optical technology technology Recently many studies indicated that PVD in patients with diabetics often occurred in the lower limbs and the microcirculation of those lower limbs appeared asynchronous pulses in photoplethysmography (PPG) signals making it a reliable PVD diagnostic method In this study a Sprott chaos synchronization (CS) classifiers based on PPG is proposed for asynchronous detection and a wolf pack search (WPS) algorithm is selected as a classifier unit Furthermore to accelerate the speed of calculation this study implemented Sprott CS algorithms in the hardware circuit The analysis results from thirty clinical patients showed that the proposed Sprott CS technique could effectively detect the asynchronous pulses with better stability and accuracy (> 90%) compared with traditional time-domain method In addition compared with the ankle-brachial blood pressure index (ABPI) technique this proposed system performed better accuracy relatively simple operation and less false positives from vascular sclerosis In summary this study confirmed that combined use of the Doppler ultrasound and optical technology is a potential candidate method to effectively evaluate the PVD caused by long-term dialysis or vascular disease of lower-extremity in patients with diabetics The proposed system provides useful information with better accuracy and convenience for clinical examination Future works include collecting more clinical data for verifying the reliability of this system investigating the relevant pathogenesis of PVD and improving the quality of clinical medical practice
Date of Award2014 Aug 22
Original languageEnglish
SupervisorTainsong Chen (Supervisor)

Cite this

Quantitative Ultrasound and Optical Technology for Vascular Occlusion Assessment
建興, 巫. (Author). 2014 Aug 22

Student thesis: Doctoral Thesis