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https://ptsldigital.ukm.my/jspui/handle/123456789/519606| Title: | Non-invasive technique for endothelial dysfunction assessment using a CBP-RPPG model |
| Authors: | Vahid Sohani (P63103) |
| Supervisor: | Mohd Alauddin Mohd Ali, Prof. Dr. |
| Keywords: | Endothelial Flow mediated dilation Non-invasive technique Artery Universiti Kebangsaan Malaysia -- Dissertations |
| Issue Date: | 2-Oct-2017 |
| Description: | The endothelial layer, which covers the internal surface of the arteries and arterioles, plays a vital role in maintaining adequate perfusion through constantly adjusting arterial diameter to metabolic demand. This explains why endothelial dysfunction is known as an early marker of cardiovascular diseases. Flow mediated dilation (FMD) is a well-known technique to assess non-invasively the endothelial function. During FMD, blood circulation of a large artery, such as the brachial, is blocked for five minutes and then suddenly released leading to reactive hyperemia due to increase in the diameter of the tested artery. Such a change in the artery diameter can be measured using high frequency ultrasound imaging. As the FMD-ultrasound technique is remarkably operator dependent and requires a very expensive setup, it has been limited to clinical research only. The main objective of the present study is to assess the endothelial performance via a forward model between central blood pressure (CBP) and radial Photoplethysmography (RPPG). To this end, CBP, RPPG and ultrasound images of the brachial artery are non-invasively and simultaneously recorded from 93 subjects. Ultrasound images are analyzed by an automatic edge-detection software providing a precise measurement of the arterial diameter. Using a threshold of 10% dilation, subjects are categorized into normal (FMD��10%) and impaired endothelium groups (FMD<10%). Using system identification techniques, an individual CBP-RPPG model is estimated for each subject. The fitness of the individual model's output is used as a feature for discriminating normal from unhealthy subjects. The difference between the fitness during baseline (before blockage) and after cuff release is found to be a powerful criteria with results showing 86% and 96% of sensitivity and specificity when compared to FMD-ultrasound as reference. These results support the possibility of using this PPG-based technique to assess the endothelial performance non-invasively, hence opening the way towards a practical, low-cost alternative to perform mass-screening.,Ph.D. |
| Pages: | 179 |
| Publisher: | UKM, Bangi |
| Appears in Collections: | Faculty of Engineering and Built Environment / Fakulti Kejuruteraan dan Alam Bina |
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