Non-invasive acoustic detection of vascular diseases from skin surface using computational techniques with fluid-structure interaction

Download

index.pdf

Date

2018

Author

Salman, Hüseyin Enes

Metadata

Show full item record

Item Usage Stats

335
views

166
downloads

Atherosclerosis is a cardiovascular disease in which arterial occlusion adversely affects blood circulation. Because of the narrowing of the artery, the blood flow is disturbed and a recirculating flow occurs at the downstream of the stenosis exit. The dynamic pressure fluctuations on the inner arterial wall cause the blood vessel wall to vibrate and the resulting acoustic energy propagates through the surrounding soft tissue and reaches the skin surface. To understand the problem in more detail, computational analyses and experimental studies have been carried out. Vein, blood, muscle, fat and bones are modeled by means of computational analysis. The turbulence-induced dynamic pressure fluctuations are applied to the inner wall of the artery and the radial displacement, velocity and acceleration responses on the skin surface are investigated considering various flow rates, stenosis severities and structural material properties. The computational results show good agreement with the experimental findings. Vibration of the phantom tissue used in the experimental studies is determined using a contact microphone, an electronic stethoscope and a laser Doppler vibrometer. 70% stenosis is an important threshold value, because severities higher than 70% lead to significant increase in vibration amplitudes. If the severity of stenosis is increased from 70% to 90%, the arterial vibration amplitudes increase by more than ten times. Arterial vibration is approximately proportional to the third power of the Reynolds number. When thickness of the tissue surrounding the artery is increased from 6.5 to 16.5 mm, the amplitudes are reduced by about 35%. The highest excitation is obtained about 20 mm downstream of the stenosis exit for a tissue thickness of 16.5 mm. The first two highly excited frequencies are determined as 30 and 60 Hz for the thigh, 100 and 200 Hz for the upper arm, 120 and 190 Hz for the neck. The optimum range for stenosis detection is between 200 and 500 Hz.

Subject Keywords

Stenosis., Biomechanics., Atherosclerosis., Cardiovascular system., Heart, Diagnostic ultrasonic imaging.

URI

http://etd.lib.metu.edu.tr/upload/12622639/index.pdf
https://hdl.handle.net/11511/27780

Collections

Graduate School of Natural and Applied Sciences, Thesis

Suggestions

OpenMETU
Core

Large eddy simulation of pressure fluctuations inside stenosed blood vessels towards noninvasive diagnosis of atherosclerosis Özden, Kamil; Sert, Cüneyt; Yazıcıoğlu, Yiğit; Department of Mechanical Engineering (2018) Atherosclerosis is a cardiovascular disease, in which plaque builds up inside a blood vessel, narrowing it down and forming a stenosis that adversely affects the flow. Because of the stenosis, turbulent flow occurs at the post-stenotic region, which causespressure fluctuations on the vessel wall. The resulting murmurpropogates through the surrounding tissue and reaches the skin surface. These sounds emitted from the stenosed vessels are evaluated as a sign of stenosis. In this study, large eddy simulations ...
Computational analysis for non-invasive detection of stenosis in peripheral arteries Salman, Huseyin Enes; Yazıcıoğlu, Yiğit (Elsevier BV, 2019-08-01) Atherosclerosis usually affects the entire cardiovascular system, including peripheral blood vessels. Peripheral arterial stenosis may indicate possible serious vascular disorders related to more vital organs. If peripheral arterial stenosis can be discerned at an early stage, it can serve as a warning sign to take precautions, such as using more invasive diagnostic techniques or adopting a healthier life style. In this study, peripheral regions, such as the thigh, upper arm, and neck are modelled consideri...
Investigation of fluid structure interaction in cardiovascular system from diagnostic and pathological perspective Salman, Hüseyin Enes; Yazıcıoğlu, Yiğit; Sert, Cüneyt; Department of Mechanical Engineering (2012) Atherosclerosis is a disease of the cardiovascular system where a stenosis may develop in an artery which is an abnormal narrowing in the blood vessel that adversely affects the blood flow. Due to the constriction of the blood vessel, the flow is disturbed, forming a jet and recirculation downstream of the stenosis. Dynamic pressure fluctuations on the inner wall of the blood vessel leads to the vibration of the vessel structure and acoustic energy is propagated through the surrounding tissue that can be de...
Flow-induced vibration analysis of constricted artery models with surrounding soft tissue Salman, Huseyin Enes; Yazıcıoğlu, Yiğit (2017-10-01) Arterial stenosis is a vascular pathology which leads to serious cardiovascular diseases. Blood flow through a constriction generates sound and vibration due to fluctuating turbulent pressures. Generated vibro-acoustic waves propagate through surrounding soft tissues and reach the skin surface and may provide valuable insight for noninvasive diagnostic purposes. Motivated by the aforementioned phenomena, vibration of constricted arteries is investigated employing computational models. The flow-induced press...
Large Eddy Simulation of Blood Flow Inside Vessels for Acoustic Diagnosis of Atherosclerosis Sert, Cüneyt; Yazıcıoğlu, Yiğit (2018-10-20) Atherosclerosis is a cardiovascular disease, in which plaque builds up inside a blood vessel, narrowing it down and forming a stenosis that adversely affects flow. Because of the constriction, turbulent flow occurs at the post-stenotic region, which leads pressure fluctuations on the vessel wall. The murmur caused by this interaction propagates through the surrounding tissue and reaches the skin surface. These sounds emitted from the stenosed vessels are evaluated as a sign of stenosis. In this study, large...

Citation Formats

H. E. Salman, “Non-invasive acoustic detection of vascular diseases from skin surface using computational techniques with fluid-structure interaction,” Ph.D. - Doctoral Program, Middle East Technical University, 2018.