Contact
Siddhartha Sikdar, Ph.D.
Assistant Professor
Department of
Electrical and Computer Engineering
4400 University Drive
MS 1G5
Fairfax, VA 22030
Ph: 703 993 1539
Fax: 703 993 1601
Email: ssikdar@gmu.edu
Office:
Science and Tech II
Room 207B
Selected Past Projects
Ultrasound Doppler Vibrometry
Medicine is going through a transformation from a model of disease diagnosis and therapy in symptomatic individuals to one of disease prevention and proactive management in asymptomatic at-risk populations. A grand challenge is the development of safe, cost-effective and accurate screening and monitoring tools. Coronary artery disease (CAD) causes 495,000 deaths annually in the US and is associated with a healthcare cost of $142 billion per year. Existing diagnostic tests for CAD are either inaccurate for early stage disease, unsuitable for periodic screening and monitoring because of invasiveness, exposure to radiation, or cost. Imaging tools, such as ultrasound, could lead to a new paradigm of point-of-care screening and monitoring if sensitive, specific and easy-to-measure indicators are identified and developed.
The objective of this project was to develop an easy-to-use low-cost clinical instrument that can be used as a screening tool for the early detection and monitoring of coronary artery stenosis in primary care settings.
The stethoscope is a venerable clinical instrument for the diagnosis of cardiovascular disease. However, its utility is limited when abnormal sounds in the human body do not have sufficient intensity to reach the skin surface. In patients with coronary artery stenosis, a characteristic high-pitched diastolic heart murmur has been reported . This coronary flow murmur, caused by turbulence in coronary blood flow downstream of the arterial stenosis, is rarely appreciated during routine auscultation because the intensity is low and the source is deep in attenuating tissue. Doppler vibrometry has the sensitivity to detect and quantitatively measure vibrations with intensity as low as 200 nanoWatts/m2. The quantitative spectral characteristics of the vibrations are dependent on the severity of the blockage. The vibration intensity depends upon the product of the pressure drop caused by the stenosis and flow through the artery. The vibration frequency is inversely related to the residual lumen diameter of the stenosis. Even early-stage disease causing only 25% diameter reduction can cause turbulence and vibrations. In addition, ultrasonic backscattering from tissue is 100~1000 times stronger than that from blood, thus Doppler vibrometry has significant advantages over conventional Doppler ultrasound for detecting and quantifying arterial stenoses, especially for difficult-to-image coronary arteries.
Principle of Doppler Vibrometry
Arterial Doppler Vibrometry
Coronary Doppler Vibrometry
