CVI Program Unit(s):
Biotechnology / Nanomedicine / Imaging
CVI Research Description:
I am interested in different aspects of ultrasound imaging and its applications to imaging cardiovascular system. The major emphasis of my lab is on innovation of new ultrasound techniques to serve clinical needs. The various studies currently being pursued include measurement of angiogenesis, vascularity, contrast agents and the effects of various physical and pharmaceuticals agents on blood flow and tissue vascularity.
A unique feature of my research is the quantification of the ultrasound images for assessing tissue structure and tissue blood flow.
A comprehensive set of software and hardware tools have been developed for quantitative image analysis. These enabling technologies allow automated analysis of large sets of sonographic and Doppler images for measuring flow, perfusion and tissue texture. They also provide semi-automated analysis of cross-sectional area to study vascular biology. These tools are of special interest to those involved in evaluating the kinetic response of drugs and pharmaceuticals. Another set of tools is being developed and tested is for computer-aided diagnosis.
While these techniques can potentially be used for a range of projects, I have listed two on cardiovascular applications.
Assessment Endothelium dysfunction by vascular ultrasound:
Endothelium-mediated vasodilation of the brachial artery reflects an individual's health. Lack of vasodilatation in response to vasoactive stimulus is associated with diseases such as atherosclerosis, hypertension, and congestive heart failure. A popular approach for evaluating endothelial function is non-invasive ultrasound imaging of vasodilation of the brachial artery. The imaging is commonly performed along the long axis of the artery, the main advantage being that longitudinal imaging offers clear artery-lumen boundary definition. Despite its good boundary definition, longitudinal imaging has several drawbacks which limits its use . My lab has developed an approach involving cross-sectional imaging of the brachial artery to effectively overcome the shortcomings of the longitudinal
approach. This involve the use of compound imaging in combination with an image segmentation procedure to delineate lumen-artery margin in ultrasound images acquired at a time resolution of 30 ms.
We have tested the feasibility of our approach in flow phantoms and in a normal volunteer. The technique can be potentially used for assessing cardiovascular risk in general patient as well as those with known diseases. Since the technique can be used repeatedly, it could be used for measuring the effects of life style factors (like smoking, exercise and diet) and also for measuring improvements in endothelial function as a result of various treatments including cholesterol lowering drugs, ACE inhibitors, vitamins C and E, folic acid and the like.
Assessing compound induced blood flow changes by Doppler ultrasound:
Many compounds occurring naturally within the body, and certain pharmaceuticals, are known to affect and regulate blood flow. Despite rapid technologic advances in cardivascular medicine, the role of diagnostic imaging in evaluating the action of various pharmaceuticals remains in
its infancy and is still relatively unexplored. Our interest has been in using diagnostic ultrasonography (US) to develop image markers that can be used as surrogate end points for evaluating the action of various pharmaceuticals. In several studies we have demonstrated the use of Doppler US for quantifying the vascularity. We extended this methodology to explore the potential use of these quantitative methods to evaluate the action of pharmaceuticals on blood flow in the kidneys. Two classes of compounds, endothelin-1 (ET-1) and fenoldopam mesylate, were investigated with opposite effects on renal blood flow. Whereas the infusion of ET-1 induces a decrease in renal blood flow, the infusion of fenoldopam mesylate, a selective and specific dopamine DA-1 receptor agonist, increases renal blood flow and is used to manage severe hypertension. The purpose of our study was to evaluate quantitative Doppler US for assessing changes in renal blood flow induced with ET-1 and fenoldopam mesylate .
While the study was performed in conscious dogs, it can be potentially used for evaluating the role of various agents in patients. This was demonstrated in a trial of a novel prostacyclin in patients with severe claudication .
For more information please see the ultrasound research website.
1. Kao YH, Mohler ER, Arger PH, Sehgal CM. Brachial artery: measurement of flow-mediated dilatation with cross sectional US-technical validation. Radiology. 2003 Sep;228(3):895-900.
2. Sehgal CM, Arger PH, Silver AC, Patton JA, Saunders HM, Bhattacharyya A, Bell CP. Renal blood flow changes induced with endothelin-1 and fenoldopam mesylate at quantitative Doppler US: initial results in a canine study. Radiology. 2001 May; 219(2):419-26.
3. Mohler ER, Sehgal CM, Ferrari VA, Parmacek M, Shih A, Wilensky RL. A novel ultrasound method for evaluation of collateral development in limb ischemia. Vasc Med. 2002 Aug;7(3):169-75.
Eraso Luis H, Reilly Muredach P, Sehgal Chandra, Mohler Emile R: Emerging diagnostic and therapeutic molecular imaging applications in vascular disease. Vascular medicine (London, England) 16(2): 145-56, Apr 2011.
Pouch Alison M, Cary Theodore W, Schultz Susan M, Sehgal Chandra M: In vivo noninvasive temperature measurement by B-mode ultrasound imaging. Journal of ultrasound in medicine : official journal of the American Institute of Ultrasound in Medicine 29(11): 1595-606, Nov 2010.
Wood Andrew K W, Schultz Susan M, Lee William M-F, Bunte Ralph M, Sehgal Chandra M: Antivascular ultrasound therapy extends survival of mice with implanted melanomas. Ultrasound in medicine & biology 36(5): 853-7, May 2010.
Wood AKW, Bunte RM, Cary TW, Sehgal CM: Contrast-enhanced sonographic evaluations of murine tumor vascularity: A review Proceedings International Veterinary Radiology Association. Veterinary Radiology and Ultrasound 51(190), 2010.
Pouch AM, Yushkevich PA, Jackson BM, Gorman III JH, Gorman RC, Sehgal CM: A semi-automated approach to mitral valve morphometry using real-time 3D echocardiography. Training Grantees Meeting of the National Institute of Biomedical Imaging and Bioengineering 2010.
Pouch AM, Cary TW, Schultz SM, Sehgal CM: In vivo noninvasive thermometry by B-mode ultrasound imaging. Annual Conference of the American Institute of Ultrasound in Medicine 2010.
Pouch AM, Yushkevich PA, Jackson BM, Gorman III JH, Gorman RC, Sehgal CM: A semi-automated approach to mitral valve morphometry using real-time 3D echocardiography. Department of Medicine Research Day, University of Pennsylvania 2010.
Arger PH Sehgal CM: Ultrasonic Principles and Imaging Introduction to the Science of Medical Imaging R. Nick Bryan (eds.). Cambridge University Press. New York, Page: 147-159, 2010.
Pouch AM, Yushkevich PA, Jackson BM, Gorman III JH, Gorman RC, Sehgal CM: A semi-automated approach to mitral valve morphometry using real-time 3D echocardiography. Biomedical Engineering Society Annual Meeting 2010.
Mohler Emile R, Sibley Alexandra A, Schultz Susan M, Zhang Lifeng, Sehgal Chandra M: High-frequency ultrasound for evaluation of intimal thickness. Journal of the American Society of Echocardiography : official publication of the American Society of Echocardiography 22(10): 1129-33, Oct 2009.
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Last updated: 01/27/2017
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