A PC based system for non-invasive, in-vivo measurement of carotid artery compliance is proposed here. The equipment is a low cost and reliable alternative to the expensive B-mode scanner for vessel wall tracking and stiffness measurement of the artery. The system gives an accurate recording of the distensibility waveform of the carotid artery that could then be used to estimate the various measures of arterial compliance. The system is tested with phantom models of the carotid artery and the accuracy and resolution has been found to meet the requirements of the application. Results obtained from human trials have also been presented to illustrate the capability of the instrument to accurately measure carotid artery compliance. © 2009 IEEE.

Varadarajan Jagadeesh Kumar

Department of Electrical Engineering

Jayaraj Joseph

V. Jayashankar

ACCURATE RECORDING

ARTERIAL COMPLIANCE

CAROTID ARTERY

IN-VIVO MEASUREMENT

Low costs

Non-invasive

NONINVASIVE MEASUREMENTS

PC-BASED

PHANTOM MODELS

Stiffness measurements

VESSEL WALLS

VIRTUAL INSTRUMENT

Wave forms

DIGITAL INSTRUMENTS

Measurement theory

Semiconductor quantum dots

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

A PC based system for non-invasive measurement of carotid artery compliance

2009 IEEE Intrumentation and Measurement Technology Conference, I2MTC 2009

Central and peripheral arteries stiffening prominently affect hemodynamics thus increasing the risk of coronary heart disease, chronic kidney disease and end stage renal disease. There are several commercially available non-invasive measurement technologies for the evaluation of stiffness that are expensive, demand dedicated expertise and fall short for mass screening. Considering this, we have developed ARTSENS®, a highly compact and portable image-free ultrasound device for evaluation of arterial stiffness. The capability of the device to perform accurate measurements of carotid artery stiffness has been validated through extensive in-vivo studies. In this paper we demonstrate the feasibility of using ARTSENS® for measuring brachial artery stiffness. An inter-operator repeatability study was done based on in-vivo experiments on 9 young healthy subjects. The study included measurement of distension, end diastolic lumen diameter, arterial compliance and stiffness index performed both on carotid artery and brachial artery by two operators successively. The degree of agreement between the measurements made by operators has been investigated based on Bland-Altman plots and paired t-test. The measurements were populated within the limits of agreement. No statistically significant difference (p-values from paired t-test for end-diastolic diameter, distension, stiffness index, arterial compliance were 0.36, 0.24, 0.47 and 0.11 respectively) was seen for the brachial artery measurements performed by the two operators. The correlation between the measurement made by the operators was highly significant (r=0.86, p-value=0.003). © 2017 IEEE.

Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBS

Brachial artery stiffness estimation using ARTSENS

Carotid Intima Media Thickness (CIMT) is an established marker of cardiovascular risk with proven utility in early detection. However, conventional B-mode ultrasound imaging based measurement of CIMT is not amenable for deployment in large scale screening due to cost and expertise required to perform the test. We had developed and validated an image -free ultrasound technique for non-invasive, automated evaluation of arterial wall dynamics, called ARTSENS®, for use in vascular screening. Here we present a novel technique to evaluate a carotid artery wall thickness surrogate (CWTS) measure using ARTSENS®, utilizing a single-element 5 MHz ultrasound transducer. The method is based on real time analysis of ultrasound echoes obtained from the far-wall of the common carotid artery. Intelligent algorithms for automated identification of arterial walls, tracking of wall motion, and extraction of far wall structural echoes and measurement of a wall-thickness estimate were developed, and integrated into a prototype ARTSENS® device to enable real time measurement of wall thickness in-vivo. The performance of the system was evaluated using dynamic arterial flow phantoms and in-vivo studies on a set of 7 volunteers. The system could track changes in wall-thickness over a cardiac cycle in both phantoms as well as volunteers in real time. Accuracy of measurements was evaluated in comparison with a reference B-mode ultrasound imaging system. The CWTS measurements showed strong agreement with CIMT values measured with observed error 2.18% and 6.19% in phantom studies and in-vivo measurements respectively. CWTS measurements were also strongly related to CIMT measurements with a R2 value 0.86. While the CWTS is not a replacement for CIMT, but the results validate that it can be potentially used for mass screening purpose, since the measuring system is very cost-effective, easily portable, includes low signal processing overhead and can be used by any general practitioner with just minimal training. © 2017 IEEE.

2017 IEEE International Symposium on Medical Measurements and Applications, MeMeA 2017 - Proceedings

An image-free ultrasound method to estimate artery wall thickness surrogate for screening

Arterial compliance (AC) is an indicator of the risk of cardiovascular diseases (CVDs) and it is generally estimated by B-mode ultrasound investigation. The number of sonologists in low- and middle-income countries is very disproportionate to the extent of CVD. To bridge this gap we are developing an image-free CVD risk screening tool-arterial stiffness evaluation for non-invasive screening (ARTSENS™) which can be operated with minimal training. ARTSENS uses a single element ultrasound transducer to investigate the wall dynamics of the common carotid artery (CCA) and subsequently measure the AC. Identification of the proximal and distal walls of the CCA, in the ultrasound frames, is an important step in the process of the measurement of AC. The image-free nature of ARTSENS creates some unique issues which necessitate the development of a new algorithm that can automatically identify the CCA from a sequence of A-mode radio-frequency (RF) frames. We have earlier presented the concept and preliminary results for an algorithm that employed clues from the relative positions and temporal motion of CCA walls, for identifying the CCA and finding the approximate wall positions. In this paper, we present the detailed algorithm and its extensive evaluation based on simulation and clinical studies. The algorithm identified the wall position correctly in more than 90% of all simulated datasets where the signal-to-noise ratio was greater than 3dB. The algorithm was then tested extensively on RF data obtained from the CCA of 30 human volunteers, where it successfully located the arterial walls in more than 70% of all measurements. The algorithm could successfully reject frames where the CCA was not present thus assisting the operator to place the probe correctly in the image-free system, ARTSENS. It was demonstrated that the algorithm can be used in real-time with few trade-offs which do not affect the accuracy of CCA identification. A new method for depth range selection that leads to significant performance improvements has also been demonstrated. © 2014 Institute of Physics and Engineering in Medicine.

Physiological Measurement

Evaluation of the algorithm for automatic identification of the common carotid artery in ARTSENS

Evaluation of arterial compliance is significant in cardiovascular diagnosis for early detection of coronary heart disease. We present ARTSENS, an image-free system for non-invasive evaluation of arterial compliance in-vivo. The system utilizes a single element ultrasound probe with intelligent measurement algorithms to ensure accurate evaluation of local arterial compliance without an image. The ability of the system to detect artery anatomy and measure compliance was verified by in-vivo measurements conducted on 106 subjects. The accuracy of compliance estimates were evaluated by comparison with a state of art imaging system. The measurements made using ARTSENS showed strong correlation with those made using the imaging system. The ability of ARTSENS to detect age-related trends in arterial compliance was also investigated. © 2013 IEEE.

ARTSENS - An image-free system for noninvasive evaluation of arterial compliance

The modulated magnetic signature based method has been recently suggested for non-invasive detection of blood pulse. Here we present our experience with the use of a Giant Magnetic Resistance (GMR) based sensor for non-invasive detection of a bio-rhythm. The influence of the biasing magnetic field on the amplitude and shape of the detected signal is presented. Guidelines for the design of a bio-medical transducer using the principle are also provided. The detected biorhythm is compared to other bio signals such as the blood flow velocity and arterial distension to gain insight into the physiological significance of the detected signal. The analysis shows that the magnetic sensor provides a signal that is strongly correlated to the blood volume in the neighbourhood of the sensor. Finally, the possibility of using the GMR based sensor for estimation of arterial compliance is investigated. Simultaneous measurements performed at two different sites on the body show that this sensor can be used to measure arterial pulse wave velocity which is a clinically accepted measure of global arterial stiffness. © 2010 IEEE.

Proceedings of 2010 IEEE EMBS Conference on Biomedical Engineering and Sciences, IECBES 2010

Magnetic sensor for non-invasive detection of blood pulse and estimation of arterial compliance

2008 30th Annual International Conference of the IEEE Engineering in Medicine and Biology Society

A virtual instrument for real time in vivo measurement of carotid artery compliance

Cardiovascular Ultrasound

Common carotid artery wall thickness and external diameter as predictors of prevalent and incident cardiac events in a large population study

Journal of Hypertension

How to assess arterial compliance in humans

European Heart Journal

Carotid stiffness and the risk of new vascular events in patients with manifest cardiovascular disease. The SMART study

European Heart Journal Supplements

Arterial stiffness in heart failure patients: dependance on diastolic dysfunction and plasma aldosterone levels

Journal	2009 IEEE Intrumentation and Measurement Technology Conference, I2MTC 2009
Open Access	No