A Virtual Instrument for Automated Measurement of Arterial Compliance
01 Dec 2010-Journal of Medical Devices-transactions of The Asme (American Society of Mechanical Engineers)-Vol. 4, Iss: 4, pp 045004
TL;DR: A simple instrument for noninvasive in vivo evaluation of arterial compliance using a single element ultrasound transducer that can measure arterial distension with a precision better than 5 and the end-diastolic arterial diameter with an accuracy of 1%.
Abstract: Measurement of arterial distensibility is very important in cardiovascular diagnosis for early detection of coronary heart disease and possible prediction of future cardiac events. Conventionally, B-mode ultrasound imaging systems have been used along with expensive vessel wall tracking systems for estimation of arterial distension and calculation of various estimates of compliance. We present a simple instrument for noninvasive in vivo evaluation of arterial compliance using a single element ultrasound transducer. The measurement methodology is initially validated using a proof of concept pilot experiment using a commercial ultrasound pulser-receiver. A prototype system is then developed around a PXI chassis using LABVIEW software. The virtual instrument employs a dynamic threshold algorithm to identify the artery walls and then utilizes a correlation based tracking technique to estimate arterial distension. The end-diastolic echo signals are averaged to reduce error in the automated diameter measurement process. The instrument allows automated measurement of the various measures of arterial compliance with minimal operator intervention. The performance of the virtual instrument was first analyzed using simulated data sets to establish the maximum measurement accuracy achievable under different input signal to noise ratio (SNR) levels. The system could measure distension with accuracy better than 10 μm for positive SNR. The measurement error in diameter was less than 1%. The system was then thoroughly evaluated by the experiments conducted on phantom models of the carotid artery and the accuracy and resolution were found to meet the requirements of the application. Measurements performed on human volunteers indicate that the instrument can measure arterial distension with a precision better than 5%. The end-diastolic arterial diameter can be measured with a precision better than 2% and an accuracy of 1%. The measurement system could lead to the development of small, portable, and inexpensive equipment for estimation of arterial compliance suitable in mass screening of "at risk" patients. The automated compliance measurement algorithm implemented in the instrument requires minimal operator input. The instrument could pave the way for dedicated systems for arterial compliance evaluation targeted at the general medical practitioner who has little or no expertise in vascular ultrasonography.
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01 Jun 2018
TL;DR: A simulation based preliminary study to validate the algorithm setup used for construction of M-Mode images of heart has been proposed and facilitates fine tuning of algorithm for measurement of left ventricular parameters.
Abstract: Heart Parameters need to be monitored for diagnosis of cardiac abnormalities. Echocardiography technique is widely used to view 2D image of heart in non invasive method using ultrasound. In practice, echocardiography devices typically use multi-element phased array transducer which involves complex algorithms and computations to develop M-Mode images, which are used to measure parameters by placing the cursors manually. A simple hardware with single element ultrasound transducer has been used to record M-Mode images on a single axis. A simulation based preliminary study to validate the algorithm setup used for construction of M-Mode images of heart has been proposed. This study facilitates fine tuning of algorithm for measurement of left ventricular parameters. Since single element transducer and simple algorithm is used, system is less complex, simple and low cost.
Cites methods from "A Virtual Instrument for Automated ..."
...ARTSENS (ARTerial Stiffness Evaluation for Non-Invasive Screening) has been developed in-house to measure the stiffness of carotid artery using single element ultrasound transducer[3][4]....
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01 Jan 2014
TL;DR: A non-invasive method for assessing AS using Finger Photoplethysmographic (PPG) Signal is proposed and the results show that the clinical parameters are estimated with good accuracy and repeatability.
Abstract: Cardiovascular disease (CVD) is currently the biggest single cause of mortality in the world; hence, the early detection of its onset is vital for effective prevention therapies. Arterial Stiffness (AS) has proved to be a direct indicator for CVD. In this study, a non-invasivemethod for assessing AS using Finger Photoplethysmographic (PPG) Signal is proposed. Virtual Instrumentation(VI) software was used for developing the front panel of the proposed system to estimate the clinical parameters of AS like Augmentation Index (AI), Arterial Stiffness Index (ASI) and pulse rate. AI is the measure of AS derived from the ascending Aortic waveform, ASI indicates degree of arterial elasticity and Pulse rate is the number of pulses per minute. All the 3 parameters are estimated by the proposed algorithm using LabVIEW. PPG signal data is collected for 10 adult volunteers and 15 aged volunteers using the proposed system. Further analysis was done using the developed virtual instrumentation front panel. The results show that the clinical parameters are estimated with good accuracy and repeatability.
Cites background or methods or result from "A Virtual Instrument for Automated ..."
...Therefore, it has become important to develop tests for checking excessive arterial stiffness in the very early stages of arteriosclerosis [3]-[4]....
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...Therefore, a more precise method for screening arterial stiffness is required [4]-[6]....
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...In fact, PWV values measured in arteriosclerosis patients were higher than those in age-matched normal control subjects [4]....
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20 Jun 2020
TL;DR: The purpose of the study reported in this work was to demonstrate the feasibility of the ARTSENS® Pen device as a high-throughput vascular screening tool for risk assessment.
Abstract: Intervention in the early stages of cardiovascular and kidney diseases is proven to be more effective in preventing disease progression. Large artery stiffness measurement can be a potential early predictor of future risks. The purpose of the study reported in this work was to demonstrate the feasibility of our ARTSENS® Pen device as a high-throughput vascular screening tool for risk assessment. The study was performed during a medical camp conducted for awareness and early-stage detection of kidney diseases. Screening procedures included biosample tests and blood pressure measurements. Alongside, various clinically relevant measures of the arterial stiffness were evaluated using the ARTSENS® Pen, by measuring vessel wall dynamics via our proprietary image-free ultrasound algorithms. Stiffness measurement from the left common carotid artery on 85 participants could be completed within 4 hours, employing two units of ARTSENS® Pen; this also includes time taken for all the procedures enlisted in the study protocol. The associations of carotid stiffness indices with age-, gender-, and risk factor-dependent variations were established.
Additional excerpts
...A detailed discussion of ARTSENS technology, image-free processing and evaluation of arterial dimensions, and measurement algorithm can be found elsewhere [7]–[10]....
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01 Jan 2014
TL;DR: An extension to the ARTSENS system to estimate the carotid arterial pressure (CAP) from the BAP is reported, using the fact that mean and diastolic pressures at both arterial sites are the same.
Abstract: Over past few years our group has been developing ARTSENS ® , a low-cost, portable and non-invasive tool for measurement of arterial stiffness (AS). AS of the common carotid artery (CCA) has high prognostic value in stratification of risk of contracting cardiovascular disease (CVD) in future. ARTSENS uses a single element ultrasound transducer to obtain A-Mode frames from the CCA and processes them to obtain the diameter distension waveform. For calculation of AS, any AS measurement system requires the pulse pressure in the artery under investigation. In absence of reliable methods to estimate the carotid arterial pressure (CAP), in conventional AS measurement systems, the brachial arterial pressure (BAP) is used as a surrogate for the CAP to calculate the AS. This can lead to large errors, as there can be large difference in systolic pressures at both sites, especially in young subjects. In this paper we report an extension to the ARTSENS system to estimate the CAP from the BAP. This uses the fact that mean and diastolic pressures at both arterial sites are the same. We made the required hardware to obtain the systolic, mean and diastolic BAP. We then use the diameter distension waveform, obtained by processing ultrasound frames from ARTSENS, as a surrogate for the CAP waveform which is scaled and shifted to obtain the CCA pulse pressure (CPP). BAP and CAP were estimated for 10 human subjects using the new system. Bland-Altman analysis shows that ARTSENS is able to get BAP within acceptable limits of accuracy and pulse pressure is on an average 17 mmHg lower in CCA compared to the brachial artery which is in consonance with findings by other investigators.
01 Oct 2018
TL;DR: ARTSENS® - an ultrasound technology for image-free, noninvasive, automated evaluation of vascular stiffness amenable for field use is developed and proposed for a live demonstration in the IEEE SENSORS 2018 Conference.
Abstract: Ultrasound-based techniques for non-invasive assessment of arterial stiffness - the earliest detectable manifestation of cardiovascular conditions, has gained significant attention over the years. State-of-the-art techniques use imaging systems for measuring carotid artery stiffness or rely on carotid-femoral pulse wave velocity to evaluate vascular stiffness. These techniques are expensive, require expertise to operate and are not suitable for field deployment. In this context, we developed ARTSENS® - an ultrasound technology for image-free, noninvasive, automated evaluation of vascular stiffness amenable for field use. The latest version of this novel technology, ARTSENS® Pen is proposed for a live demonstration in the IEEE SENSORS 2018 Conference.
References
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TL;DR: This population-based study shows that arterial stiffness is strongly associated with atherosclerosis at various sites in the vascular tree.
Abstract: Background and Purpose—Studies of the association between arterial stiffness and atherosclerosis are contradictory. We studied stiffness of the aorta and the common carotid artery in relation to se...
1,134 citations
TL;DR: The effects of current and future cardiovascular drugs on arterial stiffness are discussed, as is the relationship between arterial elasticity and endothelial function.
Abstract: Investigation of arterial stiffness, especially of the large arteries, has gathered pace in recent years with the development of readily available noninvasive assessment techniques. These include the measurement of pulse wave velocity, the use of ultrasound to relate the change in diameter or area of an artery to distending pressure, and analysis of arterial waveforms obtained by applanation tonometry. Here, we describe each of these techniques and their limitations and discuss how the measured parameters relate to established cardiovascular risk factors and clinical outcome. We also consider which techniques might be most appropriate for wider clinical application. Finally, the effects of current and future cardiovascular drugs on arterial stiffness are also discussed, as is the relationship between arterial elasticity and endothelial function.
813 citations
TL;DR: Common carotid IMT anddistensibility are clear markers of cardiovascular risk in patients who already have vascular disease or atherosclerotic risk factors and IMT appears to discriminate between low- and high-risk patients better than distensibility.
Abstract: Background—Common carotid intima-media thickness (IMT) and distensibility are markers of structural and functional vessel wall properties. Both parameters have been found in population-based studies to be associated with cardiovascular risk factors and prevalent cardiovascular disease. We investigated cross-sectionally whether IMT and distensibility are associated with cardiovascular risk in patients who already have vascular disease or atherosclerotic risk factors and evaluated the diagnostic ability of IMT and distensibility to discriminate between low- and high-risk patients. Methods and Results—IMT and distensibility (change of diameter) of the left and right common carotid arteries were measured in the first 570 patients (537 for distensibility) enrolled in the Second Manifestations of ARTerial disease (SMART) study, a cohort study among patients with a manifestation of vascular disease or cardiovascular risk factors. Three risk scores were used to classify each patient’s vascular risk. Areas under t...
378 citations
TL;DR: An overview of time-domain techniques that have appeared in the literature over the past few years is presented, and their potential advantages over Doppler are examined, and the individual techniques are compared.
Abstract: The Doppler technique has traditionally been the method used to extract motion information from ultrasonic echoes reflected by moving tissues. The Doppler technique has been around for a long time, and has been extensively reviewed and analyzed in the literature. Recently, time-domain methodologies for estimating tissue motion have gained in popularity. Time-domain methods have advantages over Doppler methods in many applications, and as of yet have not been comprehensively reviewed. An overview of time-domain techniques that have appeared in the literature over the past few years is presented. Their potential advantages over Doppler are examined, and the individual techniques are compared. >
340 citations
TL;DR: Under controlled experimental conditions there was good repeatability of measurements of indices between sessions of both intrinsic and functional arterial mechanical properties (central and carotid arterial compliance, intima-media thickness and brachial flow-mediated dilation).
Abstract: 1. Repeatability of measurements of arterial compliance and flow-mediated dilation of the brachial artery has been infrequently reported, despite increasing use in interventional and risk-factor modification studies. Furthermore, little is known about the interrelationships of the various indices. The purposes of this study were to determine the repeatability and interrelationships of a range of arterial indices.2. Fifty healthy volunteers, 20 men and 30 women, aged 20-70 (mean 46.5) years, were studied on two occasions, using an identical protocol, at a mean interval of 2.5 weeks. Tonometry, ultrasound and Doppler technique were used to measure the following: carotid wall intima-media thickness (IMT), total systemic artery compliance (SAC), arterial pulse wave velocity [PWV aorto-femoral (A-F), and femoral-dorsalis pedis (F-D)], carotid distensibility coefficient (DC) and carotid augmentation index (AI). Brachial flow-mediated dilation was measured in 30 subjects with analysis of diameter change for 4 min post ischaemia.3. There were no systematic differences over the observed range of measurements for any of the reported parameters. Coefficients of variation were as follows: IMT 2.8%, SAC 9.2%, PWV(A-F) 3.2%, PWV(F-D) 5.0%, DC 10.0%, AI 1.3%. Brachial flow-mediated dilation curves were not different between visits; changes were maximum 60-s post ischaemia. All indices of arterial compliance were significantly correlated with age. The three different indices of central arterial compliance [SAC, PWV(A-F) and AI] were significantly correlated with carotid intima-media thickness.4. Under controlled experimental conditions there was good repeatability of measurements of indices between sessions of both intrinsic and functional arterial mechanical properties (central and carotid arterial compliance, intima-media thickness and brachial flow-mediated dilation). Sample size tables for clinical trials using these indices are presented.
316 citations