An improved echo tracking algorithm for arterial distensibility measurements
01 Dec 2009-pp 1-5
TL;DR: An automatic method that uses an adaptive threshold to track the desired number of echoes and measure the artery diameter accurately is proposed that could be used along with single element transducer based ultrasound measurement systems as well as B-mode scanners.
Abstract: Arterial distensibility is often measured by non-invasively detecting the change in artery diameter over a cardiac cycle. Traditional methods using B-mode images require considerable processing power and time. Here we present a method to extract the distensibility waveform from RF signals obtained by ultrasound interrogation of the carotid artery. We propose an automatic method that uses an adaptive threshold to track the desired number of echoes and measure the artery diameter accurately. The algorithm could be used along with single element transducer based ultrasound measurement systems as well as B-mode scanners. The performance is analyzed using data obtained using phantom models of the artery as well as from human volunteers.
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TL;DR: The feasibility of the novel ARTSENS device in performing accurate in vivo measurements of arterial stiffness is verified, a device for image free, noninvasive, automated evaluation of vascular stiffness amenable for field use.
Abstract: Vascular stiffness is an indicator of cardiovascular health, with carotid artery stiffness having established correlation to coronary heart disease and utility in cardiovascular diagnosis and screening. State of art equipment for stiffness evaluation are expensive, require expertise to operate and not amenable for field deployment. In this context, we developed ARTerial Stiffness Evaluation for Noninvasive Screening (ARTSENS), a device for image free, noninvasive, automated evaluation of vascular stiffness amenable for field use. ARTSENS has a frugal hardware design, utilizing a single ultrasound transducer to interrogate the carotid artery, integrated with robust algorithms that extract arterial dimensions and compute clinically accepted measures of arterial stiffness. The ability of ARTSENS to measure vascular stiffness in vivo was validated by performing measurements on 125 subjects. The accuracy of results was verified with the state-of-the-art ultrasound imaging-based echo-tracking system. The relation between arterial stiffness measurements performed in sitting posture for ARTSENS measurement and sitting/supine postures for imaging system was also investigated to examine feasibility of performing ARTSENS measurements in the sitting posture for field deployment. This paper verified the feasibility of the novel ARTSENS device in performing accurate in vivo measurements of arterial stiffness. As a portable device that performs automated measurement of carotid artery stiffness with minimal operator input, ARTSENS has strong potential for use in large-scale screening.
53 citations
Additional excerpts
...We had previously presented the concept of an image-free system for measurement of arterial stiffness [17]–[21] and also demonstrated the accuracy and repeatability of measurements in controlled laboratory settings [22], [23]....
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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.
37 citations
15 May 2016
TL;DR: Initial results indicate a strong potential of MPG - Ultrasound arterial compliance probe in continuous, cuffless evaluation of blood pressure (BP) from superficial arteries.
Abstract: Cardiovascular diseases are the leading cause of death around the world. Non-invasive estimation of arterial parameters is significant in the early detection of cardiovascular diseases. In this work, we present an arterial compliance probe for calibration-free evaluation of carotid pulse pressure. This novel cuffless measurement technique uses dual magnetic plethysmograph (MPG) transducers for carotid local pulse wave velocity (PWV) measurement and single element ultrasound transducer for measuring arterial dimensions. Proposed arterial compliance probe can acquire two blood pulse waveforms and arterial diameter parameters simultaneously, which are then utilized in cycle-to-cycle estimation of arterial local PWV and pulse pressure without any subject or population specific calibration. The design of compliance probe and measurement system was verified by in-vivo trials. Accurate local PWV measurement and calibration free estimation of carotid pulse pressure was also validated by in-vivo studies. Initial results indicate a strong potential of MPG — Ultrasound arterial compliance probe in continuous, cuffless evaluation of blood pressure (BP) from superficial arteries.
9 citations
Cites methods from "An improved echo tracking algorithm..."
...Measurement of arterial distension and end diastolic diameter was performed by using proven, validated ARTSENS® algorithms [16], [17]....
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10 May 2011
TL;DR: In this paper, the authors presented a Virtual Instrument (VI) for automated estimation of both local and regional arterial compliance measures using an ultrasound transducer to measure the distension and lumen diameter of the carotid artery.
Abstract: The evaluation of arterial compliance is very important in cardiovascular screening of “at-risk” patients. Existing techniques for local arterial stiffness estimation put a premium on technology and operator expertise. Regional stiffness, measured in terms of the pulse wave velocity, is prone to errors in both path-length and delay estimation. Here, we present a Virtual Instrument (VI) for automated estimation of both local and regional arterial compliance measures. Local arterial compliance is evaluated by utilizing an ultrasound transducer to measure the distension and lumen diameter of the carotid artery. The regional stiffness is estimated from the pulse wave velocity, measured using two magnetic transducers in a dual-channel arrangement. The automated measurement algorithms are thoroughly analyzed, to identify and minimize possible error sources as well as to optimize the design of both the transducer and the virtual instrument. The results of a few human trials are also presented to illustrate the capability of the VI to measure arterial compliance in-vivo.
7 citations
Cites methods from "An improved echo tracking algorithm..."
...A detailed explanation of this automated measurement algorithm has been reported in earlier works [5], [10]....
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TL;DR: In this article , deep neural network (DNN) models are employed to perform carotid detection, wall localization, and inner lumen diameter measurement using a noninvasive A-mode ultrasound-based device.
Abstract: Arterial stiffness (AS) of the carotid artery is an early marker of stratifying cardiovascular disease risk. This article aims to improve the performance of ARTSENS, a noninvasive A-mode ultrasound-based device for measuring AS. The primary objective of ARTSENS is to enable the measurement of elastic modulus using A-Mode ultrasound and blood pressure. As this device is image-free, there is a need to automate: 1) carotid detection; 2) wall localization; and 3) inner lumen diameter measurement. This has been performed using conventional signal processing methods in some of the earlier works in this domain. In this article, deep neural network (DNN) models are employed to perform the above three tasks. The DNNs were trained over data acquired from 82 subjects at two different medical centers. Ground-truth labeling was performed by a trained operator using corresponding measurements from the state-of-the-art Aloka e-Tracking system. All three DNN models had significantly lower errors compared to earlier signal processing methods and could perform their measurements using a single A-Mode frame. Using the DNNs, two different machine learning pipelines have been proposed here to measure the elastic modulus; the best among them could achieve an error of 9.3% with the Pearson correlation coefficient of 0.94 ( ). The models were tested on Raspberry Pi and Jetson Nano single board computers to demonstrate real-time processing on low computational resources.
3 citations
References
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14 Oct 2008
TL;DR: The instrument gives a display of the variation of carotid diameter in real time and calculates the various estimates of arterial compliance from the analyzed data.
Abstract: A new virtual instrument for real time, non invasive measurement of carotid artery compliance is proposed. The instrument is a reliable, compact and low cost alternative to the conventional ultrasound scanner and wall tracking system for carotid artery compliance measurement. The measurement system uses an ultrasound pulse echo method to probe the carotid artery. The reflected echoes are processed using Hilbert transform techniques. Peak detection and echo tracking are implemented in LabVIEW. A comparison is done between manual and automatic method of echo identification. The instrument gives a display of the variation of carotid diameter in real time and calculates the various estimates of arterial compliance from the analyzed data. The capability of the instrument to accurately determine arterial compliance measures is demonstrated by experiments performed on human subjects.
12 citations
"An improved echo tracking algorithm..." refers background or methods in this paper
...A detailed explanation of the experimental protocol is available elsewhere [5]....
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...A pilot measurement system that proves this concept has already been demonstrated [5],[6]....
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