Malay Ilesh Shah

Bio: Malay Ilesh Shah is an academic researcher from Indian Institute of Technology Madras. The author has contributed to research in topics: Pulse wave velocity & Imaging phantom. The author has an hindex of 8, co-authored 33 publications receiving 133 citations. Previous affiliations of Malay Ilesh Shah include Indian Institutes of Technology.

ARTSENS® Pen-portable easy-to-use device for carotid stiffness measurement: technology validation and clinical-utility assessment.

Abstract: OBJECTIVE The conventional medical imaging modalities used for arterial stiffness measurement are non-scalable and unviable for field-level vascular screening. The need for an affordable, easy-to-operate automated non-invasive technologies remains unmet. To address this need, we present a portable image-free ultrasound device-ARTSENS® Pen, that uses a single-element ultrasound transducer for carotid stiffness evaluation. APPROACH The performance of the device was clinically validated on a cohort of 523 subjects. A clinical-grade B-mode ultrasound imaging system (ALOKA eTracking) was used as the reference. Carotid stiffness measurements were taken using the ARTSENS® Pen in sitting posture emulating field scenarios. MAIN RESULTS A statistically significant correlation (r > 0.80, p < 0.0001) with a non-significant bias was observed between the measurements obtained from the two devices. The ARTSENS® Pen device could perform highly repeatable measurements (with variation smaller than 10%) on a relatively larger percentage of the population when compared to the ALOKA system. The study results also revealed the sensitivity of ARTSENS® Pen to detect changes in arterial stiffness with age. SIGNIFICANCE The easy-to-use technology and the automated algorithms of the ARTSENS® Pen make it suitable for cardiovascular risk assessment in resource-constrained settings.

Assessment of Carotid Arterial Stiffness in Community Settings With ARTSENS

Abstract: Objective: We investigate the field feasibility of carotid stiffness measurement using ARTSENS® Touch and report the first community-level data from India. Method: In an analytical cross-sectional survey among 1074 adults, we measured specific stiffness index ( $\beta $ ), pressure-strain elastic modulus ( $\text{E}_{\text {p}}$ ), arterial compliance (AC), and one-point pulse wave velocity (PWV $_{\beta }$ ) from the left common carotid artery. Data for established risk factors (waist circumference, blood pressure, plasma glucose, triglycerides, and HDL-C) were also collected. The association of carotid stiffness with age, gender, hypertension/diabetes, smoking, and clustering of risk factors was studied. Results: Measurements were repeatable with a relative difference (RD) between consecutive readings of $\sim 80$ % of arterial diameter values. The average RDs for $\beta $ , $\text{E}_{\text {p}}$ , AC, and PWV $_{\beta }$ , were 20.51%, 22.31%, 25.10%, and 14.13%, respectively. Typical range for stiffness indices among females and males were $\beta $ : 8.12 ± 3.59 vs 6.51 ± 2.78, $\text{E}_{\text {p}}$ : 113.24 ± 56.12 kPa vs 92.33 ± 40.65 kPa, PWV $_{\beta }$ : 6.32 ± 1.38 ms−1 vs 5.81 ± 1.16 ms−1, and AC: 0.54 ± 0.36 mm2 kPa−1 vs 0.72 ± 0.38 mm2 kPa−1. Mean $\beta $ , $\text{E}_{\text {p}}$ , and PWV $_{\beta }$ increased (and mean AC decreased) across decades of age; the trend persisted even after excluding hypertensives and subjects with diabetes. The odds ratio of presence of multiple risk factors for $\text{E}_{\text {p}} \ge93.71$ kPa and/or PWV $_{\beta } \ge6.56$ ms−1 was ≥ 2.12 or above in males. In females, it was just above 2.00 for $\text{E}_{\text {p}} \ge91.21$ kPa and/or PWV $_{\beta } \ge5.10$ ms−1 and increased to ≥ 3.33 for $\text{E}_{\text {p}} \ge143.50$ kPa and ≥ 3.25 for PWV $_{\beta } \ge7.31$ ms−1. Conclusion: The study demonstrated the feasibility of carotid stiffness measurement in a community setting. A positive association between the risk factors and carotid artery stiffness provides evidence for the device’s use in resource-constrained settings. Clinical Impact: The device paves the way for epidemiological and clinical studies that are essential for establishing population-level nomograms for wide-spread use of carotid stiffness in clinical practice and field screening of ‘at-risk’ subjects.

Carotid and Jugular Classification in ARTSENS

Abstract: Over past few years our group has been working on the development of a low-cost device, ARTSENS, for measurement of local arterial stiffness (AS) of the common carotid artery (CCA). This uses a single element ultrasound transducer to obtain A-mode frames from the CCA. It is designed to be fully automatic in its operation such that, a general medical practitioner can use the device without any prior knowledge of ultrasound modality. Placement of the probe over CCA and identification of echo positions corresponding to its two walls are critical steps in the process of measurement of AS. We had reported an algorithm to locate the CCA walls based on their characteristic motion. Unfortunately, in supine position, the internal jugular vein (IJV) expands in the carotid triangle and pulsates in a manner that confounds the existing algorithm and leads to wrong measurements of the AS. Jugular venous pulse (JVP), on its own right, is a very important physiological signal for diagnosis of morbidities of the right side of the heart and there is a lack of noninvasive methods for its accurate estimation. We integrated an ECG device to the existing hardware of ARTSENS and developed a method based on physiology of the vessels, which now enable us to segregate the CCA pulse (CCP) and the JVP. False identification rate is less than 4%. To retain the capabilities of ARTSENS to operate without ECG, we designed another method where the classification can be achieved without an ECG, albeit errors are a bit higher. These improvements enable ARTSENS to perform automatic measurement of AS even in the supine position and make it a unique and handy tool to perform JVP analysis.

Ultrasound signal quality parameterization for image-free evaluation of arterial stiffness.

Abstract: We are in process of developing an image-free, single element ultrasound system for automated evaluation of arterial stiffness, we call it ARTSENS. The lack of a guiding image for arterial visualization necessitates intelligent analysis of ultrasound radio frequency (RF) echo signals to obtain reliable measurements. In this paper, we propose a novel algorithm to parameterize the echo signal received from the common carotid artery (CCA) to improve accuracy and reliability of arterial stiffness measurement. The echo signal quality is parameterized using features such as sharpness of arterial wall and energy ratio. A signal quality score is calculated by integrating the results from each feature. This score is used to triage the set of available echo signals recorded from each subject and select the best signal for computation of stiffness values. The performance of signal quality algorithm is tested using a database of carotid artery echo signals recorded from 28 human volunteers. It was observed that both the accuracy and reliability of the stiffness measurements were improved after triaging using the signal quality parameterization algorithm.

An Imageless Ultrasound Device to Measure Local and Regional Arterial Stiffness

Abstract: Arterial stiffness (AS) has been shown to be an important marker for risk assessment of cardiovascular events. Local arterial stiffness (LAS) is conventionally measured by evaluating arterial distensibility at particular arterial sites through ultrasound imaging systems. Regional arterial stiffness (RAS) is generally obtained by evaluating carotid to femoral pulse wave velocity (cfPWV) through tonometric devices. RAS has a better prognostic value than LAS and cfPWV is considered as the gold standard of AS. Over the past few years our group has been developing ARTerial Stiffness Evaluation for Non-Invasive Screening (ARTSENS), an inexpensive and portable device to measure the LAS. It uses a single element ultrasound transducer to obtain A-Mode frames from the desired artery and is fully automated to enable a non-expert to perform measurements. In this work, we report an extension of ARTSENS to enable measurement of cfPWV that now makes it the only fully automatic device that can measure both LAS and RAS. In this paper, we provide a general review of the ARTSENS and compare it with other state-of-the-art AS measurement systems. cfPWV measurement using ARTSENS was cross-validated against SphygmoCor by successive measurements with both devices on 41 human subjects and excellent agreement between both devices was demonstrated (Coefficient of determination $({\bf R}^{2})=0.70\, ({\bf p} and, limits of agreement $({\rm LoA}) m/s). The inter-device correlation between ARTSENS and SphygmoCor was found to be better than other similar studies reported in the literature.

Ten Years of Lateral Flow Immunoassay Technique Applications: Trends, Challenges and Future Perspectives.

Abstract: The Lateral Flow Immunoassay (LFIA) is by far one of the most successful analytical platforms to perform the on-site detection of target substances. LFIA can be considered as a sort of lab-in-a-hand and, together with other point-of-need tests, has represented a paradigm shift from sample-to-lab to lab-to-sample aiming to improve decision making and turnaround time. The features of LFIAs made them a very attractive tool in clinical diagnostic where they can improve patient care by enabling more prompt diagnosis and treatment decisions. The rapidity, simplicity, relative cost-effectiveness, and the possibility to be used by nonskilled personnel contributed to the wide acceptance of LFIAs. As a consequence, from the detection of molecules, organisms, and (bio)markers for clinical purposes, the LFIA application has been rapidly extended to other fields, including food and feed safety, veterinary medicine, environmental control, and many others. This review aims to provide readers with a 10-years overview of applications, outlining the trends for the main application fields and the relative compounded annual growth rates. Moreover, future perspectives and challenges are discussed.

Continuous Blood Pressure Measurement From Invasive to Unobtrusive: Celebration of 200th Birth Anniversary of Carl Ludwig

Abstract: The year 2016 marks the 200th birth anniversary of Carl Friedrich Wilhelm Ludwig (1816–1895). As one of the most remarkable scientists, Ludwig invented the kymograph, which for the first time enabled the recording of continuous blood pressure (BP), opening the door to the modern study of physiology. Almost a century later, intraarterial BP monitoring through an arterial line has been used clinically. Subsequently, arterial tonometry and volume clamp method were developed and applied in continuous BP measurement in a noninvasive way. In the last two decades, additional efforts have been made to transform the method of unobtrusive continuous BP monitoring without the use of a cuff. This review summarizes the key milestones in continuous BP measurement; that is, kymograph, intraarterial BP monitoring, arterial tonometry, volume clamp method, and cuffless BP technologies. Our emphasis is on recent studies of unobtrusive BP measurements as well as on challenges and future directions.

Local Pulse Wave Velocity: Theory, Methods, Advancements, and Clinical Applications

Abstract: Local pulse wave velocity (PWV) is evolving as one of the important determinants of arterial hemodynamics, localized vessel stiffening associated with several pathologies, and a host of other cardiovascular events. Although PWV was introduced over a century ago, only in recent decades, due to various technological advancements, has emphasis been directed toward its measurement from a single arterial section or from piecewise segments of a target arterial section. This emerging worldwide trend in the exploration of instrumental solutions for local PWV measurement has produced several invasive and noninvasive methods. As of yet, however, a univocal opinion on the ideal measurement method has not emerged. Neither have there been extensive comparative studies on the accuracy of the available methods. Recognizing this reality, makes apparent the need to establish guideline-recommended standards for the measurement methods and reference values, without which clinical application cannot be pursued. This paper enumerates all major local PWV measurement methods while pinpointing their salient methodological considerations and emphasizing the necessity of global standardization. Further, a summary of the advancements in measuring modalities and clinical applications is provided. Additionally, a detailed discussion on the minimally explored concept of incremental local PWV is presented along with suggestions of future research questions.

Recent advancements in structural improvements of lateral flow assays towards point-of-care testing

Abstract: Lateral flow assays (LFAs) provide some of the most attractive point-of-care instruments for broad applications with simple, rapid, user-friendly, and cost-effective characteristics. However, these technologies suffer from low sensitivity, the poor limit of detection, and just qualitative or semi-quantitative results that restrict their practical applications. Extensive research has been reported in this area involving sensitivity enhancement, multiplex analysis, the implementation for broad analytes, and development of novel electronic readers for quantitative analysis. This review presents recently reported works for the structural improvements of LFAs considering antibody immobilization, manipulation of the membrane, structural variants of LFAs, and single and dual detection mode LFAs, all these aspects focused on the visual, fluorescent, magnetic, surface-enhanced Raman scattering, electrochemical, and nanozyme-based detection.

Bi-Modal Arterial Compliance Probe for Calibration-Free Cuffless Blood Pressure Estimation

Abstract: Objective: We propose a calibration-free method and system for cuffless blood pressure (BP) measurement from superficial arteries. A prototype device with bi-modal probe arrangement was designed and developed to estimate carotid BP – an indicator of central aortic pressure. Methods: Mathematical models relating BP parameters of an arterial segment to its dimensions and local pulse wave velocity (PWV) are introduced. A bi-modal probe utilizing ultrasound and photoplethysmograph sensors was developed and used to measure diameter values and local PWV from the carotid artery. Carotid BP was estimated using the measured physiological parameters without any subject- or population-specific calibration procedures. The proposed cuffless BP estimation method and system were tested for accuracy, usability, and for potential utility in hypertension screening, on a total of 83 subjects. Results: The prototype device demonstrated its capability of detecting beat-by-beat arterial dimensions and local PWV simultaneously. Carotid diastolic BP (DBP) and systolic BP (SBP) were estimated over multiple cardiac cycles in real-time. The absolute error in carotid DBP was Conclusion: The feasibility of calibration-free, cuffless BP measurement at an arterial site of interest was demonstrated with a level of acceptable accuracy. The study also demonstrated the potential utility of the proposed method and system in hypertension screening and local evaluation of arterial stiffness indices. Significance: Novel approach for calibration-free cuffless BP estimation; a potential tool for local BP measurement and hypertension screening.