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The Impact of Vendor-Specific Ultrasound Beam-Forming and Processing Techniques on the Visualization of In Vitro Experimental “Scar”: Implications for Myocardial Scar Imaging Using Two-Dimensional and Three-Dimensional Echocardiography

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Alexandros Papachristidis, Sandro Queirós, Konstantinos C. Theodoropoulos, Jan D'hooge, Patrick Rafter, Giovanni Masoero, Spyridon Zidros, Gianpiero Pagnano, Marilou Huang, Luke Dancy, Daniel Sado, Ajay M. Shah, Francis D. Murgatroyd, Mark J. Monaghan

Original languageEnglish
Pages (from-to)1095-1105.e6
JournalJournal of The American Society of Echocardiography
Volume34
Issue number10
DOIs
Accepted/In press2021
PublishedOct 2021

Bibliographical note

Funding Information: Prof. Monaghan has received research support from Philips and is a member of the Speakers? Bureau for Philips. Mr. Rafter is an employee of Philips Healthcare, Philips, Netherlands. Publisher Copyright: © 2021 American Society of Echocardiography Copyright: Copyright 2021 Elsevier B.V., All rights reserved.

King's Authors

Abstract

Background: Myocardial scar appears brighter compared with normal myocardium on echocardiography because of differences in tissue characteristics. The aim of this study was to test how different ultrasound pulse characteristics affect the brightness contrast (i.e., contrast ratio [CR]) between tissues of different acoustic properties, as well as the accuracy of assessing tissue volume. Methods: An experimental in vitro “scar” model was created using overheated and raw pieces of commercially available bovine muscle. Two-dimensional and three-dimensional ultrasound scanning of the model was performed using combinations of ultrasound pulse characteristics: ultrasound frequency, harmonics, pulse amplitude, steady pulse (SP) emission, power modulation (PM), and pulse inversion modalities. Results: On both two-dimensional and three-dimensional imaging, the CR between the “scar” and its adjacent tissue was higher when PM was used. PM, as well as SP ultrasound imaging, provided good “scar” volume quantification. When tested on 10 “scars” of different size and shape, PM resulted in lower bias (−9.7 vs 54.2 mm3) and narrower limits of agreement (−168.6 to 149.2 mm3 vs −296.0 to 404.4 mm3, P = .03). The interobserver variability for “scar” volume was better with PM (intraclass correlation coefficient = 0.901 vs 0.815). Two-dimensional and three-dimensional echocardiography with PM and SP was performed on 15 individuals with myocardial scar secondary to infarction. The CR was higher on PM imaging. Using cardiac magnetic resonance as a reference, quantification of myocardial scar volume showed better agreement when PM was used (bias, −645 mm3; limits of agreement, −3,158 to 1,868 mm3) as opposed to SP (bias, −1,138 mm3; limits of agreement, −5,510 to 3,233 mm3). Conclusions: The PM modality increased the CR between tissues with different acoustic properties in an experimental in vitro “scar” model while allowing accurate quantification of “scar” volume. By applying the in vitro findings to humans, PM resulted in higher CR between scarred and healthy myocardium, providing better scar volume quantification than SP compared with cardiac magnetic resonance.

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