Special ArticleDefinitions for a Common Standard for 2D Speckle Tracking Echocardiography: Consensus Document of the EACVI/ASE/Industry Task Force to Standardize Deformation Imaging
Introduction
This document represents a consensus statement from the EACVI/ASE/Industry Task Force to standardize deformation imaging (‘the Task Force’) to communicate standard physical and mathematical definitions of various parameters commonly reported in myocardial deformation imaging. It is aimed primarily at the technical engineering community and also interested clinicians. The document is not intended to explore the wide range of clinical applications of deformation imaging.
There is a growing body of evidence showing that the assessment of myocardial deformation by Doppler or speckle tracking techniques provides incremental information in the clinical setting.1 Deformation imaging has been shown to provide unique information on regional and global ventricular function with some studies showing reduced inter- and intraobserver variability in assessing regional left ventricular (LV) function.2 The main areas of application of these techniques have been assessment of myocardial mechanics, ischaemic heart disease, cardiomyopathies, LV diastolic dysfunction, and in detecting subclinical myocardial dysfunction in patients undergoing chemotherapy for cancer or in those affected by heart valve diseases.3 Over the years, a number of software packages and algorithms have entered the market, but a practical limitation to the use of these techniques in routine clinical practice has been the significant variability that exists among vendors. Such a variability relates to several factors: differences in the terminology describing myocardial mechanics; the type of stored data which is used for quantitative analysis (e.g. proprietary formats vs. standard DICOM format); the modality of measuring basic parameters (tissue Doppler vs. speckle tracking); the definition of parameters (many vendors use proprietary speckle tracking algorithms or define different tracking regions for the same parameter); and the results output.1, 4, 5, 6, 7, 8
Recognizing the critical need for standardization in strain imaging,9 in 2010, the European Association of Echocardiography (now the European Association of Cardiovascular Imaging, EACVI) and the American Society of Echocardiography (ASE) invited technical representatives from all interested vendors to participate in a concerted effort to reduce intervendor variability of strain measurement.10, 11
As an initial product of the work of the EACVI/ASE/Industry initiative to standardize deformation imaging, we prepared this document which is intended to provide definitions, names, abbreviations, formulas, and procedures for calculation of physical quantities derived from speckle tracking echocardiography and thus create a common standard. This document is purely technical and provides technical information only. Therefore,
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It is not intended to provide information about the clinical relevance of different measurements.
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It is not intended to suggest which parameters a product should preferably include.
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It is not intended to favour speckle tracking over other approaches for the echocardiographic quantification of myocardial function, such as tissue Doppler, which can provide comparable parameters of comparable relevance.
By providing clear definitions of the standard quantities that any software solution should report, the differences among different products should be limited to:
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Technical: accuracy and reproducibility of the proprietary approach to speckle tracking;
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Marketing: choices about how and what different products report;
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Innovations: further parameters or representations beyond what is reported in this document.
Readers interested in a more in-depth description of the mathematics and physics are referred to the structural mechanics literature.12
Section snippets
Region of Interest
The complete myocardial region of interest (ROI, Figure 1) is defined at end-diastole by:
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Endocardial border: the inner contour of the myocardium;
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Epicardial border: the outer contour of the myocardium;
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Myocardial midline: the middle ROI axis defined in the middle between inner and outer ROI contours.
Each of these contours can be either user-defined or generated automatically. In any case, where they are generated automatically, the user should be allowed to check them and, if needed, edit them
Velocity
Velocity is a vectorial quantity with a direction and amplitude. Velocities are commonly reported just as measured, but sometimes they are reported after subtracting the average velocity of the overall LV. While in some cases this subtraction may correct for overall LV translation, it may also mask or diminish segmental motion differences in others. For example, the difference between the fast inward motion of one LV wall and the slower motion of opposite wall will become smaller when the
Discussion
The members of the EACVI/ASE/Industry Task Force to standardize deformation imaging have reached a consensus about the content of the present document to provide standardization of the definitions and the calculation of the various quantities usually reported in myocardial deformation imaging. The main purpose of this document is to provide the theoretical basis to explain physiological significance and mathematical computation of the various parameters to clinicians interested in using
Conclusions and New Beginnings
This strain standardization Task Force was initiated by EAE (presently EACVI) and ASE to develop an academia–industry consortium for achieving consensus on a list of standard definitions and nomenclature for the clinical parameters evaluated with 2D speckle tracking technology. This marks one of the first steps in reducing intervendor differences and ambiguities in the strain algorithms. We strongly encourage clinicians and researchers to remain aware of the potential variations in techniques
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Cited by (0)
Conflict of interest: none declared.
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J.-U.V., G.P., and P.L. have equally contributed to the present paper.
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J.D.T. and L.P.B. are co-chairs of this task force.