Myocardial strain imaging: review of general principles, validation, and sources of discrepancies

Abstract

Myocardial tissue tracking imaging techniques have been developed for a more accurate evaluation of myocardial deformation (i.e. strain), with the potential to overcome the limitations of ejection fraction (EF) and to contribute, incremental to EF, to the diagnosis and prognosis in cardiac diseases. While most of the deformation imaging techniques are based on the similar principles of detecting and tracking specific patterns within an image, there are intra- and inter-imaging modality inconsistencies limiting the wide clinical applicability of strain. In this review, we aimed to describe the particularities of the echocardiographic and cardiac magnetic resonance deformation techniques, in order to understand the discrepancies in strain measurement, focusing on the potential sources of variation: related to the software used to analyse the data, to the different physics of image acquisition and the different principles of 2D vs. 3D approaches. As strain measurements are not interchangeable, it is highly desirable to work with validated strain assessment tools, in order to derive information from evidence-based data. There is, however, a lack of solid validation of the current tissue tracking techniques, as only a few of the commercial deformation imaging softwares have been properly investigated. We have, therefore, addressed in this review the neglected issue of suboptimal validation of tissue tracking techniques, in order to advocate for this matter.

MRI in cardio‐oncology: A review of cardiac complications in oncologic care

“…The first myocardial strain measurements with MRI were originally achieved in the 1980s with the development of tagging methods. Tagging involves magnetically labeling regions of the myocardium by applying selective RF pulses to saturate the spins of hydrogen atoms along orthogonal planes to form a tagged grid that moves with the tissue during the cardiac cycle, from which strain can be measured . Figure shows tagged images in the setting of abnormal LV contraction.…”

“…Tagging involves magnetically labeling regions of the myocardium by applying selective RF pulses to saturate the spins of hydrogen atoms along orthogonal planes to form a tagged grid that moves with the tissue during the cardiac cycle, from which strain can be measured. [44][45][46] Figure 1 shows tagged images in the setting of abnormal LV contraction. Several techniques have been created based on the tagging principles to analyze strain, including spatial modulation of magnetization (SPAMM), delay alternating with nutations for tailored excitation (DANTE), harmonic phase (HARP), displacement encoding with stimulated echoes (DENSE), and strain encoding (SENC) and fast-SENC.…”

“…Several techniques have been created based on the tagging principles to analyze strain, including spatial modulation of magnetization (SPAMM), delay alternating with nutations for tailored excitation (DANTE), harmonic phase (HARP), displacement encoding with stimulated echoes (DENSE), and strain encoding (SENC) and fast-SENC. 44 Harmonic phase analysis allows rapid analysis of the tagged images; however, spatial resolution and strain accuracy are reduced. 47 SENC allows effective quantification of through-plane strain but has limitations in complete coverage of radial and circumferential strain analysis.…”

Myocardial Strain Analysis using CMR Feature Tracking – The Good, The Bad and The Ugly

“…Strain is a parameter that can be used to assess myocardial regional deformation. By measuring strain in the longitudinal, circumferential, and radial orientations, we can study cardiac function both regionally and globally (4). Myocardial strain imaging thus serves as a valuable diagnostic and prognostic tool for evaluating cardiac abnormalities (5).…”

“…Currently, cardiovascular magnetic resonance imaging (CMR) serves as the gold standard for the quantification of biventricular strain (6). Over the years, there have been a number of different CMR methods used for assessing strain, including myocardial tagging (MT), displacement encoding with stimulated echoes (DENSE), and most recently, feature tracking (FT) (4). Specifically, CMR FT has emerged as a simple post-processing method for quantifying strain (7).…”