Myocardial Strain Evaluation from Cardiovascular MRI and CT: Physiological Principles and Clinical Perspectives

Global markers of myocardial function are limited in the information they provide, warranting the need for local markers that are sensitive and specific to myocardial physiology. Myocardial deformation, quantified by strain, is a robust marker of myocardial function that is locally defined and can provide deeper insights beyond that of global markers. It arises as an emergent property of the mesostructure where the changes in the fiber and sheetlet structure drive the deformation pattern over the cardiac cycle. Quantifying myocardial strain can be achieved via cardiac magnetic resonance (CMR) as well as cardiac computed tomography (CCT), where numerous advancements have been made. This review discusses current CMR and CCT techniques used to quantify myocardial strain, along with the strengths and weaknesses of each technique. The applications of these techniques on a variety of clinical scenarios are also discussed, spanning heart failure, cardiomyopathies (both ischemic and non-ischemic), valvular disease, cardiotoxicity, dyssynchrony, pulmonary hypertension, and congenital heart disease, with recent studies being highlighted. Finally, future directions are presented, with myocardial strain serving not just as an important marker for detecting myocardial abnormalities, but a potential marker in predicting disease outcomes.