A noninvasive comparative study of myocardial strains in ischemic canine hearts using tagged MRI in 3-D

Abstract

Regional reduction in myocardial function has long been utilized for noninvasive detection and localization of ischemic regions in the left ventricle. In this study, we compared the ability of 13 different myocardial strain indexes to discriminate between ischemic and nonischemic tissue. Using magnetic resonance imaging with tagging and three-dimensional reconstruction, we noninvasively tracked the deformation of 24 myocardial cuboids in each of nine canine hearts with acute ischemia induced by coronary artery ligation. Monastral blue staining was used for postmortem assessment of ischemia. The ability of each index to discriminate between normal and ischemic zones was evaluated using the "t" statistic. The best discrimination was obtained by the endocardial area strain [t = 7.5 +/- 3.0 (SD)], a local measure of systolic shrinkage on the endocardial surface, and by the magnitude of the endocardial principal strain (t = 7.0 +/- 1.9). Transmural wall thickening (t = 6.1 +/- 2.3) was the third best functional index. The same three indexes correlated most closely with perfusion, as assessed by monastral blue staining. These findings imply that these are the preferable functional indexes for mapping of ischemic myocardial regions.

Myocardial function in infarcted and remote regions early after infarction in man: Assessment by magnetic resonance tagging and strain analysis

“…'This may well indicate the early beginning of dyskinesis and remodeling. The potential of 2D strain analysis to recognize infarcted myocardium is thus confirmed, in agreement with prior results of dog studies (9,14,16).…”

“…This provides a way to quantify the magnitude and direction of the intramural regional strain within the wall, which cannot be obtained by conventional MR cine imaging. MR tagging is also a superior tool for delineation of the dysfunctional zone: It was shown in dogs that 2D strain parameters obtained from MR tagged images are more sensitive than wall thickening in discriminating between ischemic and nonischemic tissue (9).…”

Dobutamine Cardiovascular Magnetic Resonance for the Detection of Myocardial Ischemia With the Use of Myocardial Tagging

“…8 Reduction of myocardial circumferential shortening and systolic wall thickening are sensitive parameters for the detection of myocardial ischemia. 3,9 The addition of myocardial tagging to dobutamine-CMR may further enhance diagnostic accuracy. 1 Without tagging, ventricular contraction is evaluated by the movement of the endocardial and epicardial boundaries.…”

MR imaging of the heart: functional imaging

“…3). This technique seems to be a unique way of assessing non-invasively myocardial shortening during systole and to evaluate various ischemic states of the myocardium [6].…”