Myocardial infarction quantification with Manganese‐Enhanced MRI (MEMRI) in mice using a 3T clinical scanner

Abstract

Manganese (Mn(2+)) was recognized early as an efficient intracellular MR contrast agent to assess cardiomyocyte viability. It had previously been used for the assessment of myocardial infarction in various animal models from pig to mouse. However, whether Manganese-Enhanced MRI (MEMRI) is also able to assess infarction in the acute phase of a coronary occlusion reperfusion model in mice has not yet been demonstrated. This model is of particular interest as it is closer to the situation encountered in the clinical setting. This study aimed to measure infarction volume taking TTC staining as a gold standard, as well as global and regional function before and after Mn(2+) injection using a clinical 3T scanner. The first step of this study was to perform a dose-response curve in order to optimize the injection protocol. Infarction volume measured with MEMRI was strongly correlated to TTC staining. Ejection fraction (EF) and percent wall thickening measurements allowed evaluation of global and regional function. While EF must be measured before Mn(2+) injection to avoid bias introduced by the reduction of contrast in cine images, percent wall thickening can be measured either before or after Mn(2+) injection and depicts accurately infarct related contraction deficit. This study is the first step for further longitudinal studies of cardiac disease in mice on a clinical 3T scanner, a widely available platform.

High Time-Resolved Cardiac Functional Imaging Using Temporal Regularization for Small Animal on a Clinical 3T Scanner

“…As illustrated in Fig. 7, interleaved cine depicted accurately the contraction deficit present in the anterior region of the MI mice and in agreement with previous experiments [9]. We measured a significant increase of LVESV and LVEDV for MI group (p < 0.01 and p < 0.05, respectively) as well as a significant decrease of the LVEF compared to the WT group (p < 0.001).…”

“…The basic sequence was a segmented turboflash cine sequence (already validated in other studies with slightly different parameters [9], [13]) with following parameters: FOV 111 mm, in-plane resolution 257 μm, slice thickness 1 mm, TE/TR 6.2/13.5 ms, flip angle 30…”

“…Following Roussakis et al [7], 11 phases per cardiac cycle are at least necessary to evaluate ejection fraction (EF). Considering a mouse heart rate of 600 beats/min, the required time resolution should be at least 9 ms whereas, in dedicated scanners, the cardiac function is accurately estimated with a temporal resolution of 8.4 ms [8]; on most clinical scanners, the available cine sequence provides a temporal resolution in the range of 11-18 ms [9], [10]. There is thus a need to acquire more cardiac phases to assess accurately cardiac function.…”

Apelin-13 infusion salvages the peri-infarct region to preserve cardiac function after severe myocardial injury

“…Thus, a precise characterization of cell viability and injury in this vulnerable region is imperative. Since the non-specific distribution of gadolinium in DEMRI overestimates the scar area, MEMRI is used to delineate the live cells within the scar, which was previously deemed infarcted by DEMRI [13–14,16,23–24]. The dual contrast MEMRI-DEMRI defines the peri-infarct region at the leading edge of the DEMRI scar signal where viable but injured myocardium is present.…”

Long-Term Left Ventricular Remodelling in Rat Model of Nonreperfused Myocardial Infarction: Sequential MR Imaging Using a 3T Clinical Scanner

“…However, our temporal resolution (7.7 ms) was higher than previously reported values with clinical and non-clinical scanners [26, 28–30]. This resolution resulted in large number of frames per cardiac cycle which enabled us to obtain accurately ED and ES frames without the need of multiple acquisitions, resulting in reduction in scan time, and accurate global and regional functional analyses [20].…”