Late gadolinium enhancement of acute myocardial infarction in mice at 7T: Cine‐FLASH versus inversion recovery

Abstract

Purpose: To investigate myocardial infarction (MI), late gadolinium (Gd) enhancement (LGE), cardiovascular magnetic resonance imaging (CMRI) is used as the current gold standard for the in vivo diagnosis in patients and preclinical studies. While inversion recovery (IR) fast gradient echo LGE imaging is the preferred technique at clinical field strengths it remains to be investigated which is the best sequence at higher field strength. We therefore compared the IR technique against cine fast low shot angle (cine-FLASH) for the quantification of MI size in mice at 7T in vivo.Materials and Methods: Five mice were used to optimize cine-FLASH and IR parameters. Nine mice were subsequently imaged with optimized parameters using both techniques 2-3 days after MI and %30 minutes post Gd injection. Results:The difference in infarct size values was within 3.3% between the two CMRI techniques and within 7.5% of histological values by Bland-Altman analysis. Contrast-to-noise-ratio between infarcted and normal tissue as well as blood was higher for cine-FLASH with the additional benefit of a 2-time-fold shorter scan time than with the IR method. Furthermore, left ventricular function/volumes could be calculated from cine-FLASH images before as well as after Gd injection. Conclusion:In conclusion, cine-FLASH LGE MRI represents an attractive alternative to IR LGE MRI for infarct size assessment in mice at high field strengths because it provides similar accuracy while being more robust, faster, and less user dependent.

High-frequency speckle tracking echocardiography in the assessment of left ventricular function and remodeling after murine myocardial infarction

“…Thinned myocardium was defined as a reduction in thickness by Ͼ60% compared with healthy myocardium, and the motionless properties of the tissue in MRI images during the cardiac cycle. Our group and others have previously demonstrated good agreement with histologically determined infarct size using triphenyltetrazolium chloride (TTC) staining (22). Intra-and interobserver variability.…”

“…Therefore, MRI remains the gold standard for absolute quantification of LV volumes but STE-derived measures may have significant utility in serial assessment and for comparison among groups. Another clear advantage of MRI remains the direct determination of infarct size, which is often critical in experimental models in ensuring equal stimuli to postinfarct LV remodeling across different study groups (21,22). On the other hand, echocardiography has a number of other potential benefits over MRI, namely 1) greater availability to researchers in many institutions; 2) greater tolerability- some groups even use echo in conscious mice that have undergone training in order to allow this (32).…”

“…MRI acquisitions were performed over a period of ϳ8 min per animal and this was comparable to that for echocardiography. Off-line analyses of LV volumes, EF, and mass from MRI were performed using a semiautomated software program developed in-house (22). This calculated the left ventricular end-diastolic volume (LVEDV) and left ventricular end-systolic volume (LVESV) after estimating end-diastolic and end-systolic blood pool volumes for each MRI slice.…”

“…For the subgroup of mice in which infarct size was estimated, this was done from the 11 consecutive short-axis views from base to apex. The infarct size was calculated as the percentage midline length of thinned myocardium against the total LV midline length (21,22). Thinned myocardium was defined as a reduction in thickness by Ͼ60% compared with healthy myocardium, and the motionless properties of the tissue in MRI images during the cardiac cycle.…”

MRI-based prediction of adverse cardiac remodeling after murine myocardial infarction

“…MRI has high accuracy in quantifying not only volumes and mass in remodeling murine heart but also infarct size (IS; Refs. 3,7,20,21,26) by the use of late gadolinium enhancement (LGE) in the acute phase (1,3,19). We therefore hypothesized that MRI-based parameters measured in the acute phase after experimental murine MI could predict the extent of delayed adverse remodeling.…”