# Left ventricle strain and T1 mapping evaluation in a mouse model with myocardial infarction

## TL;DR

This study evaluates heart function and tissue changes in mice with heart attacks using MRI techniques, providing baseline data for future research.

## Contribution

The study introduces a tailored MRI protocol to measure strain and T1 mapping in mice, offering normative values post-myocardial infarction.

## Key findings

- Myocardial infarction caused LV dilation and reduced ejection fraction, but preserved stroke volume and cardiac output.
- Circumferential strain decreased significantly in MI mice, especially at the apex.
- Post-MI mice showed higher native T1 and lower post-contrast T1 values compared to wild-type mice.

## Abstract

Myocardial strain and T1 mapping offer precise evaluation of cardiac function and tissue characteristics. The aim of this study is to provide normative myocardial strain and T1 values in mice model along with their changes after myocardial infarction (MI) using a tailored acquisition and analysis protocol. Healthy mice had MRI before and after MI. Imaging was performed to assess cardiac function and left ventricle (LV) strain. A Look-Locker Inversion-Recovery sequence was used for T1 maps reconstruction. Gadolinium doses and timing of image acquisitions were optimized. Radial and circumferential strain measurements were conducted using a custom software based on feature tracking. To address ECG signal interference, adjustments were made for accurate strain calculations. An LV dilation in MI compared to wild-type (WT) with a decrease in LV ejection fraction (p < 0.0001) were reported while stroke volume and cardiac output remained preserved (p > 0.21). Normative strain and T1 mapping data were provided revealing an increase in circumferential strain from base to apex (basal: –14 ± 1%, mid: –15 ± 2%, apical: – 21 ± 3%; p < 0.0001) and notable differences in native and post-contrast T1 values between mid-ventricular and apical LV segments. Circumferential strain differences between MI and WT mice were pronounced, with a significant drop in apical strain (p < 0.0001) in MI. Post-MI mice exhibited higher native T1 and lower post-contrast T1 compared to WT. Our methodological approach not only refines imaging sequences but also offers insights into cardiac function and tissue characteristics in mice. By describing normative values of strain and T1, our findings lay the groundwork for future research, particularly in drug therapy.