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Updated: Oct 3, 2026
Assessment of Cardiac Function and Myocardial Morphology Using Small Animal Look-locker Inversion Recovery (SALLI) MRI in Rats
Published on: July 19, 2013
Serial cine-magnetic resonance imaging of left ventricular remodeling after myocardial infarction in rats
M Nahrendorf1, F Wiesmann, K H Hiller
1Physikalisches Institut (EP5), Universität Würzburg, Germany.
Abstract:
The purpose of the present study was the serial investigation of morphological and functional changes after left coronary artery ligation in the intact rat using cine-magnetic resonance imaging (MRI). MRI studies were performed 4, 8, 12, and 16 weeks after myocardial infarction (MI) with an echocardiogram (ECG)-triggered cine-fast low-angle shot (FLASH)-sequence in a 7-Tesla magnet. MI-size, left ventricular (LV) mass and volumes, cardiac index, ejection fraction (EF), and remote wall and scar thickness of 11 Wistar rats were compared to four sham-operated rats. Stress MRI with dobutamine (10 microl/kg x minute) was performed at 16 weeks. In MI groups (small MI < 30%, N = 5, large MI > 30%, N = 6), there was significant increase of LV mass (small MI + 47.8% increase, large MI + 74.1%) and wall thickness (large MI 1.21 +/- 0.03 to 1.84 +/- 0.07 mm). Scar thickness declined from four to 16 weeks (large MI 0.92 +/- 0.06 to 0.38 +/- 0.02 mm, P < 0.05). End-diastolic volume of both MI groups was significantly elevated but increased further only in animals with large MI from four to 16 weeks (657.1 +/- 38.6 to 869.7 +/- 60.7 microL, P < 0.05). Compared to sham, EF was significantly depressed in MI (large MI 31.5 +/- 2.0%). Wall thickening declined from four to 16 weeks post-MI (large MI 50.9 +/- 9.9 to 28.9 +/- 4.4%, P < 0.05). During stress, sham and MI rats increased wall thickening from 66.5 +/- 8.2 to 111.2 +/- 6.7% and from 30.8 +/- 4.3 to 47.5 +/- 5.8%, respectively (P < 0.05). Hypertrophy was found in all animals with MI throughout the entire period of observation, whereas dilatation after four weeks was only detected in animals with large MI. These morphologic changes were accompanied by an early decline of EF; myocardial function characterized by wall thickening deteriorated later.
Insights
Serial MRI revealed that myocardial infarction (MI) in rats causes significant left ventricular (LV) hypertrophy and dilation. Cardiac function, measured by ejection fraction and wall thickening, declined early and progressively after MI.
Area of Science:
- Cardiovascular Imaging
- Cardiac MRI
- Myocardial Infarction Model
Background:
- Left coronary artery ligation is a common method to induce myocardial infarction (MI) in animal models.
- Serial imaging is crucial for understanding the dynamic changes following MI.
Purpose of the Study:
- To serially investigate morphological and functional changes after left coronary artery ligation in rats using cine-magnetic resonance imaging (MRI).
- To compare changes in MI size, left ventricular (LV) mass and volumes, cardiac index, ejection fraction (EF), and wall thickness between MI and sham groups.
Main Methods:
- Wistar rats underwent left coronary artery ligation (N=11) or sham operation (N=4).
- Echocardiogram (ECG)-triggered cine-fast low-angle shot (FLASH)-sequence MRI was performed at 4, 8, 12, and 16 weeks post-MI.
- Stress MRI with dobutamine was performed at 16 weeks.
Main Results:
- Myocardial infarction led to significant increases in LV mass and wall thickness, particularly in the large MI group.
- Scar thickness decreased over time, while end-diastolic volume increased, especially in the large MI group.
- Ejection fraction was significantly depressed in MI rats, and wall thickening declined progressively post-MI.
Conclusions:
- Morphological changes like hypertrophy and dilatation occur early after MI, with dilatation more pronounced in large MIs.
- Functional decline, including reduced ejection fraction and wall thickening, accompanies these morphological changes.
- Cine-MRI is effective for serial assessment of cardiac remodeling and function after experimental MI.
