Objectives: Permanent coronary artery ligation is a common surgical procedure to mimic coronary
artery ischemia and myocardial infarction (MI). However, the size of MI in rats varies
from 4 to 65% of left ventricular volume, which makes ongoing experiments quite difficult
regarding quantification. We present a fast and reliable method for MI quantification
in vivo using 4D high-resolution cardiac resonance tomography (4D CMRT).
Methods: Sprague-Dawley rats were divided into three groups: control (n = 10), sham (n = 10), and MI (n = 10). MI was induced by permanent ligation of the left anterior descending coronary
artery.
Two weeks after MI, hemodynamics was assessed using 4D high-resolution CMRT (7T) in
vivo. Hearts were extracted afterward, sliced in 3-µm-thick sections using a microtome,
stained in Masson–Goldner and reconstructed as a 3D model using the software “Voloom”
(microdimensions). MI infarct size was calculated using the Voloom software.
CMRT data were utilized for 3D reconstruction with the software “3D-Slicer.” The infarcted
area was analyzed as STL models. Models from CMRT and histology were compared regarding
global and regional cardiac parameters and the infarct size was correlated using Pearson’s
correlation and plotted in Altmann. Interobserver variability was evaluated.
Results: MI rats present a wide range of infarct sizes, clearly altered active and passive
cardiac properties (reduced, paradox movement) and highly increased stiffness in the
ischemic area. No significant differences in the calculation of infarct size between
4D-CMRT and histological methods could be shown (correlation r = 0.92, p < 0.01).
Conclusion: Preliminary results point toward a highly precise comparability of CMRT and histological
analysis regarding the quantification of infarct size. This noninvasive method could
become a considerable supplement for long-term experiments to already access infarct
size in vivo and will simplify analysis of induced infarcts in the rat model.
