Acute myocarditis in a rat model: late gadolinium enhancement with histopathological correlation

Abstract

The aim of the current study was to use an established animal model of autoimmune myocarditis and to judge the ability of cardiovascular MRI (CMR) in quantitatively measuring the extent of myocardial involvement compared with histopathological measurement of severity and extent. Experimental autoimmune myocarditis (EAM) was induced in 10 male Lewis rats. On day 21, all animals were investigated by CMR to measure the extent of late gadolinium enhancement (LGE). Subsequently, histopathological evaluation of the entire heart was performed. All animals of the experimental group fulfilled histopathological criteria of myocarditis, revealing necrosis in seven of eight cases. At reduced heart rate, area of LGE correlated highly with histologically proven area of myocarditis (r = 0.80-0.87, p < 0.05). LGE was mainly located in the anterior (range 50-62.5%) and lateral (range 62.5-75%) left ventricular wall and septum (range 25-50%) with a midwall to subepicardial accentuation. The LGE pattern found by CMR can be regarded as suggestive of EAM. With cellular necrosis being the main mechanism for LGE we were able to show high correlations between CMR examination results and histopathologically proven areas of myocarditis. Thus we think the current animal model can provide the opportunity for further fundamental research into myocarditis.

Non-invasive assessment of experimental autoimmune myocarditis in rats using a 3 T clinical MRI scanner

“…rats on Day 21 after the induction of EAM, mapped the distribution of LGE using a seven-segment model of the LV, and reported that LGE was located mainly in the anterior and lateral LV walls, and was correlated with histopathology findings. 3,4 In the present study, CMR accurately identified the location and the extent of myocardial damage, which corresponded with the histopathological picture of myocarditis. These findings also correlate with typical findings in humans with myocarditis, showing a subepicardial distribution of LGE mainly in basal and mid-infero-lateral segments.…”

“…Significantly, the present study expands upon previous studies by providing new findings on myocarditis in a rat model. 3,4 First, in addition to…”

“…Korkusuz et al 3,4 have already taken important steps in this direction by using late gadolinium-enhanced (LGE) MRI in a rat model of myocarditis using a 1.5 T scanner. We sought to extend this approach, where, in addition to LGE MRI at a single time point, we investigated cine MRI of LV volumes and ejection fraction and performed serial measurements of disease progression.…”

Cardiac magnetic resonance imaging in dilated cardiomyopathy in adults—towards identification of myocardial inflammation

“…In particular, assessment of LGE is a well established CMR parameter in the evaluation of heart failure in the setting of coronary artery disease, myocarditis, and various cardiomyopathies [21][22][23][24][25][26][27]35]. It is important to recognize that LGE is not specific but can reflect myocardial necrosis, non-ischemic fibrosis, and ischemic scars.…”

Assessment of Cardiac Function and Myocardial Morphology Using Small Animal Look-locker Inversion Recovery (SALLI) MRI in Rats

“…Small animal imaging is an important tool for the study of cardiovascular diseases. Techniques routinely used in clinical CMR, such as late gadolinium enhancement (LGE) cannot easily be transferred to small animal CMR due to the animals' high heart rates; but could already be shown 11 . The small animal Look-Locker inversion recovery (SALLI) approach generates multi-modal image data sets allowing for the comprehensive assessment of both cardiac function and morphology (Figures 1 and 3).…”