Novel Animal Model for Ventricular Ejection Fraction Measured by MRI

Aim: The objective of this study is to evaluate an animal model, herein called the Tunac Arterial Plaque (TAP) mouse as a model for reduced left ventricle ejection fraction (LVEF). Traditional mouse models involve genetically modified or surgically altered animals, whereas the TAP model is a wild mouse (C57Bl/6 strain) fed with a high fat diet and treated with an environmental chemical pollutant 3,3',4,4'-Tetrachlorobiphenyl (PCB) to mimic human lifestyle. Thus, the LVEF volume of treated and untreated mice will be measured per MRI, as well as an assessment for the presence of arterial plaque. Methods and results: Ten-week-old male C57/Bl6 mice were fed with either normal or high fat diet, acclimated for 1 week and then PCB was administered by gavage. Magnetic resonance imaging (MRI) was performed using a 7-Tesla Varian magnet. Briefly, the heart was aligned to the proper orientation, then an intragate scan was carried out for a CINE presentation (motion sensitive MRI in which a series of static images are obtained at various stages of the cardiac cycle and then played back as a movie). A black blood method was used that caused the blood to appear darker than the adjacent tissue and a CINE sequence to sort images, from which another program a (Medviso Segment) calculated percent ejection fraction (EF), heart rate (HR) and respiratory rate (RR). For the aorta and carotid artery imaging, cross-sectional images of the aortic arch were obtained, which produced multiple contrast weightings. Mice fed with normal diet showed normal ejection fraction volume (75.1%). The high fat diet alone without PCB also effectively reduced EF% (67.7%), and the lowest reduction in EF were for mice fed with high fat and PCB (57.2%). In the high fat-PCB-treated group, there was a gradual reduction in % EF starting at 2 weeks with 65.2% EF and 52.5% at the 8-wk time point. MRI scan of the aortal arch showed plaques in mice fed with high fat diet and PCB treatment. Conclusions: First to demonstrate LVEF per cine MRI in a wild non-surgical or non-genetically modified mouse model. Plaque formation in aortal arch was confirmed by MRI.