Gender and Strain Variations in Left Ventricular Cardiac Function and Mass Determined With Magnetic Resonance Imaging at 7 Tesla in Adult Mice

Objectives: We sought to assess with magnetic resonance imaging (MRI) the influence of strain type and gender on left ventricular (LV) global function and mass in 3 inbred mouse strains with a normal cardiac phenotype. Materials and Methods: A total of 30 mice from 3 inbred strains (C57BL/6, 29S2/SvPasCrl, and C3HFeJ) were studied on a 7.05-T MR scanner using ECG-triggered cine sequences. LV mass and volumes were calculated with inclusion and exclusion of papillary muscles (PMs) in the LV wall. Results: Significant differences were found with strain and gender (P < 0.001), with strain–effect but no gender–effect for ejection fraction (EF), end-diastolic volume (EDV), and end-systolic volume (ESV). There were no differences in LV mass between strains but lower values in female mice except in the C3H strain. The exclusion of PMs led to the relative underestimation of EF (−6.1%) and of LV mass (−6.4 mg) and the relative overestimation of EDV (6.3 &mgr;L) and ESV (5.3 &mgr;L). Inter- and intraobserver reproducibility was better when PMs were included. Conclusion: The use of MRI demonstrates cardiac interstrain and gender-related phenotypic diversities that are essential factors to consider when building genomic databases and designing studies.