Reproducibility of Systolic Strain in Mice Using Cardiac Magnetic Resonance Feature Tracking of Black-Blood Cine Images

Purpose: Mouse models are widely utilized to enhance our understanding of cardiac disease. The goal of this study is to investigate the reproducibility of strain parameters that were measured in mice using cardiac magnetic resonance (CMR) feature-tracking (CMR42, Canada).

Methods: We retrospectively analyzed black-blood CMR datasets from thirteen C57BL/6 B6.SJL-CD45.1 mice (N = 10 female, N = 3 male) that were imaged previously. The circumferential, longitudinal, and radial (E_cc, E_ll, and E_rr, respectively) parameters of strain were measured in the mid-ventricular region of the left ventricle. Intraobserver and interobserver reproducibility were assessed for both the end-systolic (ES) and peak strain.

Results: The ES strain had larger intraclass correlation coefficient (ICC) values when compared to peak strain, for both the intraobserver and interobserver reproducibility studies. Specifically, the intraobserver study showed excellent reproducibility for all three ES strain parameters, namely, E_cc (ICC 0.95, 95% CI 0.83-0.98), E_ll (ICC 0.90, 95% CI 0.59-0.97), and E_rr (ICC 0.92, 95% CI 0.73-0.97). This was also the case for the interobserver study, namely, E_cc (ICC 0.92, 95% CI 0.60-0.98), E_ll (ICC 0.76, 95% CI 0.33-0.93), and E_rr (ICC 0.93, 95% CI 0.68-0.98). Additionally, the coefficient of variation values were all < 10%.

Conclusion: The results of this preliminary study showed excellent reproducibility for all ES strain parameters, with good to excellent reproducibility for the peak strain parameters. Moreover, all ES strain parameters had larger ICC values than the peak strain. In general, these results imply that feature-tracking with CMR42 software and black-blood cine images can be reliably used to assess strain patterns in mice.