Comparison of Velocity Vector Imaging Echocardiography With MRI in Mouse Models of Cardiomyopathy

Although 2-dimensional echocardiographic strain imaging cost-effectively and objectively quantifies ventricular wall motion, only 1 small study has directly compared strain measured with echocardiography against MRI (MRI) in mice. Using a different speckle-tracking algorithm (velocity vector imaging [VVI]), we compared circumferential (CS) and radial strain (RS) to displacement encoding with stimulated-echo MRI in 2 genetic mouse models of cardiomyopathy. CS and RS were measured in groups of wild-type mice and mice with gene targeted deficiency of cardiac myosin-binding protein-C or muscle LIM protein. There was modest correlation between VVI and MRI measured strains, with global CS yielding a stronger correlation compared with global RS (CS R=0.4452 versus RS R=0.2794, both P<0.05). Overall, strain measured by VVI was more variable than MRI and the limits of agreement were slightly, but not significantly, closer for global CS than RS. Both VVI and MRI strain measurements showed significantly lower global CS strain in the knockout groups compared with the wild-type, but only the VVI CS strain measurements were different between the 2 knockout groups. These data demonstrate that measurements of LV CS and RS are feasible in mice using VVI, although correlations and agreement were modest. VVI may complement conventional methods that objectively assess global and regional LV function and be particularly useful for high through-put phenotyping of murine models.