Quantification of Biventricular Myocardial Strain Using CMR Feature Tracking: Reproducibility in Small Animals

Figures

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  Figure 1. High-resolution cine CMR images with biventricular segmentation and CMR-FT myocardial strain curves in mouse. End-diastolic frame of semi-4CH (a) and the following image after application of feature tracking algorithm (b). The LV (c) and RV (d) strain curves and peak strain obtained from semi-4CH cine images. End-diastolic (e) and end-systolic (i) frame of mid-SAX images and the following tracking pattern of end-diastolic image (f) and end-systolic image (j). The global strain curves for LV (g) and RV (k) and the segmental strain curves for LV (h) and RV (l) derived from mid-SAX cine images. LV: left ventricle; RV: right ventricle; CMR-FT: cardiovascular magnetic resonance feature tracking; 4CH: 4 chamber; SAX: short axis.

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  Figure 2. Comparison of biventricular myocardial strain of CMR-FT between nexilin knockout heterozygous (Het) and wild-type (WT) mice. LLSLAX: left ventricular long-axis longitudinal strain; LCSSAX: left ventricular short-axis circumferential strain; LRSSAX: left ventricular short-axis radial strain; RLSLAX: right ventricular long-axis longitudinal strain; RCSSAX: right ventricular short-axis circumferential strain. ∗p < 0.05 and ∗∗p < 0.01.

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  Figure 3. Bland-Altman plots with limits of agreement (1.96 standard deviations) demonstrate the intraobserver, interobserver, and interstudy reproducibilities (S1 and S2) of CMR-FT for LV and RV strain assessments. The relative variability is defined as the difference between observations divided by their mean. LLSLAX: left ventricular long-axis longitudinal strain; LCSSAX: left ventricular short-axis circumferential strain; LRSSAX: left ventricular short-axis radial strain; RLSLAX: right ventricular long-axis longitudinal strain; RCSSAX: right ventricular short-axis circumferential strain.

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  Figure 4. Bland-Altman plots with limits of agreement (1.96 standard deviations) demonstrate the intraobserver, interobserver, and interstudy reproducibilities (S1 and S2) of CMR-FT for segmental LV and RV strain assessments. The relative variability is defined as the difference between observations. LLSLAX: left ventricular long-axis longitudinal strain; LCSSAX: left ventricular short-axis circumferential strain; LRSSAX: left ventricular short-axis radial strain; RLSLAX: right ventricular long-axis longitudinal strain; RCSSAX: right ventricular short-axis circumferential strain.

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  Figure 5. Scatterplots showing the intraobserver, interobserver, and interstudy correlations between two readings (S1 and S2) for global biventricular myocardial strain of CMR-FT. Our linear regression analysis shows an excellent correlation for all LV myocardial strain values, except LRSSAX in interstudy measurement. The reproducibility of RV is variable; RCSSAX is the least reproducible myocardial strain value. The regression line is given with a 95% confidence interval. R-squares and p values are reported in the left upper corner of each graph. LLSLAX: left ventricular long-axis longitudinal strain; LCSSAX: left ventricular short-axis circumferential strain; LRSSAX: left ventricular short-axis radial strain; RLSLAX: right ventricular long-axis longitudinal strain; RCSSAX: right ventricular short-axis circumferential strain.

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  Figure 6. Influence of temporal resolution on feature tracking accuracy of biventricular strain measurement. Individual cases are shown with temporal resolution range from 10 frames to 80 frames per cardiac cycle. LLSLAX: left ventricular long-axis longitudinal strain; LCSSAX: left ventricular short-axis circumferential strain; LRSSAX: left ventricular short-axis radial strain; RLSLAX: right ventricular long-axis longitudinal strain; RCSSAX: right ventricular short-axis circumferential strain.