Comprehensive cardiac magnetic resonance T1, T2, and extracellular volume mapping to define Duchenne cardiomyopathy

Figures

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  Fig. 1. Myocardial changes defined by parametric mapping sequences. This figure demonstrates how T1, T2, and ECV can be utilized to define myocardial tissue composition. Quantification of T1, T2, and extracellular volume fraction (ECV) allow for characterization into normal, isolated high T1, fibrosis, fat, fibrofatty, and edema categories. Native T1 is on the X-axis, T2 is on the Y-axis, and ECV value is represented by the size of the circle. The cut-off for high and low native T1 is represented by the solid and dotted vertical lines (900 ms and 1050 ms, respectively). The dashed horizontal line indicates threshold for high versus normal T2 (49 ms). The cut-off for normal ECV is 28.5%. The overlap between the fibrosis and high T1 group in the figure represents the similar T1 and T2 times for these two categories, which are differentiated by ECV value. Similar methodology was applied for fat versus fibrofatty

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  Fig. 2. Myocardial characterization. Categorization performed with prespecified tissue characterization parameters. Initial dichotomization based on presence of high or normal T2 time with normal defined as ≤ 49 ms. Patients were then filtered by native T1 time (normal 900–1050 ms) and extracellular volume fraction (ECV; normal ≤ 28.5%). Color coding represents myocardial composition defined with light blue as normal, red as fibrosis, dark blue as isolated high T1, orange as fibrofatty, yellow as fat, and green as edema

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  Fig. 3. Scatterplot of tissue characterization parameters. Native T1, T2, and extracellular volume fraction (ECV) measurements for each patient. Native T1 is on the X-axis, T2 is on the Y-axis, and ECV value is represented by the size of the circle. The cut-off for high and low native T1 is represented by the solid and dotted vertical lines (900 ms and 1050 ms, respectively). The dashed horizontal line indicates threshold for high versus normal T2 (49 ms). Each patient categorization is represented by color as demonstrated in the legend and as explained in Fig. 1

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  Fig. 4. Scatterplot of age and LVEF by category. A Those with elevated T2 values (edema, fat, fibrofatty) were older (p = 0.005) than those with normal T2 values (isolated elevated T1, fibrosis) as determined by Wilcoxon rank-sum test. B Those with fibrofatty classification had significantly lower LVEF than all other groups. ANOVA was used to test for significance with Tukey post-hoc testing completed to detect intergroup difference

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  Fig. 5. Progression of slice edema on serial CMR. A Subjects with edema on CMR-1 for any slice (base, mid, or apex, represented as elevated T2 and normal or high T1 for the entire slice) are demonstrated with their categorization designation on terminal CMR available for review. B Includes subjects with slice edema detected on CMR-2 and without edema on CMR-1, as well as their cardiovascular progression as illustrated by their categorization on CMR-3. There is no overlap in slices included between (A) and (B). Those without follow-up CMR are designated as “no subsequent data”

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  Fig. 6. Progression of edema for base T2 ROI. Eight individuals had edema detected on CMR-1 in the base T2 ROI. Progression of these eight patients on CMR-2 and 3 is demonstrated. Those without follow-up CMR are designated as “no subsequent data”

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  Fig. 7. Progression of Edema for Mid T2 ROI. Eleven individuals had edema detected on CMR-1 in the mid T2 ROI. Progression of these 11 patients on CMR-2 and 3 is demonstrated. Those without follow-up CMR are designated as “no subsequent data”

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  Fig. 8. Postulated myocardial infiltrative changes. Edema and fibrosis were the most common myocardial changes detected in this study. We postulate that there is a cyclical interchange between edema and fibrosis with fat and fibrofatty replacement as the terminal myocardial composition