Native T1 Mapping and Clinical Risk Characterization in Non-Ischemic Dilated Cardiomyopathy: A Cardiac Magnetic Resonance Study

Figures

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  Figure 5. Kaplan–Meier analysis according to the septal native T1 threshold. Kaplan–Meier event-free survival according to septal native T1. Patients were stratified using the exploratory threshold of 1042 ms derived from ROC analysis. Although a numerical separation of the survival curves was observed, these findings should be considered exploratory and hypothesis-generating because of the limited sample size and number of events. Shaded areas represent 95% confidence intervals.

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  Figure 6. Receiver operating characteristic (ROC) curve evaluating the exploratory discriminatory performance of septal native T1 for the composite endpoint. The blue curve represents the ROC analysis, and the blue marker identifies the exploratory threshold of 1042 ms derived from the Youden index. The dashed diagonal line represents the line of no discrimination (AUC = 0.50). Given the limited sample size and number of events, ROC findings should be interpreted as hypothesis-generating.

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  Figure 1. Representative multiparametric CMR findings illustrating focal scar-like enhancement in a patient evaluated for dilated cardiomyopathy. (A) Cine bSSFP four-chamber view showing left ventricular dilatation with reduced systolic function. (B) Cine bSSFP two-chamber view confirming global LV enlargement and impaired contractility. (C) Short-axis PSIR images demonstrating subendocardial enhancement involving the basal-to-mid inferior wall, with approximately 50% transmural extent. Given the ischemic-like appearance, significant coronary artery disease was excluded before classification within the non-ischemic DCM cohort. (D) Native T1 mapping (pre-contrast) with region-of-interest (ROI) analysis showing mildly elevated global myocardial T1 values (approximately 1042 ms), with lower septal values (~1010 ms), suggesting relatively limited diffuse myocardial involvement compared to focal fibrosis. This pattern highlights the predominance of focal replacement fibrosis. Dashed line indicates the local upper reference limit for native T1 (1017 ms; institutional reference value: 970 ± 47 ms).

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  Figure 2. Representative CMR findings in a patient with non-ischemic dilated cardiomyopathy and predominant diffuse myocardial involvement. (A) Cine bSSFP four-chamber view showing left ventricular dilatation with mildly to moderately reduced systolic function. (B) Cine bSSFP short-axis view illustrating global ventricular remodeling. (C) Phase-sensitive inversion recovery (PSIR) two-chamber view demonstrating intramyocardial late gadolinium enhancement located in the anterior interventricular septum, consistent with non-ischemic fibrosis. (D) Native T1 mapping (pre-contrast) with ROI analysis showing borderline-high myocardial T1 values (global native T1 approximately 1005 ms; septal native T1 approximately 1010 ms) relative to the local reference range (970 ± 47 ms). This pattern illustrates the potential complementary value of quantitative mapping in characterizing diffuse myocardial abnormalities beyond focal LGE.

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  Figure 3. Septal native T1 values according to LGE status. Box-and-whisker plots showing the distribution of septal native T1 values in patients with and without LGE. Individual patient values are displayed as circles (blue: LGE absent; orange: LGE present). Green triangles indicate mean values for each group. The dashed horizontal line represents the institutional upper reference limit for septal native T1 (1017 ms).

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  Figure 4. Septal native T1 values according to clinical outcome. Distribution of septal native T1 values stratified according to the occurrence of the composite endpoint during follow-up. Patients experiencing adverse clinical events tended to demonstrate higher septal native T1 values. Given the limited sample size, this analysis should be interpreted as exploratory. Blue circles represent patients without the composite endpoint, whereas orange circles represent patients who reached the composite endpoint. Green triangles indicate group mean values. The dashed horizontal line represents the institutional upper reference limit for septal native T1 (1017 ms), and the dotted horizontal line represents the exploratory ROC-derived threshold (1042 ms).

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  Figure 7. Relationship between septal native T1 and left ventricular ejection fraction (LVEF). Scatter plot illustrating the distribution of septal native T1 values according to LVEF. The horizontal dashed line indicates the institutional upper reference limit for septal native T1 (1017 ms). Patients who experienced the composite endpoint are identified separately. This figure is presented for descriptive purposes and should be interpreted in the context of the limited sample size and number of events.

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  Figure 8. Exploratory univariable Cox regression analysis. Forest plot summarizing hazard ratios (HRs) and 95% confidence intervals for selected clinical and cardiac magnetic resonance variables associated with the composite endpoint. Functional parameters, particularly LVEF and LVEDVi, showed the strongest associations with adverse outcomes. Septal native T1 demonstrated a directionally consistent association with risk but did not reach statistical significance. The dashed vertical line indicates the null value (HR = 1.0). Given the limited number of events, all estimates should be interpreted as exploratory and hypothesis-generating.