Native T1-mapping for non-contrast assessment of myocardial fibrosis in patients with hypertrophic cardiomyopathy--comparison with late enhancement quantification.
Małek ŁA., Werys K., Kłopotowski M., Śpiewak M., Miłosz-Wieczorek B., Mazurkiewicz Ł., Petryka-Mazurkiewicz J., Marczak M., Witkowski A.
BACKGROUND: Myocardial fibrosis was shown to influence prognosis in hypertrophic cardiomyopathy (HCM). It is typically assessed by late gadolinium enhancement (LGE) on cardiac magnetic resonance. Native T1-mapping has been proposed, as a contrast-free method of fibrosis assessment. The aim of the study was to define a cut-off value for native T1 relaxation time that best reflects LGE quantification of myocardial fibrosis. METHODS: In 25 patients with HCM and 20 controls we performed T1-mapping pre-contrast using ShMOLLI technique. This was followed by LGE assessment in the studied group 10 minutes after gadolinium contrast injection. Relative myocardial fibrosis size was calculated for varying T1 time thresholds (940-1100 ms) and compared with 6 standard deviations (6SD) method for LGE. RESULTS: Median fibrosis size calculated with T1-mapping was insignificantly different from LGE only for native T1 time threshold of 1060 ms (p = 0.62). Using this threshold, Bland-Altman plots demonstrated very good agreement between fibrosis sizes from the two methods (slightly better only for 1080 ms threshold). For threshold of 1060 ms we also observed good correlation (rho = 0.73) with LGE 6SD method (insignificantly better for lower thresholds, best for threshold of 980 ms-rho = 0.88). In control group with no diagnosis of HCM, fibrosis size <1% was reached for thresholds of 1040 ms and higher. CONCLUSION: Native T1-mapping can be used for non-contrast assessment of myocardial fibrosis in HCM. The 1060 ms threshold of the native T1 relaxation time is characterized by the best balance between agreement and correlation with fibrosis assessed by LGE 6SD method.