Diffuse cardiac fibrosis quantification in early systemic sclerosis by magnetic resonance imaging and correlation with skin fibrosis.

PURPOSE: To evaluate the utility of cardiac magnetic resonance (CMR) T1 mapping in early systemic sclerosis (SSc) and its association with skin score. METHODS: Twenty-four consecutive patients with early SSc referred for cardiovascular evaluation and 12 controls without SSc were evaluated. All patients underwent cine, T1 mapping, and late gadolinium enhanced (LGE) CMR imaging. T1 mapping indices were compared between SSc patients and controls (extracellular volume fraction [ECV], gadolinium partition coefficient [λ], pre-contrast T1, and post-contrast T1). The association between T1 mapping parameters and the modified Rodnan skin score (mRSS) was determined. RESULTS: There were no significant differences in cardiac structure/function between SSc patients and controls on cine imaging, and 8/24 (33%) SSc patients had evidence of LGE (i.e., focal myocardial fibrosis). Of the T1 mapping parameters (indices indicative of diffuse myocardial fibrosis), ECV differentiated SSc patients from controls the best, followed by λ, even when the eight SSc patients with LGE were excluded. ECV had a sensitivity and specificity of 75% and 75% for diffuse myocardial fibrosis (optimal abnormal cut-off value of >27% [area under ROC curve=0.85]). In the 16 patients without evidence of LGE, each of the 4 CMR T1 mapping parameters (ECV, λ, Pre-T1 and Post-T1) correlated with mRSS (R=0.51-0.65, P=0.007-0.043), indicating a correlation between SSc cardiac and skin fibrosis. CONCLUSIONS: The four T1 mapping indices are significantly correlated with mRSS in patients with early SSc. Quantification of diffuse myocardial fibrosis using ECV should be considered as a marker for cardiac involvement in SSc clinical studies.