Abstract 10668: Measurement of Extracellular Volume Fraction by Cardiac Magnetic Resonance Imaging Detects Diffuse Myocardial Fibrosis in Systemic Sclerosis
Introduction: Primary cardiac involvement is common in systemic sclerosis (SSc) and responsible for 25% of deaths. Myocardial extravascular extracellular volume fraction (Ve), derived from cardiac magnetic resonance (CMR) T1 mapping of the myocardium, has been shown to quantify diffuse myocardial fibrosis but its utility in SSc has not been studied.
Hypothesis: We hypothesized that subjects with SSc have a higher Ve compared to controls and that patients with worse SSc severity have higher Ve.
Methods: CMR was performed in 9 SSc patients (3 diffuse and 6 limited cutaneous) and 6 age-matched controls. Cine, pre- and post-contrast T1 mapping, and late gadolinium enhanced (LGE) imaging was performed. LV mass index (LVMi), LV end-diastolic volume index (LVEDVi), ejection fraction (EF), and LGE as a percent of the LV (LGE%) were quantified (Medis QMass MR 7.2). Ve was calculated as Ve = [ΔR1myocardium/ ΔR1bloodpool • p • (1 - hematocrit)] - Vp, where R1 = 1/ T1, ΔR1 is post-contrast - precontrast R1, p is myocardial specific density (1.05), and Vp is myocardial plasma volume fraction (0.045). Skin involvement was quantified in all SSc patients using the Modified Rodnan Skin Score (mRSS).
Results: Ve differed significantly between SSc and control groups (25.9 ± 4.4 vs 19.8 ± 2.5 %, p = 0.01). In contrast, there was no significant difference between SSc and controls with regards to EF (62.9± 8.7 vs 55.1 ± 3.4%, p = 0.06), LVMi (37.9 ± 9.4 vs 40.3 ± 7.0 g/m2, p = 0.6), or LVEDVi (69.7 ± 18.3 vs 76.2 ± 15.3 ml/m2, p = 0.5). Minute focal LGE was seen in 2 SSc and no controls (LGE% 0.1 ± 0.3 vs 0.0 ± 0.0, p = 0.4). Ve correlated significantly with 1/mRSS in SSc patients (figure).
Conclusions: This is the first study to demonstrate the utility of CMR T1 mapping for identification of diffuse myocardial fibrosis in SSc. Given the high mortality associated with clinically symptomatic myocardial involvement in SSc, this technique may be valuable for detection even when conventional CMR appears normal.
- © 2011 by American Heart Association, Inc.