Early detection of myocardial involvement by T1 mapping of cardiac MRI in idiopathic inflammatory myopathy. Issue 2 (12th January 2018) - Yu, Liuyu
Abstract : Background: Polymyositis (PM) and dermatomyositis (DM) are common types of idiopathic inflammatory myopathy (IIM), wherein patients are prone to adverse cardiovascular events. Purpose: To explore the value of cardiac magnetic resonance imaging (MRI) for detecting cardiac involvement in PM/DM patients using a T1 mapping technique. Study Type: Prospective observational study. Population: In all, 25 PM/DM patients free of cardiovascular symptoms and preserved ventricular systolic function and 25 healthy volunteers matched for age and sex served as controls. Field Strength/Sequence: Cardiac MRI at 3T, including steady‐state free precession (SSFP) cine imaging, late gadolinium enhancement (LGE), and T1 mapping with modified Look–Locker inversion recovery (MOLLI). Assessment: Myocardial native T1 and extracellular volume (ECV) of the left ventricle as well as the correlations with disease activity were analyzed. Statistical Tests: Independent sample's t ‐test, Fisher's exact test, or chi‐square test, Pearson's correlation ( r ) were applied. P ≤ 0.05 was considered significant. Results: Left ventricular end‐diastolic/end‐systolic volume index ( P = 0.643, P = 0.325, respectively), mass index ( P = 0.719), and ejection fraction ( P = 0.144) were not significantly different between PM/DM patients and controls. LGE was found in 19% of PM/DM patients and none of the control subjects. PM/DM patients showed significantly higher native T1 values (1263.7 ± 84.0 msec vs. 1200.6 ± 43.0 msec, P = 0.002) and expanded extracellular volume (ECV) (32.6 ± 3.7% vs. 26.7 ± 2.3%, P < 0.001) compared with control subjects. ECV values in PM/DM patients had a high proportion (60%) over the 95% percentile of normal controls. Meanwhile, there was a significant correlation between native T1 ( r = 0.710, P = 0.0001) or ECV ( r = 0.508, P = 0.01) and N‐terminal prohormone of brain natriuretic peptide (NT‐proBNP). Data Conclusion: T1 mapping of cardiac MRI is valuable to detect subclinical myocardial involvement in PM/DM patients, and both myocardial native T1 and ECV could serve as early imaging markers for myocardial impairment in PM/DM. Level of Evidence : 2 Technical Efficacy : Stage 3 J. MAGN. RESON. IMAGING 2018;48:415–422.