Early detection of myocardial involvement by T1 mapping of cardiac MRI in idiopathic inflammatory myopathy.

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.