Tissue Characterization by Mapping and Strain Cardiac MRI to Evaluate Myocardial Inflammation in Fulminant Myocarditis

Abstract

Background: The clinical value of novel mapping techniques and strain measures to assess myocardial inflammation in fulminant myocarditis (FM) has not been fully explored.

Purpose: To evaluate the ability of mapping and strain cardiac MRI to assess myocardial inflammation in patients with FM, and to which degree the strain metrics correlate with myocardial edema.

Study type: Prospective.

Population: Twenty-nine patients (37 ± 16 years, 48% male) with FM and 29 patients with nonfulminant acute myocarditis (NFAM) (29 ± 14 years, 69% male).

Field strength/sequence: 3.0T; Cine imaging, black blood T₂ -weighted imaging, T₁ mapping, T₂ mapping, and late gadolinium enhancement.

Assessment: Native T₁ , extracellular volume (ECV), and T₂ were measured. Myocardial strain was evaluated by feature tracking.

Statistical tests: Student's t- or Mann-Whitney U-test. Spearman correlation analysis.

Results: The myocardial edema rate (2.6 ± 0.7 vs. 1.6 ± 0.2, P < 0.001) and late gadolinium enhancement (LGE) mass (16.5 [11.7, 41.7] vs. 6.9 [2.2, 15.8] g, P < 0.001) were significantly increased in FM patients when compared to the NFAM group. LGE in the FM group was predominantly located in the septal wall, and 38% of the patients showed a diffuse LGE pattern. Native T₁ , ECV, and T₂ values in the FM group were significantly more elevated than those with NFAM, while global peak radial, circumferential, and longitudinal strain values were significantly reduced (all P < 0.001). Circumferential strain showed the strongest correlations with ECV (r = 0.72, P < 0.001).

Data conclusion: Patients with FM showed significant differences in LGE patterns, increased edema, and decreased strain measurements compared to those with NFAM. Circumferential strain showed significant associations with quantitative cardiac MRI parameters of myocardial inflammation.

Level of evidence: 2 TECHNICAL EFFICACY STAGE: 2 J. Magn. Reson. Imaging 2020;52:930-938.

Keywords: T1 mapping; cardiac magnetic resonance imaging; late gadolinium enhancement; myocarditis; strain.