Baseline and Follow-Up Cardiac Magnetic Resonance Imaging Findings in Children with Acute Myocarditis and Factors Associated with Late Gadolinium Enhancement

Abstract

Objectives: Cardiac magnetic resonance (CMR) plays a central role in the diagnosis and follow-up of acute myocarditis (AM). In this study, we aimed to evaluate baseline and follow-up CMR findings and associated factors in children with AM. Methods: A retrospective analysis of CMR in pediatric patients with clinical presentations suggestive of myocarditis was performed. Patients' demographic characteristics, clinical data, and diagnostic test results, as well as CMR imaging results, were evaluated. Results: All 28 pediatric patients with acute myocarditis included in this study had late gadolinium enhancement (LGE) on initial CMR imaging. Additionally, 14 (50%) patients had increased extracellular volume (ECV), 4 (50%) patients had focal high-intensity areas on T2 STIR images, 15 (53.6%) patients had increased T1 relaxation time, and 17 (60.7%) patients had increased T2 relaxation time. At a median follow-up CMR of 6 months, 24 (85.7%) patients had LGE, 5 (17.9%) patients had increased ECV, and 7 (25%) patients had increased T1 relaxation time, while other parameters showed complete recovery. Baseline troponin and CRP levels, T1 relaxation time, T2 relaxation time, and increased ECV were found to be factors associated with the resolution of LGE. Conclusions: Baseline troponin and CRP levels, as well as T1 relaxation time, T2 relaxation time, and increased ECV, were effective parameters that seemed to predict the resolution of LGE. Larger and multicenter experiences would confirm these hypotheses.

Keywords: Lake Louise criteria; T1 mapping; T2 mapping; cardiac magnetic resonance imaging; children; heart; myocarditis.

Figure 1

Distribution of LGE in AHA myocardial segments: This figure illustrates that patients with LGE involvement in specific myocardial segments during baseline and follow-up cardiac MR examinations. Color descriptions: Gray: LGE involvement positive, White: LGE involvement negative, Green: Segments that show LGE involvement in the first CMR but no involvement in the second CMR. (Baseline MRI LGE involvement by segment: Segment no 3: 7.1% (n = 2), Segment no 4: 39% (n = 11), Segment no 5: 78.6% (n = 22), Segment no 6: 14.3% (n = 4), Segment no 9: 21.4% (n = 6), Segment no 10: 39.3% (n = 11), Segment no 11: 78.6% (n = 22), Segment no 12: 28.6% (n = 8), Segment no 14: 7.1% (n = 2), Segment no 15: 14.3% (n = 4), Segment no 16: 35.7% (n = 10), Follow-up MRI LGE involvement by segment: Segment no 3: 7.1% (n = 2), Segment no 4: 21.4% (n = 6), Segment no 5: 67.9% (n = 19), Segment no 6: 10.7% (n = 3), Segment no 9: 14.3% (n = 4), Segment no 10: 14.3% (n = 4), Segment no 11: 46.4% (n = 13), Segment no 12: 14.3% (n = 4), Segment no 15: 3.6% (n = 1), Segment no 16: 3.6% (n = 1)). Abbreviations: AHA: American Heart Association, MRI: Magnetic resonance imaging.

Figure 2

A 17-year-old male patient presented with acute chest pain. CMR was performed within the first week following symptom onset (CMR-I) and after 6 months (CMR-II). In the CMR-I images; T2-w STIR image (A) shows a hyperintense subepicardial rim (arrows) representing myocardial edema in the basal inferolateral and inferior segments of the left ventricle. LGE image (B) shows an increase in gadolinium uptake (arrows) in the same segments representing myocardial necrosis and acute extracellular edema. T2 map (C) and T1 map (D) images confirm the findings of acute myocardial inflammation: T2 mapping value is higher than 55 ms; native T1 value is higher than 1050 ms. In the CMR-II images; no edema is seen on T2-w STIR image (E) and T2 map image (G). T2 mapping value is lower than 55 ms. LGE image (F) shows increase of gadolinium uptake (arrows) representing fibrosis. T1 map (H) image confirms the findings of fibrosis; nativ T1 value is higher than 1050 ms. Abbreviations: LGE: late gadolinium enhancement.