Early myocardial gadolinium enhancement in patients with myocarditis: Validation of "Lake Louise consensus" criteria using a single bolus of 0.1mmol/Kg of a high relaxivity gadolinium-based contrast agent

Multimodality imaging in acute myocarditis

The diagnosis of acute myocarditis often involves several noninvasive techniques that can provide information regarding volumes, ejection fraction, and tissue characterization. In particular, echocardiography is extremely helpful for the evaluation of biventricular volumes, strain and ejection fraction. Cardiac magnetic resonance, beyond biventricular volumes, strain, and ejection fraction allows to characterize myocardial tissue providing information regarding edema, hyperemia, and fibrosis. Contemporary cardiac computed tomography angiography (CCTA) can not only be extremely important for the assessment of coronary arteries, pulmonary arteries and aorta but also tissue characterization using CCTA can be an additional tool that can explain chest pain with a diagnosis of myocarditis.

Epicardial Adipose Tissue: A Novel Potential Imaging Marker of Comorbidities Caused by Chronic Inflammation

The observation of correlations between obesity and chronic metabolic and cardiovascular diseases has led to the emergence of strong interests in “adipocyte biology”, in particular in relation to a specific visceral adipose tissue that is the epicardial adipose tissue (EAT) and its pro-inflammatory role. In recent years, different imaging techniques frequently used in daily clinical practice have tried to obtain an EAT quantification. We provide a useful update on comorbidities related to chronic inflammation typical of cardiac adiposity, analyzing how the EAT assessment could impact and provide data on the patient prognosis. We assessed for eligibility 50 papers, with a total of 10,458 patients focusing the review on the evaluation of EAT in two main contexts: cardiovascular and metabolic diseases. Given its peculiar properties and rapid responsiveness, EAT could act as a marker to investigate the basal risk factor and follow-up conditions. In the future, EAT could represent a therapeutic target for new medications. The assessment of EAT should become part of clinical practice to help clinicians to identify patients at greater risk of developing cardiovascular and/or metabolic diseases and to provide information on their clinical and therapeutic outcomes.

Early T1 Myocardial MRI Mapping: Value in Detecting Myocardial Hyperemia in Acute Myocarditis

Background Hyperemia is a key component of acute myocarditis (AM). Early gadolinium uptake because of myocardial hyperemia may be quantified by using T1 mapping. Purpose To evaluate the value of early enhanced T1 shortening for the diagnosis of acute myocarditis. Materials and Methods Study participants suspected of having AM and healthy control (HC) participants were prospectively enrolled from September 2016 to May 2019. Participants underwent 1.5-T cardiac MRI including Lake Louise criteria, T2 mapping, native T1, and extracellular volume, with the addition of early enhanced T1 mapping (2 minutes after intravenous administration of 0.15 mmol/kg gadobutrol). Color-coded maps of the percentage of T1 shortening from precontrast to early postcontrast were generated. Optimal early T1 shortening cut-off value and its diagnostic performance in the identification of acute myocarditis were calculated. Results Forty-five study participants with AM (median age, 40 years; interquartile range [IQR], 20-46 years; 22 women) diagnosed according to multidisciplinary clinical evaluation, electrocardiography, laboratory test, echocardiography, cardiac MRI, and coronary CT and/or invasive angiography. Findings were confirmed by endomyocardial biopsy in 64% (29 of 45) of participants. MRI parameters were compared with 19 HC participants (median age, 39 years; IQR, 28-46 years; seven women). Median early T1 shortening was 75% (IQR, 72%-78%) in participants with AM versus 65% (IQR, 61%-66%) in HC participants (P < .001). Early T1 shortening showed high diagnostic performance (area under the receiver operating characteristic curve [AUC], 0.97; 95% confidence interval [CI]: 0.94, 1.00) and excellent interobserver reproducibility (intraclass correlation coefficient: 0.98; 95% CI: 0.96, 1.00). Early T1 shortening of 70% or greater identified acute myocarditis with 93% sensitivity, 100% specificity, and 95% diagnostic accuracy. Early T1 shortening had better diagnostic performance than late percentage T1 shortening (AUC, 0.97 vs 0.90, respectively; P = .03) and extracellular volume (AUC, 0.97 vs 0.88, respectively; P = .046), and similar to native T1 (AUC, 0.97 vs 0.93, respectively; P = .63) and T2 mapping (AUC, 0.97 vs 0.97, respectively; P > .99). Conclusion In this proof-of-concept study, percentage of T1 shortening at early enhanced T1 mapping showed high accuracy for the diagnosis of acute myocarditis. © RSNA, 2020 Online supplemental material is available for this article. See also the editorial by De Cecco and Monti in this issue.

Diagnostic Performance of Extracellular Volume, Native T1, and T2 Mapping Versus Lake Louise Criteria by Cardiac Magnetic Resonance for Detection of Acute Myocarditis: A Meta-Analysis

BACKGROUND

The Lake Louise Criteria (LLC) were established in 2009 and are the recommended cardiac magnetic resonance imaging criterion for diagnosing patients with suspected myocarditis. Subsequently, newer parametric imaging techniques which can quantify T1, T2, and the extracellular volume (ECV) have been developed and may provide additional utility in the diagnosis of myocarditis. However, whether their diagnostic accuracy is superior to LLC remains unclear. In this meta-analysis, we compared the diagnostic performance of native T1, T2, ECV to LLC in diagnosing acute myocarditis.

METHODS AND RESULTS

We searched PubMed for published studies of LLC, native T1, ECV, and T2 diagnostic criteria used to diagnose acute myocarditis. Seventeen studies were included, with a total of 867 myocarditis patients and 441 control subjects. Pooled sensitivity, specificity, and diagnostic odds ratio of all diagnostic tests were assessed by bivariate analysis. LLC had a pooled sensitivity of 74%, specificity of 86%, and diagnostic odds ratio of 17.7. Native T1 had a significantly higher sensitivity than LLC (85% versus 74%, P=0.025). Otherwise, there was no significant difference in sensitivity, specificity, and diagnostic odds ratio when comparing LLC to native T1, T2, or ECV.

CONCLUSIONS

Native T1, T2, and ECV mapping provide comparable diagnostic performance to LLC. Although only native T1 had significantly better sensitivity than LLC, each technique offers distinct advantages for evaluating and characterizing myocarditis when compared with the LLC.