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Myocarditis is defined as a non-ischemic inflammatory disease of the myocardium. It remains a challenge to diagnose given non-specific symptoms and lack of specific blood biomarkers. Cardiac imaging plays an important role in the evaluation of myocarditis with unique strengths and limitations of different imaging modalities, including cardiac magnetic resonance imaging, echocardiography, cardiac computed tomography, and positron emission tomography. The purpose of this review is to discuss the strengths and limitations of various cardiac imaging techniques in the evaluation of myocarditis, review imaging findings in specific causes of myocarditis including COVID-19 and after vaccination, evaluate the role of imaging in differentiating myocarditis from potential mimics and differential considerations, identify current gaps in knowledge, and propose future directions.

Historically thoracic MRI has been limited by the lower proton density of lung parenchyma, cardiac and respiratory motion artifacts and long acquisition times. Recent technological advancements in MR hardware systems and improvement in MR pulse sequences have helped overcome these limitations and expand clinical opportunities for non-vascular thoracic MRI. Non-vascular thoracic MRI has been established as a problem-solving imaging modality for characterization of thymic, mediastinal, pleural chest wall and superior sulcus tumors and for detection of endometriosis. It is increasingly recognized as a powerful imaging tool for detection and characterization of lung nodules and for assessment of lung cancer staging. The lack of ionizing radiation makes thoracic MRI an invaluable imaging modality for young patients, pregnancy and for frequent serial follow-up imaging. Lack of familiarity and exposure to non-vascular thoracic MRI and lack of consistency in existing MRI protocols have called for clinical practice guidance. The purpose of this guide, which was developed by the Canadian Society of Thoracic Radiology and endorsed by the Canadian Association of Radiologists, is to familiarize radiologists, other interested clinicians and MR technologists with common and less common clinical indications for non-vascular thoracic MRI, discuss the fundamental imaging findings and focus on basic and more advanced MRI sequences tailored to specific clinical questions.

Myocarditis is an established but rare adverse event following administration of messenger RNA-based coronavirus disease 2019 (COVID-19) vaccines and is most common in male adolescents and young adults. Symptoms typically develop within a few days of vaccine administration. Most patients have mild abnormalities on cardiac imaging with rapid clinical improvement with standard treatment. However, longer term follow-up is needed to determine whether imaging abnormalities persist, to evaluate for adverse outcomes, and to understand the risk associated with subsequent vaccination. The purpose of the review is to evaluate the current literature related to myocarditis following COVID-19 vaccination, including the incidence, risk factors, clinical course, imaging findings, and proposed pathophysiologic mechanisms.

Heritable Thoracic Aortic Disease (HTAD) is caused by mutation of a gene that confers a high risk for thoracic aortic aneurysms and dissections. Syndromic HTAD are associated with systemic manifestations and include Marfan, Loeys-Dietz, vascular Ehlers Danlos and Turner Syndromes. The purpose of this review is to summarize the pathophysiology, cardiovascular imaging features and management of HTAD. Imaging plays an important role in screening for aortic dilatation and monitoring progression. Echocardiogram, Computed tomography and Magnetic resonance imaging are the commonly used modalities. Based on consensus guidelines, prophylactic aortic replacement is indicated when a certain threshold diameter is reached.

Myocarditis is a nonischemic inflammatory disease of the myocardium that can be triggered by a multitude of events, including viral infection and toxins. Recently, there has been heightened interest in myocarditis given its association with COVID-19 vaccination. Timely identification of myocarditis can affect patient management and prognosis. Therefore, it is crucial for radiologists and cardiac imagers to understand the role of cardiac imaging to establish a diagnosis and inform treatment decisions. Cardiac MRI is the most important noninvasive imaging modality for evaluation of myocarditis, with typical findings of focal or diffuse myocardial edema and myocardial damage, including presence of late gadolinium enhancement. There are currently limited data available to indicate that the pattern of myocardial injury following COVID-19 vaccination is similar to other causes of myocarditis, although the severity of disease may be relatively mild. A description of the role of imaging and typical imaging features will be reviewed here, with a focus on emerging data in the setting of myocarditis after COVID-19 vaccination. Keywords: MRI, Heart, Inflammation © RSNA, 2021