While vaccines to prevent SARS-CoV-2 infection
have demonstrated effectiveness in reducing morbidity and mortality related to respiratory complications
(1,2), infrequent but important side effects associated
with vaccination have also been reported. One such rare
side effect that the mRNA vaccines have been linked to
is myocarditis (3–7).
Cardiac MRI (4,7,8) and fluorine 18 (18F) fluorodeoxyglucose (FDG) PET/CT imaging (9–11) have been routinely used in the noninvasive diagnosis of myocardial inflammation of diverse origin, including viral myocarditis,
cardiac sarcoidosis, and cancer therapy–related cardiac dysfunction. Good agreement has been reported between late
gadolinium enhancement or T2 hyperintensity on cardiac
MRI scans and 18F-FDG uptake on PET scans in patients
suspected of having myocarditis (12).
A recent cardiac MRI study used late gadolinium enhancement and T2 intensity and reported myocardial injury from the SARS-CoV-2 vaccine was similar to that from
myocarditis due to COVID-19, while severity was less (13).
Similarly, an 18F-FDG PET/MRI study showed myocardial
inflammation after COVID-19 illness (14), but it is not
known whether 18F-FDG uptake would occur in asymptomatic individuals after SARS-CoV-2 vaccination.