Metabolic reprogramming in radiation-induced heart disease: the emerging role of PET imaging.

Radiation therapy is widely used to treat various cancers, but it can lead to radiation-induced heart disease, which is the main cause of long-term morbidity and mortality in cancer survivors. Traditional imaging methods, such as echocardiography and cardiac magnetic resonance, often find structural or functional changes in the late stage of the injury, missing early subclinical injury. This narrative review summarizes the evidence from positron emission tomography studies and shows that molecular imaging can identify early metabolic reprogramming in the radiation-induced heart disease, including the shift from fatty acid oxidation to increased glucose utilization, as well as microvascular dysfunction and fibroblast activation. Tracers like fluorodeoxyglucose and fibroblast activation protein inhibitors may be able to detect metabolic inflammation and active fibroblast remodeling before obvious structural changes. In radiation-induced heart disease, myocardial fluorodeoxyglucose uptake needs to be interpreted according to different stages. There are, however, still challenges remain, including physiological myocardial fluorodeoxyglucose uptake, lack of standardized imaging protocols, limited prospective data and the need to reduce cumulative radiation exposure. Future research should focus on large multicenter longitudinal studies, hybrid positron emission tomography and magnetic resonance imaging, risk stratification based on artificial intelligence to integrate molecular imaging into conventional cardiac tumor monitoring and achieve timely cardiac protection interventions.