Quantification of metabolic activity in the evaluation of cardiac sarcoidosis

Sarcoidosis is a systemic disorder characterized by non-necrotizing granulomatous inflammation and fibrosis affecting multiple organs, notably the lungs and lymph nodes. Cardiac sarcoidosis (CS), a subset of the disease predominantly involving the heart, significantly heightens the associated morbidity and mortality of sarcoidosis. Early detection of CS is crucial for optimal management. Positron emission tomography/computed tomography (PET/CT) using 18F-fluorodeoxyglucose (18F-FDG) has emerged as an important diagnostic, prognostic, and monitoring tool for CS. Guidelines emphasize a combined approach of visual interpretation and adjunctive quantitative metrics to enhance diagnostic accuracy and treatment monitoring. Various quantitative parameters including maximum standardized uptake value (SUVmax), coefficient of variation, and texture analysis show promise as auxiliary tools diagnosing and prognosticating CS. However, standardization and validation of these quantitative methods remain challenging due to inter-center variability and technological differences. Further validation through large-scale, multi-center studies is needed to optimize their use and better delineate their role in CS diagnosis, prognostication, and therapy monitoring.