Diagnostic and prognostic importance of 18F-fluorodeoxyglucose PET/computed tomography in primary extranodal and atypically presenting lymphomas

OBJECTIVE: This study aimed to evaluate metabolic activity profiles of extranodal and atypical lymphoma lesions detected by 18 F-fluorodeoxyglucose ( 18 F-FDG) PET/computed tomography (CT), and to elucidate the predictive value of this modality in the diagnostic and prognostic workflow. METHODS AND RESULTS: Seventy-four patients diagnosed with lymphoma underwent 18 F-FDG PET/CT. Patients aged greater than or equal to 60 years had significantly higher mean maximum standardized uptake value (SUV max ) and mean standardized uptake value (SUV mean ) values. Lesions larger than 2 cm showed significantly elevated SUV mean values. In patients over 60 years, nodal SUV max was also considerably higher. The SUV mean of extranodal lesions was significantly higher in female patients. A positive correlation was found between extranodal lesion SUV max and both lesion size and nodal SUV max . CONCLUSION: The significant increase in SUV values with advancing age and larger lesion size, along with the high sensitivity of 18 F-FDG PET/CT in detecting distant organ involvement such as bone marrow, highlights its potential to reflect tumor behavior. The observed sex-related metabolic differences further emphasize the need for individualized imaging strategies.