Abstract
1245
Objectives: 18F-FDG PET/CT is a widely used imaging tool that is considered the cornerstone of management and diagnosis in cancer patients, especially in those with lymphoma. However, its utility in distinguishing secondary testicular involvement from normal physiologic uptake needs further investigation. The purpose of this study is to evaluate the normal level of testicular 18F-FDG uptake in patients with lymphoma and explore the effect of age on physiologic FDG uptake.
Methods: This retrospective study was approved by the Institutional Review Board. A Radiology Information System (RIS) search was conducted for all PET/CT studies performed from 7/1/2010 to 6/30/2016 on adult male patients with a diagnosis of lymphoma. Patients with clinical or pathological diagnosis of testicular lymphoma were excluded. A total of 2045 testes were included in the study from 1087 scans in 606 patients. PET/CT imaging was reviewed and measurements were performed for standardized uptake values (SUV) in both testicles (SUVmax) as well as in the liver (SUVmaxand SUVmean).
Results: The mean age of included patients was 51 ± 16 years (range 18- 85). The mean SUVmaxof the testicles was 3.75 ± 0.90. The mean ratio of testis SUVmax/ liver SUVmeanwas 1.78 ± 0.43. Trends in SUVmax and age were significant for a negative correlation by a small magnitude of 0.066 per 10 years (p<0.001). The SUVmax/ liver SUVmean had similar changes with significant low magnitude decrease with increasing age (0.059 per 10-year increase, p < 0.001).
Conclusions: The mean SUVmaxin a lymphoma patient with no pathologic or clinical diagnosis of testicular lymphoma was 3.75 ± 0.90. Testicular SUV uptake was found to be negatively correlated with increasing age. Our findings can help define cut-off values for normal testicular SUV uptake in patients with lymphoma.