Does Treatment with Somatostatin Analogs Affect the Radioactivite Uptake of Normal Target Organs and Malignant Lesions on68GaDOTATATE PET/CT imaging?

Objective: Somatostatin analogs (SSA) are used in treating low-grade neuroendocrine tumors (NET), mainly because of their antiproliferative effect. 68Ga tetraazacyclododecantetraacetic acid-DPhe1-Tyr3-octreotate (DOTATATE) PET/CT as somatostatin receptor imaging has been widely used in recent years. However, there are conflicting publications in the literature, although there are guidelines for discontinuing the use of SSA before imaging. This study aims to investigate the effect of SSAs on Somatostatin receptor imaging. Material and Method: We retrospectively analyzed 253 patients who underwent 68Ga-DOTATATE PET/CT imaging between 2018 and 2022. Among these patients, those with low grades (grade 1 and grade 2) using SSA were included in the study. SUVmax (maximum standard uptake volume) of normal target organs, primary tumors, and metastases with the highest SUVmax in each organ were compared before and after SSA treatment. Results: 28 patients (16 females; 12 males, age [mean±SD], 54.82±14.27, range 18-78) with low-grade NET and68Ga-DOTATATE PET/CT imaging with SSA therapy were included in the study. Although SUVmax was decreased in the values measured after SSA application in the liver and spleen, it was not statistically significant (p>0.05). There was no significant difference between SUVmax values in primary tumors and metastatic lesions in the liver, bone, lung, or lymph nodes before and after SSA application (P> 0.05). Conclusion: In conclusion, these drugs do not need to be discontinued before 68Ga-DOTATATE PET/CT imaging for treatment follow-up in neuroendocrine tumor patients using SSAs. In addition, these drugs may help report interpretation by increasing the intensity of metastatic lesions in the liver and spleen.