Physiological and tumoral uptake of 68Ga-DOTATATE: standardized uptake values and challenges in interpretation

Purpose The objective of this study is to determine the range of SUV max of 68Ga-DOTATATE in normal organs and tumoral lesions and establish uptake unrelated to NET. Materials and methods One hundred and twenty patients (57 men, 63 women), who underwent 68 Ga-DOTATATE PET/CT imaging in our institution were analyzed. Patients were indicated for 68 Ga-DOTATATE PET/CT imaging to detect primary tumor or metastasis of suspected or previously known NET, to determine SSTR positivity and to detect occult source of ectopic Cushing syndrome. Normal range of uptake was calculated for the organs that were proven to have no pathology by either conventional radiological imaging or clinical follow-up, using SUV max as a semiquantitative measure. Uptake and tumor to background ( T / B ) ratios of tumoral lesions in liver, pancreas, bone, brain and lymph nodes were calculated. Uptakes due to lesions unrelated to NET were also documented. Results Significant uptake was found in spleen, kidneys, adrenal glands, liver and pituitary gland with mean SUV max of 24.67, 14.30, 13.73, 9.12 and 9.74 respectively. Uptake was measured separately for the pancreatic head and body separately, however, besides a slightly heterogeneous uptake; the difference was not statistically significant. Uptake in the tumoral lesions had high ( T / B ) ratios with mean SUV max of 28.72, 25.21, 18.28, 34.73 and 12.59 for liver, pancreas, bone, brain and lymph nodes, respectively. Incidental benign tumoral lesions were detected in 3 patients (2.5 %) which were meningioma and fibrous dysplasia demonstrating significant and breast fibroadenoma demonstrating mild 68 Ga-DOTATATE uptake. Non-neoplastic processes were detected in 4 patients (14.1 %), including postsurgical inflammation, reactive lymph nodes, arthritis and demonstrated faint to mild 68 Ga-DOTATATE uptake, with the exception of significant uptake in accessory spleen. Conclusion 68 Ga-DOTATATE has high T / B ratio with physiological biodistribution comparable to its counterparts. However, the presence of SSTRs in benign and malignant lesions unrelated to NET may be challenging in interpretation particularly where the physiological uptake is variable.