Sex-differences in [⁶⁸Ga]Ga-DOTANOC biodistribution

Introduction: Still little is known about factors, influencing the organ uptake of somatostatin receptor (SSTR)-targeting radiopharmaceuticals. The aim of this study was to assess the influence of gender on [⁶⁸Ga]Ga-DOTANOC uptake. Further on, we assessed other factors such as diabetes, proton pump inhibitors (PPIs) and oral antidiabetics (OADs).

Methods: In 118 studies of patients with a [⁶⁸Ga]Ga-DOTANOC PET/CT (m = 60, f = 58; mean age: 61 ± 15 yrs) SUV_max and SUV_mean of the stomach, liver, spleen, kidneys, adrenal glands, and pancreas were assessed. Patients with history of splenectomy and significant tumor burden were excluded. Additionally, clinical information (gender, diabetes, age, pre-medications such as PPIs, OADs and somatostatin analogues (SSAs), were collected.

Results: [⁶⁸Ga]Ga-DOTANOC uptake proved to be significantly lower in female patients compared to males for the SUV_max of the stomach (7.1, 9.1; P = 0.04), liver (8.3, 9.4; P = 0.0007), adrenal glands (15.9, 19.9; P = 0.05) kidneys (20.3, 18.9; P = 0.05) and the SUV_mean of the pancreatic tail (2.9, 3.2; P = 0.03) and the kidneys (11.8, 10.6, P = 0.004). Additionally, patients with diabetes and below the age of 50 yrs. showed significantly higher SUV_max and SUV_mean values of the stomach (diabetes: 9.1, 7.8; P = 0.01 and 6.0, 5.3; P = 0.004; age: 6.3, 8.3; P = 0.01 and 4.4, 5.5; P = 0.03). In contrast, intake of PPIs only affected the SUV_mean of the liver (11.0, 9.0; P = 0.005), whereas OADs caused higher SUV_max values in the stomach (10.0, 7.8; P = 0.02), spleen (42.5, 32.6; P = 0.0005) adrenal glands (25.0, 16.9; P = 0.0003) and also higher SUV_mean in the spleen (26.1, 21.4; P = 0.002) and adrenal glands (14.8, 12.4; P = 0.02).

Conclusion: Factors such as gender, diabetes and age influence [⁶⁸Ga]Ga-DOTANOC uptake, whereas ongoing medications such as PPIs and OADs exerted less influence.