Objectives: The aim of this work was the evaluation of biodistribution and radiation dosimetry of (68)Ga-DOTANOC in patients affected by neuroendocrine tumors.
Materials and methods: We enrolled nine patients (six male and three female) affected by different types of neuroendocrine tumors (NETs). Each patient underwent four whole body positron emission tomography (PET) scans, respectively, at 5, 20, 60, and 120 min after the intravenous injection of about 185 MBq of (68)Ga-DOTANOC. Blood and urine samples were taken at different time points post injection: respectively, at about 5, 18, 40, 60, and 120 min for blood and every 40-50 min from injection time up to 4 h for urine. The organs involved in the dosimetric evaluations were liver, heart, spleen, kidneys, lungs, pituitary gland, and urinary bladder. Dosimetric evaluations were done using the OLINDA/EXM 1.0 software.
Results: A physiological uptake of (68)Ga-DOTANOC was seen in all patients in the pituitary gland, the spleen, the liver, and the urinary tract (kidneys and urinary bladder). Organs with the highest absorbed doses were kidneys (9.0E-02+/-3.2E-02mSv/MBq). The mean effective dose equivalent (EDE) was 2.5E-02+/-4.6E-03 mSv/MBq.
Discussion and conclusions: The excretion of the compound was principally via urine, giving dose to the kidney and the urinary bladder wall. As SSTR2 is the most frequently expressed somatostatin receptor and (68)Ga-DOTANOC has high affinity to it, this compound might play an important role in PET oncology in the future. The dosimetric evaluation carried out by our team demonstrated that (68)Ga-DOTANOC delivers a dose to organs comparable to, and even lower than, analogous diagnostic compounds.