Optimizing Somatostatin Receptor Imaging in Patients With Neuroendocrine Tumors

Aim The presence of somatostatin receptors in neuroendocrine tumors allows visualization with radiolabeled somatostatin analogs in vivo. The aim of this prospective study was to compare somatostatin receptor imaging using 99m Tc-HYNICTOC with 68 Ga-DOTATATE (DOTA-DPhe1,Tyr3-octreotate) with respect to sensitivity, specificity, and impact upon clinical decision making. Methods Sixty-eight patients (30 men, 38 women; aged 56.4 ± 13.5 years) with disseminated, histologically proven neuroendocrine tumor were enrolled. All patients with previous 99m Tc-HYNICTOC (Tektrotyd; POLATOM, Otwock, Poland) underwent 68 Ga-DOTATATE PET/CT. Both examinations were compared on a per-patient and per-lesion basis. Results The sensitivity, specificity, positive and negative predictive values, and accuracy of 68 Ga-DOTATATE and 99m Tc-HYNICTOC were 100% versus 82%, 85% versus 69%, 97% versus 92%, 100% versus 47%, and 97% versus 79%, respectively. Concordant results were observed in 58 patients (49/68 positive on both 68 Ga-DOTATATE and 99m Tc-HYNICTOC and 9/68 negative in both examinations). Ten of 68 patients had 68 Ga-DOTATATE–positive, 99m Tc-HYNICTOC–negative studies. Two hundred eighteen lesions were detected using 99m Tc-HYNICTOC, compared with 546 lesions using 68 Ga-DOTATATE ( P < 0.0001). 68 Ga-DOTATATE detected a higher number of lesions in bone and lymph nodes, liver, intestine, and pancreas and had a higher sensitivity for subcentimeter abnormalities than 99m Tc-HYNICTOC. 68 Ga-DOTATATE led to management change in 23 (34%) of 68 patients. Conclusions 68 Ga-DOTATATE has a higher sensitivity than 99m Tc-HYNICTOC for the detection of neuroendocrine tumors. 68 Ga-DOTATATE proved superior to 99m Tc-HYNICTOC in detecting subcentimeter skeletal, lymph node, and liver metastases. 68 Ga-DOTATATE PET/CT changed clinical decision making in one third of patients.