Optimizing Somatostatin Receptor Imaging in Patients With Neuroendocrine Tumors: The Impact of 99mTc-HYNICTOC SPECT/SPECT/CT Versus 68Ga-DOTATATE PET/CT Upon Clinical Management.

ABSTRACT

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 Tc-HYNICTOC with 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 Tc-HYNICTOC (Tektrotyd; POLATOM, Otwock, Poland) underwent 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 Ga-DOTATATE and 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 Ga-DOTATATE and Tc-HYNICTOC and 9/68 negative in both examinations). Ten of 68 patients had Ga-DOTATATE-positive, Tc-HYNICTOC-negative studies. Two hundred eighteen lesions were detected using Tc-HYNICTOC, compared with 546 lesions using Ga-DOTATATE (P < 0.0001). 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 Tc-HYNICTOC. Ga-DOTATATE led to management change in 23 (34%) of 68 patients. CONCLUSIONS: Ga-DOTATATE has a higher sensitivity than Tc-HYNICTOC for the detection of neuroendocrine tumors. Ga-DOTATATE proved superior to Tc-HYNICTOC in detecting subcentimeter skeletal, lymph node, and liver metastases. Ga-DOTATATE PET/CT changed clinical decision making in one third of patients.