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

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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 99mTc-HYNICTOC with 68Ga-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 99mTc-HYNICTOC (Tektrotyd; POLATOM, Otwock, Poland) underwent 68Ga-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 68Ga-DOTATATE and 99mTc-HYNICTOC were 100% versus 82%, 85% versus 69%, 97% versus 92%, 100% versus 47%, and 97% versus 79%, respectively.

Results

Concordant results were observed in 58 patients (49/68 positive on both 68Ga-DOTATATE and 99mTc-HYNICTOC and 9/68 negative in both examinations). Ten of 68 patients had 68Ga-DOTATATE–positive, 99mTc-HYNICTOC–negative studies. Two hundred eighteen lesions were detected using 99mTc-HYNICTOC, compared with 546 lesions using 68Ga-DOTATATE (P < 0.0001). 68Ga-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 99mTc-HYNICTOC. 68Ga-DOTATATE led to management change in 23 (34%) of 68 patients.

Conclusions

68Ga-DOTATATE has a higher sensitivity than 99mTc-HYNICTOC for the detection of neuroendocrine tumors. 68Ga-DOTATATE proved superior to 99mTc-HYNICTOC in detecting subcentimeter skeletal, lymph node, and liver metastases. 68Ga-DOTATATE PET/CT changed clinical decision making in one third of patients.

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