Radioguided surgery in neuroendocrine tumors using Ga-68-labeled somatostatin analogs: A pilot study

Background: Previous studies of the intraoperative use of a hand-held gamma probe to localize metastases and primary tumors have shown improved assessment of tumor spread and changes in surgical management based on additional information gained by radioguided surgery (RGS). Purpose: The aim was to test the feasibility and advantages of doing RGS using a gallium-68 labeled with somatostatin receptor analogs in the intraoperative detection of neuroendocrine tumors. Methods: Ga-68 somatostatin receptor PET/CT imaging was performed preoperatively in 9 patients with gastroenteropancreatic neuroendocrine tumors. Statistical analyses were performed to find out the correlation between the pathologic size of the tumor lesions and the maximum standardized uptake value on PET/CT as well as the target/nontarget ratio (T/NT) of gamma probe counts. Thereafter, the impact of the planned operation procedure and the lesion-based sensitivity of tumor detection (surgical palpation vs. PET/CT vs. gamma probe) had been observed. Results: Overall, 72 locations in 9 patients were examined intraoperatively using gamma probes. The gamma probe detected 94% of the whole histologically quantified lesions, whereas the PET/CT allocated 69% and surgical palpation, 50%. RGS resulted in change in the operative procedure in 56%. There was a significant correlation between the maximum standardized uptake value and tumor size (0.74; P < 0.005). Conclusions: Hand-held gamma probe surgery using gallium-68-labeled somatostatin analogs is a feasible and an attractive option for real-time detection of small metastases and primaries of neuroendocrine tumors.