Endocrine Abstracts

Despite a wide spectrum of imaging diagnostics, GEP-NETs often stay undetectable until the time of dissemination. Removing of a primary tumour together with disseminated lymph nodes even with the presence of liver metastases is the most appropriate treatment to delay progression of the disease. SRS followed by RGS gives a possibility to detect occult GEP-NET intra-opratively. ^99mTc-HYNIC/EDDA-octreotate, a somatostatin analogue with high affinity to sst2 was applied in the study. The aim of the study was to determine whether intra-operative radio-detection with the use of ^99mTc-EDDA/HYNIC-octreotate, is able to reveal unknown primary tu and metastases of GEP-NET thereby improving surgical treatment and final prognosis.

Materials and methods: There were ten patients under examination with GEP-NET (with positive SRS and negative different pre-operative imaging tests). Insulinoma was suspected in 5 pts, non-functioning pancreatic NET - 1, and carcinoid in 5 cases. At surgery, suspected lesions were measured in vivo and ex vivo (Navigator-GPS) and the exact exploration of the abdominal cavity was performed.

Results: Amongst patients with pancreatic NET, ^99mTc-EDDA/HYNIC-octreotate SRS followed by RGS detected 4 insulinomas, 1 glucagonoma and in one patient false positive result appeared to be a cyst but nesidoblastosis was finally recognised. Three carcinoids with metastases were detected; in two cases the use of hand-held gamma probe extended the surgical procedure resulting in the successful excision of the metastatic lymph nodes. In one case the liver metastases were confirmed previously revealed by SRS only. Another false positive result was caused by ileitis.

Conclusion: In our study ^99mTc-EDDA/HYNIC-octreotate SRS followed by RGS localized all primary GEP-NETs undetected with other imaging diagnostics. The main advantage of RGS in comparison to SRS is high sensitivity in detection of metastatic lymph nodes. The imaging properties of the ^99mTc-EDDA/HYNIC-octreotate creates abilities for more common application of this tracer followed by RGS in oncology.