Intraoperative tumour detection using 111In-DTPA-D-Phe1-octreotide and a scintillation detector

Intraoperative tumour detection has been used in many applications. The examined tumour forms have varied and different detector systems and radiopharmaceuticals have also been used. The aim of this study was to evaluate and compare the ability of an NaI(T1) scintillation detector to detect primary tumours and metastases in patients with different endocrine tumour types (e.g. carcinoid tumours, endocrine pancreatic tumours and thyroid tumours) and in patients with breast carcinoma or benign thyroid lesions, on the basis of their somatostatin receptor expression after i.v. injection of 111In-DTPA-D-Phe1-octreotide. Thirty patients were injected with 111In-DTPA-D-Phe1-octreotide intravenously. Scintigraphic images were taken 1 day after injection of the radiopharmaceutical, and surgery was performed 1-7 days post injection. An NaI(T1) scintillation detector was used for intraoperative tumour detection. Tissue samples were collected during surgery for determination of 111In activity concentration and histopathological examination. The scintigraphic images were positive in 29 out of 30 patients. Intraoperative tumour detection was successful in 43 of 66 collected biopsies: 10 out of 11 for carcinoid tumours, 7 out of 10 for medullary thyroid carcinoma (MTC) and 14 out of 22 for breast cancer. On the basis of our findings we conclude that intraoperative tumour detection with 111In-DTPA-D-Phe1-octreotide using this NaI(T1) detector can be successful especially for carcinoid tumours and endocrine pancreatic tumours, due to the relatively high activity concentrations in these tumour types, but is less successful in other forms of thyroid cancer, including MTC, and breast cancer. For successful intraoperative detection, the detector characteristics are also very important, and further improvement of the detector systems is required to increase the sensitivity and specificity.