Localization of neuroendocrine tumours with In111-Octreotide scintigraphy

Aim: The aim of the study was to evaluate the management of the In111-Octreotide scintigraphy for the localization of the primary tumour and its metastases in patients with proven or high clinical suspicion of gastroenteropancreatic endocrine tumours and the results were compared with CT scanning. Material and Methods: Twenty-four patients (10 females and 14 men; mean 60 years) were studied by planar and tomography imaging at 4 and 24h after 222 MBq In111-Octreotide injection. Scintigraphy findings were retrospectively compared with computed tomography. Our series included 16 patients with carcinoid tumours, 7 patients with gastrinomas and 1 patient with a neuroendocrine tumour of the pancreas. Results: The sensitivity of the scintigraphy study was 87% and its positive predictive value was 87%. Seven of 16 patients had positive In111-Octreotide scintigraphy carcinoid and the scintigraphy identified unexpected extra liver lesions not detected by CT in 8 cases. Three of 7 patients, with previously negative CT, had negative scintigraphy gastrinomas, and in 1 patient only scintigraphy detected a suspicion lesion that was missed by CT. In111-Octreotide and CT scanning identified another unexpected liver and lymph node metastases in 3 of these patients. Scintigraphy study failed in detection on 1 islet-cell tumour of the pancreas that was identified on CT imaging, the definitive diagnosis of this lesion was neuroectodermic tumour. We only had one false positive study on scintigraphy scanning with positive In111-octreotide intestinal lesion that was inflammatory disease. Non visualization of liver metastases on scintigraphy study only happened in 1 case of seven and we found unexpected bone metastases In111-Octreotide positive in 4 patients with carcinoid tumours. Conclusion: In111-Octreotide contributes to the management of patients with gastroenteropancreatic tumours in localization of primary tumour and, combined with CT imaging, improves the preoperative localization of suspicion lesions. The scintigraphy has a higher sensitivity in the identification of unexpected extra liver lesions not detected by CT