LOCALIZATION OF METASTATIC GASTROENTEROPANCREATIC TUMORS BY SOMATOSTATIN RECEPTOR SCINTIGRAPHY WITH [IN-111-DTPA-D-PHE(1)]-OCTREOTIDE

Most gastroenteropancreatic tumours express somatostatin receptors, al lowing imaging using radiolabelled somatostatin analogues. Octreotide can be modified by coupling a DTPA moiety to the N-terminal D-phenylal anine to allow labelling with In-111. We studied the comparative effec tiveness of this radiopharmaceutical in identifying tumour extent. Twe nty-two patients with metastatic gastroenteropancreatic tumours were s canned using [In-111-DTPA-D-Phe(1)]-octreotide. In 11 patients with th e carcinoid syndrome, one of six primary lesions was identified by CT scanning and by [In-111-DTPA-D-Phe(1)]-octreotide scanning. Hepatic me tastases were present in all patients, 9 of whom had positive scintigr aphy. Two other sites of intra-abdominal uptake and four distant sites , not previously identified, were demonstrated. Five other distant sit es were confirmed to be carcinoid metastases. All 11 patients with oth er gastroenteropancreatic tumours had positive scans, demonstrating 7/ 9 primary lesions, 12 intra-abdominal lesions, including hepatic metas tases in all cases, and one distant lesion, all previously identified. Thus [In-111-DTPA-D-Phe(1)]-octreotide imaging effectively identified the extent of metastatic disease from gastroenteropancreatic tumours, and confirmed lesions whose significance was uncertain following prev ious imaging procedures.