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- Title
PET in the Diagnosis of Neuroendocrine Tumors.
- Authors
SUNDIN, ANDERS; ERIKSSON, BARBRO; BERGSTRÖM, MATS; LÅNGSTRÖM, BENGT; ÖBERG, KJELL; ÖRLEFORS, HÅKAN
- Abstract
For general oncological imaging, positron emission tomography (PET) using [18F]fluoro-deoxy-glucose (FDG) has evolved as a powerful functional imaging modality. Unfortunately, FDG-PET has not been as advantageous for imaging gastropancreatic neuroendocrine tumors, and only tumors with high proliferative activity and low differentiation have shown an increased FDG uptake. Therefore, the 11C-labeled amine precursors Ldihydroxyphenylalanine and 5-hydroxy-L-tryptophan (5-HTP) were developed for PET imaging of these tumors. Because of the higher tumor uptake of the latter tracer in a study of patients with endocrine pancreatic tumors, 11C- 5-HTP was chosen for further evaluation. In comparative studies of patients with carcinoids and endocrine pancreatic tumors, 5-HTP-PET proved better than CT and somatostatin receptor scintigraphy for tumor visualization, and many small, previously overlooked lesions were diagnosed by 11C-5-HTP-PET. The strong correlation found during medical treatment between the changes in the transport rate constant at repeated PET and those of U-HIAA indicates the possible use of 11C-5-HTP-PET also for therapy monitoring. By premedication of patients with Carbidopa orally before PET examination, in order to block the aromatic amino acid decarboxylase enzyme, the decarboxylation rate of 11C-5-HTP was decreased, leading to a higher tumor uptake and a considerably lower urinary radioactivity concentration.
- Subjects
POSITRON emission tomography; NEUROENDOCRINE tumors; SOMATOSTATIN; COMPUTER-aided diagnosis; MEDICAL sciences; DIAGNOSIS
- Publication
Annals of the New York Academy of Sciences, 2004, Vol 1014, Issue 1, p246
- ISSN
0077-8923
- Publication type
Article
- DOI
10.1196/annals.1294.027