Carbidopa pretreatment improves image interpretation and visualisation of carcinoid tumours with 11C-5-hydroxytryptophan positron emission tomography
2006 (English)In: European Journal of Nuclear Medicine and Molecular Imaging, ISSN 1619-7070, E-ISSN 1619-7089, Vol. 33, no 1, 60-65 p.Article in journal (Refereed) Published
PURPOSE: Positron emission tomography (PET) with 11C-5-hydroxytryptophan (5-HTP) as tracer is a promising imaging instrument in the management of patients with neuroendocrine tumours (NETs). However, high radioactivity concentrations in the urinary collecting system sometimes produce image reconstruction artefacts that can make detection of small NETs difficult. As a means to decrease urinary excretion of radioactivity and thereby improve image quality, we examined the effect of pretreatment with carbidopa (CD), a peripheral inhibitor of aromatic amino acid decarboxylase (AADC), which converts 5-HTP to serotonin (5-hydroxytryptamine, 5-HT). METHODS: Six patients with midgut carcinoid metastases were examined with 11C-5-HTP PET before and 1 h after oral administration of 100 or 200 mg of CD. RESULTS: There was a fourfold significant reduction of tracer uptake in the urinary collecting system after CD administration (p=0.0277, n=6), with a mean standard uptake value (SUV) of 155+/-195 before CD and 39+/-14 after CD. In tumour lesions there was a significant increase in SUV after CD administration (p<0. 0001, n=18), with a mean SUV of 11+/-3 before CD and 14+/-3 after CD. There was no difference between the doses (100 and 200 mg) of CD in this respect. In all patients, image interpretation and tumour detection were markedly improved after CD administration. CONCLUSION: We conclude that CD premedication improves 11C-5-HTP PET image quality and facilitates detection of NET lesions. Because of the similarity of metabolic pathways, this method could probably be applied to improve PET imaging using other tracers like 18F-DOPA and 11C-DOPA.
Place, publisher, year, edition, pages
2006. Vol. 33, no 1, 60-65 p.
5-Hydroxytryptophan/*diagnostic use, Carbidopa/*diagnostic use, Carbon Radioisotopes, Carcinoid Tumor/*radionuclide imaging/*secondary, Female, Humans, Image Enhancement/*methods, Liver Neoplasms/*radionuclide imaging/*secondary, Lymphatic Metastasis, Male, Positron-Emission Tomography/*methods, Radiopharmaceuticals/diagnostic use, Reproducibility of Results, Sensitivity and Specificity
Medical and Health Sciences
IdentifiersURN: urn:nbn:se:uu:diva-16734DOI: 10.1007/s00259-005-1891-zPubMedID: 16184369OAI: oai:DiVA.org:uu-16734DiVA: diva2:44505