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A Journal on Nuclear Medicine and Molecular Imaging
Affiliated to the and to the International Research Group of Immunoscintigraphy
Indexed/Abstracted in: Current Contents/Clinical Medicine, EMBASE, PubMed/MEDLINE, Science Citation Index (SciSearch), Scopus
Impact Factor 2,413
Online ISSN 1827-1936
NEUROENDOCRINE UPDATE AND METABOLIC THERAPY
Traub-Weidinger T. 1, Von Guggenberg E. 1, Dobrozemsky G. 1, Kendler D. 1, Eisterer W. 2, Bale R. 3, Putzer D. 1, Gabriel M. 1, Virgolini I. 1
1 Department of Nuclear Medicine, Medical University of Innsbruck, Innsbruck, Austria;
2 Department of Internal Medicine, Medical University of Innsbruck, Innsbruck, Austria;
3 Department of Radiology, Medical University of Innsbruck, Innsbruck, Austria
AIM: Positron emission tomography (PET) of 68Ga-radiolabelled (SST) somatostatin receptor (R) binding peptides has recently been evaluated in SSTR positive tumor patients. First promising results in lung and thyroid tumor patients with 111In-DOTA-Lanreotide (DOTA-LAN) scintigraphy have been described. We report our first experience with 68Ga-labeled DOTA-LAN.
METHODS: Eleven patients (3 non small cell lung cancer [NSCLC], 3 small cell lung cancer [SCLC], 3 radioiodine negative thyroid cancer, 2 medullary thyroid cancer [MTC]) were investigated. After intravenous injection of 75-150 MBq 68Ga-DOTA-LAN dynamic studies were acquired over the tumor site for the first 40 min with a dedicated PET scanner in 3 patients, and 2 partial body scans were acquired at 20 and 50 min p.i. in 2 patients. Whole body acquisitions at 90 min after injection were acquired in all 11 patients. Image reconstruction was performed by iterative reconstruction utilizing additional transmission scans for attenuation correction. Vital parameters were recorded during the PET study and up to 24 h p.i. Blood and urinary sampling was done up to 4 hr after tracer injection in 8 patients. PET results were compared to conventional imaging techniques (CIT), i.e. computed tomography (CT) and/or magnetic resonance imaging (MRI). In 5 patients, 68Ga-DOTA-LAN was compared with 2-[18F]fluoro-2-deoxy-D-glucose (18F-FDG).
RESULTS: After intravenous (i.v.) injection of 68Ga-DOTA-LAN the radioactivity in the blood rapidly decreased to less then 20% of the injected dose (ID) within the first 20 min and further decreased to less than 9% ID after 4 h. A cumulative urinary excretion of 68Ga-DOTA-LAN up to 29.2±13.2% ID at 4 h was found. No acute side effects were observed. Tumor sites were visualized already during the first min after injection. Comparison of positron emission tomography (PET) and CIT showed concordant results in 3/8 patients and partial concordant results in 5/8 patients with matched results for the primary/recurrent tumor, mediastinal lymph nodes, or adrenal gland metastases. Partial concordant results were seen for the lung, bone, liver and cervical lymph node metastases. Micronodular metastases of the lung and the cerebrum were not visualized by 68Ga-DOTA-LAN PET. The maximal standardized uptake values of the lung and bone tumor lesions ranged from 6 to 8 g/ml at 90 min p.i..
CONCLUSIONS: 68Ga-DOTA-LAN visualized the majority of tumor lesions. Further studies are required to assess the clinical value, and to obtain the best imaging protocol of this new PET SSTR tracer.