Published in:
Open Access
01-08-2016 | Original Article
Direct comparison of 68Ga-DOTA-TOC and 18F-FDG PET/CT in the follow-up of patients with neuroendocrine tumour treated with the first full peptide receptor radionuclide therapy cycle
Authors:
Bernhard Nilica, Dietmar Waitz, Vlado Stevanovic, Christian Uprimny, Dorota Kendler, Sabine Buxbaum, Boris Warwitz, Llanos Gerardo, Benjamin Henninger, Irene Virgolini, Margarida Rodrigues
Published in:
European Journal of Nuclear Medicine and Molecular Imaging
|
Issue 9/2016
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Abstract
Purpose
To determine the value of 68Ga-DOTA-TOC and 18F-FDG PET/CT for initial and follow-up evaluation of patients with neuroendocrine tumour (NET) treated with peptide receptor radionuclide therapy (PRRT).
Methods
We evaluated 66 patients who had histologically proven NET and underwent both PRRT and three combined 68Ga-DOTA-TOC and 18F-FDG PET/CT studies. 68Ga-DOTA-TOC PET/CT was performed before PRRT, 3 months after completion of PRRT and after a further 6 – 9 months. 18F-FDG PET/CT was done within 2 months of 68Ga-DOTA-TOC PET/CT. Follow-up ranged from 11.8 to 80.0 months (mean 34.5 months).
Results
All patients were 68Ga-DOTA-TOC PET-positive initially and at follow-up after the first full PRRT cycle. Overall, 62 of the 198 18F-FDG PET studies (31 %) were true-positive in 38 of the 66 patients (58 %). Of the 66 patients, 28 (5 grade 1, 23 grade 2) were 18F-FDG-negative initially and during follow-up (group 1), 24 (5 grade 1, 13 grade 2, 6 grade 3) were 18F-FDG-positive initially and during follow-up (group 2), 9 patients (2 grade 1, 6 grade 2, 1 grade 3) were 18F-FDG-negative initially but 18F-FDG-positive during follow-up (group 3), and 5 patients (all grade 2) were 18F-FDG-positive initially but 18F-FDG-negative during follow-up (group 4).18F-FDG PET showed more and/or larger metastases than 68Ga-DOTA-TOC PET in five patients of group 2 and four patients of group 3, all with progressive disease. In three patients with progressive disease who died during follow-up tumour SUVmax increased by 41 – 82 % from the first to the last follow-up investigation.
Conclusion
In NET patients, the presence of 18F-FDG-positive tumours correlates strongly with a higher risk of progression. Initially, patients with 18F-FDG-negative NET may show 18F-FDG-positive tumours during follow-up. Also patients with grade 1 and grade 2 NET may have 18F-FDG-positive tumours. Therefore, 18F-FDG PET/CT is a complementary tool to 68Ga-DOTA-TOC PET/CT with clinical relevance for molecular investigation.