Neuroendocrine tumors (NETs) can produce neuroendocrine amines resulting in symptoms. Selecting the most active amine-producing tumor lesions for local treatment might be beneficial for patients with metastatic small intestinal NET. Tumor burden correlates with catecholamine pathway activity. We analyzed interlesional heterogeneity with 18F-DOPA PET scans in patients with small intestinal NET and investigated if lesions with substantially higher 18F-DOPA uptake could be identified.
In this retrospective, observational study, the 18F-DOPA uptake was calculated by dividing SUVpeak of the lesion by the SUVmean of the background organ. The magnitude of heterogeneity between lesions within a patient was calculated by dividing the lesion with the highest by the one with the lowest 18F-DOPA uptake. Lesions with a higher 18F-DOPA uptake than the upper inner or outer fence (>1.5 or 3 times the interquartile range above the third quartile) were defined as lesions with mild or extreme high 18F-DOPA uptake, respectively, and presence of these was determined in patients with 10 lesions or more.
18F-DOPA was detected over 680 lesions in 38 patients, of which 35 were serotonin producing. 18F-DOPA uptake varied with a median of 8-fold up to 44-fold between lesions within a patient. In 12 of 20 evaluable patients, lesions with mild high 18F-DOPA uptake were found, and in 5, lesions with extreme high 18F-DOPA uptake.
18F-DOPA-PET showed considerable heterogeneity in 18F-DOPA uptake between tumor lesions and identified lesions within patients with mild or extreme high 18F-DOPA uptake.
From the Departments of *Medical Oncology,
‡Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands.
Received for publication October 26, 2018; revision accepted April 11, 2019.
Aline M. van der Loo–van der Schaaf is now with the Medical Center Zuiderzee, Lelystad, the Netherlands.
Conflicts of interest and sources of funding: none declared.
Correspondence to: Annemiek M. E. Walenkamp, MD, PhD, Department of Medical Oncology, University of Groningen, University Medical Center Groningen, DA11 PO Box 30.001, 9700 RB Groningen, the Netherlands. E-mail: firstname.lastname@example.org.
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Online date: June 14, 2019