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Eur J Nucl Med Mol Imaging. 2019 Mar;46(3):686-695. doi: 10.1007/s00259-018-4245-3. Epub 2019 Jan 7.

Early 18F-FDOPA PET/CT imaging after carbidopa premedication as a valuable diagnostic option in patients with insulinoma.

Author information

1
Biophysics and Nuclear Medicine, University Hospitals of Strasbourg, Strasbourg, France.
2
Endocrinology, Diabetes and Metabolic Disorders, La Timone University Hospital, Aix-Marseille University, Marseille, France.
3
Hepato-Pancreato-Biliary Surgery and Liver Transplantation, University Hospitals of Strasbourg, University of Strasbourg, Strasbourg, France.
4
Endocrine Surgery, La Timone University Hospital, Aix-Marseille University, Marseille, France.
5
General, Digestive, and Endocrine Surgery, IRCAD-IHU, University of Strasbourg, Strasbourg, France.
6
Endocrine and General Surgery, University Hospital of Nancy, Nancy, France.
7
Endocrinology, University Hospital of Nancy, Nancy, France.
8
Diabetology, University Hospital of Strasbourg, University of Strasbourg, Strasbourg, France.
9
Internal Medicine, Diabetes and Metabolic Disorders, University Hospitals of Strasbourg, Strasbourg University, Strasbourg, France.
10
Nuclear Medicine, University Hospital of Nancy, Nancy, France.
11
Nuclear Medicine, La Timone University Hospital, Aix-Marseille University, Marseille, France.
12
European Center for Research in Medical Imaging, Aix-Marseille University, Marseille, France.
13
Biophysics and Nuclear Medicine, University Hospitals of Strasbourg, Strasbourg, France. alessio.imperiale@chru-strasbourg.fr.
14
ICube, UMR 7357 Strasbourg University / CNRS & FMTS, Faculty of Medicine of Strasbourg, Strasbourg, France. alessio.imperiale@chru-strasbourg.fr.
15
Department of Nuclear Medicine, Hautepierre University Hospital, 1, Avenue Molière, 67098, Strasbourg Cedex, France. alessio.imperiale@chru-strasbourg.fr.

Abstract

PURPOSE:

Data on the diagnostic value of 18F-FDOPA PET/CT in patients with insulinoma are limited and are focused on small patient populations explored using different PET/CT protocols and the inconsistent use of carbidopa premedication. The aim of this study was to improve the current knowledge about the diagnostic value of 18F-FDOPA PET/CT combined with oral carbidopa premedication and early pancreatic imaging for tumour localization in patients with insulinoma-related hyperinsulinaemic hypoglycaemia (HH). The relationships among 18F-FDOPA quantitative uptake parameters, insulin secretion and tumour pathological features were also investigated.

METHODS:

Of 34 patients with suspicion of insulinoma-related HH examined by dual time-point carbidopa-assisted 18F-FDOPA PET/CT, 24 with histologically proven insulinoma were retrospectively included. One patient underwent two PET/CT examinations for relapsing insulinoma after surgical excision. Thus, 25 preoperative 18F-FDOPA PET/CT studies were finally retained and analysed. All studies were performed under carbidopa premedication (200 mg orally, 1-2 h prior to tracer injection). The PET/CT acquisition protocol included an early acquisition (5 min after 18F-FDOPA injection) over the upper abdomen and a delayed whole-body acquisition starting 20-30 min later. The cytological and/or histopathological diagnosis of insulinoma was the diagnostic standard of truth.

RESULTS:

18F-FDOPA PET/CT localized insulinoma in 21 of the 25 studies, leading to a primary lesion detection rate of 84%. Four lesions (19%) were detected only on early acquisitions. The false-negative tumour detection rates were, respectively, 22% and 12.5% in patients receiving and not receiving treatment for hypoglycaemic symptoms at the time of PET/CT. In benign insulinomas, the early maximum standardized uptake value (SUVmax) was significantly higher than the delayed SUVmax. Compared to the 21 benign lesions, four malignant insulinomas showed significantly higher 18F-FDOPA uptake. Lesion size, fasting-end insulin and C-peptide levels correlated with tumour 18F-FDOPA uptake, dopaminergic tumour volume and metabolic burden.

CONCLUSION:

The present study showed that 18F-FDOPA PET/CT combined with carbidopa premedication and early pancreatic acquisitions is a valuable diagnostic option in patients with insulinoma when GLP1R-based imaging is not available. The results also provide new insights into the relationships between tumour secretion and imaging phenotype in insulinomas.

KEYWORDS:

18F-FDOPA; Carbidopa; Hyperinsulinism; Insulinoma; Neuroendocrine tumours; PET

PMID:
30617961
DOI:
10.1007/s00259-018-4245-3

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