18F-DOPA PET/CT biodistribution consideration in 107 consecutive patients with neuroendocrine tumours.
ABSTRACT L-6-fluoro 3,4-dihydroxyphenylalanine (18F-DOPA), an amino acid-based radiopharmaceutical, is increasingly being used in the detection and management of neuroendocrine tumours. Knowledge of the normal biodistribution of this radiopharmaceutical is essential for the proper interpretation of such studies, but the literature available is scanty due to the rarity of these tumours. The aim of this study is to evaluate the biodistribution pattern and normal variants of 18F-DOPA in a cohort of patients with neuroendocrine tumours using semiquantitative analysis (maximum standardized uptake value).
We analysed 107 consecutive 18F-DOPA PET/CT studies of patients referred with medullary carcinoma of the thyroid (43), phaeochromocytoma including cases of Von Hippel Lindau syndrome and multiple endocrine neoplasia type IIA cases (34), paraganglioma (14) and other neuroendocrine tumours (16). The study population were divided into two groups: those with negative 18F-DOPA PET/CT scans (32) and those with positive scans (75). The biodistribution of 18F-DOPA in each group was measured and compared between the two groups.
The physiological biodistribution in the basal ganglia and liver parenchyma showed no variability between the two groups. Conversely, uptake in the pancreas (particularly the uncinate process) and adrenals showed considerable variability between the groups. However, these differences were found not to be significant on statistical analysis.
The data presented may provide useful information in understanding the physiologic biodistribution of DOPA and its variants, for the purpose of improving the interpretation of 18F-DOPA PET/CT.
- SourceAvailable from: Marc Pretze
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- "Beyond glioma imaging, recent studies have also shown the increasing importance of [18F]F-DOPA for the visualization of various peripheral tumor entities via PET  which can be attributed to the upregulation of amino acid transporters in malignant tissues due to an often increased proliferation [21, 22]. [18F]F-DOPA, which is transported via the dopamine transporter (DAT) into cells, has thus shown diagnostic advantages in the imaging of high- and low-grade malignancies like neuroendocrine tumors [23–27], pheochromocytoma [28, 29], and pancreatic adenocarcinoma [30–32] regarding diagnostic efficiency and sensitivity. [18F]FDG on the contrary is taken up by the glucose transporter not only by malignant tissues but also by inflamed and healthy tissues exhibiting a high glucose metabolism, resulting in low tumor-to-background ratios  in CNS malignancies. "
ABSTRACT: For many years, the main application of [18F]F-DOPA has been the PET imaging of neuropsychiatric diseases, movement disorders, and brain malignancies. Recent findings however point to very favorable results of this tracer for the imaging of other malignant diseases such as neuroendocrine tumors, pheochromocytoma, and pancreatic adenocarcinoma expanding its application spectrum. With the application of this tracer in neuroendocrine tumor imaging, improved radiosyntheses have been developed. Among these, the no-carrier-added nucleophilic introduction of fluorine-18, especially, has gained increasing attention as it gives [18F]F-DOPA in higher specific activities and shorter reaction times by less intricate synthesis protocols. The nucleophilic syntheses which were developed recently are able to provide [18F]F-DOPA by automated syntheses in very high specific activities, radiochemical yields, and enantiomeric purities. This review summarizes the developments in the field of [18F]F-DOPA syntheses using electrophilic synthesis pathways as well as recent developments of nucleophilic syntheses of [18F]F-DOPA and compares the different synthesis strategies regarding the accessibility and applicability of the products for human in vivo PET tumor imaging.BioMed Research International 05/2014; 2014:674063. DOI:10.1155/2014/674063 · 2.71 Impact Factor
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- "Knowledge of the physiological uptake of radiopharmaceuticals, as well of their distribution and normal variants, represents an important step toward the correct interpretation of pathological findings. In 2011, our group published a study on the physiological biodistribution pattern and the physiological variants of 18F-DOPA PET/CT in a cohort comprising 107 patients (53 men and 54 women; mean age 54.6 years, range 9–85 years) 20. Patients were referred to our center for suspected NETs, mainly pheochromocytoma (PCC), PGL, and MTC. "
ABSTRACT: Dihydroxyphenylalanine (DOPA) is a neutral amino acid that resembles natural L-dopa (dopamine precursor). It enters the catecholamine metabolic pathway of endogenous L-DOPA in the brain and peripheral tissues. It is amenable to labeling with fluorine-18 (F) for PET imaging and was originally used in patients with Parkinson's disease to assess the integrity of the striatal dopaminergic system. The recent introduction and use of hybrid PET/CT scanners has contributed significantly to the management of a series of other pathologies including neuroendocrine tumors, brain tumors, and pancreatic cell hyperplasia. These pathologic entities present an increased activity of L-DOPA decarboxylase and therefore demonstrate high uptake of F-DOPA. Despite these potentially promising applications in several clinical fields, the role of F-DOPA has not been elucidated completely yet because of associated difficulties in synthesis and availability. Unfortunately, the available literature does not provide recommendations for procedures or administered activity, acquisition timing, and premedication with carbidopa. The aim of this paper is to outline the physiological biodistribution and normal variants, including possible pitfalls that may lead to misinterpretations of the scans in various clinical settings.Nuclear Medicine Communications 10/2013; 34(12). DOI:10.1097/MNM.0000000000000008 · 1.37 Impact Factor
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ABSTRACT: Here, we outline how islet cells use autocrine and paracrine 'circuits' of classical neurotransmitters and their corresponding receptors and transporters to communicate with vicinal β-cells to regulate glucose-stimulated insulin secretion. Many of these same circuits operate in the central nervous system and can be visualized by molecular imaging. We discuss how these techniques might be applied to measuring the dynamics of β-cell function in real time.Diabetes Obesity and Metabolism 10/2012; 14 Suppl 3(s3):91-100. DOI:10.1111/j.1463-1326.2012.01651.x · 5.46 Impact Factor