18F-FDOPA - Ronny Allan - Living with Neuroendocrine Cancer

Tag: 18F-FDOPA

L-DOPA (L-dihydroxyphenylalanine) is the immediate precursor of dopamine, a neurotransmitter in the central nervous system predominantly found in the nigrostriatal region, and defects in this region are strongly related to neurodegenerative and movement disorders (3). Although dopamine in the circulation does not cross the blood–brain barrier, L-DOPA is carried into the brain by the large neutral amino acid transport system, converted into dopamine by the action of L-aromatic amino acid decarboxylase, and then stored in intraneuronal vesicles, from which it is released when the nerve cell fires. Because ¹⁸F-DOPA is an analog of L-DOPA, this positron-emitting compound is clinically used to trace the dopaminergic pathway and to evaluate striatal dopaminergic presynaptic function.

The large neutral amino acid transport system is highly expressed not only in the nigrostriatal region as a physiologic feature of normal brain but also in brain tumours as a pathologic feature, causing an increased uptake of amino acids, compared with that in normal brain. Because of this observation, some researchers have used ¹⁸F-DOPA for the functional evaluation of brain neoplasms.

A similar characteristic is present in extracranial APUD tumours. APUD, or “amine precursor uptake and decarboxylation,” indicates the capacity to take up amino acids and transform them into biogenic amines by means of decarboxylation. Having that capacity is why APUD tumours show a markedly increased uptake of ¹⁸F-DOPA and can be evaluated by means of ¹⁸F-DOPA PET. Like APUD tumours, normal islets in the pancreas also take up a small amount of ¹⁸F-DOPA and decarboxylate it to produce insulin. In hyperfunctioning islets (as in cases of insulinomas or primary hyperinsulinemia), the uptake can be quite pronounced, and ¹⁸F-DOPA PET can be of value for evaluating those patients.

See my article on scans – click here

14Dec 2016 by Ronny Allan 4 Comments

Neuroendocrine Tumours: a spotlight on Pheochromocytoma and Paraganglioma

A spotlight on NENs - Types, Awareness, Patient Advocacy, Spotlight on NENs - Types Series

Updated 6th August 2023I spend a lot of time talking about the most common forms of Neuroendocrine Tumours (NETs), but what about the less well-known types? As part of my commitment to all types of NETs, I'd like to shine a light on two less common tumour types known as Pheochromocytomas and Paragangliomas - with an incidence rate of approximately 8 per million per year. They are normally grouped together, and the definitions below will confirm why. If you think it's difficult to diagnose a mainstream NET, this particular sub-type is a real challenge.So, let's get definitions out of the way:Pheochromocytomas (Pheo for short)Pheochromocytomas are tumours of the adrenal gland that produce excess adrenaline. They arise from the central portion of the adrenal gland, which is called the adrenal medulla…

05Nov 2016 by Ronny Allan 8 Comments

Neuroendocrine Cancer – If you can see it, you can detect it!

Living with Neuroendocrine Cancer, Survivorship

Content in my review queue (line). Background Scanning is a key diagnostic support and surveillance tool for any cancer. Even though you have elevated bloods or urine (....or not), a picture of your insides is really like a thousand words.... and each picture has a story behind it. Scanning can be a game changer in the hunt for tumours and although scans do not normally confirm the cancer type and grade, they certainly help with that piece of detective work and are key in the staging of the cancer. When I read stories of people in a difficult diagnosis, I always find myself saying 'a scan might resolve this' and I always suggest people should try to get one. Even in the case of a story about late diagnosis or a misdiagnosis, I…