Incidental Detection of Meningioma in Suspected Parkinsonism Patients - A Case Series on 18 F-DOPA PET/MRI

Fluorine-18-l-dihydroxyphenylalanine (18F-DOPA) is a versatile positron emission tomography (PET) agent that can be utilised for Parkinson's disease diagnosis as well as for tumour imaging. The neutral amino acid DOPA is similar to the natural dopamine precursor L-DOPA. The activity of the aromatic L-amino acid decarboxylase and the density of catecholaminergic terminals are both reflected in the uptake of 18F-DOPA in the striatal nuclei. Therefore, the number of surviving dopaminergic cells will affect measurements of 18F-DOPA uptake in the striatum of PD patients. The prolonged retention of 18F-FDOPA in tumours that release serotonin and catecholamines is likely explained by the L-amino acid transporters' role in transporting amino acids, which are subsequently used for protein synthesis in malignancies. This study demonstrates the versatility of 18F-DOPA by presenting two unique cases that came for an 18F-DOPA PET/scan with a clinical suspicion of Parkinson's disease. Coincidentally, we discovered DOPA avid meningioma in these two patients.