Importance of proper window setting in visual assessment of dopamine transporter imaging: A case of early-onset Parkinsonism related to Park2 gene mutation

In the early stages or atypical manifestation of parkinsonism, dopamine transporter imaging can assist the early diagnosis. We describe a 19 year-old man presenting with progressive gait disturbance, cervical dystonia and head tremor. 18F-FP-CIT PET (FluoroPropyl-Carbomethoxylodopropyl-nor-BTropane positron emission tomography) was done and interpreted as normal at other hospital, and his diagnosis remained baffling. He visited our hospital several months later, and the FP-CIT PET image was reviewed by the nuclear medicine physician in our hospital, who also interpreted it as normal. However, we reviewed his FP CIT-PET image because his clinical picture was strongly suggestive of juvenile parkinsonism. After adjusting the window setting of the PET image, we could appreciate the decreased uptake in the bilateral basal ganglia. Thus he was finally diagnosed as juvenile parkinsonism and gene test confirmed Park2 gene mutation. In conclusion, proper window setting is important during visual assessment of dopamine transporter imaging. Neurology Asia 2016; 21(2) : 187 – 189 Address correspondence to: Beomseok Jeon, MD, PhD, Department of Neurology, Seoul National University Hospital, Seoul, 110-744, Korea. Tel: 82-2-2072-2876, e-mail: [email protected] INTRODUCTION Dopamine transporter imaging discriminates patients with Parkinson’s disease from healthy individuals, identifying presynaptic dopaminergic deficits in the caudate and putamen with high specificity and sensitivity, even in the early course of the disease, and can be used to differentiate between neurodegenerative parkinsonism and its mimics. Diagnosis of early-onset parkinsonism is often challenging, because rigidity and painful cramps as the predominant initial symptoms are more frequent in the younger group while gait instability as the predominant initial symptoms is more frequent in the older group. In those cases, biomarkers such as dopamine system imaging can assist the diagnosis. However, misinterpretation of dopamine transporter imaging can lead to confusion of diagnosis. We describe a young man with gait difficulty, painful cramps, dystonia, and tremor. In this case, misreading of 18F-FP-CIT positron emission tomography (PET) resulted in confusion in diagnostic process.