Doença de Parkinson: neuroimagem do transportador de dopamina em casos de dúvida diagnóstica (Resumo)

Introduction: Misdiagnosis in Parkinson’s disease (PD) can reach 25%. Recently, single-photon emission computer tomography (SPECT), using dopamine transporter (DAT) radioligands, has become useful to help diagnose clinically unclear cases of Parkinsonism (CUCP). Objectives: Study 1 reported the rationale of molecular imaging in CUCP. Study 2 evaluated the role of DAT neuroimaging in CUCP. Study 3 studied a sub-group of CUCP with psychogenic Parkinsonism. Study 4 investigated the relationship between DAT and depression in PD. Methods: Brain SPECT imaging was undertaken using the DAT radiotracer [99mTc]-TRODAT-1 at baseline to determine pre-synaptic dopaminergic dysfunction. Patients were followed-up, and a final clinical diagnosis was made. Results: In study 1, convincing evidence showed that molecular imaging can reduce diagnostic uncertainty in PD. In study 2, disagreement rate between SPECT imaging versus golden standard clinical diagnosis reached 20%. Sensitivity and specificity (DAT scan) were, respectively, 100 and 70%. However, in study 3, two out of five subjects with psychogenic Parkinsonism had DAT densities under the cut-off suggesting a degenerative Parkinsonism. In study 4, DAT density was greater in PD patients with depression. Conclusions: This thesis confirmed the useful role of molecular imaging in CUCP, and provided in vivo information about different underlying PD-related physiopathology mechanisms.