Striatal dopamine transporter imaging (FMT-PET) in patients with idiopathic rapid eye movement sleep behavior disorder – A cross-sectional study

Abstract

Introduction It has become clear that Parkinson’s disease (PD) can have a premotor stage such as idiopathic REM sleep behavior disorder (IRBD). Imaging technologies such as dopamine transporter imaging currently offer the highest degree of accuracy for identifying premotor PD. Recent dopamine transporter SPECT and PET studies demonstrated decreased striatal dopaminergic innervations in IRBD patients. Materials and methods Positron emission tomography (PET) with 6-[(18)F](FMT), which can assess the level of the presynaptic dopaminergic nerve, were performed in 44 patients with IRBD, 14 patients with PD and 14 control subjects to assess nigrostriatal function. Results There were significant differences in the group 6-[18F] FMT uptake levels in bilateral putamen between PD patients and both IRBD patients and control subjects. IRBD patients with no signs of parkinsonism had almost intact striatal dopaminergic innervation, similar to the controls. In contrast, PD patients had parkinsonism by definition and had lost striatal dopaminergic innervation, as evidenced by decreased striatal uptake. Conclusion PET imaging seem to be helpful in identifying patients with IRBD potentially at risk to develop PD, dementia of Lewy body (DLB), or multiple system atrophy (MSA). However, more longitudinal follow-up studies are necessary to estimate the ratio of patients with dopaminergic cell loss in the basal ganglia who will develop PD, DLB, or MSA in the future. Acknowledgements This work was supported by Grant-in-Aid for Scientific Research (C) from the Ministry of Education, Culture, Sports, Science and Technology (MEXT) of Japan (Grant No. 24621009 ). The authors thank Junichi Saitou and Toshihiko Satou (PET Center, Ustunomiya Central Clinic) for their technical support in performing FMT/PET.