Rapid eye movement sleep behavior disorder in tremor and non-tremor Parkinson’s disease show different patterns of ¹¹C-CFT and ¹⁸F-FDG PET/CT imaging

Introduction: Rapid eye movement sleep behavior disorder (RBD) is a parasomnia characterized by loss of atonia during the rapid eye movement (REM) period, and accompanied by recurrent dream enactment, often violent. Previous studies have suggested that RBD can be a prodromal symptom of Parkinson’s disease (PD), and it will gradually progress into PD by the time. However, for those patients who have been already diagnosed as PD, RBD can be also regarded as a non-motor accompanied symptom of PD. This often indicates a greater disease burden, cognitive impairment or mental disorder, and poor prognosis of PD. To explore the relationship between the metabolic patterns and different PD clinical phenotypes, and whether the metabolic characteristics can reflect the PD disease progression, we investigated the dopamine transporter (DAT) and glucose metabolic PET imaging in RBD associated PD patients with or without tremor. Materials and Methods: ¹¹C-2-beta-carbomethoxy-3-beta-(4-fluorophenyl) tropane (CFT) together with ¹⁸F-Fluorodeoxyglucose (FDG) PET/CT scans of 41 consecutive patients with a clinical diagnosis of PD and abnormal DAT binding [31 tremor: 10 RBD positive (+) and 21 RBD negative (-); 10 non-tremor: 5 RBD(+) and 5 RBD(-)] were enrolled. ¹¹C-CFT uptake values in caudate nucleus, anterior putamen and posterior putamen as well as ¹⁸F-FDG uptake values in all the brain regions were processed manually and automatically by regions of interest (ROI) approach.

Results: Caudate dopamine depletion of the ¹¹C-CFT PET/CT imaging in PD patients with tremor was milder than patients without tremor (2.94±0.59 vs 2.62±0.59; P<0.05). Yet thalamus glucose uptake of non-tremor PD patients showed more active than tremor patients (1.15±0.05 vs 1.11±0.04; P<0.01). Sorted by RBD symptom, tremor-dominant RBD(+) patients showed severe dopamine depletion in caudate and anterior putamen than RBD(-) patients with tremor (caudate: 2.59±0.52 vs 3.10±0.56,anterior putamen: 2.26±0.40 vs 2.57±0.50;P<0.05, respectively). As for RBD(+) PD, non-tremor patients were characterized by glucose uptake increase in putamen and thalamus than tremor-dominant patients (putamen: 1.01±0.05 vs 0.96±0.04,thalamus: 1.15±0.04 vs 1.10±0.04; P<0.01, respectively). And glucose metabolic decrease of posterior parietal cortex was found in RBD(-) patients with tremor rather than RBD(+) tremor-dominant PD (0.99±0.05 vs 1.03±0.05; P<0.05).

Conclusions: Multimode PET/CT imaging of dopamine transporter together with glucose metabolic phenotypes contribute to the dynamic integration of non-motor symptom RBD as well as different PD motor subtypes, thus provide information for clinical practice and differential diagnosis. Acknowledgement: This work was supported by grants from National Natural Science Foundation of China (No. 81701725), and Shanghai "Rising Stars of Medical Talent" Youth Development Program (SHDC2012105).