Can nigrosome 1 assessment via susceptibility map-weighted imaging (SMwI) predict presynaptic DAT PET results in RBD patients?

Motivation: RBD is a prodromal symptom of Parkinson's disease, and DAT-PET aids in diagnosis. However, its accessibility is limited, and SMwI has not been studied as a screening tool. Goal(s): This study aims to evaluate how accurately SMwI predicts presynaptic dopaminergic function in RBD patients, addressing a critical gap in current research. Approach: A review of RBD patients diagnosed by polysomnography was conducted, with all undergoing MRI, DAT-PET, and SMwI comparison analysis Results: In 64 patients, DAT-PET showed decreased uptake in 56.3%, with SMwI missing 15.6% of these. SMwI detected abnormalities in 6.3% not found by DAT-PET, with 72.2% sensitivity and 85.7% specificity. Impact: In RBD patients, nigrosome 1 evaluation using SMwI showed moderate agreement with DAT PET. However, SMwI's diagnostic sensitivity was lower than in Parkinson's disease, indicating it may not sufficiently replace DAT PET in RBD diagnosis.