MIBG Myocardial Scintigraphy Identifies Premotor PD/DLB During a Negative DAT Scan Period: Second Report

Objectives Neuroimaging markers for Parkinson's disease (PD)/dementia with Lewy bodies (DLB) include dopamine transporter (DAT) scanning and metaiodobenzylguanidine (MIBG) myocardial scintigraphy. It is unknown which marker is useful to identify the premotor phase PD/DLB. We reported four patients who, during a negative DAT scan period, had a positive MIBG result that suggested premotor PD/DLB. Here we report 18 additional patients. Methods This study was a prospective cohort study. The recruiting period was five years; prospective follow‐up period, 5.5 ± 3.0 years; and a once a year (minimum) follow‐up visit. We recruited 745 referred subjects. The inclusion criteria were having at least one of the following known PD nonmotor features: (1) autonomic: postural hypotension (pure autonomic failure [PAF]), constipation, bladder dysfunction; (2) sleep: REM sleep behavior disorder (RBD); and (3) cognitive: mild cognitive impairment or psychiatric symptoms. Also, the patient had to have undergone both DAT and MIBG tests. Results Only 18 patients fulfilled these criteria. Their characteristics were: elderly (mean age 75.5 years), with long histories (onset 61.0 years; duration 14.5 years), and predominately male (14 men, four women). The patients' neurologic diagnoses were constipation/RBD in 10, constipation/RBD/PAF in six, and constipation/PAF in two. During the follow‐up period, seven patients developed PD or DLB. An abnormal MIBG result was noted in 94%, and an abnormal DAT result was noted in 56%. Conclusions MIBG has the potential to be a useful marker during the DAT scan negative period to identify premotor PD/DLB, but further studies are needed.