Iranzo A et al. – The study evaluated the use of dopamine transporter (DAT) imaging for the identification of patients with idiopathic rapid eye movement (REM) sleep behavior disorder (IRBD), who are at a risk of short–term development of clinically defined synucleinopathy.

Methods

• A total of 87 patients with polysomnography–confirmed IRBD, who underwent 123I–fluoropropyl–2–beta–carbomethoxy–3–beta–(4–iodophenyl)nortropane (FP–CIT) DAT–SPECT (123I–FP–CIT DAT–SPECT) imaging were compared with 20 matched controls without RBD underwent DAT–SPECT.
• Patients were followed up to 5.7 ± 2.2 years after DAT–SPECT.

Results

• A total of 58.6% patients showed baseline DAT deficit, whereas 28.7% patients developed clinically–defined synucleinopathy (Parkinson disease [n = 11], dementia with Lewy bodies [n = 13], and multiple system atrophy [n = 1] during follow–up, with mean latency of 3.2 ± 1.9 years from imaging.
• An increased risk of incident synucleinopathy was observed in patients with abnormal DAT–SPECT compared with normal DAT–SPECT (20% vs 6% at 3 years; 33% vs 18% at 5 years).
• At 5–year follow–up, DAT–SPECT showed a sensitivity, specificity, positive predictive value, and negative predictive value of 75%, 51%, 44%, and 88%, respectively, along with a like–hood ratio of 1.54 to predict synucleinopathy.