Contribution of MRI for the Early Diagnosis of Parkinsonism in Patients with Diagnostic Uncertainty

Background International clinical criteria are the reference for the diagnosis of degenerative parkinsonism in clinical research, but they may lack sensitivity and specificity in the early stages. Objectives To determine whether magnetic resonance imaging (MRI) analysis, through visual reading or machine‐learning approaches, improves diagnostic accuracy compared with clinical diagnosis at an early stage in patients referred for suspected degenerative parkinsonism. Materials Patients with initial diagnostic uncertainty between Parkinson's disease (PD), progressive supranuclear palsy (PSP), and multisystem atrophy (MSA), with brain MRI performed at the initial visit (V1) and available 2‐year follow‐up (V2), were included. We evaluated the accuracy of the diagnosis established based on: (1) the international clinical diagnostic criteria for PD, PSP, and MSA at V1 (“Clin1”); (2) MRI visual reading blinded to the clinical diagnosis (“MRI”); (3) both MRI visual reading and clinical criteria at V1 (“MRI and Clin1”), and (4) a machine‐learning algorithm (“Algorithm”). The gold standard diagnosis was established by expert consensus after a 2‐year follow‐up. Results We recruited 113 patients (53 with PD, 31 with PSP, and 29 with MSA). Considering the whole population, compared with clinical criteria at the initial visit (“Clin1”: balanced accuracy, 66.2%), MRI visual reading showed a diagnostic gain of 14.3% (“MRI”: 80.5%; P = 0.01), increasing to 19.2% when combined with the clinical diagnosis at the initial visit (“MRI and Clin1”: 85.4%; P