Automated Volumetric Assessment of the Pallidum and Ventral Diencephalon for Differentiating Progressive Supranuclear Palsy from Parkinson’s Disease

Background/Objectives: Progressive supranuclear palsy (PSP) and Parkinson’s disease (PD) share several clinical manifestations, which may complicate differential diagnosis. The aim of this study was to evaluate whether automated volumetric measurements of the pallidum and ventral diencephalon can differentiate PSP from PD. Methods: Thirty-two patients were included, comprising 20 patients with PD and 12 patients with PSP. All participants underwent 3-T brain magnetic resonance imaging. Automated segmentation and volumetric analysis were performed using the vol2Brain pipeline. Absolute and normalized volumes of the pallidum and ventral diencephalon were compared between groups. Receiver operating characteristic (ROC) analysis was used to assess diagnostic performance. Results: Patients with PSP demonstrated lower pallidal and ventral diencephalic volumes than patients with PD. Differences were observed for both absolute and normalized volumetric measurements (all p ≤ 0.002). Total pallidal volume showed the highest diagnostic performance, with an area under the ROC curve (AUC) of 0.958, sensitivity of 85%, and specificity of 100%. Total ventral diencephalon volume also differentiated PSP from PD, yielding an AUC of 0.829, seNsitivity of 70%, and specificity of 92%. Conclusions: Pallidal and ventral diencephalic volumes differed between patients with PSP and PD. Automated measurements of pallidal and ventral diencephalic volumes may complement conventional MRI findings in patients with parkinsonian syndromes. Further studies are needed to validate these findings in larger cohorts.