Magnetic Susceptibility and Area in the Subthalamic Nucleus Measured by QSM for Diagnosis of Progressive Supranuclear Palsy.

Background: Iron deposition and atrophy of the subthalamic nucleus (STN) have been reported in progressive supranuclear palsy (PSP). Quantitative susceptibility mapping (QSM), an advanced MRI technique, enables noninvasive assessment of the magnetic susceptibility of biological tissue and has been reported to have good ability to delineate STN.

Objective: The aim of this study is to evaluate the diagnostic accuracy of a model using magnetic susceptibility and area of the STN assessed by QSM to differentiate PSP from Parkinson's disease (PD).

Methods: A total of 35 patients with PSP and 28 patients with PD were recruited. Magnetic susceptibility and area of the STN were measured by QSM. Axial and coronal scans were acquired to measure the STN magnetic susceptibility and area. The area under the receiver operating characteristic curve (AUC) was used to evaluate the diagnostic accuracy for differentiating PSP from PD.

Results: In the axial scan group, STN susceptibility was significantly higher in PSP than PD (p = 0.047), with no difference in the coronal scan group (p = 0.066). PSP patients had a smaller STN area than PD in both axial (p < 0.001) and coronal (p = 0.002) scan groups. The combination of these metrics showed high diagnostic accuracy (Axial, AUC = 0.87; Coronal, AUC = 1.00) and excellent performance (AUC = 0.98) in cases within 3 years of onset.

Conclusions: A combination of magnetic susceptibility and area of the STN measured by QSM can be used to discriminate PSP from PD, even at early stages.