Tectal Plate Morphometric Measurements as Biomarker for Differentiating Progressive Supranuclear Palsy, Multiple System Atrophy and Parkinson`s Disease

Backround: Progressive supranuclear palsy (PSP) can be difficult to distinguish clinically from Parkinson`s disease (PD) and multiple system atrophy (MSA), particularly at presentation. This study evaluated tectal plate morphometric measurements on MRI and their utility in differentiating PSP, MSA, and PD.

Methods: This retrospective study included patients with established diagnoses of PD, PSP, and MSA who underwent volumetric T1-weighted brain MRI. PD and PSP cohorts were age- and sex-matched; the MSA group was included without matching. Tectal plate length, width, and surface area, as well as superior and inferior collicular widths, were measured and adjusted for total brain volume. ROC analysis was performed to evaluate the diagnostic performance of tectal plate length alone and in models incorporating age and sex.

Results: The cohort comprised 65 patients with PD, 66 with PSP, and 47 with MSA. Age- and sex-matched PD and PSP groups had similar mean ages (70.8 ± 7.5 and 70.4 ± 7.5 years) and sex distributions (66.2% and 66.7% male). MSA patients were younger (55.3 ± 7.9 years), with 55.8% male. Tectal plate surface area differed across diagnostic groups (overall p = 0.019), with lower values in PSP than in MSA and PD. Tectal plate length alone yielded AUCs of 0.764 for PSP versus MSA, 0.644 for PD versus MSA, and 0.625 for PSP versus PD. Models incorporating tectal plate length, age, and sex yielded AUCs of 0.924, 0.928, and 0.621, respectively.

Conclusions: Tectal plate morphometry differs among parkinsonian syndromes. Tectal plate length showed moderate discrimination between PSP and MSA but limited discrimination between PD and MSA or PSP and PD when considered alone. The substantially higher performance of models incorporating age and sex for comparisons involving MSA warrants further evaluation in age-matched cohorts.