Objective: To characterize choroid plexus (ChP) morphology and enhancement in multiple system atrophy (MSA) and Parkinson’s disease (PD), investigate their associations with ventricular morphology and infratentorial neurodegeneration, and evaluate their diagnostic performance for early MSA.

Background: MSA and PD share overlapping clinical manifestations but arise from distinct neurodegenerative processes. While MRI studies have largely focused on regional atrophy, the choroid plexus (ChP), a regulator of cerebrospinal fluid (CSF) production and the blood–CSF barrier, may capture disease-specific interactions among CSF dynamics, ventricular morphology, and neurodegeneration.

Method: Age- and sex-matched patients with PD (n=62) and MSA (n=62) underwent non-contrast and contrast-enhanced T1-weighted MRI. After spatial normalization, ChP volume and its contrast enhancement ratio (ER) were quantified, together with ventricular and infratentorial structures. Associations among these measures were analyzed. Diagnostic performance was evaluated using logistic regression with stratified 5-fold cross-validation in the overall cohort and in early-stage (≤2.31 years) and late-stage (>2.31 years) MSA versus PD. Performance was assessed using the area under the receiver operating characteristic curve (AUC) and balanced accuracy (ACC) with 95% bootstrap confidence intervals.

Results: MSA showed significantly larger ChP volume (0.193±0.043% vs 0.159±0.033%; p<0.0001) and higher ER (1.575±0.494 vs 1.059±0.955; p<0.001) than PD. In MSA, ChP volume correlated positively with lateral and third ventricular volumes, while cerebellar white matter (CbWM) volume inversely correlated with the fourth ventricular volume. In PD, CbWM volume inversely correlated with lateral and third ventricular volumes. Integrating ChP with regional atrophy markers improved discrimination of early MSA. Specifically, combining ChP with CbWM increased balanced accuracy from 0.82 to 0.89 and AUC from 0.89 to 0.92 (p=0.026 for ACC).

Conclusion: MSA and PD demonstrate distinct coupling patterns between ChP, ventricular morphology, and regional atrophy, suggesting differential interactions between CSF regulation and neurodegeneration. Incorporating ChP metrics with regional atrophy improves early diagnostic discrimination, supporting ChP as a complementary imaging marker for differentiating MSA and PD.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/choroid-plexus-morphology-and-enhancement-as-imaging-markers-for-early-differentiation-of-multiple-system-atrophy-and-parkinsons-disease/