Objective: To evaluate whether partial volume–corrected cerebral blood flow (pvCBF), with and without additional spatial smoothing (5 mm), improves detection of perfusion differences and clinical correlations in Parkinson’s disease participants without and with mild cognitive impairment (PD-NC and PD-MCI).

Background: Parkinson’s disease (PD) is frequently accompanied by cognitive impairment, including PD-MCI (Aarsland et al., 2021). Disease progression is typically monitored using clinical measures such as the Unified Parkinson’s Disease Rating Scale (UPDRS-III), disease duration (DDX), medication dosage (levodopa equivalent daily dose; LEDD), and neuropsychological testing; however, these measures may not fully capture underlying brain changes. Cerebral blood flow (CBF) measured using arterial spin labeling (ASL) MRI is a sensitive marker of neurodegeneration in PD. Raw CBF maps may be confounded by partial volume effects, potentially reducing sensitivity to detect perfusion differences across cognitive subgroups and their associations with clinical variables.

Method: Fifty-one participants were included: 30 healthy controls (HC), 10 PD-NC, and 11 PD-MCI. Multidelay 3D GraSE pCASL MRI (post-labeling delays: 0.5–2.5 s) was acquired. Using the FSL BASIL toolbox, CBF, partial volume–corrected CBF (pvCBF), and 5 mm–smoothed CBF and pvCBF maps were generated to assess the impact of smoothing. Statistical analyses were performed using PALM (Permutation Analysis of Linear Models) within FSL with family-wise error correction (FWEP) (Winkler et al., 2016). Group differences and correlations with clinical variables—LEDD, disease duration (DDX), and motor severity (UPDRS-III)—were assessed using threshold-free cluster enhancement (TFCE-FWEp < 0.05).

Results: No significant group-level differences were detected across any CBF maps. However, significant positive correlations with LEDD were identified. pvCBF produced the largest cluster of significant voxels compared with standard CBF and 5 mm–smoothed pvCBF (Figure 1A–C).

Conclusion: Partial volume correction improves sensitivity for detecting CBF-LEDD correlations, with pvCBF outperforming both standard CBF and smoothed pvCBF. These findings suggest that pvCBF should be included alongside conventional CBF analyses to better characterize PD pathophysiology.

Fig.1

References: 1. Aarsland D, Batzu L, Halliday GM, et al. Cognitive decline in Parkinson’s disease. Nat Rev Neurol. 2021 ;7:47.
2. Winkler AM, Ridgway GR, Douaud G, Nichols TE, Smith SM. Faster permutation inference in brain imaging. NeuroImage 2016;141:502-516.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/correlations-between-clinical-variables-and-cerebral-perfusion-in-parkinsons-disease-with-mild-cognitive-impairment-a-multi-delay-pcasl-study/