Variability of FP-CIT PET Patterns Associated with Clinical Features of Multiple System Atrophy

Objective To validate the role of the dopamine transporter (DAT) imaging as a biomarker in multiple system atrophy (MSA), we analyzed the association between spatial patterns of [¹⁸F]fluoro-propyl-carbomethoxy-iodophenyl-tropane ([¹⁸F]FP-CIT) PET and the clinical characteristics of MSA.

Methods Sixty-five MSA patients who underwent [¹⁸F]FP-CIT PET between 2009 and 2018 were retrospectively enrolled. To identify spatial patterns of [¹⁸F]FP-CIT PET, principal component analysis (PCA) was employed and correlated with the clinical presentation.

Results Of the 65 subjects, 42 presented with Parkinsonian subtype of MSA (MSA-P), and 23 presented with cerebellar subtype of MSA (MSA-C) (mean age, 63.7 ± 9.3 years; disease duration, 1.8 ± 1.8 years). Each PC represents a specific pattern of degeneration: PC1 and PC2 were associated with the DAT binding of the entire putamen and the posterior putamen, respectively. PC3 was associated with increased [¹⁸F]FP-CIT uptake of the caudate and decreased uptake of the dorsal pons. PC2 was significantly correlated with the presence of parkinsonism (p = 5.34 × 10⁻⁵) and a positive levodopa response (p = 0.044), with age as a cofactor. PC3 was correlated with the presence of urinary incontinence (p = 0.036). Onset age was significantly correlated with both PC2 (R = 0.48, p = 5.0 × 10⁻⁵) and PC3 (R = −0.39, p = 0.0013).

Conclusions The spatial pattern of DAT binding can reflect distinct clinical features of MSA and provides insight about the underlying pathophysiology of a broad spectrum of clinical features in MSA.