The value of putaminal diffusion imaging versus 18‐fluorodeoxyglucose positron emission tomography for the differential diagnosis of the Parkinson variant of multiple system atrophy

Abstract

Differentiating the Parkinson variant of multiple system atrophy (MSA-P) from idiopathic Parkinson's disease (PD) and other forms of atypical parkinsonism can be difficult because symptoms overlap considerably. 18-Fluorodeoxyglucose positron emission tomography (FDG-PET) is a powerful imaging technique that can assist in the diagnosis of MSA-P via detection of putaminal and cerebellar hypometabolism. Recent studies suggest that diffusion-weighted imaging (DWI) might be of similar diagnostic value, as it can detect microstructural damage in the putamen by means of an increased mean diffusivity (MD). The aim of this study was a direct comparison of DWI and FDG-PET by using both methods on the same subject cohort. To this end, combined DWI and FDG-PET were employed in patients with MSA-P (n = 11), PD (n = 13), progressive supranuclear palsy (n = 8), and in 6 control subjects. MD values and FDG uptake ratios were derived from volumetric parcellations of the putamen and subjected to further analysis of covariance (ANCOVA) and receiver operating characteristics analyses. MSA-P was found to be associated with an increased posterior putaminal MD (P < 0.001 in all subgroup comparisons) that correlated strongly with local reductions in FDG uptake (r = -0.85, P = 0.002). DWI discriminated patients with MSA-P from other subgroups nearly as accurately as FDG-PET (area under the curve = 0.89 vs 0.95, P = 0.27 [pooled data]). Our data suggest a close association between the amount of putaminal microstructural damage and a reduced energy metabolism in patients with MSA-P. The clinical use of DWI for the differential diagnosis of MSA-P is encouraged.

Diagnosis of multiple system atrophy

“…Movement of water molecules is typically increased in degenerating and ischemic neural tissue. Compared to PD, increased putaminal diffusivity in MSA-P has been consistently reported, even in early disease stages (Barbagallo et al, 2016; Baudrexel et al, 2014; Pellecchia et al, 2009; Schocke et al, 2002; Schocke et al, 2004; Seppi et al, 2004). DWI might be useful in distinguishing MSA-P from PSP (Paviour et al, 2007).…”

Imaging biomarkers in Parkinson’s disease and Parkinsonian syndromes: current and emerging concepts

“…MSA patients exhibit impaired glucose metabolism in the bilateral basal ganglia, putamen, pons and cerebellum, compared to PD and controls [156, 157]. A multimodal study combining FDG-PET with DTI detected an elevated D̄ in posterior putamen of MSA- P patients that corresponded with local reductions in FDG metabolism [158], suggesting an association between putaminal microstructural damage and related metabolic dysfunction in the brain.…”

Imaging-based differential diagnosis between multiple system atrophy and Parkinson's disease

“…To address this issue, many objective methods have been tested for the differential diagnosis, such as proteins in cerebrospinal fluid (CSF), [5,6] magnetic resonance imaging (MRI) and positron emission tomography (PET) [7][8][9][10][11][12][13][14][15][16][17][18]. PET could be a reliable tool for the differential diagnosis of parkinsonian syndromes, [15,17,18] although the use of PET was limited due to radiation and invasive properties. In contrast, MRI can be performed without radiation or invasion, and MRI sequences permit examination of size and water diffusivity in targeted regions.…”

“…In contrast, MRI can be performed without radiation or invasion, and MRI sequences permit examination of size and water diffusivity in targeted regions. Volume, area, width and apparent diffusion coefficient (ADC) have been utilized to make a differential diagnosis in the putamen, cerebellum and middle cerebellar peduncle (MCP) [7][8][9][10][11][12][13][14][15][16]. These methods provided relatively high sensitivity and specificity.…”