Co-registration Analysis of Fluorodopa and Fluorodeoxyglucose Positron Emission Tomography for Differentiating Multiple System Atrophy Parkinsonism Type From Parkinson's Disease

Abstract

It is difficult to differentiate between Parkinson's disease and multiple system atrophy parkinsonian subtype (MSA-P) because of the overlap of their signs and symptoms. Enormous efforts have been made to develop positron emission tomography (PET) imaging to differentiate these diseases. This study aimed to investigate the co-registration analysis of ¹⁸F-fluorodopa and ¹⁸F-flurodeoxyglucose PET images to visualize the difference between Parkinson's disease and MSA-P. We enrolled 29 Parkinson's disease patients, 28 MSA-P patients, and 10 healthy controls, who underwent both ¹⁸F-fluorodopa and ¹⁸F-flurodeoxyglucose PET scans. Patients with Parkinson's disease and MSA-P exhibited reduced bilateral striatal ¹⁸F-fluorodopa uptake (p < 0.05, vs. healthy controls). Both regional specific uptake ratio analysis and statistical parametric mapping analysis of ¹⁸F-flurodeoxyglucose PET revealed hypometabolism in the bilateral putamen of MSA-P patients and hypermetabolism in the bilateral putamen of Parkinson's disease patients. There was a significant positive correlation between ¹⁸F-flurodeoxyglucose uptake and ¹⁸F-fluorodopa uptake in the contralateral posterior putamen of MSA-P patients (rs = 0.558, p = 0.002). Both ¹⁸F-flurodeoxyglucose and ¹⁸F-fluorodopa PET images showed that the striatum was rabbit-shaped in the healthy control group segmentation analysis. A defective rabbit-shaped striatum was observed in the ¹⁸F-fluorodopa PET image of patients with Parkinson's disease and MSA-P. In the segmentation analysis of ¹⁸F-flurodeoxyglucose PET image, an intact rabbit-shaped striatum was observed in Parkinson's disease patients, whereas a defective rabbit-shaped striatum was observed in MSA-P patients. These findings suggest that there were significant differences in the co-registration analysis of ¹⁸F-flurodeoxyglucose and ¹⁸F-fluorodopa PET images, which could be used in the individual analysis to differentiate Parkinson's disease from MSA-P.

Keywords: F-DOPA; FDG; PET; Parkinson's disease; mutiple system atrophy.

Figure 1

PET/CT image co-registration processing. (A) The first step was to make the co-registration of two CT images using 3D Slicer software. (B) The second step was to make automatic registration of the ¹⁸F-FDG and ¹⁸F-Dopa PET images.

Figure 2

Segmentation of striatal PET images of participants. The striatal segments of ¹⁸F-Dopa PET (PD: blue color; MSA-P: green color; HC: yellow color) and ¹⁸F-FDG PET (red color) images were labeled with different colors. Co-registration analysis showed that the segments of striatum in ¹⁸F-FDG and ¹⁸F-Dopa PET of PD patients were mismatched, with intact striatal segments in ¹⁸F-FDG PET and damaged striatal segments in¹⁸F-Dopa PET. The segments of striatum in MSA-P and HC groups were matched in ¹⁸F-FDG and ¹⁸F-Dopa PET images. The striatal segments were defective in MSA-P patients, whereas intact in the HC group.

Figure 3

Three-dimensional visualization of striatal PET images of participants. The striatal segments of ¹⁸F-Dopa PET (PD: blue color; MSA-P: green color; HC: yellow color) and ¹⁸F-FDG PET (red color) images were labeled with different colors. Both ¹⁸F-FDG and ¹⁸F-Dopa PET images showed that the striatum had a rabbit-shaped appearance in the HC group. A defective rabbit-shaped striatum was shown in the ¹⁸F-Dopa PET image of patients with PD and MSA-P. In the ¹⁸F-FDG PET image, an intact rabbit-shaped striatum was shown in PD patients, whereas a defective rabbit-shaped striatum was shown in MSA-P patients.

Figure 4

SPM analysis of 18F-FDG PET. (A) MSA patients vs. normal controls showed hypometabolism in the bilateral putamen. (B) PD patients vs. normal controls showed hypermetabolism in the bilateral putamen, cerebellum, and occipital lobes, along with hypometabolism in the frontal, parietal, postcentral cortices, and cingulate areas.