Characteristics of cerebral glucose metabolism in patients with cognitive impairment in multiple system atrophy

We aimed to conduct ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography (PET) to investigate the metabolic changes in brain regions associated with cognitive decline in patients with multiple system atrophy (MSA) and to assess the diagnostic efficacy of ¹⁸F-FDG PET imaging for evaluating the cognitive status of MSA patients.

This study included 44 MSA patients (MSA group) and 30 healthy controls (HC group) who underwent brain ¹⁸F-FDG PET imaging. All patients were subjected to the Mini-Mental State Examination and categorized into the MSA with normal cognition (MSA-NC) and MSA with cognitive impairment (MSA-CI) groups. Statistical parametric mapping (version 12) was used to analyze PET images and compare the differences in brain metabolism between the MSA and HC groups. The PET images of MSA-CI and MSA-NC patients were compared to analyze the metabolic characteristics, and the regional cerebral metabolic rate of glucose (rCMRglc) was calculated for different brain regions. Receiver operating characteristic (ROC) curves were used to analyze the ability of the rCMRglc of different brain regions to assess the cognitive status of MSA patients.

Compared with the HC group, the MSA group showed diffuse reductions in glucose metabolism in the cerebellar regions, decreased metabolism in specific areas of the left inferior parietal lobule, right putamen, and left middle temporal gyrus, and increased metabolism in the left postcentral gyrus, right postcentral gyrus, left precuneus. Compared with the MSA-NC group, the MSA-CI group exhibited decreased metabolism in the right superior frontal gyrus and right superior parietal lobule. The rCMRglc value of the right superior frontal gyrus (Montreal Neurological Institute coordinates: 18, -6, 70) showed better diagnostic efficacy for identifying MSA-CI, with an area under the ROC curve of 0.829 (95%CI = 0.696-0.963), sensitivity of 84.6% (95%CI = 66.5-93.9%), and specificity of 83.3% (95%CI = 60.8-94.2%).

Compared with MSA-NC patients, the MSA-CI patients show decreased metabolism in the right superior frontal gyrus and right superior parietal lobule. The rCMRglc value of the right superior frontal gyrus may be a potential molecular imaging biomarker for diagnosing MSA-CI.