Abstract

Background
Assessing amyloid-positivity in patients with mild cognitive impairment (MCI) is crucial as amyloid-positive individuals have a higher risk of dementia conversion than amyloid-negative patients. This study aimed to investigate whether the asymmetry of white matter lesions (WML) on T2-fluid attenuated inversion recovery (FLAIR) magnetic resonance imaging (MRI), measured by artificial intelligence (AI) hyperintensity segmentation, could be a potential indicator for amyloid positron emission tomography (PET) positivity in patients with MCI.

Method
This retrospective cohort study included MCI patients who visited the memory clinic of Yeouido St. Mary’s Hospital. All participants underwent a set of clinical and neuropsychological assessments, brain MRI, and amyloid PET using [18F]-Flutemetamol. Our in-house AI software was utilized on paired T1 and T2-FLAIR MRIs to process to segment and separate WML into left and right hemispheres. From the processed segmentation, we measured the subjects' individual WML differences through a volumetric assessment.

Results
Total 122 subjects were enrolled in this study. By the amyloid-PET positivity, 53 and 69 patients were in the amyloid-negative and amyloid-positive groups, respectively. The two groups were comparable with no significant differences of age (p = 0.189), sex (p = 0.057), education years (p = 0.411) and MMSE scores (p = 0.861). However, the amyloid-positive group had a significantly higher frequency of having an e4 allele of APOE genotype (p = 0.033) and Clinical Dementia Rating scale (p = 0.024). The average volume between hemispheres significantly differed in the amyloid-negative group (p = 0.020) but not in the amyloid-positive group (p = 0.220). Both groups had a larger WML volume in the left hemisphere, which did not differ significantly between groups.

Conclusion
Our findings suggest that evaluating the asymmetry of WML rather than the total hyperintensity lesion load is necessary in MCI patients, particularly in those without amyloid pathology. In conclusion, WML asymmetry may serve as a potential indicator of amyloid positivity in MCI patients.