Abstract
Objectives: To evaluate whether 3D amide proton transfer weighted (APTw) imaging based on magnetization transfer analysis can be used as a novel imaging marker to distinguish amnestic mild cognitive impairment (aMCI) patients from the normal elderly population by measuring changes in APTw signal intensity in the hippocampus and amygdala.Materials and Methods: Seventy patients with aMCI and 74 age- and sex-matched healthy volunteers were recruited for routine MRI and APT imaging examinations. Magnetic transfer ratio asymmetry (MTRasym) of the amide protons (at 3.5 ppm), or APTw values, were measured in the bilateral hippocampus and amygdala on three consecutive cross-sectional APT images and were compared between the aMCI and control groups. The independent sample t-test was used to evaluate the difference in APTw values of the bilateral hippocampus and amygdala between the aMCI and control groups. Receiver operator characteristic analysis was used to assess the diagnostic performance of the APTw. The paired t-test was used to assess the difference in APTw values between the left and right hippocampus and amygdala, in both the aMCI and control groups.Results: The APTw values of the bilateral hippocampus and amygdala in the aMCI group were significantly higher than those in the control group (left hippocampus 1.01 vs. 0.77% p < 0.001; right hippocampus 1.02 vs. 0.74%, p < 0.001; left amygdala 0.98 vs. 0.70% p < 0.001; right amygdala 0.94 vs. 0.71%, p < 0.001). The APTw values of the left amygdala had the largest AUC (0.875) at diagnosis of aMCI. There was no significant difference in APTw values between the left and right hippocampus and amygdala, in either group. (aMCI group left hippocampus 1.01 vs. right hippocampus 1.02%, p = 0.652; healthy control group left hippocampus 0.77 vs. right hippocampus 0.74%, p = 0.314; aMCI group left amygdala 0.98 vs. right amygdala 0.94%, p = 0.171; healthy control group left amygdala 0.70 vs. right amygdala 0.71%, p = 0.726).Conclusion: APTw can be used as a new imaging marker to distinguish aMCI patients from the normal elderly population by indirectly reflecting the changes in protein content in the hippocampus and amygdala.
Highlights
Mild cognitive impairment (MCI) is the transitional stage between normal aging and dementia, in which cognitive function is slightly impaired, but daily living is not affected, and the condition has not yet reached the diagnostic criteria for dementia [1, 2]
We found that there was no significant difference in Amide proton transfer (APT) weighted (APTw) values between the left and right hippocampus and amygdala, in either the amnestic MCI (aMCI) or the control group
Our study found that the bilateral APTw values of the hippocampus and amygdala were significantly higher in aMCI patients than those in the normal elderly population, consistent with the results of Zhang et al [25]
Summary
Mild cognitive impairment (MCI) is the transitional stage between normal aging and dementia, in which cognitive function is slightly impaired, but daily living is not affected, and the condition has not yet reached the diagnostic criteria for dementia [1, 2]. The research focus has gradually shifted to MCI, which is considered a pre-dementia stage. According to the impairment of specific cognitive domains, MCI can be further categorized as amnestic MCI (aMCI), presenting with impaired learning and memory functions, and non-amnestic MCI (naMCI), presenting with impaired cognitive domains [3, 4]. MCI is often progressive, with aMCI having a higher risk of conversion to Alzheimer’s disease and naMCI having a higher risk of conversion to non-Alzheimer’s dementia. If treatment can be applied early in the course of the disease, impaired cognitive function is reversible [7]
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