Integrated cortical structural marker for Alzheimer's disease

Abstract

In this paper we propose an approach to integrate cortical morphology measures for improving the discrimination of individuals with and without very mild AD. FreeSurfer was applied to scans collected from 83 participants with very mild AD and 124 cognitively normal individuals. We generated cortex thickness, white matter convexity (aka “sulcal depth”) and white matter surface metric distortion measures on a normalized surface atlas in this first study to integrate high resolution gray matter thickness and white matter surface geometric measures in identifying very mild AD. Principal component analysis (PCA) was applied to each individual structural measure to generate eigenvectors. Discrimination power based on individual and combined measures are compared, based on stepwise logistic regression and 10-fold cross-validation. Global AD likelihood index and surface-based likelihood maps were also generated. Our results show complementary patterns on the cortical surface between thickness, which reflects gray matter atrophy, convexity, which reflects white matter sulcal depth changes; and metric distortion, which reflects white matter surface area changes. The classifier integrating all three types of surface measures significantly improved classification performance compared to classification based on single measures. The PCA-based approach provides a framework for achieving high discrimination power by integrating high-dimensional data, and this method could be very powerful in future studies for early diagnosis of diseases that are known to be associated with abnormal gyral and sulcal patterns.

Frequency-Dependent Altered Functional Connections of Default Mode Network in Alzheimer’s Disease

“…In this study, our results in the standard LFO band by NBS showed several functional connections between different brain regions in DMN were decreased, while only two functional connections were increased. It was broadly consistent with the previous studies within the DMN in AD using multiple imaging techniques, and indicated AD might reduce the cognitive ability by impaired the functional connections in DMN ( Brier et al, 2012 ; Dubois et al, 2014 ; Zhong et al, 2014 ; Ming et al, 2015 ). The separation results in the four frequency bands demonstrated the altered functional connections were only in the slow-4 and slow-5 bands.…”

Sulcal morphology in Alzheimer's disease: an effective marker of diagnosis and cognition

“…Those were only presented as exploratory results and should be confirmed in an independent sample. In parallel, data reduction strategies such as PCA were adopted to decrease the number of variables (Ming et al 2015).…”

Sulcal morphology as a new imaging marker for the diagnosis of early onset Alzheimer's disease

“…The sulcal shape abnormalities that are observed may be primarily affected by cortical atrophy, following the well-known progression of tau pathology in AD, 41 and by the reduction of gyral white matter volume. 42,43,44 .Further studies are needed to clarify this point and to investigate the role of sulcal shape abnormalities in the differential diagnosis of AD. Legend : A computer vision pipeline mimicking a human anatomist.…”