Shape abnormalities of subcortical and ventricular structures in mild cognitive impairment and Alzheimer's disease: Detecting, quantifying, and predicting

Abstract

This article assesses the feasibility of using shape information to detect and quantify the subcortical and ventricular structural changes in mild cognitive impairment (MCI) and Alzheimer’s disease (AD) patients. We first demonstrate structural shape abnormalities in MCI and AD as compared with healthy controls (HC). Exploring the development to AD, we then divide the MCI participants into two subgroups based on longitudinal clinical information: (1) MCI patients who remained stable; (2) MCI patients who converted to AD over time. We focus on seven structures (amygdala, hippocampus, thalamus, caudate, putamen, globus pallidus, and lateral ventricles) in 754 MR scans (210 HC, 369 MCI of which 151 converted to AD over time, and 175 AD). The hippocampus and amygdala were further subsegmented based on high field 0.8 mm isotropic 7.0T scans for finer exploration. For MCI and AD, prominent ventricular expansions were detected and we found that these patients had strongest hippocampal atrophy occurring at CA1 and strongest amygdala atrophy at the basolateral complex. Mild atrophy in basal ganglia structures was also detected in MCI and AD. Stronger atrophy in the amygdala and hippocampus, and greater expansion in ventricles was observed in MCI converters, relative to those MCI who remained stable. Furthermore, we performed principal component analysis on a linear shape space of each structure. A subsequent linear discriminant analysis on the principal component values of hippocampus, amygdala, and ventricle leads to correct classification of 88% HC subjects and 86% AD subjects.

Structural imaging of hippocampal subfields in healthy aging and Alzheimer’s disease

“…This result is consensual as it is independent from the specific method used: it has been reported using radial atrophy (Frisoni et al, , 2006Scher et al, 2007), large deformation high-dimensional brain mapping (Csernansky et al, 2000;Tang et al, 2014;Tepest et al, 2008;Wang et al, 2006Wang et al, , 2003, spherical harmonics (Gerardin et al, 2009;Lindberg et al, 2012) or a VBM-based analysis (Chételat et al, 2008); see Figure 1 for an illustration. In some studies, abnormalities were also found in medial regions of the surface, mostly corresponding to the (pre)subiculum (Frisoni et al, , 2006Wang et al, 2006) or even in all subfields Chow et al, 2012Chow et al, , 2015.…”

“…Among MCI patients, shape analysis identified a more focal pattern of atrophy, usually restricted to the lateral side of the hippocampus corresponding to CA1, and sometimes also including the subiculum (Chételat et al, 2008;Gerardin et al, 2009;Tang et al, 2014;Tepest et al, 2008). Volumetric studies showed a volume reduction predominant in CA1, and also involving either CA3/DG (Yassa et al, 2010b), CA4/DG (Pluta et al, 2012) or the subiculum La Joie et al, 2013).…”

Relation between subcortical grey matter atrophy and conversion from mild cognitive impairment to Alzheimer's disease

“…Tang et al 15 reported that atrophy in the hippocampus and amygdala, and lateral ventricular expansion could discriminate MCI progressing to AD from stable MCI. In contrast, Liu et al 13 found that the volumes of the caudate nucleus and amygdala rather than of the hippocampus were independent predictors of progression from MCI to AD.…”

Neural correlates of spelling difficulties in Alzheimer’s disease

“…The basal ganglia are known to be affected by atrophy caused by AD (Tang, Holland, Dale, Younes, & Miller, 2014). Moreover, the putamen has been shown to be active during generative writing (Beeson et al, 2003) and is consistently associated to the central processes of spelling (Purcell et al, 2011).…”