Measuring and comparing brain cortical surface area and other areal quantities

Department of Psychiatry, Yale University School of Medicine, New Haven, CT, USA.
NeuroImage (Impact Factor: 6.36). 03/2012; 61(4):1428-43. DOI: 10.1016/j.neuroimage.2012.03.026
Source: PubMed


Structural analysis of MRI data on the cortical surface usually focuses on cortical thickness. Cortical surface area, when considered, has been measured only over gross regions or approached indirectly via comparisons with a standard brain. Here we demonstrate that direct measurement and comparison of the surface area of the cerebral cortex at a fine scale is possible using mass conservative interpolation methods. We present a framework for analyses of the cortical surface area, as well as for any other measurement distributed across the cortex that is areal by nature. The method consists of the construction of a mesh representation of the cortex, registration to a common coordinate system and, crucially, interpolation using a pycnophylactic method. Statistical analysis of surface area is done with power-transformed data to address lognormality, and inference is done with permutation methods. We introduce the concept of facewise analysis, discuss its interpretation and potential applications.


Available from: Anderson Winkler
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    • "Statistical analyses are now often conducted both using standard univariate methods and multi-voxel pattern analysis (MVPA) (Haynes and Rees, 2006; Kriegeskorte et al., 2006; Norman et al., 2006). Brain structure is often analyzed using voxel-(Ashburner, 2009) and surface-based (Winkler et al., 2012) morphometry, and gyrification indices (Schaer et al., 2008). Registration between individuals can use relatively low-dimensional warping to a template, or higher dimensional registration (Ashburner, 2007, 2009). "
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    • "Not all variables in our study met all these requirements. In addition, measurements related to biological morphology, such as lengths, areas, volumes and weights, are well known to follow non-normal distributions (Winkler et al., 2012). "
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    • "Given explicit models for the white/grey and grey/ cerebrospinal fluid (CSF) surfaces, the measure of absolute CT at any given point on the white/grey matter surface was taken to be the closest distance from the grey/ white boundary to the grey/CSF boundary at each vertex on the tessellated surface (Fischl and Dale, 2000). Vertex-based estimates of SA were obtained as outlined by Winkler et al. (2012). Estimates of regional cortical volume were derived by multiplying CT and SA at each vertex on the cortical surface, or CV¼ CT Â SA. "
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