Computational Methods for Reconstructing and Unfolding the Cerebral Cortex

Abstract

We describe computational methods for constructing three-dimensional models and unfolded, two-dimensional maps of the cerebral cortex. These methods consist of four procedures, including (1) sampling of a surface within the cortex, (2) reconstruction of a three-dimensional model of that surface, (3) unfolding of the surface to generate a two-dimensional cortical map, and (4) visualization of data on the model and the map. These methods produce structurally accurate representations of the cortex and have practical advantages over previous manual and automated approaches for flattening the cortex. We illustrate the application of these methods to neuroanatomical data obtained from histological sections of cerebral cortex in the macaque monkey. The approach should be equally useful for structural and functional studies in other species, including humans.

The U Sign: Tenth Landmark to the Central Region on Brain Surface Reformatted MR Imaging

“…This view continuously depicts the entire frontoparietal sulci and gyri without any sectioning, by unfolding the convex hemispheres to a flat map via multiplanar reformatting. However, the unfolding of the convex hemisphere leads to distortions, 20 which increase toward the margins and deform the shapes and sizes of anatomic structures. This phenomenon is well-known from world maps like the Mercator projection, which gives a disproportionate image of areas, depending on their location from the equator.…”

CRUISE: Cortical reconstruction using implicit surface evolution

“…The central surface, in particular, demonstrates accuracy and repeatability in the range of 0.5 and 0.25 mm, respectively. We believe that the central surface is useful for characterization and analysis of the 2-D geometry of the cortex-for example, computation of curvatures (Cachia et al, 2003a;Zeng et al, 1999), geodesic distances (Cachia et al, 2003b;Rettmann et al, 2002), segmenting sulci or gyri (Behnke et al, 2003;Cachia et al, 2003b;Rettmann et al, 2002), surface flattening (Carman et al, 1995;Drury et al, 1996), and spherical mapping (Angenent et al, 1999;Fischl et al, 1999a;Tosun and Prince, 2001).…”

“…Reconstructed cortices enable the visualization and study of the sulcal and gyral patterns of an individual subject (Carman et al, 1995;Essen et al, 2001;Fischl et al, 1999a,b;Thompson et al, 2001) and allow morphometric measurements such as volume (Kim et al, 2000), surface area (Magnotta et al, 1999), thickness (Kruggel et al, 2003;Yezzi and Prince, 2003), and sulcal depth (Manceaux-Demiau et al, 1998). These measures provide valuable information about the cortical characteristics of both normal development and pathological disease.…”

“…Correspondences between cortical reconstructions from different subjects can also be used for image registration (Cachier et al, 2001;Davatzikos, 1997;Hellier and Barillot, 2003;Tao et al, 2002), digital atlas labeling (Jaume et al, 2002;Sandor and Leahy, 1997), and population-based probabilistic atlas generation (Thompson et al, 1997). In addition, cortical reconstruction is important for functional brain mapping (Dale and Sereno, 1993), surgical planning (Grimson et al, 1998), and cortical unfolding or flattening (Carman et al, 1995;Drury et al, 1996;Essen et al, 2001;Fischl et al, 1999a,b;Tosun and Prince, 2001).…”

Longitudinal Cortical Registration for Developing Neonates

“…Several researchers have presented algorithms to unfold and align the cerebral cortex in cross-sectional studies in adulthood [2,3,4,5]. Methods based on cortex unfolding aim to inflate the highly folded surfaces and map the whole or a piece of cortex to some standard representations like a flat surface or a sphere.…”