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A Deformable High Resolution Anatomic Reference for PET Activation Studies
Source: 1996;:398-403.
Author: Toga AW, Mazziotta JC, Woods RP.
Abstract:
Presently available anatomic atlases provide useful coordinate systems such as the ubiquitous Talairach system but are sorely lacking in both spatial resolution and completeness. An appropriately sampled anatomic specimen can provide the additional detail necessary to accurately localize activation sites as well as provide other structural perspectives such as chemoarchitecture. As part of the International Consortium for Brain Mapping (ICBM), whose goal it is to develop a probabilistic reference system for the human brain, we collected serial section postmortem anatomic data from several whole human head and brain specimens using a cryosectioning technique. Tissue was imaged so that voxel resolution was -200 microns or better at full color (24 bits/pixel). The collected data sets were used in one of several ways as an anatomic reference for functional studies: first, on an individual basis as a traditional, n=1 structural atlas with unprecedented spatial resolution and complete coverage of the forebrain, midbrain, and hindbrain (the data set can be registered to a functional data set using either anatomic landmarks or an automatic approach); second, several of these high resolution data sets were placed within the Talairach system and used to produce a probabilistic representaion (this approach represents anatomy within a coordinate system as a probability). Coordinate locations are assigned a confidence limit to describe the likelihood that a given location belongs to an anatomic structure based on the population of specimens. These data produce an anatomic reference that is digital, high in spatial and densitometric resolution, 3D, comprehensive, and in combination, probabilistic. The superior resolution makes it possible to delineate structures impossible to visualize in other structural modalities. These data are an important and necessary part of the comprehensive structural and functional analyses that focus on the mapping of the human brain. METHODS: We collected high-resolution image data from frozen human cadaver preparations that included fixed and unfixed whole head, fixed whole brain, and fixed isolated regions of interest. Image data were used for 2D anatomic segmentation, digital 3D reconstruction, and visual comparison to in vivo MRI. Five whole head and brain data sets were reconstructed into the Talairach and Tournoux stereotactic atlas space for comparison to 3D reconstsructed in vivo MRI from 10 normal male subjects. RESULTS AND DISCUSSION: Digital images of the whole head and brain possessed average spatial resolutions of 200 and 170 microns/pixel, repectively, in the imaging plane. This method produced anatomically detailed data sets for the brain stem, pons, cerebellum, cingulate cortex, and optic tract and hippocampus. Spatial resolution in the orthogonal axis was determined by frequency of image acquisition. High-resolution cryosectioned anatomy demonstrated gyral and sulcal anatomy as well as laminar structures and nuclear regions. We were easily able to identify subcortical structures in high-resolution digital images based on color pigment differentiation and texture contrast to adjacent tissues.
Source: 1996;:398-403.
Author: Toga AW, Mazziotta JC, Woods RP.
Abstract:
Presently available anatomic atlases provide useful coordinate systems such as the ubiquitous Talairach system but are sorely lacking in both spatial resolution and completeness. An appropriately sampled anatomic specimen can provide the additional detail necessary to accurately localize activation sites as well as provide other structural perspectives such as chemoarchitecture. As part of the International Consortium for Brain Mapping (ICBM), whose goal it is to develop a probabilistic reference system for the human brain, we collected serial section postmortem anatomic data from several whole human head and brain specimens using a cryosectioning technique. Tissue was imaged so that voxel resolution was -200 microns or better at full color (24 bits/pixel). The collected data sets were used in one of several ways as an anatomic reference for functional studies: first, on an individual basis as a traditional, n=1 structural atlas with unprecedented spatial resolution and complete coverage of the forebrain, midbrain, and hindbrain (the data set can be registered to a functional data set using either anatomic landmarks or an automatic approach); second, several of these high resolution data sets were placed within the Talairach system and used to produce a probabilistic representaion (this approach represents anatomy within a coordinate system as a probability). Coordinate locations are assigned a confidence limit to describe the likelihood that a given location belongs to an anatomic structure based on the population of specimens. These data produce an anatomic reference that is digital, high in spatial and densitometric resolution, 3D, comprehensive, and in combination, probabilistic. The superior resolution makes it possible to delineate structures impossible to visualize in other structural modalities. These data are an important and necessary part of the comprehensive structural and functional analyses that focus on the mapping of the human brain. METHODS: We collected high-resolution image data from frozen human cadaver preparations that included fixed and unfixed whole head, fixed whole brain, and fixed isolated regions of interest. Image data were used for 2D anatomic segmentation, digital 3D reconstruction, and visual comparison to in vivo MRI. Five whole head and brain data sets were reconstructed into the Talairach and Tournoux stereotactic atlas space for comparison to 3D reconstsructed in vivo MRI from 10 normal male subjects. RESULTS AND DISCUSSION: Digital images of the whole head and brain possessed average spatial resolutions of 200 and 170 microns/pixel, repectively, in the imaging plane. This method produced anatomically detailed data sets for the brain stem, pons, cerebellum, cingulate cortex, and optic tract and hippocampus. Spatial resolution in the orthogonal axis was determined by frequency of image acquisition. High-resolution cryosectioned anatomy demonstrated gyral and sulcal anatomy as well as laminar structures and nuclear regions. We were easily able to identify subcortical structures in high-resolution digital images based on color pigment differentiation and texture contrast to adjacent tissues.