3 research outputs found
Automated identification of neurons and their locations
Individual locations of many neuronal cell bodies (>10^4) are needed to
enable statistically significant measurements of spatial organization within
the brain such as nearest-neighbor and microcolumnarity measurements. In this
paper, we introduce an Automated Neuron Recognition Algorithm (ANRA) which
obtains the (x,y) location of individual neurons within digitized images of
Nissl-stained, 30 micron thick, frozen sections of the cerebral cortex of the
Rhesus monkey. Identification of neurons within such Nissl-stained sections is
inherently difficult due to the variability in neuron staining, the overlap of
neurons, the presence of partial or damaged neurons at tissue surfaces, and the
presence of non-neuron objects, such as glial cells, blood vessels, and random
artifacts. To overcome these challenges and identify neurons, ANRA applies a
combination of image segmentation and machine learning. The steps involve
active contour segmentation to find outlines of potential neuron cell bodies
followed by artificial neural network training using the segmentation
properties (size, optical density, gyration, etc.) to distinguish between
neuron and non-neuron segmentations. ANRA positively identifies 86[5]% neurons
with 15[8]% error (mean[st.dev.]) on a wide range of Nissl-stained images,
whereas semi-automatic methods obtain 80[7]%/17[12]%. A further advantage of
ANRA is that it affords an unlimited increase in speed from semi-automatic
methods, and is computationally efficient, with the ability to recognize ~100
neurons per minute using a standard personal computer. ANRA is amenable to
analysis of huge photo-montages of Nissl-stained tissue, thereby opening the
door to fast, efficient and quantitative analysis of vast stores of archival
material that exist in laboratories and research collections around the world.Comment: 38 pages. Formatted for two-sided printing. Supplemental material and
software available at http://physics.bu.edu/~ainglis/ANRA
Multi-Material Mesh Representation of Anatomical Structures for Deep Brain Stimulation Planning
The Dual Contouring algorithm (DC) is a grid-based process used to generate surface meshes from volumetric data. However, DC is unable to guarantee 2-manifold and watertight meshes due to the fact that it produces only one vertex for each grid cube. We present a modified Dual Contouring algorithm that is capable of overcoming this limitation. The proposed method decomposes an ambiguous grid cube into a set of tetrahedral cells and uses novel polygon generation rules that produce 2-manifold and watertight surface meshes with good-quality triangles. These meshes, being watertight and 2-manifold, are geometrically correct, and therefore can be used to initialize tetrahedral meshes.
The 2-manifold DC method has been extended into the multi-material domain. Due to its multi-material nature, multi-material surface meshes will contain non-manifold elements along material interfaces or shared boundaries. The proposed multi-material DC algorithm can (1) generate multi-material surface meshes where each material sub-mesh is a 2-manifold and watertight mesh, (2) preserve the non-manifold elements along the material interfaces, and (3) ensure that the material interface or shared boundary between materials is consistent. The proposed method is used to generate multi-material surface meshes of deep brain anatomical structures from a digital atlas of the basal ganglia and thalamus. Although deep brain anatomical structures can be labeled as functionally separate, they are in fact continuous tracts of soft tissue in close proximity to each other. The multi-material meshes generated by the proposed DC algorithm can accurately represent the closely-packed deep brain structures as a single mesh consisting of multiple material sub-meshes. Each sub-mesh represents a distinct functional structure of the brain.
Printed and/or digital atlases are important tools for medical research and surgical intervention. While these atlases can provide guidance in identifying anatomical structures, they do not take into account the wide variations in the shape and size of anatomical structures that occur from patient to patient. Accurate, patient-specific representations are especially important for surgical interventions like deep brain stimulation, where even small inaccuracies can result in dangerous complications. The last part of this research effort extends the discrete deformable 2-simplex mesh into the multi-material domain where geometry-based internal forces and image-based external forces are used in the deformation process. This multi-material deformable framework is used to segment anatomical structures of the deep brain region from Magnetic Resonance (MR) data
Diffusion-snakes using statistical shape knowledge
We present a novel extension of the Mumford-Shah functional that allows to incorporate statistical shape knowledge at the computational level of image segmentation. Our approach exhibits various favorable properties: non-local convergence, robustness against noise, and the ability to take into consideration both shape evidence in given image data and knowledge about learned shapes. In particular, the latter property distinguishes our approach from previous work on contour-evolution based image segmentation. Experimental results conrm these properties