Abstract: An apparatus and method for segmenting three-dimensional (3D) medical images containing a region of interest is provided that identifies a first set of seed points within the region of interest and a second set of seed points outside the region of interest. A first sphere is constructed within the region of interest. Voxels contained within the medical image are classified using a spatial constrained fuzzy clustering algorithm. A plurality of second spheres is generated. Ones of the plurality of second spheres are accepted that satisfy the homogeneity function threshold as defined by the spatial constricted fuzzy clustering algorithm. A three-dimensional area is grown that defines the region of interest. The region of interest defined by the three-dimensional area is displayed.

Abstract: A method and system for segmenting three-dimensional (3D) medical images containing an object of interest are provided. The method comprises generating a plurality of successive layers of fixed radius spheres about a circumference of a sphere containing at least one seed point placed within the object of interest when a plurality of respective voxels contained within the spheres exceed a selected threshold. The generation of the layers is repeated until no further voxels contained within an outer surface of each respective layer exceed the selected threshold or a stop seed point is encountered. The layers form a segmented representation of the object of interest.

Abstract: The invention provides tomographic image generation from four-dimensional projection data of an imaged object. The ability is provided to extract implicit information from time dependent aspects of volumetric projection data corresponding to multiple data acquisition cycles. The result is improved volumetric image quality from volumetric projection data previously used for slice by slice image reconstruction. The invention provides particular advantages for volumetric imaging of a patient's heart, or a portion thereof, at a selected phase of the cardiac cycle.

Abstract: A method and apparatus for reducing noise in a three dimensional rectilinear parallelepiped data point array includes both erosion and dilation processes for each array point value. The erosion process includes the steps of determining gradients along all three axis which pass through a data point and modifying the point value as a function of the gradients to generate an updated point value. The dilation process includes the steps of using point values from the updated array, determining gradients along all three axis which pass through the point, and modifying the updated point value as a function of the gradients to generate a final and revised point value.

Abstract: A magnet assembly system for use in an open Magnetic Resonance Imaging (MRI) system comprises a first assembly and a second assembly opposing each other in a longitudinally spaced apart relationship. The first and second assemblies generate a static magnetic field for use in imaging. Further provided is a plurality of support posts attached between the first and second assemblies for maintaining an open imaging volume between the first and second assemblies and for further providing structural support. Each of the support posts comprises a first support element and a second support element attached to first support element on the surface away from the imaging volume. A method for reducing vibration in an open MRI system comprises attaching a second support element to each of the support posts on a surface away from the imaging volume.

Abstract: The present invention provides a model and a method and apparatus for utilizing the model to simulate an imaging scenario. The model is mathematically defined by analytical basis objects and/or polygonal basis objects. Preferably, the model is a model of the human heart and thorax. Polygonal basis objects are only used to define structures in the model that experience torsion, such as certain structures in the heart that experience torsion during the cardiac cycle. The manner in which the basis objects comprising the model are transformed by scaling, translation and rotation is defined for each basis object. In the case where a basis object experiences torsion, the rotation of the basis object will change as a function of the length along the axis of the basis object about which rotation is occurring.

Abstract: An imaging system enables cardiac functioning within a particular cardiac chamber to be imaged. The system acquires imaging data that includes intensity values for four-dimensional voxels within a region of interest (ROI). A seed voxel is identified, and neighbor voxels to the seed voxel are also identified. The intensity values for each neighbor voxel are compared to a threshold to determine whether the voxel corresponds to blood or muscle tissue. For each neighbor voxel corresponding to blood, its neighbor voxels are identified and compared to the threshold, and this process is repeated until a pre-established spatial boundary is encountered or the number of new neighbor voxels indicates that processing is migrating into an adjacent cardiac chamber. At that point, the identified blood voxels are counted into bins of cardiac phases, cardiac images for each phase are reconstructed, and parameters such as ejection fraction are calculated.

Abstract: An apparatus and method for Magnetic Resonance Imaging (MRI) by spiral trajectory scanning comprises an MR imaging device for acquiring and processing data samples of an object to be imaged, wherein the data samples are acquired by spiral trajectory scanning. An interface is coupled to the MR imaging device for receiving operator-defined spiral scanning parameters, and a computer is coupled to the interface and the MR imaging device. The computer is configured to generate an approximated spiral trajectory in k-space in accordance with operator-defined spiral scanning parameters. The approximated spiral trajectory is used by the MR imaging system to perform spiral trajectory scanning.

Abstract: An MRI system acquires image data using a spiral pulse sequence in which k-space is sampled in a trajectory comprised of a spiral segment and a symmetric spiral tail segment. The spiral segments partially sample throughout the extent of k-space and the symmetric spiral tail segment samples only in a central region of k-space. The central region of k-space is fully sampled and a phase correction method is used to reconstruct an image from the under-sampled peripheral k-space data set.

Abstract: A patient surface is registered with a model surface based on curvature by acquiring patient range data and determining the curvature of the patient surface based on the range data. The patient surface is generated and shaded based on the curvature. A model surface is generated from image data and processed to determine the curvature of the model surface. The model surface is shaded to represent the curvature. The shaded patient surface and the shaded model surface are aligned in registration with each other by manipulating the patient surface and/or the model surface until the curvature features coincide.

Abstract: An MRI system is employed to acquire image data using a pulse sequence in which k-space is sampled in a Fibonacci spiral trajectory. A single pulse sequence may be used to sample all of k-space with a single spiral arm, or k-space can be sampled with a plurality of interleaved Fibonacci spiral arms by performing a corresponding series of pulse sequences.

Abstract: An imaging system enables cardiac functioning within a particular cardiac chamber to be imaged. The system acquires imaging data that includes intensity values for four-dimensional voxels within a region of interest (ROI). A seed voxel is identified, and neighbor voxels to the seed voxel are also identified. The intensity values for each neighbor voxel are compared to a threshold to determine whether the voxel corresponds to blood or muscle tissue. For each neighbor voxel corresponding to blood, its neighbor voxels are identified and compared to the threshold, and this process is repeated until a pre-established spatial boundary is encountered or the number of new neighbor voxels indicates that processing is migrating into an adjacent cardiac chamber. At that point, the set of identified blood voxels represents a blood volume for the desired cardiac chamber. Voxels adjacent to the interior and exterior surface boundaries of the blood volume are added to the set.

Abstract: Anisotropic data having data spacing significantly larger between layers of data compared with spacing between adjacent data values, is supplemented with additional data to approximate isometric data. The ratio of spacing in one dimension to another is referred to as an aspect ratio A. Preferably, spacing is halved until spacing a modified aspect ratio A′ is near unity. Intermediate values are interpolated between existing values of the anisotropic data to create approximate isotropic data having a modified aspect ratio A′. Surface voxels are determined from the approximate isotropic data. The values of the adjacent voxels are then used to determine a vector normal to the surface at the central voxel. This is repeated for a number of central voxels to determine a surface. The viewing elevation angle is converted to an effective elevation angle. The surface is then rendered into a 2D screen image as if it were created from isotropic data.

Abstract: An imaging method and system generates images of non-planar portions of a three dimensional data point array wherein the non-planar portion corresponds to a non-planar object. The method includes selecting at least two different intermediate imaging planes, each selected plane including at least a portion of the object to be imaged, generating cross-sectional views perpendicular to each intermediate plane, selecting a viewing plane, projecting the cross-sectional views onto the viewing plane to generate transition value sets, and combining the transition value sets to generate values for each pixel in a display.

Abstract: The noise reduction system of the present invention takes into account that noise is random with little between images adjacent physically, and in sampling time. It also takes into account the fact that some sequences of images are cyclical and “wrap around” in time with the beginning closely resembling the end of the cycle. A filter was developed which would smooth noise in a direction along an edge, but will not blur across an edge. It operates by determining vectors tangential to a surface point p, at a current voxel, and projecting 4D data onto the tangential vectors. A curvature matrix B&agr;&bgr; is determined. The eigenvalues of curvature matrix B&agr;&bgr; are determined to result in three curvatures for 4 dimensions. If the sign of all of the eigenvalues is the same, the current voxel is filtered, else, it is unchanged. This filtering is repeated for a number of voxels as the current voxel within a desired region for a single iteration.

Abstract: In three-dimensional imaging of ultrasound data, speckle artifact data are reduced before the acquired data from a volume of interest are projected onto an image plane. A master controller performs an algorithm that iteratively morphologically filters the pixel data in a volume of interest and then iteratively projects the morphologically filtered data onto a plurality of rotated image planes using a ray-casting technique. Morphological filtering is performed by stepping a seven-point kernel through a source data volume of pixel data. The kernel, made up of a central pixel value and the six pixel values adjacent to the central pixel value, is stepped through the entire source data volume. The morphological filtering operation includes at least one erosion step, which removes speckle, followed by an equal number of dilation steps, which restore the imaging data.

Abstract: A system for displaying surfaces of volumetric data determines surface cubes by a simple method without interpolation. A central voxel is selected. The central voxel is tested against a threshold. If it is below the threshold, a different voxel is chosen as a central voxel. When one is found which is above the threshold, diagonal cubes, those at each of the corners of the central voxel, are tested against the threshold. When one is encountered with at least one voxel below the threshold, it is categorized as a surface voxel. The values of the adjacent voxels are then used to determine a vector normal to the surface at the central voxel. This is repeated for a number of central voxels to determine a surface. The surface then may be displayed. If anisotropic voxels are used, the elevation angle is converted to an effective elevation angle. The normal vectors to the surface are also adjusted to compensate for the anisotropic nature of the data.

Abstract: A volumetric data set having a high intensity, dominant structure, near smaller, less intense structures is smoothed and segmented to separate the dominant structure. The dominant structure is masked out to result in the smaller, less intense structures which are displayed. For example, dominant structures such as the blood pool in atria, ventricles, and the aorta of a 3D angiography data set is segmented and removed from the data set using mathematical morphology operations to result in an enhanced data set. The enhanced data set is displayed by conventional means such as a maximum intensity projection (MIP) at different views to yield images of coronary arteries.

Abstract: A cardiac segmentation system acquires a series of images acquires as slices through a volume, and as images at different time periods throughout a cardiac cycle. It displays an image to an operator which interactively selects a region of interest (ROI) of the image to be segmented, such as the left ventricle. A seed point is also selected within the ROI and the structure desired to be segmented. The image is then thresholded by a masking device classifying points within the ROI as above the threshold, or not above the threshold. A 3D connectivity device identifies points within the ROI having the same classification as an expanded seed point which are also contiguous with the seed point as the segmented structure. The segmented structure is expanded and a histogram is constructed. A new threshold is selected which separates modes of the histogram, and used to carry out a revised, final, segmentation of the current image. The centroid of the current image is used as a seed point in segmenting adjacent images.

Abstract: A system for display of interfaces within a block of raw data values comprises a model building portion groups data points into a cubes, receives a threshold and identifies cubes which a vertex data values which straddle the threshold. These are surface cubes. Gradient vectors for each vertex of each cube are determined by comparing the change in data values in three dimensions in a neighborhood around each vertex. The surface cubes and their associated gradient vectors are stored as a cube/vector model. his model may be tessellated and then displayed by conventional CAD/CAM workstations. A second display system is shown which employs a modified "Dividing Cubes" method to subdivide the cubes, interpolate each to a center point and associated vector, then backprojected to produce perspective.