Abstract: The present invention relates to a way of storing 3D images. The 3D image is composed of a stack of two-dimensional video data subsets represented by arrays of pixel data. Each array of pixel data is partitioned into a plurality of overlapping and adjacent vertical stripes of pixel data having a width at most equal to a cacheline of the memory. The upper most left stripe is stored first and each stripe is stored after the left adjacent stripe. When storing each stripe having multiple rows of pixel data, the upper row is stored first and the first pixel data of each subsequent row of the stripe is stored in a memory location coming after a memory location where the last pixel data of the preceding row in the stripe is stored.

Abstract: The invention relates to a method and a unit for automatically adjusting a collimator (6). In this connection, a region (9) of interest inside the body is determined in an application-specific way from an analysis of first X-ray pictures, and the collimator (6) is then adjusted thereon. The region (9) of interest can, in particular, be chosen to be large enough for the irradiation field to cover all those positions of an organ (10) of interest that occur as a result of heartbeat and/or respiration. Preferably, a movement estimate' is undertaken during a current examination in order to be able to readjust the collimator (6) if necessary. If the region of interest cannot be localized, the collimator (6) is opened to a standard adjustment.

Abstract: The present invention relates to direct volume rendering based on a light model applied to a 3D array of information data samples. Gradients are first estimated for the individuals samples, and a simple shading is done on the samples with low gradient, i.e. homogenous areas.

Abstract: The invention relates to a method of segmenting a three-dimensional structure, contained in an object, from one or more two-dimensional images which represent a slice of the object. The method utilizes a deformable model whose surface is formed by a network of meshes which connect network points on the surface of the model to one another. First there are determined the meshes which intersect at least one image and a point on the surface of the structure to be segmented is searched along a search line which traverses the mesh and extends in the image. Subsequently, the position of the network points of the model is calculated anew. These steps are repeated a number of times and the model ultimately obtained, that is, after several deformations, is considered to be the segmentation of the three-dimensional structure from the two-dimensional images.

Abstract: The invention relates to a method and a unit for automatically adjusting a collimator (6). In this connection, a region (9) of interest inside the body is determined in an application-specific way from an analysis of first X-ray pictures, and the collimator (6) is then adjusted thereon. The region (9) of interest can, in particular, be chosen to be large enough for the irradiation field to cover all those positions of an organ (10) of interest that occur as a result of heartbeat and/or respiration. Preferably, a movement estimate' is undertaken during a current examination in order to be able to readjust the collimator (6) if necessary. If the region of interest cannot be localized, the collimator (6) is opened to a standard adjustment.

Abstract: The invention relates to a method of adapting imaging parameters for a computer tomographic radiograph of a body volume, comprising the following steps: obtaining a three-dimensional pilot radiograph with a low dose of radiation (1); determining a region of interest and a desired image quality in the pilot radiograph (2) with the aid of a patient model (4) or interactively (3); determining optimal imaging parameters (5); generating an X-ray image using the determined imaging parameters (6). Optionally, the X-ray image is combined (7) with the pilot radiograph.

Abstract: The invention relates to a method for the registration of a series of at least three temporally successively acquired images (I1–In) of an object. Individual images (I2–In) to be registered are transformed into registered images (I2?-In?) using an individual mapping rule (T2–Tn). A similarity measure (M) is used to determine a mapping rule (T2–Tn), where to achieve a higher registration accuracy, a common similarity measure (M) of all images (I1?-In?) in order to determine the mapping rules (T2–Tn) for all images is implemented. The invention also relates to a corresponding registration device.

Abstract: An object, such as an example blood vessel, in a two or three dimensional image data set is segmented. An adaptable model, such as an example cylinder model, is defined around a starting point in the example blood vessel and is adapted or fit to the blood vessel. A plurality of candidate next active points are defined around the starting point and the adaptable model is defined around each candidate point. The models around the candidate points are adapted to the blood vessel. Based on results of the fitted models, a next active point is selected. In this manner, the blood vessel is segmented by adapting a series of cylinder models to an inner surface of the blood vessel.

Abstract: A method of segmenting a selected region from a multi-dimensional dataset, which method comprises the steps of setting up a shape model representing the general outline of the selected region and setting up an adaptive mesh. The adaptive mesh represents an approximate contour of the selected region. The adaptive mesh is initialized on the basis of the shape model. Furthermore, the adaptive mesh is deformed in dependence on the shape model and on feature information of the selected region.

Abstract: The invention relates to the assistance of the navigation of a catheter (1) in a vessel (2). A sequence of cross-sectional images of the portion of the vessel that is of interest is first obtained with the help of an intravascular ultrasound (IVUS) probe (3) and stored as a roadmap of the vessel. A cross-sectional image (10) that is obtained at the current position of the IVUS probe (3) can then be sorted to the position on the roadmap that is the best fit. A model (3?) of the probe, and a model (11?) of the instrument (a stent (11), for example) coupled to the probe, can be shown on a display (6) at the corresponding position on the roadmap.

Abstract: The invention relates to a method of computing the transformation which transforms two different images (10, 10?) of an object one into the other while describing the motion or deformation of the object. In accordance with the method first the local transformation parameters are computed for sub-regions (1, 2, 3, 4, 5). By choosing the sub-regions so as to be sufficiently small, a rigid transformation can be used for this purpose. Starting from at least one first predetermined sub-region (1), the local transformation parameters of the neighboring sub-regions (2, 3, 4, 5) are successively computed, the starting values on which each computation is based being the already determined local transformation parameters of neighboring sub-regions. Using the local transformation parameters thus determined for sub-regions, the overall transformation can subsequently be computed.

Abstract: The invention relates to a method of measuring geometric variables of a three-dimensional structure contained in an object from at least on image representing the object, having the following steps:—use of a deformable first model describing the structure, the shape of which model can be described by parameters,—adjustment of the first model to the structure in the image,—determination of the parameters at which the first model exhibits optimum conformity with the structure,—use of a deformable second model describing the structure, which second model in shape corresponds to the first model, and which in addition contains at least one geometric variable,—modification of the second model according to the parameters determined, and—derivation of the geometric variable(s) from the modified second model.

Abstract: Method and device for determining the position of a medical instrument, partially introduced into an object being examined, in a three-dimensional image data set of the object. In order to achieve a high accuracy of the position determination and minimize the expenditure required and thus save intricate registration steps prior to an intervention, simultaneously with the acquisition of an X-ray image, the spatial positions of the X-ray image and the spatial position of a medical instrument are acquired. Then, the spatial correlation between an X-ray image and a three-dimensional image data set is determined. This correlation is used to transform the spatial position of the medical instrument into a position relative to the three-dimensional image data set. This enables the formation of images containing image information acquired pre-operatively as well as intra-operatively, and also the reproduction of the instantaneous position of the medical instrument in the images.

Abstract: The invention relates to a method and an apparatus for segmentation of an object in a 2D or 3D image data set by extracting a path along the object.

Abstract: The invention relates to a method of segmenting a three-dimensional structure, contained in an object, from one or more two-dimensional images which represent a slice of the object. The method utilizes a deformable model whose surface is formed by a network of meshes which connect network points on the surface of the model to one another. First there are determined the meshes which intersect at least one image and a point on the surface of the structure to be segmented is searched along a search line which traverses the mesh and extends in the image. Subsequently, the position of the network points of the model is calculated anew. These steps are repeated a number of times and the model ultimately obtained, that is, after several deformations, is considered to be the segmentation of the three-dimensional structure from the two-dimensional images.

Abstract: A method of segmenting a selected region from a multi-dimensional dataset, which method comprises the steps of setting up a shape model representing the general outline of the selected region and setting up an adaptive mesh. The adaptive mesh represents an approximate contour of the selected region. The adaptive mesh is initialized on the basis of the shape model. Furthermore, the adaptive mesh is deformed in dependence on the shape model and on feature information of the selected region.

Abstract: In an X-ray examination device and a method for generating distortion-free X-ray images the imaging properties are calculated and distortions are corrected by providing at least one calibration member (7, 8) for forming a reference pattern; a correction unit (13) corrects the distortions in X-ray images on the basis of the pattern of the calibration members (7, 8) actually formed in the patient X-ray image (FIG. 4) and the calculated reference pattern.

Abstract: The invention relates to a method for the registration of a series of at least three temporally successively acquired images I1-In) of an object, where individual images (I2-In) to be registered are transformed into registered images (I2′-In′) by means of an individual mapping rule (T2-Tn) and where a similarity measure (M) is used so as to determine the mapping rule (T2-Tn). In order to achieve a higher registration accuracy, in accordance with the invention it is proposed to utilize a common similarity measure (M) of all images (I1′-In′) in order to determine the mapping rules (T2-Tn) for all images. The invention also relates to a corresponding registration device.

Abstract: The invention relates to a method of computing the transformation which transforms two different images (10, 10′) of an object one into the other while describing the motion or deformation of the object. In accordance with the method first the local transformation parameters are computed for sub-regions (1, 2, 3, 4, 5). By choosing the subregions so as to be sufficiently small, a rigid transformation can be used for this purpose. Starting from at least one first predetermined sub-region (1), the local transformation parameters of the neighboring sub-regions (2, 3, 4, 5) are successively computed, the starting values on which each computation is based being the already determined local transformation parameters of neighboring sub-regions. Using the local transformation parameters thus determined for sub-regions, the overall transformation can subsequently be computed.

Abstract: The invention relates to an X-ray examination apparatus for and a method of forming distortion-free X-ray images, which apparatus and method enable the imaging properties of the C-arm X-ray system to be derived from the patient image. To this end, a reference image (FIG. 4) is formed in a reference orientation of the X-ray examination apparatus and the reference imaging properties of the C-arm X-ray system are determined on the basis of the positions of calibration members (7, 8), which are mounted on the image intensifier (2) and/or the X-ray source (3) and are reproduced, and the known geometry and position relative to the image intensifier (2) and/or the X-ray source (3); the positions of the calibration members (7, 8) reproduced in a patient X-ray image (FIG. 5) are compared with the positions of the calibration members (7, 8) in the reference image (FIG.