Abstract: A method for determining an optimal trajectory for 3-dimensional rotational X-ray coronary angiography for a C-arm X-ray system that has at least two degrees of freedom, where the C-arm X-ray system is defined by a rotational movement of the C-arm expressed in a left/right coronary artery oblique angle, and a roll motion of the C-arm expressed in a caudal/cranial angle. The method includes generating of a 3-dimensional representation of a center-line of a body vessel in a region of interest. generating at least one optimal view map. Further, an optimal trajectory for the X-ray system within the optimal view map is determined, where an optimal trajectory is at least determined by movements of the C-arm within its two degrees of freedom allowing image projections with minimal foreshortening and/or overlap while minimizing an exposure to X-rays.

Abstract: For the reconstruction of the coronary arteries from rotational coronary angiography data, a crucial point is the selection of the optimal cardiac phase for data reconstruction. According to an exemplary embodiment of the present invention, an automatic approach for deriving optimal reconstruction windows is provided by fully automatically selecting the optimal cardiac phase on the basis of a delayed acquisition protocol where at least one heart phase needs to be acquired in a static projection geometry.

Abstract: An automated and semi-automated determination of an optimal table position for rotational angiography is provided which is performed on the basis of the determination of a translation vector pointing from a point of gravity of the object of interest to an iso-center of the examination apparatus. This may reduce the amount of X-ray and contrast agent dose for the iso-centering procedure and may not depend on the user's skills.

Abstract: A method for the three-dimensional reconstruction of an object, or its surroundings, in a moving body volume of a patient includes obtaining a series of X-ray projection photographs produced from different directions, with a relevant ECG phase or respiration being recorded simultaneously. Projection photographs of the moving body volume are transformed such that the images of feature points that are located on the projection photographs respectively come to rest at a place on which randomly set spatial reference positions for the feature points are projected. With the projection photographs aligned onto the reference positions, three-dimensional reconstruction of the object can subsequently take place.

Abstract: It is described a method for acquiring a series of two-dimensional X-ray attenuation data of an object under examination (310) by means of an X-ray imaging apparatus (100) having a rotatable scanning unit (301). In order to increase the angular range of the scanning unit (301), when a region of interest (HOa) located not in the center of the object (310) is examined the object under examination (310) is shifted such that the region of interest is temporarily positioned outside the center of rotation. By coupling the rotational movement of the scanning unit (301) with the translative movement of the object (310) in a synchronized manner a collision between the scanning unit (301) and the object (310) can be effectively avoided. By employing an automated motorized object table (312) a precise pre-determined movement of the object (310) can be achieved during the data acquisition.

Abstract: A method is provided for analysis of a multi-dimensional structure which includes a tubular structure from two-dimensional datasets for respective pre-determined projection directions. A pair of corresponding initial projected centre points of the tubular structure is identified in two respective initial and further two-dimensional datasets. Projected edges of the tubular structure in said initial two-dimensional datasets and in said further two-dimensional dataset near the respective projected centre points are identified. A local size of the tubular structure is derived at the three-dimensional spatial position of the centre point of the tubular structure from said projected edges and the predetermined projection directions.

Abstract: It is described a virtual pullback as a visualization and quantification tool that allows an interventional cardiologist to easily assess stent expansion. The virtual pullback visualizes the stent and/or the vessel lumen similar to an Intravascular Ultrasound (IVUS) pullback. The virtual pullback is performed in volumetric data along a reference line. The volumetric data can be a reconstruction of rotational 2D X-ray attenuation data. Planes perpendicular to the reference line are visualized as the position along the reference line changes. This view is for interventional cardiologists a very familiar view as they resemble IVUS data and may show a section plane through a vessel lumen or a stent. In these perpendicular section planes automatic measurements, such as minimum and maximum diameter, and cross sectional area of the stent can be calculated and displayed. Combining these 2D measurements allows also volumetric measurements to be calculated and displayed.

Abstract: For the reconstruction of the coronary arteries from rotational coronary angiography data, a crucial point is the selection of the optimal cardiac phase for data reconstruction. According to an exemplary embodiment of the present invention, an automatic approach for deriving optimal reconstruction windows is provided by fully automatically selecting the optimal cardiac phase on the basis of a delayed acquisition protocol where at least one heart phase needs to be acquired in a static projection geometry.

Abstract: It is described a method for acquiring a series of two-dimensional X-ray attenuation data of an object under examination (310) by means of an X-ray imaging apparatus (100) having a rotatable scanning unit (301). In order to increase the angular range of the scanning unit (301), when a region of interest (HOa) located not in the center of the object (310) is examined the object under examination (310) is shifted such that the region of interest is temporarily positioned outside the center of rotation. By coupling the rotational movement of the scanning unit (301) with the translative movement of the object (310) in a synchronized manner a collision between the scanning unit (301) and the object (310) can be effectively avoided. By employing an automated motorized object table (312) a precise pre-determined movement of the object (310) can be achieved during the data acquisition.

Abstract: In three-dimensional rotational x-ray coronary imaging problems may arise when estimating the motion of small vessels. According to an exemplary embodiment of the present invention, an examination apparatus is provided which is adapted for performing a hierarchical motion estimation by global affine transformation for every heart phase, followed by vessel branch selective affine and non-affine transformations. This may provide for an improved image quality.

Abstract: It is described a method for determining an optimal trajectory (25) for 3-dimensional rotational X-ray coronary angiography for a C-arm X-ray system. The C-arm X-ray system has at least two degrees of freedom. They are defined by a rotational movement of the C-arm (11) expressed in a left/right coronary artery oblique angle, and a roll motion of the C-arm (11) expressed in a caudal/cranial angle. The method performs the following steps in a sequence. Firstly, a generation of a 3-dimensional representation of a centre-line of a body vessel in a region of interest is performed. Secondly, at least one optimal view map is generated. Finally, an optimal trajectory (25) for the X-ray system within the optimal view map is determined, wherein an optimal trajectory (25) is at least determined by movements of the C-arm within its two degrees of freedom allowing image projections with minimal foreshortening and/or overlap while minimizing an exposure to X-rays.

Abstract: The invention relates to a method for the reconstruction of a three-dimensional model of a vascular tree from two-dimensional X-ray projection images (A, B, C) that are taken from different spatial directions. On a first projection image (A) at least one reference point (CA) is specified. The gray-value profiles along the epipolar lines (EB, EC) for said reference point (CA) in other projection images (B, C) are then projected on the projection line (L) of the reference point (CA) and added there punctiformly to form a sum profile (S). The sum profile (S) has an extreme, for example, a gray-value minimum, at the position of the space point (C3D) belonging to the reference point (CA). In this way, it is possible to reconstruct semiautomatically a vascular tree from X-ray projections.

Abstract: An automated and semi-automated determination of an optimal table position for rotational angiography is provided which is performed on the basis of the determination of a translation vector pointing from a point of gravity of the object of interest to an iso-centre of the examination apparatus. This may reduce the amount of X-ray and contrast agent dose for the iso-centring procedure and may not depend on the user's skills.

Abstract: The analysis of a stenosis of a coronary vessel in three dimensions requires a motion compensated reconstruction. According to an exemplary embodiment of the present invention, an examination apparatus for local motion compensated reconstruction data set is provided, wherein the local motion compensated reconstruction vectors relating to a start point and an end point of the stenosis.

Abstract: The invention provides a method for 3D modeling of a three-dimensional tubular structure of an examination object from 2D projection images (D) of the structure taken from different projection directions. The method has the following steps: reconstruction of a 3D image from the 2D projection images (D); selection of at least one 3D central line point (MO) in the 3D image, said 3D central line point being located in the structure; segmentation of 3D central line points (M) of the structure in the 3D image; forward projection of the 3D central line points (M), which have been segmented in the 3D image, into 2D projection images (D?); determination of border points of the structure in the 2D projection images (D?) on the basis of 3D central line points (Z) that have been projected in; and back-projection of the border points from the 2D projection image (D?) into the 3D image.

Abstract: An X-ray imaging method forms a set of a plurality of two-dimensional X-Ray projection images of a medical or veterinary object to be examined through a scanning rotation by an X-Ray source viz à viz the object. Such X-Ray images are acquired at respective predetermined time instants with respect to a functionality process produced by the object. From said set of X-Ray projection images by back-projection a three-dimensional volume image of the object is reconstructed. In particular, an appropriate motion correction is derived for the respective two-dimensional images, and subsequently as based on a motion vector field from the various corrected two-dimensional images the intended three-dimensional volume is reconstructed.

Abstract: The invention relates to a method for the three-dimensional reconstruction of an object such as for example a stent (5) in the coronary vessels of a patient. In the course of this, a series of X-ray projection photographs (A,) are produced from different directions, with the relevant ECG phase (E,) being recorded simultaneously. On the projection photographs (A,), the position of feature points (R, Q) is segmented (a). The photographs (A,) are furthermore allocated (b) into classes (Kp) according to their belonging to different sections (Epcl) of the heartbeat phase. For each of these classes, the corresponding spatial position ((x,y,z)Qp) of the feature points is established (e). In the next step (d), from the positions of the feature points (R, Q) that are now known for various heartbeat phases, the displacement vectors (SRp-m, SQp-m) or generally the transformations (Epm) are calculated which link (d) the positions of the feature points for different heartbeat phases (p, m).

Abstract: The invention relates to a method and a device for generating a threedimensional image of an object (9) such as in particular the heart, from a series of (X-ray) projection pictures (Pi, Pj, Pk, Pl). For the reconstruction only those projection pictures are used in which the projection lines (li, lk, ll) of a characteristic object feature intersect at approximately the same spatial point (r0). The characteristic object feature can in particular be a vessel branch which can easily be located on the projection pictures.

Abstract: E.g. in cardiac cone-beam CT, the source path is interrupted due to the fact that the projection data is gated. According to the present invention, a method is provided to obtain projection data corresponding to an uninterrupted source trajectory from such a gated data set. For this purpose, a motion compensation is applied. Advantageously, a complete data set may be determined allowing for an approximate or an exact reconstruction method to be applied to the completed data set without interruption of the image generation.

Abstract: The invention relates to a method for the reconstruction of a three-dimensional model of a vascular tree from two-dimensional X-ray projection images (A, B, C) that are taken from different spatial directions. On a first projection image (A) at least one reference point (CA) is specified. The gray-value profiles along the epipolar lines (EB, EC) for said reference point (CA) in other projection images (B, C) are then projected on the projection line (L) of the reference point (CA) and added there punctiformly to form a sum profile (S). The sum profile (S) has an extreme, for example, a gray-value minimum, at the position of the space point (C3D) belonging to the reference point (CA). In this way, it is possible to reconstruct semiautomatically a vascular tree from X-ray projections.