Method for superimposing a two-dimensional X-ray image on projective images of three-dimensional structures

Inventors

König, Thomas • Hörndler, Klaus • Kachelriess, Marc • KNAUP, Michael

Assignees

Ziehm Imaging GmbH

Abstract

Medical imaging methods for processing a three-dimensional (3D) image data set with two-dimensional X-ray images from an X-ray machine using a target function. Methods can include providing a 3D image data set of at least one examination zone in which anatomical structures are present, segmenting the image data set to provide a 3D vascular structure model and a 3D bone structure model, recording a first two-dimensional (2D) X-ray image containing at least a portion of the vascular structure and at least a portion of the bone structure, recording a second 2D X-ray image of the examination zone at a different contrast agent concentration, and subtracting the first and second 2D X-ray images to generate a subtraction image. An optimum projective geometry may then be determined using a three-part target function based on the 3D image data and the 2D X-ray images.

Core Innovation

The method processes a three-dimensional image data set of at least one examination zone that includes anatomical structures and segments the data set into a three-dimensional vascular structure model and a three-dimensional bone structure model. Two two-dimensional X-ray images are recorded with the same recording geometry in the presence of different contrast agent concentrations, and the first and second two-dimensional X-ray images are subtracted to generate a subtraction image that includes the vascular structure.

An optimum projective geometry is determined using a three-part target function. The first part represents a similarity between a forward projection of the bone structure model and the bone structure in at least one of the first and second X-ray images, the second part represents a similarity between a forward projection of the vascular structure model and the vascular structure of the subtraction image, and the third part represents a similarity between all image data of the forward projection and all image data of at least one of the first and second X-ray images, while varying the assumed projective geometry.

A superimposition of a forward projection under the optimum projective geometry with a live X-ray image can be displayed and suppressed when movement of the X-ray device, a change in the recording geometry, or a shift of position of a corresponding patient is detected. In another variant, a measurement field narrowly delimits a structure which may change over time, and a monitored sum value of pixel values in the measurement field is used so that, for a predetermined percentage change compared with a previous live X-ray image, the superimposition is no longer shown on the display.

Claims Coverage

The provided material contains two independent claims that share the same core pipeline: segmenting a three-dimensional image data set into vascular and bone structure models; recording two two-dimensional X-ray images with different contrast agent concentrations using the same recording geometry; subtracting the images to generate a subtraction image including the vascular structure; and determining an optimum projective geometry using a three-part target function with bone-similarity, vascular/subtraction-similarity, and overall image-data similarity while varying the assumed projective geometry. The independent claims differ in whether they provide a threshold-based abort and switch to an alternative two-dimensional method, or a live X-ray superimposition with movement, recording-geometry, patient-shift suppression, and measurement-field monitoring.

Across the independent claims, the coverage centers on using a three-part target function that jointly evaluates bone similarity from forward projections, vessel similarity derived from a subtraction image, and overall image-data similarity while varying assumed projective geometry, and then using this optimum projective geometry to support either a threshold-based abort and switch option or a live-X-ray display of superimposition that is suppressed based on detected movement, recording-geometry change, patient shift, and measurement-field pixel-sum changes.

Stated Advantages

Documented Applications