Patent Description:
In percutaneous coronary interventions, it is of importance that a coronary stent is fully expanded and in full contact with the coronary vessel wall after placement in a coronary stenotic lesion. Furthermore, correct positioning of the stent with respect to side branches of the vessel is crucial, especially when stenting a coronary bifurcation. A stent is not always clearly visible under fluoroscopy or in an exposure run. Improvement of stent visibility in X-ray exposure thus facilitates the interventional cardiologist to correctly place the stent and in judging the clinical success of the intervention.

There are some complicated situations in which stents in different vessels of a bifurcated vessel structure overlap. In those situations, an improvement of the stent visibility cannot be performed since the stents cannot be correctly detected.

<CIT> describes a prosthesis deployment apparatus using a real-time monitoring method for monitoring the position of a vessel branching from another vessel. First a multi-dimensional data set of a portion of the vessels is acquired. Then, at least one marker is secured to the vessels near the branch-off. The position of the marker is determined in real-time. Then, the position of a portion of the multi-dimensional data set is updated based on the position of the marker. This method determines the location and/or the orientation of a vessel or a vessel branch prior or during a prosthesis deployment. However, a determination of the location of several stents may not be performed with this method.

<CIT>, according to its abstract, relates to a method for enhancing the visualization of a plurality of objects within an imaged subject. The method includes acquiring a plurality of images of the plurality of objects disposed in the imaged subject and supported by a plurality of guide wires; generating a complex deformation field based at least in part on a plurality of landmarks disposed in the plurality of images; and generating a composite image based at least in part on the complex deformation field. The complex deformation field models deformation induced on the plurality of objects by at least two or more guide wires of the plurality.

<CIT> , according to its abstract, relates to detecting an object of interest in a sequence of images. Said object of interest is detected by first locating localizers related to said object of interest and by locating borders related to said object of interest using the location of said localizers. The viewing system is able to produce a sequence of enhanced images in which the object of interest is enhanced, to measure some characteristics and to build a three dimensional representation of said object of interest. The viewing system is also able to register and combine said sequence of enhanced images with a sequence of reference images.

There may thus be a need to provide a device and a method that improve the determination of the position of stents in complicated situations.

The object of the present invention is solved by the subject-matter of the independent claims; further embodiments are incorporated in the dependent claims. It should be noted that the following described aspects of the invention apply also for the system, the method, the computer program element, and the computer readable medium.

Thus, according to the present invention the markers can be associated to the correct stents such that stent positions may be consistently determined. Furthermore, the consistency of existing determined stent positions can be checked. This provides an improved determination of stents in complicated situations.

In an example, the processing unit may select at least one preliminary marker group before detecting the path indicators. This means that the processing unit will check the consistency of the selection according to the above description.

In an example, the device is used during a percutaneous coronary intervention (PCI).

In an example, the marker group comprises two markers.

The term "marker for identifying a stent position" relates to a marker that is indicative of a possible position of a stent. The markers can also be referred to as "stent markers". However, it must be noted that the markers can be provided on the stent itself or also not on the stent itself but provided separately on a stent element, e.g. on a balloon or another device used for stent positioning.

In an example, the vessel branch is detected from an angiogram, i.e. a contrast enhanced image, and the wire is detected from a non-contrast-enhanced image since in an angiogram, the contrast filled vessel obscures the wire. In an example, the marker positions are detected from a non-contrast-enhanced image.

In an example, a sequence of images including both contrast-enhanced and non-contrast-enhanced images is provided.

According to the invention, the input unit is configured to receive a sequence of images of a vasculature structure comprising at least two vessel branches; wherein the processing unit is configured to: detect positions of at least three markers for identifying a stent position; and detect path indicators for the at least two vessel branches in at least one of the images of the vasculature structure at least for vessel regions in which the positions of the markers are detected; associate the at least three markers to the path indicators based on the detected positions of the markers and the location of the path indicators; and assign markers which are associated to the same path indicator to a marker group to indicate positions of at least two stents in the vasculature structure.

According to the invention, the image of vasculature structure comprises at least two vessel branches in which the stents are positioned. In an embodiment, one stent is arranged in one vessel branch, another stent in the other vessel branch. The at least two stents may overlap close to the bifurcation of the vessel branches.

Each stent may be located using at least two markers, i.e. with two stents in the image there are at least four markers. In the image of vasculature structure, two markers may overlap which are positioned on different stents since close to the bifurcation the stents may be arranged on the same position in the image of vasculature structure. Thus, in an image having four markers at least three markers are visible in the image. The position of those at least three markers are detected in the image by the processing unit.

The processing unit further detects at least two path indicators in the image of vasculature structure. Each path indicator indicates a path along one of the at least two vessel branches. Based on the path indicators, the processing unit determines the vessel branches. In an example, the path indicators may be defined in a separate image of vasculature structure prior to receiving the image of vasculature structure showing the stents and the markers.

After detecting the path indicators and thus the vessel branches, the processing unit compares the positions of the markers with the extension of the vessel branches. If the comparison results that the position of a marker and a path are positioned in the same vessel branch, the respective marker is associated to the respective path indicator. A marker may be associated to several path indicators, for example if the vessels intersect each other and the marker is positioned at the intersection.

The processing unit groups all markers into a marker group which are associated to the same path, i.e. which are arranged in the same vessel branch. A marker group determines the position of a stent in the image. Since the markers of a marker group each are arranged on the same path, a marker group determines the position of a stent in the image.

According to an example, the device further comprises an image enhancement module for further image processing; wherein the output data is provided to the image enhancement module; and wherein the image enhancement module is configured to provide stent enhancement for the at least one stent in at least a part of the sequence of images to provide a stent enhanced image.

The stent enhancement is also referred to as stent boosting. The stent enhanced image is also referred to as stent boost image.

For example, <CIT> describes an image enhancement concerning the stents shown in the image. The image enhancement is known as StentBoost (trademark of Koninklijke Philips N.

According to an example, the device further comprises a display; wherein the display is configured to display the enhanced stent boost image.

In an example, boosting may mean a change of contrast, bordering the stents, and/or a change of color.

According to an embodiment, for detecting the path indicators, the processing unit is configured to: detect wires and/or guide wires in the at least one of the images of the vasculature structure that connect markers as the path indicators.

For detecting two path indicators, the processing unit is configured to detect at least two wires and/or guide wires in the image of the vasculature structure that connect positions markers as the path indicators.

According to an embodiment, for detecting the path indicators, the processing unit is configured to: detect at least two separate vessel branches in the at least one of the images of the vasculature structure as the path indicators; and/or detect at least two segmented vessel features for the at least two separate vessel branches in the at least one of the images of the vasculature structure as the path indicators.

In an example, the contrasted bifurcated vasculature is a priori contrasted before a stent is introduced into that vasculature, i.e. before the image of bifurcated vasculature with at least two stents in two different vessel branches is received.

In an example, the segmented vessel feature is a vessel centerline as determined from an angiogram.

According to an example, the processing unit is further configured to detect at least two stent elements in the image of bifurcated vasculature that extend in different vessel branches and that connect the positions of two of the at least two markers as path indicator.

According to an example, the stent element is a balloon.

According to an embodiment of the present invention, also a system for enhancing the images of stents in an image of vasculature structure is provided, the system comprising: an image acquisition device; and a device for determining the position of stents in an image of vasculature structure according to the preceding description; wherein the image acquisition device is configured to acquire and provide the sequence of images of the vasculature structure.

In an example, the processing unit is configured to indicate the marker group in real-time during a PCI.

According to an example, the image acquisition device is: an ultrasound device; or an X-ray image acquisition device, preferably an angiography device.

According to the present invention, also a method according to claim <NUM> is provided. Furthermore, an embodiment according to claim <NUM> is provided.

According to the present invention, also a computer program element for controlling a device according to the above description or system according to the above description is provided, which, when being executed by a processing unit, is adapted to perform the method steps according to the above description.

According to the present invention, also a computer readable medium having stored the program element according to the above description is provided.

<FIG> shows a system <NUM> for enhancing stent images in an image of vasculature structure. The system <NUM> comprises an image acquisition device <NUM> and a device <NUM> for determining the position of stents <NUM>, <NUM> in an image of vasculature structure.

The image acquisition device <NUM> acquires a sequence of images <NUM> of the vasculature structure <NUM>. In one exemplary embodiment, the image acquisition device <NUM> may be an ultrasound device. In another exemplary embodiment, the image acquisition device <NUM> X-ray image acquisition device, preferably an angiography device. Moreover, the image acquisition device <NUM> may be any image acquisition device which can acquire images of vasculature structure <NUM>.

According to the invention, the image <NUM> of vasculature structures <NUM> comprises at least two vessel branches <NUM>, <NUM>.

The vessel branches <NUM>, <NUM> may comprise stents <NUM>, <NUM>. However, the stents <NUM>, <NUM> may be hardly visible in the image <NUM> of vasculature structure <NUM>.

The image acquisition device <NUM> provides the sequence of images <NUM> of the vasculature structure <NUM> to the device <NUM> for determining the position of stents <NUM>, <NUM> in an image of vasculature structure.

Markers <NUM>, <NUM>, <NUM>, <NUM> which are visible in the image of vasculature structure are arranged at or close to the stents <NUM>, <NUM>. The markers <NUM>, <NUM>, <NUM>, <NUM> may be arranged on the stents <NUM>, <NUM> or on stent elements of the stents <NUM>, <NUM>, e.g. on balloons being connected to the stents <NUM>, <NUM>. Furthermore, the markers <NUM>, <NUM>, <NUM>, <NUM> may be radiopaque.

The device <NUM> comprises an input unit <NUM> for receiving the provided sequence of images <NUM> of vasculature structure <NUM>. Furthermore, the device <NUM> may comprise a processing unit <NUM>, an output unit <NUM>, an image enhancement module <NUM>, and a display <NUM>.

The processing unit <NUM> searches the sequence of images <NUM> to detect the positions of at least two markers <NUM>, <NUM>, <NUM>, <NUM> for identifying a stent position <NUM>, <NUM> in at least one of the images <NUM>. This search process is shown in <FIG>. The result of that search process is shown in <FIG>.

<FIG> shows an image <NUM> of the vasculature structure <NUM> comprising two vessel branches <NUM>, <NUM>. The image <NUM> is provided by the image acquisition device <NUM>. Each vessel branch <NUM>, <NUM> comprises a stent <NUM>, <NUM>. Markers <NUM>, <NUM>, <NUM>, <NUM> are associated to the stents <NUM>, <NUM>. Markers <NUM> and <NUM> are located on stent <NUM> and markers <NUM> and <NUM> are located on stent <NUM>.

In an exemplary embodiment, the processing unit <NUM> may preliminary group the markers <NUM>, <NUM>, <NUM>, <NUM> immediately after the detection, wherein each group refers to a preliminary position of a stent <NUM>, <NUM>. In this embodiment, the processing unit <NUM> will then provide a consistency check whether those preliminary positions are consistent with the vasculature structure <NUM> since there may be the case that markers <NUM> and <NUM> are preliminary grouped such that a position of a non-existing stent between the markers <NUM> and <NUM> would be determined. However, in another exemplary embodiment, the processing unit <NUM> will not determine a preliminary position of the stents <NUM>, <NUM> from the markers <NUM>, <NUM>, <NUM>, <NUM> and directly start with the detecting the path indicators <NUM>, <NUM>, <NUM>, <NUM>.

The processing unit <NUM> is configured to detect path indicators <NUM>, <NUM>, <NUM>, <NUM> for the at least two vessel branches <NUM>, <NUM>. A path indicator <NUM>, <NUM>, <NUM>, <NUM> indicates a path along the vessel branch <NUM>, <NUM>. This means, the path indicators <NUM>, <NUM>, <NUM>, <NUM> provide a position of a vessel branch <NUM>, <NUM> in the image <NUM> of the vasculature structure <NUM>. Examples of path indicators <NUM>, <NUM>, <NUM>, <NUM> are shown in <FIG> and will be discussed in detail below.

In <FIG>, a first exemplary embodiment of the path indicators <NUM>, <NUM>, <NUM>, <NUM> is shown as wires of guidewires which are the path indicators <NUM> and <NUM>. Those wires or guidewires are shown as a line of crosses along the vessel branches <NUM>, <NUM>. The paths which are indicated by the path indicators <NUM>, <NUM> are shown in <FIG> as single hatching patterns along the vessel branches <NUM>, <NUM>. In the region where the paths cross or overlap, i.e. at the bifurcation of the vasculature structure <NUM>, the two hatching patterns form a cross hatch. The processing unit <NUM> searches at least the region for the path indicators <NUM>, <NUM>, <NUM>, <NUM> in which the markers <NUM>, <NUM>, <NUM>, <NUM> are detected.

After identifying the position of the vessel branches <NUM> and <NUM> with the path indicators <NUM>, <NUM>, <NUM>, <NUM>, the processing unit <NUM> correlates the markers <NUM>, <NUM>, <NUM>, <NUM> with the vessel branches <NUM> and <NUM>. According to <FIG>, markers <NUM> and <NUM> are associated with the paths, i.e. the path indicators <NUM>, <NUM>, <NUM>, <NUM> which indicate the path in the vessel branch <NUM>. Markers <NUM> and <NUM> are associated with the path indicator <NUM>, <NUM>, <NUM>, <NUM> which indicate the path and the vessel branch <NUM>. Moreover, also marker <NUM> may be associated to the path indicators <NUM>, <NUM>, <NUM>, <NUM> which indicate the path and the vessel branch <NUM> since marker <NUM> is in the overlapping region which is covered by both paths of the vessel branches <NUM>, <NUM>.

According to <FIG>, the processing unit <NUM> groups markers <NUM> and <NUM> which are associated with the same path indicators <NUM>, <NUM>, <NUM>, <NUM> into a marker group. This marker group comprising the markers <NUM> and <NUM> indicates the stent position <NUM> of stent <NUM>.

Moreover, according to <FIG>, markers <NUM> and <NUM> are grouped into a marker group by the processing unit <NUM> and indicate the stent position <NUM> of stent <NUM>. In an exemplary embodiment, the processing unit <NUM> may further be configured to leave out marker <NUM> from that marker group indicating the stent position <NUM> since marker <NUM> is already part of the marker group indicating the stent position <NUM>. Furthermore, a portion of each stent <NUM>, <NUM> is arranged in the bifurcation of the vasculature structure <NUM>. This means, that markers <NUM> and <NUM> are close to each other. In some exemplary cases, those markers <NUM> and <NUM> may overlap such that they appear to be one single marker. In that exemplary case the processing unit <NUM> may associate the single marker in the bifurcation to more than one marker group.

The output unit <NUM> provides output data indicative of the positions of the markers <NUM>, <NUM>, <NUM>, <NUM> of the marker groups.

The image enhancement module <NUM> for further image processing receives the output data from the output unit <NUM>. The image enhancement module <NUM> provides a stent enhancement for the stents <NUM>, <NUM> and at least a part of the sequence of images <NUM> to provide a stent enhanced image <NUM>.

<FIG> shows the stent enhanced image <NUM>. Instead of the stents <NUM> and <NUM>, the stent enhanced image <NUM> comprises a boosted stent image <NUM> for stent <NUM>, the stent image <NUM> providing a boosted image of the stent <NUM>, and a boosted stent image <NUM> for stent <NUM>. Also, the boosted stent image <NUM> provides a boosted image of the stent <NUM>.

The boosting may for example be performed by changing the contrast of the images of the stents <NUM>, <NUM>, by bordering the stents <NUM>, <NUM> in the image <NUM> of the vasculature structure <NUM>, and/or by changing the color of the stents <NUM>, <NUM> in the image <NUM>.

The processing unit <NUM> and the image enhancement module <NUM> may process the image of vasculature structures <NUM> in real-time, i.e. on the fly, during a PCI.

The display <NUM> may display the stent enhanced image <NUM>. The display <NUM> may then provide a stent enhanced image <NUM> of which both stents <NUM>, <NUM> are replaced by the boosted stent images <NUM>, <NUM>, respectively.

In another exemplary embodiment shown in <FIG>, the display <NUM> may be configured to show <NUM> images <NUM>, <NUM>, wherein in image <NUM> only stent <NUM> is replaced by the boosted stent image <NUM> and stent <NUM> is not replaced and wherein in image <NUM>, only stent <NUM> is replaced by the boosted stent image <NUM> and stent <NUM> is not replaced.

<FIG> shows an exemplary embodiment of the path indicating elements <NUM>, <NUM>, <NUM>, <NUM>. The image of vasculature structure <NUM> shown in <FIG> comprises wires or guidewires <NUM>, <NUM> depicted as a line of crosses along the vessel branches <NUM>, <NUM>. The wires or guidewires <NUM>, <NUM> extend along the vasculature were in one wire or guidewires <NUM> extends along the vessel branch <NUM> and the other wire or guidewire <NUM> extends along vessel branch <NUM>. The wire or guidewires <NUM>, <NUM> may be used as path indicating elements <NUM>, <NUM>, <NUM>, <NUM> by the processing unit <NUM>. The wires or guidewires <NUM>, <NUM> connect the markers <NUM>, <NUM>, <NUM>, <NUM> in the image of vasculature structure <NUM>. According to <FIG>, the wire or guidewire <NUM> connects markers <NUM> and <NUM>. The wire or guidewire <NUM> connects markers <NUM> and <NUM>.

A further exemplary embodiment of the path indicating elements <NUM>, <NUM>, <NUM>, <NUM> is shown in <FIG> shows a contrast-enhanced image <NUM> of vasculature structure which may be an angiogram. Before acquiring the contrast-enhanced image 62of vasculature structure, a contrast agent is introduced into the vessel branches <NUM>, <NUM>. Consequently, the vessel branches <NUM>, <NUM> are clearly visible and the contrast-enhanced image 62of vasculature structure. The processing unit <NUM> may analyze the contrast-enhanced image <NUM> of vasculature structure to detect the extension of the vessel branches <NUM>, <NUM> as centerline of the vessel branches <NUM>, <NUM>. Alternatively or additionally, the analysis of the contrast-enhanced image <NUM> of vasculature structure provides segmented vessel features of the vessel branches <NUM>, <NUM>. The contrasted vessel branches <NUM>, <NUM> then provide path indicators <NUM>, <NUM> wherein path indicator <NUM> denotes a position of a path in the vessel branch <NUM> and path indicator <NUM> denotes a position of a path in vessel branch <NUM>.

<FIG> shows a flow chart of the method <NUM> for determining the position of stents <NUM>, <NUM> in the image of vasculature structure <NUM>.

An image acquisition device may provide <NUM> a series of images of vasculature structures comprising at least two vessel branches. A device for determining the position of stents in the image of vasculature structure may receive the image of vasculature structure. The images may be received using an input unit of the device. In step a), a processing unit of the device detects <NUM> positions of at least three markers for identifying a stent position in at least one of the images.

According to step b) path indicators are detected <NUM> in at least two vessel branches in at least one of the images. The detection is performed in a vessel region in which the positions of the markers have been detected before. Moreover, the detection may be performed using the processing unit. The path indicators may for example be wires or guidewires along the vessel branches according to step b1), for example be previously acquired positions of separate vessel branches in the vasculature according to step b2), or at least two segmented vessel features with at least two separate vessel branches according to step b3). For the detection of the wires or the guidewires along the vessel branches, an image of vasculature structure may be used, wherein the image of vasculature structure does not comprise a contrast enhancement for the vessels. For the detection of the position of the vessel branches a contrast-enhanced image of vasculature structure may be analyzed.

According to step c), the at least three markers are associated <NUM> to the path indicators based on the detected positions of the markers and the location of the path indicators. This means, the positions of the three markers are mapped to the position of the path indicators. If the positions of the markers match the position of the path indicators, this means, that the markers are in the same vessel branch as the path indicator. The association may be performed by the processing unit.

Markers which are associated with the same path indicator are assigned <NUM> to a marker group in step d). A marker group indicates a position of at least two stents in the vasculature. The assignment may be performed by the processing unit.

The positions of the markers of the marker group are provided <NUM> as output data. This means, that the output data indicates that positions of the marker in the marker group. The output data may be provided by an output unit.

That output data may be used to perform <NUM> the stent enhancement with at least one stent in at least part of the sequence of images. The standard enhancement provides a stent enhanced image. Furthermore, the stent enhancement may be performed with a stent enhancement module.

Furthermore, the stent enhanced image may be received by a display. The display may display <NUM> the stent enhanced image to a user. The display may display the stent enhanced image as a single image with all stents being enhanced. Alternatively, or additionally, the display may display several stent enhanced images, each stent enhanced image showing a single enhanced stent, wherein the remaining stents are not shown in an enhanced manner. The enhancement of the stents in the stent enhanced imaged may be provided by the change of contrast, a change of color, or by bordering the stent.

The method <NUM> may be performed on the real-time, i.e. on the fly, during a PCI.

In another exemplary embodiment of the present invention, a computer program or a computer program element <NUM> being shown in <FIG> is provided that is characterized by being adapted to execute the method steps of the method according to one of the preceding embodiments, on an appropriate system.

The computer program element <NUM> might therefore be stored on a computer unit, which might also be part of an embodiment of the present invention. This computing unit may be adapted to perform or induce a performing of the steps of the method described above. Moreover, it may be adapted to operate the components of the above described apparatus. The computing unit can be adapted to operate automatically and/or to execute the orders of a user. The data processor may thus be equipped to carry out the method of the invention.

According to a further exemplary embodiment of the present invention, a computer readable medium <NUM> being shown in <FIG>, such as a CD-ROM, is presented wherein the computer readable medium <NUM> has a computer program element <NUM> stored on it which computer program element <NUM> is described by the preceding section. A computer program may be stored and/or distributed on a suitable medium, such as an optical storage medium or a solid-state medium supplied together with or as part of other hardware, but may also be distributed in other forms, such as via the internet or other wired or wireless telecommunication systems.

While the invention has been illustrated, and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive. The scope of the invention and its embodiments is defined by the appended claims.

Claim 1:
A device for determining the position of stents in an image of vasculature structure, the device (<NUM>) comprising:
- an input unit (<NUM>);
- a processing unit (<NUM>); and
- an output unit (<NUM>);
wherein the input unit (<NUM>) is configured to receive a sequence of images (<NUM>) of a vasculature structure (<NUM>) comprising at least two vessel branches (<NUM>, <NUM>);
wherein the processing unit (<NUM>) is configured to:
- detect positions of at least three markers (<NUM>, <NUM>, <NUM>, <NUM>) for identifying a stent position (<NUM>, <NUM>) in at least one of the images (<NUM>);
- detect path indicators (<NUM>, <NUM>, <NUM>, <NUM>) for the at least two vessel branches (<NUM>, <NUM>) in at least one of the images (<NUM>) of the vasculature structure (<NUM>) at least for vessel regions in which the positions of the markers (<NUM>, <NUM>, <NUM>, <NUM>) are detected;
- associate the at least three markers (<NUM>, <NUM>, <NUM>, <NUM>) to the path indicators (<NUM>, <NUM>, <NUM>, <NUM>) based on the detected positions of the markers (<NUM>, <NUM>, <NUM>, <NUM>) and the location of the path indicators (<NUM>, <NUM>, <NUM>, <NUM>);
- assign markers (<NUM>, <NUM>, <NUM>, <NUM>) which are associated to the same path indicator (<NUM>, <NUM>, <NUM>, <NUM>) to a marker group to indicate a position (<NUM>, <NUM>) of at least two stents (<NUM>, <NUM>) in the vasculature structure (<NUM>); and
wherein the output unit (<NUM>) is configured to provide output data indicative of the positions of the markers (<NUM>, <NUM>, <NUM>, <NUM>) of the marker group.