Patent Description:
Interventional cardiology involves detecting, clearing, and/or stenting coronary arteries that have become obstructed due to the buildup of plaque on the walls of the arteries. When a coronary artery becomes blocked, a surgeon may attempt to clear and/or stent the occlusion by performing a retrograde navigation within the artery. A retrograde navigation involves introducing a guidewire into a non-blocked artery and navigating the guidewire antegrade within a non-blocked artery, through a collateral artery that connects the non-blocked artery and the blocked artery, and entering into the distal end of the blocked artery in order to approach the occlusion from the downstream side. After the guidewire reaches its destination, the guidewire serves as a guide for a larger catheter (i.e., a balloon catheter) which is then used to complete the procedure. An angiogram may be used to visualize the guidewire as it is moved through the body.

<CIT> describes a method for enhanced visualization of objects in interventional angiographic examinations. X-ray images are recorded during the system dose regulation phase with pure anatomy and during the filling phase with the vessels filled with contrast agent. A mask image is produced from both of the images. Native X-ray images are produced during a working or intervention phase with an object, for example a wire, a catheter or a "coil", moved in the vessel. The images have a matrix-shaped array of pixels. The pure anatomy images are subtracted from the filling images and from the native images for generating a first subtraction image and a second subtraction image respectively. The first and the second subtraction image are processed for generating a vessel image and an object image respectively. The vessel image and the object image are processed for generating a roadmap image which is played back on a monitor.

<CIT> describes a system and method for allowing the user to change the patient table position or x-ray detector position during an angiographic roadmapping procedure while still displaying a properly registered roadmap display by adapting the mask image to the new position. A system and method are also described for allowing the user to change the field of view size (i.e., zoom factor) of the x-ray detector during an angiographic roadmapping procedure by matching the size of the existing mask to the live image.

<CIT> describes a system and method for reconstructing an instrument in <NUM> dimensions for use during interventional medical procedures to provide enhanced instrument visualization with respect to a patient's vasculature. A patient vessel tree volume is co-registered with a live fluoroscopic image of a percutaneously-inserted instrument, such as a guidewire. The fluoroscopic image is segmented to eliminate images of surrounding tissue and to retain the guidewire image. The black pixels of the image are backprojected to the focal point of the x-ray source, through the co-registered vessel tree. The vessel tree is divided into segments that are scored based on proximity to the backprojected black pixels. Candidate instrument-containing vessel paths are identified based on the scores of the segments, and errant candidate vessel paths are eliminated to produce a refined list of candidate paths. Thresholding and visualization are performed to further refine the candidate vessel paths. 3D curve fitting is used to reconstruct an image of the instrument along with a 3D rendering of the final vessel path.

<CIT> describes a system (<NUM>) and a corresponding method for automatic roadmapping for endovascular interventions. In order to enable an enhanced roadmapping visualization without unnecessary device-footprints, the system (<NUM>) comprises: an x-ray imaging device (<NUM>) for acquiring x-ray images and a calculation unit (<NUM>). The x-ray imaging device (<NUM>) is adapted for acquiring a first x-ray image (<NUM>) with an interventional device (<NUM>) present in the vessels (<NUM>) while no contrast agent is present in the vessels (<NUM>). Furthermore, the x-ray imaging device (<NUM>) is adapted for acquiring a second x-ray image (<NUM>) with the interventional device (<NUM>) present in the vessels (<NUM>) while contrast agent is present in the vessels (<NUM>). The calculation unit is adapted for creating a roadmap image (<NUM>) by subtracting the first x-ray image (<NUM>) from the second x-ray image (<NUM>). Moreover, the calculation unit (<NUM>) is adapted for automatically minimizing the visibility of the interventional device (<NUM>) in the roadmap image (<NUM>). A display unit (<NUM>) is adapted to display the roadmap image (<NUM>) or an overlay of a current fluoroscopy image (<NUM>) with the roadmap image (<NUM>).

The present disclosure provides a method according to claim <NUM>.

The present disclosure also provides a system according to claim <NUM>.

The present disclosure also provides a computer readable storage medium according to claim <NUM>.

Various aspects of this disclosure may be better understood upon reading the following detailed description with reference to the drawings in which:.

The drawings illustrate specific acts of the described components, systems, and methods for visualizing a guidewire in a roadmap image. Together with the following description, the drawings demonstrate and explain the structures, methods, and principles described herein. In the drawings, the thickness and size of components may be exaggerated or otherwise modified for clarity. Well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the described components, systems, and methods.

One or more specific embodiments of the present disclosure are described below. These described embodiments are only examples of the systems and methods for visualizing a guidewire in a roadmap image. The skilled artisan will understand that specific details described in the embodiments can be modified when being placed into practice without deviating from the spirit of the present disclosure.

The terms "first," "second," and the like, do not denote any order, quantity, or importance, but rather are used to distinguish one element from another. As the terms "connected to," "coupled to," etc. are used herein, one object (i.e., a material, element, structure, number, etc.) can be connected to or coupled to another object regardless of whether the one object is directly connected or coupled to the other object or whether there are one or more intervening objects between the one object and the other object. In addition, it should be understood that references to "one embodiment" or "an embodiment" of the present disclosure are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features.

While performing an interventional cardiology procedure it is vital to clearly observe the guidewire as it moves through the body. As previously discussed, an angiogram may be used to visualize a guidewire while it moves through an artery. During an angiogram imaging procedure, a patient is injected with a contrast agent that is visible when X-rayed. The contrast agent aids in contrasting the guidewire from a background of the image and/or an artery that contains the guidewire.

Some angiography procedures for guidewire viewing use iodine as a contrast and include digitally subtracting a fluoroscopic image from an earlier generated image (or mask) of the same region. In the fluoroscopic image the guidewire is dark and in the previously generated mask blood vessels appear dark as well. After subtraction, background and bony structure in both the fluoroscopic image and the mask are canceled out and the dark blood vessels are inversed to white. Thus, the guidewire appears as dark and the blood vessels appear as white in a fluoroscopic image that depicts the guidewire in a blood vessel. The guidewire within the blood vessel may be displayed to a surgeon performing the interventional cardiology procedure in the form of a roadmap image. As used herein, a roadmap image includes a live fluoroscopic image that is superimposed on or otherwise combined with a previously generated digitally subtracted angiogram. Accordingly, a roadmap image based on iodinated digital subtraction angiography (an "iodinated angiographic roadmap" based on "iodinated DSA") clearly displays the guidewire and blood vessel as the guidewire and blood vessel contrast.

Unfortunately, iodine is not a suitable contrast agent for all patients. For example, iodine cannot be used for patients with renal failure or hypersensitivity to iodine. In such cases, carbon dioxide (CO<NUM>) may be alternatively used as a contrast agent. When CO<NUM> is injected into a blood vessel, the CO<NUM> replaces blood which results in a lower X-ray attenuation. Unfortunately, current roadmap images wherein the contrast agent is CO<NUM> are generated using the same procedure as iodinated contrast agents and as a result, CO<NUM> roadmap images are not optimal as both blood vessel and guidewire appear as either dark or white rendering it difficult to view the guidewire. Thus, there is a need for a method and/or a system that generates a CO<NUM> angiographic roadmap wherein the guidewire and blood vessel contrast from one another.

Referring to the figures generally, the present disclosure describes systems and methods for visualizing a guidewire in a CO<NUM> angiographic roadmap image. While the embodiments herein are described with respect to an X-ray fluoroscopic imaging system (i.e., an X-ray angiographic imaging system as depicted in <FIG>), it is understood that other embodiments may include other devices such as computed tomography ("CT") imaging systems, positron emission tomography ("PET") systems, real-time endoscopic imaging systems, and/or other imaging systems that utilize a contrast agent. It is further understood that embodiments described herein may be used to analyze objects within any material which can be internally imaged. As such, embodiments disclosed herein are not limited to analyzing objects with human tissue.

While the embodiments disclosed herein are described with respect to an X-ray based fluoroscopic imaging system (as shown in <FIG>), it is to be understood that embodiments of the present invention are equally applicable to other devices such as Computed Tomography ("CT") X-ray imaging systems, Magnetic Resonance Imaging ("MRI") systems, Positron Emission Tomography ("PET"), real-time endoscopic imaging, and/or any other type of imaging systems that utilize CO<NUM> as a contrast agent. As will be appreciated, embodiments of the present invention related imaging systems may be used to analyze objects within any material which can be internally imaged, generally. As such, embodiments of the present invention are not limited to analyzing objects within human tissue.

Referring now to <FIG>, an imaging system <NUM> is shown in accordance with an exemplary embodiment. In one embodiment, the imaging system <NUM> is an X-ray angiographic imaging system. While <FIG> depicts a stationary c-arm imaging system <NUM>, in a second embodiment, the imaging system <NUM> may be a mobile c-arm imaging system. In yet another embodiment, the imaging system <NUM> may be a non c-arm imaging system. The imaging system <NUM> is operative to image one or more structures (i.e., an internal organ, blood vessel, etc.) within a patient <NUM>. For example, the patient <NUM> may be suffering from one or more blocked coronary arteries and the imaged structures may be the one or more blocked coronary arteries. As illustrated in <FIG>, in some embodiments, the imaging system <NUM> includes a patient support <NUM> adapted to support the patient <NUM> while the patient <NUM> is being imaged, a radiation source <NUM>, and a radiation sensitive detector <NUM>. Collectively, the radiation patient support <NUM>, the radiation source <NUM>, and the radiation sensitive detector array <NUM> form imaging device <NUM>. In one embodiment, the imaging device <NUM> is an X-ray angiographic imaging device.

The imaging system <NUM> further includes a computing device <NUM>, and a display <NUM>. As used herein, a computing device is any device/system capable of processing and transmitting data (i.e., tablet, handheld computing device, smart phone, personal computer, laptop, network computer, server, mobile communication device, etc.). While the computing device <NUM> and display <NUM> are depicted as separate from the imaging device <NUM>, in some embodiments, the imaging device <NUM> may include the computing device <NUM> and the display <NUM>.

The computing device <NUM> is connected to and in communication with the imaging device <NUM> and the display <NUM> via a wired or wireless connection thereby allowing computing device <NUM> to transmit data to/receive data from the imaging device <NUM> and output an image and/or a video to the display <NUM>. The imaging device <NUM> and the computing device <NUM> may be connected to a network (i.e., a wide area network (WAN), a local area network (LAN), a public network (the Internet), etc.) which allows the imaging device <NUM> and the computing device <NUM> to communicate with one another when connected to a same network. In some embodiments, the network may be regarded as a private network connection and may include, for example, a virtual private network or an encryption or other security mechanism employed over the public Internet. In one embodiment, the computing device <NUM> may be remotely located with respect to the imaging device <NUM>. In another embodiment, the computing device <NUM> may be located in a same room as the imaging device <NUM>.

The computing device <NUM> includes a processor <NUM> and a system memory <NUM>. The processor <NUM> is in communication with the system memory <NUM> and may execute computer readable program instructions stored in the system memory <NUM>. In one embodiment, a processor may include a central processing unit (CPU). In another embodiment, a processor may include other electronic components capable of executing computer readable program instructions, such as a digital signal processor, a field-programable gate array (FPGA), or a graphics board. In yet another embodiment, a processor may be configured as a graphics processing unit (GPU) with parallel processing capabilities. In yet another embodiment, a processor may include multiple electronic components capable of carrying out computer readable instructions. For example, a processor may include two or more electronic components selected from a list of electronic components including: a CPU, a digital signal processor, an FPGA, and a GPU.

The system memory <NUM> is a computer readable storage medium. As used herein a computer readable storage medium is any device that stores computer readable program instructions for execution by a processor and is not construed as being transitory per se. Computer readable program instructions include programs, logic, data structures, modules, architecture etc. that when executed by a processor create a means for implementing functions/acts. Computer readable program instructions when stored in a computer readable storage medium and executed by a processor direct a computer system and/or another device to function in a particular manner such that a computer readable storage medium comprises an article of manufacture. System memory as used herein includes volatile memory (i.e., random access memory (RAM) and dynamic RAM (DRAM)) and nonvolatile memory (i.e., flash memory, read-only memory (ROM), magnetic computer storage devices, etc.). In some embodiments, the system memory may further include cache.

The display <NUM> displays a graphical user interface (GUI). As used herein, a GUI includes editable data (i.e., patient data) and/or selectable icons. A user may use an external device (i.e., keyboard, mouse, touch screen, etc.) connected to the computing device <NUM> to select an icon and/or edit the data. Selecting an icon/entering information causes a processor to execute computer readable program instructions stored in a computer readable storage medium which cause the processor to perform various tasks. For example, a user may use an external device to select an icon which causes the processor <NUM> to control the medical imaging device <NUM> to carry out an imaging session. As used herein, an imaging session includes acquisition/generation of a plurality of medical images including angiogram images of a blood vessel of interest.

Referring now to <FIG>, a block diagram of the imaging system <NUM> is shown in accordance with an exemplary embodiment.

When the processor <NUM> executes computer readable program instructions to begin a medical imaging procedure, the processor <NUM> sends a signal to the radiation source <NUM> to emit radiation. In some embodiments, the radiation source <NUM> is an X-ray tube. In response, the radiation source <NUM> emits radiation <NUM> that traverses an examination region <NUM>. The radiation sensitive detector <NUM> detects the radiation <NUM> that has traversed the examination region <NUM> and has been attenuated by the patient <NUM>. In response to detecting the radiation <NUM>, the radiation sensitive detector generates projection data. The intensity of the detected radiation is dependent upon the attenuation by the patient <NUM>. The radiation sensitive detector <NUM> includes elements that each produce separate electrical signal that is a measurement of the attenuation at the element location. The attenuation measurements from all the detector elements are acquired separately to produce a transmission profile.

The imaging device <NUM> sends the projection data to the computing device <NUM>. In response to receiving the projection data, the processor <NUM> may execute computer readable program instructions stored in the system memory <NUM> to processes the projection data to reconstruct an image and/or a video. As used herein, the phrase "reconstructing an image" is not intended to exclude embodiments of the present invention in which data representing an image is generated but a viewable image is not. Therefore, as used herein, the term "image" broadly refers to both viewable images and data representing a viewable image. Once reconstruction is complete, the processor <NUM> may output the reconstructed image/video to the display <NUM> in the form of image data.

In one embodiment, wherein the processor <NUM> outputs a video to the display <NUM>, the video may include a plurality of composite images/frames. The term "composite image", as used herein, means an image generated from two or more other images. For instance, in embodiments, a single composite image may be generated by registering one or more live images to an earlier acquired mask. In some embodiments a video feed output to the display <NUM> may be a live/real-time and/or near-real-time feed.

In one embodiment, the medical imaging procedure is an angiography imaging procedure of a blood vessel of interest. An angiography imaging procedure includes injecting a contrast agent (i.e., CO<NUM>) into the blood vessel of interest or into a blood vessel that is upstream of the blood vessel of interest. During an angiography imaging procedure, an imaging device (i.e., the imaging device <NUM>) continuously captures projection data and a processor (i.e., the processor <NUM>) outputs reconstructed images (based on the projection data) to a display (i.e., the display <NUM>) in real-time.

The contrast agent causes the lumen of the blood vessel of interest to have a different attenuation value than an area that surrounds the blood vessel of interest (i.e., a background of the blood vessel of interest). For example, when the contrast agent is CO<NUM> or another contrast agent that displaces blood within a blood vessel of interest, the contrast agent causes the lumen of the blood vessel of interest to have a lower attenuation value than a background of the blood vessel of interest. Since the blood vessel with the contrast agent has a different attenuation value than the background, processor may output images to the display wherein the blood vessel of interest is visible. Stated another way, during an angiography imaging procedure, a processor outputs a live video of a blood vessel of interest based on projection data captured by an imaging device, wherein the blood vessel of interest is visible. Stated yet another way, during an angiography imaging procedure, a processor outputs a live fluoroscopic image of a blood vessel of interest based on projection data captured by an imaging device, wherein the blood vessel of interest is visible.

In one embodiment, wherein the imaging procedure is an angiography imaging procedure of a blood vessel of interest, the angiography imaging procedure may be performed during an interventional procedure that includes inserting a guidewire into the blood vessel of interest. The guidewire may have a different attenuation value than the blood vessel with the contrast agent and/or the background of the blood vessel of interest. In this embodiment, during the angiography imaging procedure, the processor may output images/a live video/a live fluoroscopic image wherein the blood vessel of interest and the guidewire is visible.

In another embodiment, wherein the imaging procedure is an angiography imaging procedure of a blood vessel of interest that is performed during an interventional procedure that includes inserting a guidewire into the blood vessel of interest, an imaging device may capture projection data of the blood vessel of interest before the angiography imaging procedure. A processor may reconstruct the previously captured image data to form a mask image of the blood vessel of interest. During the angiography imaging procedure that is performed while a guidewire is in the blood vessel of interest, the processor may reconstruct an image from projection data captured during the angiography imaging procedure and subtract the mask from the image generated during the angiography imaging procedure to form a roadmap image. The processor may output the roadmap image to a display as a plurality of images or a live video.

Referring now to <FIG> a cloud computing environment <NUM> is shown in accordance with an exemplary embodiment. As illustrated in <FIG>, in some embodiments, the cloud computing environment <NUM> includes one or more nodes <NUM>. Each node <NUM> may include a computer system/server (i.e., a personal computer system, a server computer system, a mainframe computer system, etc.). The nodes <NUM> may communicate with one another and may be grouped into one or more networks. Each node <NUM> may include a computer readable storage medium and a processor that executes instructions in the computer readable storage medium. As further illustrated in <FIG> one or more devices (or systems) <NUM> may be connected to the cloud computing environment <NUM>. The one or more devices <NUM> may be connected to a same or different network (i.e., LAN, WAN, public network, etc.). One or more nodes <NUM> may communicate with the devices <NUM> thereby allowing the nodes <NUM> to provide software services to the devices <NUM>. In one embodiment, a node <NUM> may include the computing device <NUM>. In another embodiment, a device <NUM> may include the computing device <NUM>.

Referring now to <FIG>, a flow chart of a method <NUM> for visualizing a guidewire in an angiographic roadmap is shown in accordance with an exemplary embodiment. Various aspects of the method <NUM> depicted in <FIG> may be carried out by a "configured processor. " As used herein, a configured processor is a processor that is configured according to an aspect of the present disclosure. A configured processor(s) may be the processor <NUM>, a processor of a node <NUM>, or a processor of a device <NUM>. A configured processor executes various computer readable program instructions to perform the steps of the method <NUM>. The computer readable program instructions, that when executed by a configured processor, cause a configured processor to carry out the steps of the method <NUM> are stored in a computer readable storage medium including, but not limited to, the system memory <NUM>, a system memory of a node <NUM>, or a system memory of a device <NUM>. When performed by a configured processor, the steps of the method <NUM> cause the configured processor to output an angiographic roadmap image wherein a blood vessel contrasts with respect to a guidewire within the blood vessel. While the method <NUM> implements CO<NUM> as the contrast agent to generate the roadmap, it is understood that other negative contrast agents (i.e., oxygen, etc.) may be used to generate the roadmap.

At <NUM>, the configured processor receives a sequence of background images {IBackground (l), l = <NUM>,<NUM>,···, L}. In some embodiments, the background images are generated by the imaging system <NUM>. The background images include the bony structure, tissue structure, and a blood vessel of interest filled with blood. The imaging system <NUM> generates the background images during an imaging session, wherein no contrast (i.e., CO<NUM> contrast) or guidewire is present in the blood vessel of interest. For example, during an imaging session, the imaging system <NUM> may generate sixteen images of a blood vessel of interest of the patient <NUM> during an imaging session that does not include a CO<NUM> contrast nor guidewire. Accordingly, in this example, {IBackground (l), l = <NUM> - <NUM>}.

At <NUM>, the configured processor generates a background mask image (MBackground). The configured processor generates MBackground by temporally averaging the image data (i.e., pixel values) of the received background images acquired with no contrast injection nor any object being inside the blood vessel. As such, the configured processor may generate MBackground as a function of EQUATION <NUM>: <MAT>.

At <NUM>, the configured processor receives a sequence of CO<NUM> injected images {ICO<NUM>(k), k = <NUM>,<NUM>,···, K}. Since the x-ray attenuation of CO2 is smaller than the X-ray attenuation of blood, these CO<NUM> injected images can be considered as if the blood vessel is empty. In one example, the configured processor receives <NUM> contrast agent injected images. Accordingly, in this example, {ICO<NUM>(k), k = <NUM> - <NUM>}. In one embodiment, the sequence of CO<NUM> injected images and the sequence of background images are generated by the imaging system <NUM> during a same imaging session. In another embodiment, the imaging system <NUM> generates the sequence of CO<NUM> injected images and the sequence of background images during different imaging sessions. The sequence of CO<NUM> injected images includes the blood vessel of interest through peak opacification of CO<NUM> within the blood vessel of interest. In some embodiments, the first image in the sequence of CO<NUM> injected images, the blood vessel of interest does not include any injected CO<NUM> within the blood vessel of interest. That is, the first image may have been acquired before the injected CO<NUM> arrives at the blood vessel of interest.

At <NUM>, the configured processor generates a CO<NUM> mask image (MCO<NUM>) as a function of the CO<NUM> injected images. The configured processor generates MCO<NUM> according to EQUATION <NUM>: <MAT> where the CO<NUM> peak opacification is the operation of finding the most positive pixel value for each of the pixel locations over the K CO<NUM> injected images {ICO<NUM> (k), k = <NUM>,<NUM>,···, K}.

At <NUM>, the configured processor receives a sequence of live guidewire images {FGWire (n), n = <NUM>,<NUM>,···, N} (or "a set of guidewire images"). The guidewire images include a guidewire within the blood vessel of interest. In one embodiment, the set of guidewire images is generated by the imaging system <NUM>. In this embodiment, the imaging system <NUM> generates the guidewire images as the guidewire is moved through the blood vessel of interest. In one example, the configured processor receives three hundred guidewire images. That is, during an imaging session, the imaging device <NUM> generates three hundred guidewire images. Accordingly, in this example, {FGWire(n), n = <NUM> - <NUM>}. In some embodiments, the number N guidewire image is the last image acquired/reconstructed during an angiography imaging procedure. In this embodiment, {FGWire(n), n = <NUM>,<NUM>, ···, N} corresponds to a set of guidewire images acquired during an angiography imaging procedure. Furthermore, the number of guidewire images in the set of guidewire images may increase as an imaging procedure proceeds. That is, the number N image may correspond to a live image most recently generated by an imaging system.

At <NUM>, the configured processor registers MBackground and MCO<NUM> and subtracts MBackground from MCO<NUM> in linear domain as a function of the registration according to EQUATION <NUM>: <MAT> wherein the logarithm operation ln(·) transforms pixel values of the image into linear domain for subtraction. Since MCO<NUM> contains the empty blood vessel as well as the tissue and bony structures while MBackground contains the blood filed blood vessel as well as the tissue and bony structures of the anatomy, [ln(MCO<NUM>) - ln(MBackground)] removes the background (e.g. tissue and bony structures as well as the blood filed blood vessel) and generates an image that contains only the blood vessel of interest. In one embodiment, the blood vessel of interest is white in MCO<NUM>. In this embodiment, [ln(MCO<NUM>) - ln(MBackground)] contains only a white blood vessel of interest.

At <NUM>, the configured processor registers MBackground and a guidewire image in the set of guidewire images FGWire(n) and subtracts MBackground from FGWire(n) in linear domain as a function of the registration according to EQUATION <NUM>: <MAT> Since FGWire(n) contains the guidewire as well as the background and MBackground contains only the background, [ln(FGWire(n)) - ln(MBackground)] removes the background and generates an image that contains only the guidewire. In one embodiment, the guidewire is a dark color (i.e., dark gray, black, etc.). In this embodiment, [ln(FGWire(n)) - ln(MBackground)] contains only a dark guidewire.

At <NUM>, the configured processor generates a roadmap image (i.e., a CO<NUM> roadmap image). The configured processor generates the roadmap image by registering the generated image at <NUM> (the image that contains only the blood vessel of interest) and the image generated at <NUM> (image that contains only the guidewire) and super imposing (or otherwise combining) the image generated at <NUM> on the image generated at <NUM> as a function of the registration. As such, the roadmap image contains the blood vessel of interest and the guidewire.

The configured processor applies a weighting factor α to the images generated at <NUM> and <NUM> in order to balance the contrast between the blood vessel and the guidewire in the roadmap image. The weighting factor is determined as a function of at least one patient parameter (i.e., a patient thickness, a patient weight, etc.) and may be greater than <NUM> and less than <NUM> (<NUM> < α < <NUM>). Accordingly, in this embodiment, the configured processor generates the roadmap image according to EQUATION <NUM>: <MAT> wherein RMAP(n) is the CO<NUM> roadmap image for image n in the set of guidewire images. In one embodiment, the weighting factor increases with a patient thickness or patient weight. For example, a first patient may be larger (i.e., has a thicker abdomen cross section) than a second patient. In this example a first weighting factor that corresponds to the first patient is greater than a second weighting factor that corresponds to the second patient.

While EQUATIONS <NUM>-<NUM> include performing a logarithmic linearization of FGWire(n), MBackground, and MCO<NUM>, EQUATIONS <NUM>-<NUM> may linearize FGWire(n), MBackground, and MCO<NUM> by applying other functions (i.e., a polynomial function, a linear-logarithm function where linear function is used on smaller signal and logarithm function is used on larger signal, etc.) to FGWire(n), MBackground, and MCO<NUM>.

Briefly turning to <FIG>, a roadmap image <NUM> is depicted in accordance with an exemplary embodiment. In one embodiment, the roadmap image <NUM> is generated at <NUM> and includes a blood vessel of interest <NUM> and a guidewire <NUM>. Since, in some embodiments, [ln(MCO<NUM>) - ln(MBackground)] contains only a white blood vessel of interest and [ln(FGWire(n)) - ln(MBackground)] contains only a dark guidewire, the blood vessel of interest <NUM> may be white and the guidewire <NUM> may be dark. Due to this contrast, the method <NUM> may generate a roadmap image (i.e., a CO<NUM> roadmap image) wherein a guidewire is more visible.

Returning to <FIG>, at <NUM>, the configured processor outputs the CO<NUM> roadmap image to a display.

At <NUM>, the configured processor determines if n = N on FGWire(n). Stated another way, at <NUM>, the configured processor determines if the n'th image used to generate RMAP(n) is the last image in the set of guidewire images. As previously discussed, in some embodiments, FGWire (n) corresponds to a live image and as such, FGWire(N) may correspond to a last image in an imaging procedure.

In response to determining FGWire(n), n ≠ N, the configured processor repeats steps <NUM> - <NUM> for FGWire(n + <NUM>).

At <NUM>, in response to determining FGWire(n), n = N the configured processor ends method <NUM>. While <FIG> depicts method <NUM> proceeding in an ordered operation, any steps of the method <NUM> may occur simultaneously. For example, the configured processor may simultaneously perform steps <NUM> - <NUM>. Also, the configured processor may output RMAP(N) immediately after the imaging device acquires FGWire(N) such that the configured processor outputs RMAP(N) as a live image. Furthermore, the configured processor may output a first roadmap image (i.e., RMAP(n)) and immediately thereafter output a second roadmap image (i.e., RMAP(n + <NUM>)) such that the configured processor outputs the roadmap images as a video.

Claim 1:
A computer-implemented method for visualizing a guidewire in a roadmap image (<NUM>) comprising:
generating (<NUM>) a background mask as a function of at least one background image, by temporally averaging the image data of the at least one background image, wherein the at least one background image includes a blood vessel of interest, wherein no contrast agent or guidewire is present in the blood vessel;
generating (<NUM>) a contrast mask as a function of at least one contrast image, by finding the most positive pixel value for each of the pixel locations over the at least one contrast image, wherein the at least one contrast image includes a contrast agent within the blood vessel of interest;
receiving a guidewire image (<NUM>), wherein the guidewire image includes a guidewire within the blood vessel of interest;
linearizing the background mask, the contrast mask and the guidewire image, wherein the linearizing comprises applying a logarithmic function, a polynomial function or a linear-logarithm function, whereby in the linear-logarithm function a linear function is used on smaller signal and logarithm function is used on larger signal;
generating (<NUM>) a roadmap image as a function of the linearized background mask, the linearized contrast mask, the linearized guidewire image, and a weighting factor, wherein the weighting factor is determined as a function of a patient parameter, and wherein the roadmap image includes the blood vessel of interest, and the guidewire; and
outputting (<NUM>) the roadmap image to a display,
wherein generating the roadmap image comprises:
subtracting (<NUM>) the linearized background mask from the linearized contrast mask; and
subtracting (<NUM>) the linearized background mask from the linearized guidewire image.