Computational system, system and method for imaging a coronary artery of interest

Abstract

The present application relates to computing systems, systems and methods for imaging coronary arteries of interest. The present invention provides systems and methods for imaging a coronary artery tree via registration of angiographic projections with computed tomography data. In one example, a method for imaging a coronary artery of interest in a patient may include acquiring computed tomography (CT) imaging data depicting a coronary artery tree, acquiring a single angiographic projection of the coronary artery of interest, registering the single angiographic projection to the CT imaging data, and determining a fractional flow reserve (FFR) of the coronary artery of interest based on the single angiographic projection registered to the CT imaging data.

Description

Technical Field

[0001] Embodiments of the subject matter disclosed herein relate to medical imaging, and more particularly to the registration of images obtained via invasive angiographic techniques with computed tomography data. Background Art

[0002] Invasive angiography may involve inserting a catheter and threading it into an artery through which a contrast agent may be injected. X-rays attenuated by the contrast-filled artery may then be acquired via x-ray imaging techniques to generate high-resolution two-dimensional (2D) projections of the coronary artery tree region. In some examples, multiple 2D projections may be employed to obtain an accurate three-dimensional (3D) and functional representation of the coronary artery tree by manually or automatically registering the 2D projections to each other.

[0003] Computed tomography (CT) angiography is an alternative non-invasive technique for diagnosing coronary artery disease. Specifically, in CT angiography, contrast agents may be provided via intravenous injection (e.g., via a needle) instead. Thus, patient discomfort may be significantly reduced compared to invasive angiography. In addition, CT angiography may be used to image the entire coronary artery tree. However, images obtained from CT angiography may have lower resolution in certain circumstances (such as when the patient has stenosis or a high heart rate). Summary of the invention

[0004] In one embodiment, a method for imaging a coronary artery of interest in a patient may include acquiring computed tomography (CT) imaging data depicting a coronary artery tree, acquiring a single angiographic projection of the coronary artery of interest, registering the single angiographic projection to the CT imaging data, and determining a fractional flow reserve (FFR) of the coronary artery of interest based on the single angiographic projection registered to the CT imaging data.

[0005] It should be understood that the above brief description is provided to introduce in a simplified form selected concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is solely defined by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] The present disclosure will be better understood by reading the following description of non-limiting embodiments with reference to the accompanying drawings, in which:

[0007] Figure 1 shows a pictorial view of an exemplary medical imaging system according to one embodiment;

[0008] Figure 2 shows a schematic block diagram of an exemplary medical imaging system according to one embodiment;

[0009] Figure 3A and Figure 3B A flow chart showing a method for automatically registering angiographic projections to computed tomography imaging data and determining fractional flow reserve therefrom, according to one embodiment;

[0010] Figure 4 a schematic diagram showing an exemplary reduced order model of an exemplary portion of a coronary artery tree according to one embodiment; and

[0011] Figure 5 An exemplary user interface display of a display device of an exemplary medical imaging system is shown according to one embodiment. DETAILED DESCRIPTION

[0012] The following description relates to various embodiments of medical imaging systems and methods for automatically registering two-dimensional (2D) angiographic projections to three-dimensional (3D) computed tomography (CT) imaging data thereon. One such medical imaging system configured to acquire 2D angiographic projections and 3D CT imaging data is depicted in Figure 1 and Figure 2 and one such method for automatically registering 2D angiographic projections to 3D CT imaging data is provided in Figure 3A and Figure 3B In one embodiment, a reduced order model (such as Figure 4 An exemplary reduced order model of ) is used to estimate FFR. Figure 5 An exemplary user interface display of a display device of a medical imaging system is depicted in which a reconstructed image based on 2D angiographic projections registered to 3D CT imaging data, the FFR of a coronary artery of interest, and a diagnosis and recommended treatment based on the FFR are simultaneously displayed.

[0013] Generally speaking, FFR is a physiological index that can be used, for example, to determine the severity of hemodynamic problems of a lesion within a coronary artery or to identify a lesion causing ischemia. Therefore, FFR can be used as an indicator of a treatment strategy for treating a coronary artery of interest in a given patient. For example, a relatively small FFR can indicate the selection of a vascular recanalization technique (e.g., angioplasty) as a treatment for the corresponding constricted coronary artery, while a relatively large FFR can indicate the selection of another medical treatment (e.g., a prescription drug) as a treatment.

[0014] Specifically, FFR is the ratio of the arterial pressure distal to the lesion (e.g., upstream) to the arterial pressure proximal to the lesion (e.g., downstream). For example, the arterial pressure proximal to the lesion can be obtained at the ostium of the coronary artery tree and can therefore be considered as the aortic pressure during congestion. In some cases, the arterial pressure distal to the lesion can be measured invasively, for example, via a pressure sensor placed distal to the lesion. However, from a patient workflow perspective, a less invasive approach may be desirable (e.g., to reduce patient discomfort).

[0015] In some examples, FFR may be determined via CT angiography imaging alone. Once the CT angiography imaging data is received, the vessel centerline and vessel edges may be segmented to determine the length and three-dimensional shape of the coronary arteries. Such segmentation methods remain a huge challenge in the art, requiring top-quality imaging for accurate diagnosis. In addition, automated processing of the imaged vessel lumen may be difficult for patients with calcified vessels (e.g., stenosis) or high heart rates. As a result, medical professionals may verify segmentation, which may lead to inconsistencies in diagnosis, treatment, and health outcomes.

[0016] In other examples, FFR may be determined via invasive angiographic imaging alone. Invasive angiographic imaging data may be received as multiple 2D angiographic projections that present different views of the coronary artery of interest. The multiple 2D angiographic projections may then be registered with each other, for example, via a stereoscopic imaging algorithm, in order to obtain a 3D model of the coronary artery of interest. However, acquiring multiple 2D angiographic projections may be uncomfortable for the patient. In addition, the location of the coronary artery of interest in each of the multiple 2D angiographic projections may typically be manually marked by a medical professional for input into the stereoscopic imaging algorithm. Similar to CT angiographic imaging, such manual interaction with imaging data may lead to inconsistencies in diagnosis, treatment, and health outcomes.

[0017] Therefore, in the embodiments described herein, a system and method for automatically registering a single 2D angiographic projection to 3D CT angiographic imaging data is provided. Therefore, a 3D representation of the entire coronary artery tree can be obtained via CT angiographic imaging, and a single 2D angiographic projection can be used for regions of the coronary arteries that may be difficult to capture in 3D CT angiographic imaging data. In some embodiments, FFR can be estimated subsequently by segmenting the resulting imaging data and thereby forming a reduced-order model. In addition, in certain embodiments, the 3D CT angiographic imaging data may have been pre-imaged and can therefore be collected from an imaging library, so that only a single 2D angiographic projection needs to be imaged. Therefore, by combining invasive angiographic imaging data with CT angiographic imaging data in this way, patient discomfort can be alleviated, and total imaging time can be shortened by maximally simplifying the imaging procedure. In addition, the method for automatic registration provided herein can reduce the above-mentioned inconsistencies in diagnosis, treatment, and health outcomes. Therefore, the overall experience of the patient can be improved.

[0018] Reference now Figure 1 , depicting an exemplary imaging system 100 according to one embodiment. In the illustrated embodiment, the imaging system 100 is an x-ray imaging system configured to perform angiographic imaging. In some embodiments, the angiographic imaging may include invasive angiographic imaging techniques and / or CT angiographic imaging techniques. However, it should be understood that other types of medical imaging modalities (e.g., x-ray, magnetic resonance (MR), ultrasound (US), positron emission tomography (PET), single photon emission CT (SPECT), and combinations thereof, such as multimodal imaging, such as PET / CT, PET / MR, SPECT / CT, etc.) may be used to implement the embodiments described herein. In addition, it should be understood that other embodiments do not actively acquire medical images. Instead, the embodiments may retrieve images or imaging data previously acquired by the imaging system and analyze the image data as described herein.

[0019] The imaging system 100 may be configured to image a subject 112 (such as a patient, an inanimate object, one or more manufactured parts) and / or a foreign object (such as a dental implant, a stent, and / or a contrast agent present in the body). In one embodiment, the imaging system 100 may include a gantry 102, which in turn may also include at least one x-ray source 104 configured to project an x-ray radiation beam 106 (see Figure 2 ) for imaging a subject 112 placed on an examination table 114. Specifically, the x-ray source 104 can be configured to project x-rays 106 toward a detector array 108 positioned on an opposite side of the gantry 102. Figure 1A single x-ray source 104 is depicted, but in certain embodiments, multiple x-ray sources and / or detectors may be employed to project multiple x-ray radiation beams 106 for acquiring projection data at different energy levels or angular orientations corresponding to the subject 112. In some CT imaging embodiments, the x-ray source 104 may implement dual energy gem spectrum imaging (GSI) by rapid peak kilovolt (kVp) switching. In some embodiments, the x-ray detector employed is a photon counting detector capable of distinguishing x-ray photons of different energies. In other embodiments, two sets of x-ray sources and detectors are used to generate dual energy projections, where one set of x-ray sources and detectors is set to low kVp and the other set to high kVp. It should therefore be understood that the methods described herein may be implemented with single energy acquisition techniques as well as dual energy acquisition techniques.

[0020] In certain embodiments, the gantry 102 may be a C-arm gantry configured such that the x-ray source 104 may project a beam of x-ray radiation 106 toward a predetermined target location within a subject 112. For example, in an invasive angiographic imaging application, a catheter may be inserted into the subject 112 to inject a contrast agent at a predetermined target location where the beam of x-ray radiation 106 is expected to pass through the subject 112. Thus, after passing through the subject 112 and being attenuated by various anatomical features and the contrast agent, the beam of x-ray radiation 106 may be received by a detector array 108 disposed opposite the x-ray source 104.

[0021] In some embodiments, the imaging system 100 also includes an image processor unit 110 configured to reconstruct an image of a target volume of a subject 112 using an iterative or analytical image reconstruction method, or a combination of both. For example, in CT imaging applications, the image processor unit 110 may use an analytical image reconstruction method such as filtered back projection (FBP) to reconstruct an image of a patient's target volume. As another example, the image processor unit 110 may use an iterative image reconstruction method such as advanced statistical iterative reconstruction (ASIR) or model-based iterative reconstruction (MBIR) to reconstruct an image of a target volume of a subject 112. In some examples, the image processor unit 110 may use an analytical image reconstruction method such as FBP in addition to an iterative image reconstruction method.

[0022] In some imaging system configurations (e.g., CT imaging system configurations), an x-ray source projects a cone-shaped x-ray radiation beam that is collimated to lie in an XYZ plane (often referred to as an "imaging plane") of a Cartesian coordinate system. The x-ray radiation beam passes through an object being imaged, such as a patient or subject. The x-ray radiation beam, after being attenuated by the object, impinges upon an array of radiation detectors. The intensity of the attenuated x-ray radiation beam received at the detector array depends on the attenuation of the x-ray radiation beam by the object. Each detector element of the array produces a separate electrical signal that is a measurement of the attenuation of the x-ray beam at the detector location. The attenuation measurements from all detector elements are collected individually to produce a transmission distribution.

[0023] In some imaging systems (e.g., CT imaging systems), a gantry is used to rotate an x-ray source and a detector array around an imaging plane around an object to be imaged, so that the angle at which the radiation beam intersects the object is constantly changing. A set of x-ray radiation attenuation measurements (e.g., projection data) from a detector array at one angular position of the gantry is referred to as a "view". A "scan" of an object includes a set of views obtained at different angular positions or viewing angles during one rotation of the x-ray source and detector about the object. It is conceivable that the benefits of the methods described herein are derived from many medical imaging modalities, so as used herein, the term "view" is not limited to the use described above with respect to projection data from one gantry angle. The term "view" is used to mean a data acquisition and / or any other modality (including modalities yet to be developed) whenever there are multiple data acquisitions from different angles (whether from CT, x-ray radiography, positron emission tomography (PET), or single photon emission CT (SPECT) acquisitions) and their combination in fusion embodiments.

[0024] The projection data is processed to reconstruct an image corresponding to one or more two-dimensional slices acquired through the object, or in some examples where the projection data includes an extended axial coverage (e.g., Z-axis illumination), an image corresponding to a three-dimensional image volume of the object is reconstructed. A method for reconstructing an image based on a projection data set is referred to in the art as a filtered back-projection technique. Transmission and emission tomography reconstruction techniques also include statistical iterative methods such as maximum likelihood expectation maximization (MLEM) and ordered subset expectation maximization reconstruction techniques and iterative reconstruction techniques. The method converts the attenuation measurements from the scan into an integer (referred to as a "CT number" or "Hounsfield unit" in terms of a CT imaging system), which is used to control the brightness of the corresponding pixel on the display device.

[0025] To reduce the total scan time, a "helical" scan can be performed. To perform a "helical" scan, the patient is moved while acquiring data for a specified axial coverage. Such systems produce a single spiral from a cone beam helical scan. The spiral mapped out by the cone beam produces projection data from which an image in each specified slice can be reconstructed.

[0026] As used herein, the phrase "reconstructing an image" is not intended to exclude embodiments of the present disclosure in which data representing an image is generated rather than a visible image. Thus, as used herein, the term "image" broadly refers to both a visible image and data representing a visible image. However, many embodiments generate (or are configured to generate) at least one visible image.

[0027] Reference now Figure 2 , depicting something like Figure 1 An exemplary imaging system 200 of the imaging system 100 is provided. That is, the imaging system 200 may be an x-ray imaging system configured for invasive angiographic imaging and / or CT angiographic imaging. As shown, the imaging system 200 may include a plurality of components. These components may be coupled to each other to form a single structure, may be separate but located in a common room, or may be remote from each other. For example, one or more of the modules described herein may be operated in a data server that has a different and remote location relative to the other components of the imaging system 200.

[0028] According to aspects of the present disclosure, the imaging system 200 can be configured to image a subject 204 (eg, Figure 1 In one embodiment, the imaging system 200 may include a detector array 108 (see Figure 1 ). The detector array 108 may also include a plurality of detector elements 202 that together sense the x-ray radiation beam 106 passing through a subject 204 (such as a patient) to acquire corresponding projection data. Thus, in one embodiment, the detector array 108 may be fabricated including a multi-row unit or multi-slice configuration of detector elements 202. In such a configuration, one or more additional rows of detector elements 202 may be arranged in a parallel configuration to acquire projection data.

[0029] In certain embodiments, the imaging system 200 can be configured to include a substantially C-shaped or semicircular gantry or "C-arm" 102. The gantry 102 can movably support an x-ray source 104 and a detector array 108 mounted on opposite ends relative to each other. A subject 204 can thus be supported by an examination table 114 and disposed between the x-ray source 104 and the detector array 108.

[0030] It should be understood that in some embodiments, the examination table 114 may also be movable to achieve the desired image acquisition. During such image data acquisition, the gantry 102 may be movable to change the position and / or orientation of the x-ray source 104 and / or the detector array 108 relative to the subject 204.

[0031] Thus, in some embodiments, such as in invasive angiographic imaging applications, the gantry 102 may remain stationary during a given imaging session to image a single 2D projection of the subject 204. In such embodiments, the position of the gantry 102 and / or the table 114 may be adjusted between imaging sessions to image another view of the subject 204.

[0032] In other embodiments, such as in CT imaging applications, the imaging system 200 can be configured to traverse different angular positions around the subject 204 to collect the desired projection data. Thus, the gantry 102 and components mounted thereon can be configured to rotate about the rotation center 206 to collect, for example, projection data at different energy levels. Alternatively, in embodiments where the projection angle relative to the subject 204 changes over time, the mounted components can be configured to move along a generally curved line rather than along a segment of a circle.

[0033] In such embodiments, the detector array 108 may collect data of the attenuated x-ray beam as the x-ray source 104 and the detector array 108 rotate. The data collected by the detector array 108 may undergo pre-processing and calibration to condition and process the data to represent the line integral of the attenuation coefficient of the scanned subject 204. The processed data is often referred to as a projection.

[0034] In some examples, individual detectors or detector elements 202 in detector array 108 may include photon counting detectors that register interactions of individual photons into one or more energy bins. It should be appreciated that the methods described herein may also be implemented using energy integrating detectors.

[0035] The acquired projection data sets may be used for base material decomposition (BMD). During BMD, the measured projections may be converted into a set of material density projections. The material density projections may be reconstructed to form a pair or set of material density maps or images (such as bone, soft tissue, and / or contrast agent maps) for each corresponding base material. The material density maps or images may then be correlated to form a volume rendering of the base material (e.g., bone, soft tissue, and / or contrast agent) in the imaging volume.

[0036] Once reconstructed, the base material image produced by the imaging system 200 can reveal internal features of the subject 204 represented by the density of the two base materials. The density image or a combination of multiple density images can be displayed to show these features. In traditional methods of diagnosing medical conditions (such as disease states), and more generally diagnosing medical events, a radiologist or physician will consider a hard copy or display of a density image or a combination thereof to discern characteristic features of interest. Such features can include lesions, size and shape of specific anatomical structures or organs, as well as other features that should be discernible in the image based on the skills and knowledge of the individual practitioner.

[0037] In one embodiment, the imaging system 200 may include a control mechanism 208 to control movement of components, such as rotation of the gantry 102 and operation of the x-ray source 104. In certain embodiments, the control mechanism 208 may also include an x-ray controller 210 configured to provide power and timing signals to the x-ray source 104. In additional or alternative embodiments, the x-ray controller 210 may also provide operating signals and / or control signals to the adjustable collimator 222 to shape the x-ray beam from the x-ray source 104 according to a given imaging procedure to be performed. Additionally, the control mechanism 208 may include a gantry motor controller 212 configured to control the rotational speed and / or position (linear or curved) of the gantry 102 or various components thereof (e.g., the x-ray source 104, the detector array 108, etc.) based on imaging requirements.

[0038] In certain embodiments, the control mechanism 208 may also include a data acquisition system (DAS) 214 that is configured to sample analog data received from the detector elements 202 and convert the analog data to digital signals for subsequent processing. For a photon counting imaging system, the DAS 214 may download measured photon counts in one or more energy bins from the detector array 108. The DAS 214 may also be configured to selectively aggregate analog data from a subset of the detector elements 202 into a so-called macro-detector, as further described herein.

[0039] The data sampled and digitized by the DAS 214 may be transmitted to a computer or computing device 216. In the illustrated embodiment, the computing device 216 may be configured to interact with various components of the imaging system 200. As such, the computing device 216 may be configured to control the operation of the imaging system 200. In various embodiments, the computing device 216 may take the form of a mainframe computer, a server computer, a desktop computer, a laptop computer, a tablet device, a network computing device, a mobile computing device, a mobile communication device, etc. In one embodiment, the computing device 216 may take the form of an edge device for use in Figure 2In some embodiments, one or more components of the imaging system 200 configured to collect x-ray radiation may be considered an x-ray imaging subsystem (e.g., x-ray source 104, detector array 108, etc.) of the entire imaging system 200, which may be a computing system further configured to interact with a user and perform various computing processes (e.g., imaging or non-imaging). Thus, other components of the imaging system 200 (e.g., computing device 216, etc.) can be communicatively coupled to the x-ray imaging subsystem.

[0040] In some embodiments, the computing device 216 may store data in a storage device or mass storage device 218, which is included in the computing device 216 (in such examples, the computing device 216 may be referred to as a controller) or is a separate device that can be communicatively coupled to the computing device 216 (in such examples, the computing device 216 may be referred to as a processor). The storage device 218 may include removable media and / or built-in devices. Specifically, the storage device 218 may include one or more physical, non-transient devices that are configured to store data and / or instructions that can be executed by the computing device 216 to implement the methods described herein. Therefore, when implementing such methods, the state of the storage device 218 can be converted (for example, to save different or changed data). The storage device 218 may include, for example, a magnetoresistive random access memory (MRAM), a hard disk drive, a floppy disk drive, a tape drive, a compact disk-read / write (CD-R / W) drive, a digital versatile disk (DVD) drive, a high-definition DVD (HD-DVD) drive, a Blu-ray drive, a flash drive, and / or a solid-state storage drive. It should be appreciated that the storage device 218 may be a non-transitory storage medium.

[0041] In addition, the computing device 216 can provide commands and parameters to one or more of the DAS 214, the x-ray controller 210, and the gantry motor controller 212 to control system operations, such as data acquisition and / or processing. In certain embodiments, the computing device 216 controls system operations based on operator input, such as via a user interface 234. The computing device 216 receives operator input, such as commands and / or scan parameters, via an operator console 220 operably coupled to the computing device 216. The operator console 220 can include a physical keyboard, a mouse, a touch pad, and / or a touch screen to allow an operator to specify commands and / or scan parameters.

[0042] Although Figure 2Only one operator console 220 is shown, but more than one operator console 220 may be coupled to the imaging system 200, e.g., for inputting or outputting system parameters, requesting exams, plotting data, and / or viewing images. In addition, in certain embodiments, the imaging system 200 may be coupled to multiple displays, printers, workstations, and / or the like located locally or remotely, e.g., within an institution or hospital or at an entirely different location, via one or more configurable wired and / or wireless networks (such as the Internet and / or a virtual private network, a wireless telephone network, a wireless local area network, a wired local area network, a wireless wide area network, a wired wide area network, etc.).

[0043] In one embodiment, for example, the imaging system 200 may include or may be coupled to a picture archiving and communication system (PACS) 224. In an exemplary embodiment, the PACS 224 may be further coupled to remote systems, such as a radiology information system (e.g., RIS), an electronic health or medical record and / or a hospital information system (e.g., EHR / HIS), and / or to an internal or external network (not shown) to allow operators located in different locations to provide commands and parameters and / or have access to image data.

[0044] The computing device 216 can use operator-supplied and / or system-defined commands and parameters to operate a table motor controller 226, which in turn can control the table 114, which can be a motorized table. Specifically, the table motor controller 226 can move the table 114 to properly position the subject 204 in the gantry 102 to acquire projection data corresponding to a target volume of the subject 204.

[0045] As previously described, the DAS 214 samples and digitizes the projection data acquired by the detector elements 202. Subsequently, the image reconstructor 230 uses the sampled and digitized x-ray data to perform high-speed reconstruction. Figure 2 The image reconstructor 230 is shown as a separate entity, but in certain embodiments, the image reconstructor 230 may form part of the computing device 216. Alternatively, the image reconstructor 230 may not be present in the imaging system 200, and instead the computing device 216 may perform one or more functions of the image reconstructor 230. Furthermore, the image reconstructor 230 may be located locally or remotely, and may be operably connected to the imaging system 200 using a wired or wireless network. For example, one embodiment may use computing resources in a "cloud" network cluster for the image reconstructor 230.

[0046] In one embodiment, the image reconstructor 230 may be configured as follows: Figure 2The computing device 216 shown may store the reconstructed image in a storage device 218, or via a direct connection (not shown). Alternatively, the image reconstructor 230 may transmit the reconstructed image to the computing device 216 to generate usable patient information for diagnosis and evaluation. In certain embodiments, the computing device 216 may transmit the reconstructed image and / or the patient information to a display or display device 232 that is communicatively coupled to the computing device 216 and / or the image reconstructor 230. In some embodiments, the reconstructed image may be transmitted from the computing device 216 or the image reconstructor 230 to the storage device 218 for short-term or long-term storage.

[0047] Various methods or processes further described herein (such as the following references Figure 3A and Figure 3B The methods described herein may be stored as executable instructions in a non-transitory memory on a computing device (or controller) in the imaging system 200 or communicate with the computing device (or processor). In one embodiment, the image reconstructor 230 may include such executable instructions in a non-transitory memory and may apply the methods described herein to reconstruct an image from the scan data. In another embodiment, the computing device 216 may include instructions in a non-transitory memory and may apply the methods described herein, at least in part, to the reconstructed image after receiving the reconstructed image from the image reconstructor 230. In yet another embodiment, the methods and processes described herein may be distributed across the image reconstructor 230 and the computing device 216.

[0048] In operation, the computing device 216 may acquire imaging data and other medical data, which may be converted, for example, via the user interface 234 for display to a user (e.g., a medical professional) on the display device 232. As an example, the medical data may be converted and displayed at the display device 232 as a user-oriented graphical and / or textual format, which may be standardized across all embodiments of the imaging system 200, or may be specific to a given institution, department, professional, or individual user. As another example, imaging data (e.g., three-dimensional (3D) volume data sets, two-dimensional (2D) imaging slices, etc.) may be used to generate one or more images at the computing device 216, which may then be displayed to an operator or user at the display device 232. In this way, the display device 232 may allow an operator to evaluate the imaged anatomical structure. The display device 232 may also allow an operator to select a volume of interest (VOI) and / or request patient information, for example, via a graphical user interface (GUI), for subsequent scanning or processing. Reference is made below to Figure 5 Specific examples of displays that may be presented to a user via display device 232 are provided.

[0049] It should be understood that the above reference Figure 1 and Figure 2 The imaging system may be configured for CT angiographic imaging, invasive angiographic imaging, another imaging modality, or a combination thereof. Thus, in some embodiments, multiple racks 102 may be provided for different imaging applications, each rack having a corresponding x-ray source 104, a detector array 108, etc. In other embodiments, a separate imaging system may be provided for each of the multiple imaging modalities, wherein the separate imaging systems may be communicatively coupled via a wired or wireless network. In such embodiments, imaging data may be transmitted and received between the separate imaging systems via the network.

[0050] See now Figure 3A and Figure 3B , depicts a flow chart showing a method 300 for automatically registering angiographic projections to CT imaging data and thereby determining FFR. Specifically, the angiographic projections may depict coronary arteries of interest, which may be associated with a coronary artery tree segmented from the CT imaging data. The FFR may then be determined based on the coronary arteries of interest associated with the coronary artery tree. Thus, a diagnosis may be generated and treatment may be recommended, which may be displayed to a user of the medical imaging system. It should be understood that the diagnosis and recommended treatment, as well as various other information (e.g., FFR, reconstructed images, etc.), may be displayed to the user at a display device of the medical imaging system. Therefore and as described below with reference Figure 5 As described in detail, a user may interact with the display device via a user interface to add, remove, or change the displayed information. Although such displayed information is described with reference to the specific steps of method 300, it should also be understood that each of the diagnosis, recommended treatment, FFR, reconstructed image, etc. may be displayed at any time after the given information is generated or received.

[0051] See below Figure 1 to Figure 2 The systems and components shown depict the method 300. For example, in some embodiments, the method 300 may be performed in Figure 2 However, it should be understood that the method 300 may be implemented with other systems and components without departing from the scope of the present disclosure. In some embodiments, the method 300 may be implemented as described above with reference to Figure 1 and Figure 2 In one embodiment, method 300 may be implemented in a non-transitory memory of a computing device, such as a Figure 2 The computing device 216 of the imaging system 200. It should also be understood that the various steps discussed with reference to the method 300 may be added, removed, replaced, or interchanged within the scope of the present disclosure.

[0052] Method 300 may begin at Figure 3A At 305 of the method 300, wherein the method 300 may include receiving a selection of one or more coronary arteries of interest for the patient. For example, the selection may be a user selection received at a user interface (e.g., 234) of the medical imaging system (e.g., 200), such as from a medical professional. Specifically, a given coronary artery of interest may be identified as contributing to the patient's coronary artery disease. For example, a given coronary artery of interest may have a stenosis (e.g., an area of ​​calcification) or a coronary artery lesion. As an additional contributing factor, the patient may have a heart rate (e.g., a resting heart rate) that is above a threshold heart rate (e.g., 90 bpm). In some embodiments, the selection may include a single coronary artery of interest. In other embodiments, the selection may include multiple coronary arteries of interest.

[0053] At 310, method 300 may include acquiring CT imaging data. In some embodiments, the CT imaging data may be acquired as x-ray radiation attenuated by the patient. Specifically, in CT imaging, a contrast agent may be provided to the patient in a "non-invasive" manner (e.g., via intravenous injection). The contrast agent may be selected so as to absorb more x-ray photons than surrounding tissues, arterial cavities, etc. Therefore, the contrast between the attenuated x-rays of the stained coronary arteries and their surroundings may be intensified. The attenuated x-rays may be acquired via an x-ray detector array (e.g., 108) disposed on a rack (e.g., 102) of a medical imaging system (e.g., 200), which may be processed and received by a computing device (e.g., 216) as 3D CT imaging data. In some embodiments, the 3D CT imaging data may depict at least a portion of the coronary artery tree corresponding to one or more coronary arteries of interest or the entire coronary artery tree.

[0054] In other embodiments, CT imaging data may be acquired from an imaging library stored on a storage device of a medical imaging system (e.g., 200). In some embodiments, the imaging library may include CT imaging data depicting the coronary artery tree of a patient (e.g., CT imaging data previously acquired in a separate imaging session). In additional or alternative embodiments, the imaging library may include CT imaging data depicting the coronary artery tree of multiple previous patients, wherein each of the multiple previous patients may also be associated with patient information including one or more of the patient's age, patient's weight, patient's heart rate, patient's blood pressure (e.g., systolic and diastolic blood pressure), and patient's medical history. A computing device (e.g., 216) may receive patient information for multiple previous patients from the imaging library. Thus, for a patient having one or more coronary arteries of interest, patient information including one or more of the patient's age, patient's weight, patient's heart rate, patient's blood pressure (e.g., systolic and diastolic blood pressure), and patient's medical history may also be received and matched with the patient information of a specific previous patient. CT imaging data of a specific previous patient may then be received from the imaging library, wherein the CT imaging data may depict the coronary artery tree of the specific previous patient. It should be appreciated that while the coronary artery tree depicted by the CT imaging data of a particular previous patient may be an approximation of the patient's coronary artery tree, the accuracy of the approximation may be improved by utilizing a larger and more diverse library. By acquiring CT imaging data from an imaging library, patients having one or more coronary arteries of interest may undergo fewer imaging procedures, thereby improving the overall patient experience.

[0055] At 315, method 300 may include reconstructing and displaying a first image based on the CT imaging data. In some embodiments, the CT imaging data may be reconstructed into a visible image (e.g., a first image) using an image reconstructor (e.g., 230) (e.g., via an analysis or iterative method). The first image may then be displayed to a user at a display device (e.g., 232) of a medical imaging system (e.g., 200). Thus, the user may manipulate the first image (e.g., change its magnification, move within the first image, obtain an alternative view, etc.) via a user interface (e.g., 234) including the display device.

[0056] At 320, method 300 may include determining whether to request one or more angiographic projections. In some embodiments, it may be determined (e.g., by computing device 216, a user, or a combination thereof) that the CT imaging data is sufficient to determine a diagnosis. In such embodiments, one or more angiographic projections may not be requested, and method 300 may proceed to 325, where method 300 may include receiving a manual diagnosis. For example, a user may determine a manual diagnosis based on a first image displayed via a display device (e.g., 232). A user may provide a manual diagnosis to an imaging system (e.g., 200) by inputting the manual diagnosis via a user interface (e.g., 234).

[0057] In other embodiments, it may be determined (e.g., by the computing device 216, a user, or a combination thereof) that the CT imaging data is insufficient to determine a diagnosis. For example, it may be determined by the computing device that the CT imaging data is insufficient to determine that the FFR of each of the one or more coronary arteries of interest is above a threshold confidence level. In such embodiments, one or more angiographic projections may be requested, and the method 300 may proceed to 330, where the method 300 may include acquiring the one or more angiographic projections. Specifically, the one or more angiographic projections may respectively depict one or more coronary arteries of interest, each of which has one or more coronary artery lesions. In some embodiments, the one or more angiographic projections may be acquired via invasive angiographic imaging. That is, a catheter may be sequentially inserted and penetrated into each of the one or more coronary arteries of interest, and a contrast agent may be injected via these coronary arteries. As described above at 310, the contrast agent may absorb more X-ray photons than surrounding tissues, lumens, etc., and thus intensify the contrast between the X-rays attenuated by the patient's staining features and their surroundings. The attenuated x-rays may then be acquired via an x-ray detector array (e.g., 108) of a medical imaging system (e.g., 200), which may be processed and received as an angiographic projection at a computing device (e.g., 216). Specifically, the angiographic projection may include a single 2D depiction of a given coronary artery of interest and its adjacent coronary arteries.

[0058] In some embodiments, a single angiographic projection may be acquired for each of the one or more coronary arteries of interest. Thus, in embodiments including a single coronary artery of interest, only one angiographic projection may be acquired. Thus, patient discomfort due to invasive angiographic imaging may be effectively minimized.

[0059] In other embodiments, multiple angiographic projections may be acquired for a given coronary artery of interest. In such embodiments, a single angiographic projection may be selected from the multiple angiographic projections, wherein the single angiographic projection may have the least amount of vessel overlap of the multiple angiographic projections (e.g., due to another coronary artery overlapping the coronary artery of interest or due to projection reduction of the given coronary artery of interest). Thus, the single angiographic projection may be selected as the highest resolution depiction of the coronary artery of interest among the multiple angiographic projections.

[0060] At 335, method 300 may include automatically registering one or more angiographic projections to CT imaging data. Specifically, the centerline and / or vessel edge of each coronary artery in the coronary artery of the coronary artery tree (or a portion thereof) depicted by the CT imaging data may be segmented. In embodiments where the centerline is segmented in the CT imaging data, the length and 3D shape of each centerline in the centerline may be determined so that the centerline may be drawn in a Cartesian coordinate system. Based on the length and rotational projection of the 3D shape of each centerline in the centerline of the coronary artery tree, one or more coronary arteries of interest may be associated (e.g., registered) with the length and rotational projection of the 3D shape of the centerline corresponding to the matching coronary artery in the coronary artery tree (e.g., via least squares fitting). In some embodiments, each coronary artery in the coronary artery of the coronary artery tree may be uniquely identified and labeled (e.g., identified and labeled as "left circumflex artery", "right marginal artery", etc.) based on the length and 3D shape of the corresponding centerline. Based on such identification, one or more coronary arteries of interest may then be registered to one or more matching coronary arteries of the coronary artery tree. Thus, each of the one or more angiographic projections may be registered to the CT imaging data based on the length and the 3D shape of each of the segmented centerlines.

[0061] In a specific embodiment, one or more angiographic projections may be paired with CT imaging data via an iterative algorithm that maintains pairing consistency by preserving the topological structure of the coronary artery tree. The iterative algorithm can achieve such pairing consistency by not only assuming a correspondence between bifurcation points observed in one or more angiographic projections and CT imaging data. Instead, the iterative algorithm relies primarily on matching the centerline of one or more coronary arteries of interest with the centerline of the coronary artery tree while limiting connectivity at the bifurcation point. In some embodiments, the iterative algorithm may also attach a spline to each centerline of the coronary artery tree, wherein the control points of each spline may be optimized under a dual constraint that minimizes the distance from a given angiographic projection depicting the corresponding coronary artery of interest and maintains a constant length of the corresponding coronary artery of interest.

[0062] In general, acquiring multiple angiographic projections can provide increased accuracy for a given coronary artery of interest because dynamic changes in cardiac motion may be relevant to the accurate determination of certain functional physiological indicators. However, collecting multiple angiographic projections can increase the overall imaging time, complicate the overall workflow, and increase patient discomfort. As described herein, by acquiring 3D CT imaging data for use in conjunction with (2D) angiographic projections, the total number of angiographic projections can be reduced. Specifically, the 3D CT imaging data can provide increased accuracy for the 3D structure of at least a portion of the coronary artery tree, which when registered to a given angiographic projection, may result in improved accuracy in determining functional physiological indicators (e.g., FFR) relative to using angiographic projections alone, thereby not using multiple angiographic projections. For example, the total number of angiographic projections can be limited to the total number of coronary arteries of interest.

[0063] As another example, in a specific embodiment in which a single coronary artery of interest is selected, a single angiographic projection depicting the coronary artery of interest may be sufficient for subsequent determination of a cardiac health function indicator (e.g., FFR). In such embodiments, no additional angiographic projections may be registered to the CT imaging data. Thus, when the single angiographic projection is registered with the CT imaging data, the CT imaging data may provide a 3D representation of the coronary artery of interest, which in an alternative example would be provided by multiple angiographic projections.

[0064] In fact, acquiring a single angiographic projection of a given coronary artery of interest rather than multiple angiographic projections further eliminates the manual marking of the coronary artery of interest that is typically used to register multiple 2D angiographic projections with each other to obtain a 3D representation of the coronary artery of interest. That is, in some embodiments, manual marking or marking of any angiographic projections is not employed.

[0065] At 340, method 300 may include reconstructing and displaying a second image of the coronary artery tree based on one or more angiographic projections registered to the CT imaging data. Thus, the second image may include one or more angiographic projections "stitched" into the reconstructed 2D projections of the (3D) CT imaging data (as described below with reference to Figure 5Detailed description). In some embodiments, the reconstructed second image can be an image visible to a user of the medical imaging system (e.g., 200) when displayed at a display device (e.g., 232). Thus, the user can manipulate the second image (e.g., change its magnification, move within the second image, obtain alternative views, etc.) via a user interface (e.g., 234) including the display device. In such embodiments, one or more visual indicators can be generated on the second image for each stenosis or coronary lesion in one or more coronary arteries of interest. Thus, the user can easily locate a specific stenosis or coronary lesion depicted by the second image.

[0066] At 345, method 300 may include determining and displaying an FFR for each of the one or more coronary arteries of interest based on the one or more angiographic projections registered to the CT imaging data. In some embodiments, the FFR for each of the one or more coronary arteries of interest may be estimated based on one or more of a length of a corresponding centerline and a three-dimensional shape of the corresponding centerline.

[0067] In a specific embodiment in which the vessel edges are segmented in the CT imaging data, a transverse cross-section of each of the coronary arteries of the depicted coronary artery tree (or a portion thereof) may be determined based on the corresponding vessel edges. In such embodiments, once one or more angiographic projections have been registered to the CT imaging data, a transverse cross-section of each of the one or more coronary arteries of interest may be determined, and the FFR of each of the one or more coronary arteries of interest may also be estimated based on their transverse cross-sections. It will be understood by those of ordinary skill in the art that, as used herein in conjunction with the coronary arteries, "transverse" may refer to a cross-section of a given coronary artery in any plane perpendicular to the directional path of blood flow through the given coronary artery.

[0068] In some embodiments, the reduced order model (such as the one described below) may be used to Figure 4 In one embodiment, the FFR is estimated based on a reduced order model (described in detail in the ). In such embodiments, the reduced order model may be formed based on the length of each of the centerlines of the coronary arteries of the coronary artery tree and the vessel diameter of each of the coronary arteries of interest (where each vessel diameter may be determined based on a transverse cross-section of the corresponding coronary artery of interest). Thus, each of the coronary arteries of interest may be modeled based on each of the one or more angiographic projections and the CT imaging data, and the remaining coronary arteries in the coronary artery tree (or a portion thereof) may be modeled based on the CT imaging data.

[0069] At 350, method 300 may include automatically generating and displaying a diagnosis based on the FFR. Specifically, a relatively low FFR may indicate significant stenosis or coronary artery lesions in a coronary artery of interest. For example, if the FFR is less than a threshold FFR (e.g., 0.80), the stenosis or coronary artery lesions may be diagnosed as significant. The diagnosis may then be displayed to the user at a display device (e.g., 232), wherein a user interface (e.g., 234) including the display device may be configured to enable the user to accept or reject the diagnosis (e.g., via a confirmation checkbox, a text input field, etc.). In a specific embodiment, a computing device (e.g., 216) may indicate to the user that it has not yet been determined that the FFR of at least one of the one or more coronary arteries of interest is above a threshold confidence level. In such embodiments, the user may be prompted to view the diagnosis at the user interface. In some embodiments, the computing device may wait for confirmation from the user, regardless of whether the FFR of each of the one or more coronary arteries of interest has been determined to be above a threshold confidence level. However, in other embodiments, the computing device may automatically confirm that the FFR for each of the one or more coronary arteries of interest has been determined to be above a threshold confidence level and may automatically accept the diagnosis.

[0070] At 355, method 300 may include determining whether to accept the diagnosis. For example, the user may evaluate the diagnosis and may determine that the diagnosis may be incorrect. Therefore, the user may indicate that the diagnosis is rejected, and method 300 may proceed to 325 to receive a manual diagnosis from the user. For example, the user may determine the manual diagnosis based on the second image displayed via the display device (e.g., 232). The user may provide the manual diagnosis to the imaging system (e.g., 200) by inputting the manual diagnosis via the user interface (e.g., 234).

[0071] However, the user or computing device (eg, 216) may alternatively indicate that the diagnosis is accepted, and method 300 may proceed to Figure 3B 360, wherein method 300 may include automatically recommending and displaying a treatment based on the generated diagnosis. For example, if the stenosis or coronary artery lesions have been diagnosed as significant (e.g., FFR is less than a threshold FFR), automatically recommending a treatment may include determining a stent in the coronary artery of interest or recommending coronary artery bypass surgery. For another example, if the stenosis or coronary artery lesions have been diagnosed as less significant (e.g., FFR is greater than a threshold FFR), automatically recommending a treatment may include recommending the administration of a prescribed medication. The recommended treatment may then be displayed to the user at a display device (e.g., 232).

[0072] At 365, method 300 may include determining whether a user request to update the recommended treatment has been received by the user interface (e.g., 234). For example, the user (e.g., a medical professional) may disagree with the recommended treatment and may provide an updated treatment as an alternative. If a user request has not been received (or if a user request to confirm the recommended treatment has been received), method 300 may proceed to 370, where method 300 may include maintaining the current display at the display device (e.g., 232). Method 300 may then end.

[0073] If a user request has been received, method 300 may proceed to 375, where method 300 may include updating the recommended treatment based on the user request. At 380, method 300 may include displaying the updated treatment at a display device (e.g., 232), such as over the initially displayed recommended treatment. Method 300 may then end.

[0074] See now Figure 4 , depicts a schematic diagram 400 showing an exemplary reduced order model or lumped parameter model of an exemplary portion of a coronary artery tree. In one embodiment, the exemplary reduced order model may be employed to simulate blood flow and estimate the FFR of a coronary artery of interest depicted by a single angiographic projection in an exemplary portion of a coronary artery tree depicted by CT imaging data (such as at 345 of method 300, as described above with reference to Figure 3A as detailed).

[0075] As shown, an exemplary reduced order model may be depicted as a circuit diagram based on windkessel physiology (referred to herein as a "windkessel circuit"). As will be readily appreciated by at least one of ordinary skill in the art, a windkessel circuit may be defined by a plurality of graphical elements representing corresponding physiological parameters. Thus, while a four-element windkessel circuit is depicted, it should be understood that a windkessel circuit having any number of elements may be considered within the scope of the present disclosure.

[0076] As shown in schematic diagram 400, current 402 represents volume inflow from cardiac pumping. A first resistor 404 may represent, for example, a total peripheral resistance at a stenosis in a coronary artery of interest. Thus, the total peripheral resistance may be based on a vessel length of the coronary artery of interest (e.g., the length of the centerline of the coronary artery of interest) and a vessel diameter of the coronary artery of interest at the stenosis. Additionally, capacitor 406 may represent total arterial compliance, and potential 408 may represent total fluid pressure.

[0077] Each of the above illustrated elements may be present in a dual element elastic reservoir circuit. Thus, the dual element elastic reservoir circuit may be improved by adding a second resistor 410 and an inductor 412, the second resistor may represent the resistance to blood flow due to the characteristic resistance of the aorta, and the inductor may represent the inertia of blood flow. It will also be understood by those of ordinary skill in the art that Figure 4 The exemplary reduced order model of may be extended for multiple coronary arteries of interest, wherein the total peripheral resistance at each stenosis of each respective coronary artery of interest may be represented by an additional resistor.

[0078] See now Figure 5 , depicts an exemplary user interface display 500 of a display device 502. In one embodiment, the display device 502 may be Figure 2 The display device 232 of the medical imaging system 200 is shown. The exemplary user interface display 500 may include a simultaneous display of a reconstructed image 504, an FFR 516, a diagnosis 518, and a recommended treatment 520.

[0079] As shown in the exemplary user interface display 500, the reconstructed image 504 may include an angiography projection 508 "stitched" into the CT imaging data 506. Specifically, the angiography projection 508 may be registered to the CT imaging data by registering the coronary artery 510 depicted by the imaging data to the coronary artery of interest 512 depicted by the angiography projection 508. In some embodiments, the reconstructed image 504 may be selected by a user of the medical imaging system (e.g., via touch, mouse, keyboard, etc.) for further user manipulation. In a specific embodiment, a view of a portion of the reconstructed image 504 may be displayed, rather than a view of the entire reconstructed image 504. Thus, the user may be able to move the view of the reconstructed image 504. As an example, the user-actuated icon 522 may be operable to move the view of the reconstructed image 504 up, down, left, and right. As another example, the magnification bar 524 may be operable to increase or decrease the magnification of the reconstructed image 504. As another example, the catalog 526 may provide additional views or reconstructed images that can be selected for display.

[0080] As shown, the coronary artery of interest 512 may have stenosis. The stenosis may be marked with one or more visual indicators 514a, 514b, 514c. In some embodiments, as shown in visual indicator 514a, the stenosis may be indicated by a pointing arrow marked with an alphanumeric character or string (e.g., "A"). In additional or alternative embodiments, as shown in visual indicators 514b and 514c, the stenosis may be indicated by a proximal dashed line (e.g., visual indicator 514b) and a distal dashed line (e.g., visual indicator 514c), wherein the proximal dashed line and the distal dashed line may be parallel to the corresponding transverse planes of the coronary artery of interest 512, and wherein each of the proximal dashed line and the distal dashed line may be marked with an alphanumeric character or string (e.g., "A'", "A"").

[0081] Each of FFR 516, diagnosis 518, and recommended treatment 520 may be a text box that a user can edit. In such embodiments, when a user selects a given text box for editing and changes the text contained within the text box (e.g., if the user updates recommended treatment 520), the background color of the text box may be changed relative to the rest of the exemplary user interface display 500, or the thickness of the outer edge of the text box may be increased. In addition, check boxes 519 and 521 may be displayed proximal to diagnosis 518 and recommended treatment 520, respectively. Thus, a user may select check box 519 to accept or reject diagnosis 518 (e.g., by filling check box 519 with a check mark or X, respectively). Similarly, a user may select check box 521 to accept or reject the recommended treatment (e.g., by filling check box 521 with a check mark or X, respectively).

[0082] In this way, a single two-dimensional (2D) projection of a region of the coronary artery tree obtained via an invasive angiography technique can be automatically registered to three-dimensional (3D) computed tomography (CT) imaging data. Specifically, a single 2D projection can be selected to image a specific coronary artery with high resolution. The technical effect of automatically registering a single 2D projection to 3D CT imaging data is that a lower resolution region in the 3D CT imaging data can be supplemented by a single 2D projection, thereby improving the accuracy of the blood flow reserve fraction calculated for a specific coronary artery and ultimately improving the accuracy of the diagnosis of coronary artery disease. In addition, via such automatic registration, the consistency of diagnosis, treatment, and health outcomes can be increased while improving the overall patient experience. In addition, by not acquiring multiple 2D projections, patient discomfort caused by invasive angiography can be alleviated.

[0083] In one embodiment, a method for imaging a coronary artery of interest in a patient includes acquiring computed tomography (CT) imaging data depicting a coronary artery tree, acquiring a single angiographic projection of the coronary artery of interest, registering the single angiographic projection to the CT imaging data, and determining a fractional flow reserve (FFR) of the coronary artery of interest based on the single angiographic projection registered to the CT imaging data. In a first example of the method, the coronary artery of interest has a stenosis, or the patient has a heart rate above a threshold heart rate. In a second example of the method, optionally including the first example of the method, acquiring the single angiographic projection is responsive to determining that the CT imaging data is insufficient to determine that the FFR is above a threshold confidence level. In a third example of the method, optionally including one or more of the first and second examples of the method, acquiring CT imaging data depicting the coronary artery tree includes receiving patient information for the patient, the patient information including one or more of patient age, patient weight, patient heart rate, patient blood pressure, and patient medical history, matching the patient with a previous patient based on the patient information; and receiving CT imaging data depicting the coronary artery tree from an imaging library, wherein the coronary artery tree is a coronary artery tree of a previous patient. In a fourth example of the method, optionally including one or more of the first to third examples of the method, the method further includes automatically determining placement of a stent in the coronary artery of interest in response to the FFR being less than a threshold FFR. In a fifth example of the method, optionally including one or more of the first to fourth examples of the method, registering the single angiographic projection to the CT imaging data includes segmenting the centerline of the coronary artery tree depicted by the CT imaging data, determining the length and three-dimensional shape of each of the centerlines, and registering the single angiographic projection to the CT imaging data based on the length and three-dimensional shape of each of the centerlines. In a sixth example of the method, optionally including one or more of the first to fifth examples of the method, determining the FFR of the coronary artery of interest based on the single angiographic projection registered to the CT imaging data includes determining a transverse cross-section of the coronary artery of interest based on the single angiographic projection registered to the CT imaging data, and estimating the FFR of the coronary artery of interest based on one or more of the cross-section, the length of the corresponding centerline, and the three-dimensional shape of the corresponding centerline. In a seventh example of the method, optionally including one or more of the first to sixth examples of the method, acquiring the single angiographic projection includes selecting a single angiographic projection from a plurality of angiographic projections, the single angiographic projection having a minimal amount of vascular overlap of the plurality of angiographic projections.

[0084] In another embodiment, a computing system includes: an x-ray imaging subsystem configured to acquire x-ray radiation; a user interface including a display device; a processor communicatively coupled to each of the user interface and the x-ray imaging subsystem; and a memory communicatively coupled to the processor, the memory storing processor-executable instructions that cause the processor to receive from the x-ray imaging subsystem a single two-dimensional (2D) angiographic projection of a coronary artery depicting a coronary artery tree and three-dimensional (3D) computed tomography (CT) imaging data depicting the coronary artery tree, register the single 2D angiographic projection to the 3D CT imaging data, determine a fractional flow reserve (FFR) of the coronary artery based on the single 2D angiographic projection registered to the 3D CT imaging data, generate a diagnosis of the coronary artery based on the FFR, and display the diagnosis and the FFR on the display device. In a first example of the computing system, the memory stores additional processor-executable instructions that cause the processor to automatically recommend a treatment for the coronary artery based on the diagnosis, and display the recommended treatment with the diagnosis and the FFR on the display device. In a second example of a computing system, optionally including the first example of the computing system, the memory stores additional processor-executable instructions that cause the processor to receive a user request to update the recommended treatment via a user interface, and update the recommended treatment based on the user request. In a third example of a computing system, optionally including one or more of the first and second examples of the computing system, registering a single 2D angiographic projection to the 3D CT imaging data includes segmenting a centerline of a coronary artery tree depicted by the 3D CT imaging data, determining a length and a 3D shape of each of the centerlines, and registering the single 2D angiographic projection to the 3D CT imaging data based on the length and the 3D shape of each of the centerlines. In a fourth example of a computing system, optionally including one or more of the first to third examples of the computing system, determining an FFR of a coronary artery based on a single 2D angiographic projection registered to the 3D CT imaging data includes determining a vessel diameter of the coronary artery based on the single 2D angiographic projection registered to the 3D CT imaging data, and estimating the FFR of the coronary artery based on the vessel diameter and the length of the corresponding centerline. In a fifth example of the computing system, optionally including one or more of the first to fourth examples of the computing system, estimating the FFR of the coronary arteries based on the vessel diameters and the lengths of the corresponding centerlines includes forming a reduced order model based on the length of each of the centerlines and the vessel diameters of the coronary arteries, and estimating the FFR based on the reduced order model.In a sixth example of the computing system, optionally including one or more of the first to fifth examples of the computing system, in the reduced order model, the coronary arteries are modeled based on each of a single 2D angiography projection and the 3D CT imaging data, and the remaining coronary arteries in the coronary artery tree are modeled based on the 3D CT imaging data.

[0085] In yet another embodiment, a system for imaging one or more coronary artery lesions of a subject includes: an x-ray source; an x-ray detector array configured to detect x-ray radiation emitted by the x-ray source and attenuated by the subject; and a controller configured with instructions in a non-transitory memory that, when executed, cause the controller to acquire computed tomography (CT) imaging data of the subject, register one or more angiographic projections to the CT imaging data, acquire one or more angiographic projections that respectively depict one or more coronary arteries, the one or more coronary arteries respectively having one or more coronary artery lesions, and reconstruct an image of the coronary artery tree of the subject based on the one or more angiographic projections registered to the CT imaging data. In the first example of the system, the instructions can be further executed to generate a visual indicator on the reconstructed image for each of the one or more coronary artery lesions. In the second example of the system, optionally including the first example of the system, the system also includes a display device, and the instructions can be further executed to display the reconstructed image with a visual indicator for each of the one or more coronary artery lesions via the display device. In a third example of the system, optionally including one or more of the first and second examples of the system, the instructions can be further executed to determine a blood flow reserve fraction for each of the one or more coronary arteries based on one or more angiographic projections registered to the CT imaging data. In a fourth example of the system, optionally including one or more of the first to third examples of the system, the CT imaging data depicts a coronary artery tree including the one or more coronary arteries, and registering the one or more angiographic projections to the CT imaging data includes segmenting a centerline of the coronary artery tree depicted by the CT imaging data, and registering each of the one or more coronary arteries to the centerline of the coronary artery tree.

[0086] As used herein, the elements or steps listed in the singular and beginning with the word "one" or "a kind of" should be understood as not excluding a plurality of the elements or steps, unless such exclusion is explicitly stated. In addition, the reference to "an embodiment" of the present invention is not intended to be interpreted as excluding the existence of additional embodiments that also include the cited features. In addition, unless explicitly stated to the contrary, the embodiment of "including", "comprising" or "having" an element or multiple elements with a specific characteristic may include additional such elements without the characteristic. The terms "including" and "in..." are used as the concise language equivalents of the corresponding terms "including" and "wherein". In addition, the terms "first", "second" and "third" etc. are only used as marks, and are not intended to impose numerical requirements or specific positional order on their objects.

[0087] This written description uses examples to disclose the invention, including the best mode, and also to enable a person of ordinary skill in the relevant art to practice the invention, including making and using any devices or systems and performing any included methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to a person of ordinary skill in the art. Such other examples are intended to fall within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insignificant differences from the literal language of the claims.

Claims

1. A method for imaging a coronary artery of interest in a patient, the method comprising: Acquisition of computed tomography CT imaging data depicting the coronary artery tree; acquiring a single angiographic projection of the coronary artery of interest; registering the single angiography projection to the CT imaging data; as well as determining a fractional flow reserve (FFR) of the coronary artery of interest based on the single angiographic projection registered to the CT imaging data, wherein registering the single angiographic projection to the CT imaging data comprises: segmenting a centerline of a coronary artery tree depicted by the CT imaging data, determining a length and a three-dimensional shape of each of the centerlines, and registering the single angiographic projection to the CT imaging data based on the length and the three-dimensional shape of each of the centerlines, A reduced order model is formed based on the length of each centerline of the coronary artery tree and the vessel diameter to determine the fractional flow reserve (FFR), wherein the reduced order model is implemented as an elastic reservoir circuit including a plurality of electronic components representing a plurality of physiological parameters.

2. The method of claim 1, wherein the coronary artery of interest has a stenosis, or Wherein the patient has a heart rate above a threshold heart rate. 3 . The method of claim 1 , wherein acquiring the single angiographic projection is responsive to determining that the CT imaging data is insufficient to determine that the FFR is above a threshold confidence level.

4. The method of claim 1 , wherein acquiring the CT imaging data depicting the coronary artery tree comprises: receiving patient information for the patient, the patient information comprising one or more of patient age, patient weight, patient heart rate, patient blood pressure, and patient medical history; matching the patient with a previous patient based on the patient information; and The CT imaging data depicting the coronary artery tree is received from an imaging repository, wherein the coronary artery tree is the coronary artery tree of the previous patient.

5. A computing system, the system comprising: an x-ray imaging subsystem configured to acquire x-ray radiation; A user interface, the user interface comprising a display device; a processor communicatively coupled to each of the user interface and the x-ray imaging subsystem; and a memory communicatively coupled to the processor, the memory storing processor-executable instructions, the processor-executable instructions causing the processor to: receiving from the x-ray imaging subsystem a single two-dimensional angiographic projection of a coronary artery depicting a coronary artery tree and three-dimensional computed tomography imaging data depicting the coronary artery tree; registering the single two-dimensional angiographic projection to the three-dimensional computed tomography imaging data by segmenting centerlines of a coronary artery tree depicted by the three-dimensional computed tomography imaging data, determining a length and a three-dimensional shape of each of the centerlines, and registering the single two-dimensional angiographic projection to the three-dimensional computed tomography imaging data based on the length and the three-dimensional shape of each of the centerlines; determining a fractional flow reserve (FFR) of the coronary artery based on the single two-dimensional angiographic projection registered to the three-dimensional computed tomography imaging data; generating a diagnosis of the coronary artery based on the FFR; and displaying the diagnosis and the FFR on the display device, A reduced order model is formed based on the length of each centerline of the coronary artery tree and the vessel diameter to determine the fractional flow reserve (FFR), wherein the reduced order model is implemented as an elastic reservoir circuit including a plurality of electronic components representing a plurality of physiological parameters.

6. The computing system of claim 5, wherein the memory stores further processor-executable instructions that cause the processor to: automatically recommending treatment of the coronary artery based on the diagnosis; and The recommended treatment with the diagnosis and the FFR is displayed on the display device.

7. A system for imaging one or more coronary artery lesions of a subject, the system comprising: X-ray source; an x-ray detector array configured to detect x-ray radiation emitted by the x-ray source and attenuated by the subject; and A controller configured with instructions in a non-transitory memory, the instructions, when executed, causing the controller to: Acquiring computer tomography (CT) imaging data of the subject; acquiring one or more angiographic projections respectively depicting one or more coronary arteries, the one or more coronary arteries respectively having the one or more coronary artery lesions; registering the one or more angiographic projections to the CT imaging data by segmenting centerlines of a coronary artery tree depicted by the CT imaging data, determining a length and a three-dimensional shape of each of the centerlines, and registering the one or more angiographic projections to the CT imaging data based on the length and the three-dimensional shape of each of the centerlines; and reconstructing an image of the subject's coronary artery tree based on the one or more angiographic projections registered to the CT imaging data, A reduced order model is formed based on the length of each centerline of the coronary artery tree and the vessel diameter, thereby determining the fractional flow reserve (FFR) of the coronary arteries of the coronary artery tree, wherein the reduced order model is implemented as an elastic reservoir circuit including a plurality of electronic components representing a plurality of physiological parameters.

8. The system of claim 7, wherein the instructions are further executable to generate a visual indicator on the reconstructed image for each of the one or more coronary artery lesions.

9. The system according to claim 8, further comprising a display device, and The instructions are further executable to display, via the display device, the reconstructed image with the visual indicator for each of the one or more coronary artery lesions.

10. The system of claim 7, wherein the instructions are further executable to determine a fractional flow reserve of each of the one or more coronary arteries based on the one or more angiographic projections registered to the CT imaging data.

Images