Technique for generating images of anatomical elements in poses indicated by planning data

Abstract

To provide a technique for generating an image including a representation of an anatomical element of a patient's body.SOLUTION: Disclosed is a technique for generating an image including a representation of an anatomical element of a patient's body, the method being implemented with a computing system and comprising: obtaining medical image data of at least one anatomical element of a patient's body; obtaining planning data indicative of at least three planned positions associated with the at least one anatomical element, where one or more of the planned positions are associated with at least one planned medical implant; and generating, based on the medical image data and the planning data, an image comprising a representation of the at least one anatomical element in a pose defined by the at least three planned positions.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates generally to methods, systems, computer programs and carrier media for generating images that include depictions of anatomical elements of a patient's body. [Background technology]

[0002] Medical image data of a patient, such as X-ray image data, magnetic resonance (MR) image data, or computed tomography (CT) image data, may be used to plan a surgical procedure. For example, the placement of medical implants, such as bone screws, bone plates, spinal cages, pedicle screws, etc., relative to the patient's body may be planned by a surgeon based on pre-operative medical image data of the patient's body before a surgical procedure is performed. At a later stage, a user may wish to be provided with an image representing a portion of the patient's body and, optionally, the planned implant.

[0003] It may be desirable for a portion of a patient's body to have a predefined pose in an image. For example, in the field of spine surgery, surgeons are primarily interested in images in which the spinous processes of the vertebrae of the patient's body are shown extending vertically upwards. In some solutions, an image is provided that includes the vertebrae, and a user may change the rotation of the image to orient the vertebrae in a predefined pose. Other solutions rely on complex segmentation algorithms to determine the orientation of a particular portion of the patient's body represented in the medical image data. Summary of the Invention

[0004] There is a need in the art for a technique that addresses one or more of the above or other problems.

[0005] According to a first aspect, there is provided a method of generating an image including a representation of an anatomical element of a patient's body. The method is performed by a computing system. The method may be referred to as a computer-implemented method or a data processing method. The method does not include surgical steps.

[0006] The method includes obtaining medical image data of at least one anatomical element of a patient's body. The medical image data may be pre-operative medical image data. The medical image data may include or consist of X-ray image data, magnetic resonance (MR) image data, or computed tomography (CT) image data.

[0007] The method further includes obtaining planning data, which may be part of a dataset including both medical image data and planning data.

[0008] The planning data indicates at least three planned positions associated with at least one anatomical element. One or more (e.g., all) of the (e.g., at least three) planned positions are associated with at least one planned medical implant. One or more (e.g., all) of the at least three planned positions are associated with one or more medical implants and thus associated with at least one anatomical element. One or more (e.g., all) of the planned positions are associated with a medical plant to be implanted in the at least one anatomical element (e.g., in response to the planning data) and / or a medical plant attached to the at least one anatomical element (e.g., in response to the planning data) and / or a medical plant placed in contact with the at least one anatomical element (e.g., in response to the planning data).

[0009] The method further includes generating an image based on the medical image data and the planning data, the image including a representation (e.g., a depiction or rendering) of the at least one anatomical element in a pose (e.g., a position and / or an orientation) defined by the at least three planned positions. The pose may also be referred to as an alignment of the at least one anatomical element relative to a coordinate system of the generated image, e.g., relative to a vertical and / or horizontal image axis of the generated image. The pose may be determined without the need to segment the at least one anatomical element. The pose of the at least one anatomical element may be defined or determined solely by the planned positions associated with the anatomical element.

[0010] The images may be generated such that two or more of the at least three planned locations lie in the same plane or parallel planes (e.g., virtual or cutting planes) that correspond to the image plane of the generated images.

[0011] Two or more of the planned locations may be associated with the same planned medical implant. At least two of the planned locations associated with the same planned medical implant may be located on a line that defines an orientation of the same planned medical implant (e.g., in at least two or three dimensions). The line may correspond to a longitudinal axis, an axis of symmetry, and / or an insertion trajectory of the same planned medical implant.

[0012] At least three of said planned positions associated with a same planned medical implant may lie in a plane (e.g., in at least two or three dimensions) that defines an orientation of the same planned medical implant. The plane may be a part of an outer surface of the same planned medical implant, a central plane of the same planned medical implant, a symmetry plane of the same planned medical implant and / or a contact plane of the same planned medical implant. The plane that includes at least three planned positions associated with the same planned medical implant may correspond to an image plane or may be a plane parallel to the image plane.

[0013] The images can be generated by orienting (e.g., rotating or aligning) or including (e.g., generating or projecting) the representation of at least one anatomical element such that (i) an angle between a line indicating the orientation of the same planned medical implant and (ii) a vertical or horizontal image axis of the generated images satisfies at least one predetermined criterion.

[0014] The images can be generated such that multiple (e.g., all) planned locations associated with the same planned medical implant lie in the same plane that corresponds to or is parallel to the image plane of the generated images, which may include multiple (e.g., all) planned locations associated with the same planned medical implant.

[0015] The at least three planned locations include at least two pairs of planned locations, each pair associated with a different planned medical implant.

[0016] The planned positions of each pair can lie on a (e.g., respective) line that defines the orientation of the planned medical implant associated with that pair, which line can correspond to a longitudinal axis, an axis of symmetry, and / or an insertion trajectory of the planned medical implant associated with that pair.

[0017] The images can be generated such that the planning positions of at least two pairs of planning positions (e.g., all pairs) lie in the same plane that corresponds to or is parallel to an image plane of the generated images. The image plane can include the planning positions of at least two pairs.

[0018] The images can be generated by orienting (e.g., rotating or aligning) or including a representation of at least one anatomical element such that (i) an angle bisector that bisects an angle between a line (e.g., a straight line) indicating the orientation of the different medical implants and (ii) an angle between a vertical or horizontal image axis of the generated image satisfies at least one predetermined condition, which may be different from or correspond to at least one predetermined criterion.

[0019] The medical image data may include volumetric image data. The image may be generated as a two-dimensional image representing a cross-section (e.g., along an image plane) of the volumetric image data. The generated image may include a representation (e.g., of a contour) of at least a portion (e.g., of each) of at least one planned medical implant (e.g., intersecting the image plane).

[0020] The medical implant can include at least one component selected from (i) a spinal cage, (ii) a bone screw, such as a pedicle fixation screw, (iii) a pedicle fixation hook, and (iv) a pedicle fixation band. The at least one anatomical element can include a bone, such as a vertebra.

[0021] The method may further include storing the generated image. Additionally, the method may include initiating a display of the generated image.

[0022] The method can further include obtaining a user input indicating a selected one of the at least one anatomical element, the user input can correspond to a tracked pose of the surgical instrument or pointer.

[0023] The image may be generated based on at least three planned positions (e.g., only the at least three planned positions) associated with the selected anatomical element (e.g., only the selected anatomical element).

[0024] For each of the two or more instances of at least one anatomical element, a respective image can be generated. Each image can be generated based on medical image data and a planned position associated with the respective anatomical element. Since each image is generated based on at least three planned positions associated with each same anatomical element, multiple images (e.g., each image) are generated based on medical image data and planning data (e.g., during or by the repeated image generation steps). It is also possible to activate so that only images generated based on at least three planned positions associated with the selected anatomical element are displayed.

[0025] The method can include updating the displayed image according to user input. For example, a first generated image including a representation of a first vertebra can be triggered to be displayed based on a first tracked pose of the pointer or surgical instrument as user input. Thereafter, a second generated image including a representation of a different second vertebra can be triggered to be displayed based on a second, different pose of the pointer or surgical instrument as user input.

[0026] In a second aspect, a system, which may also be generally referred to as a processing system, is provided, comprising at least one processor, the at least one processor configured to carry out the method according to the first aspect.

[0027] The system may further include at least one of the following components: a medical image acquisition unit configured to generate medical image data; a user input device configured to obtain user input (e.g., defining one or more of the at least three planning locations and / or indicating a subset of the planning locations and / or indicating a selected one of the at least one anatomical element); a display unit configured to display at least the generated image;

[0028] In a third aspect, a computer program is provided. The computer program comprises instructions that, when executed on at least one processor (e.g., at least one processor of a system according to the second aspect), cause the at least one processor to perform a method according to the first aspect. The computer program may be stored on or carried by a carrier medium. The carrier may be one of an electronic signal, an optical signal, a radio signal, or a (e.g., non-transitory) computer-readable storage medium.

[0029] In a fourth aspect, there is provided a storage medium, which may be a non-transitory computer storage medium, the storage medium storing a computer program according to the third aspect. [Brief description of the drawings]

[0030] Further details, advantages and aspects of the present disclosure will become apparent from the following embodiments taken in conjunction with the figures. [Figure 1] FIG. 1 is a schematic diagram of a system of the present disclosure. [Diagram 2] 1 is a flowchart of the present disclosure. [Diagram 3] 1 shows typical medical image data and renderings based on two proposed medical implant presentations. [Figure 4]4 shows a rendering image and a display of the plane of FIG. 3. [Diagram 5] 5 shows a cross-sectional image along the plane indicated in FIG. 4 and a representation of the outline of two planned medical implants. [Figure 6] The cross-sectional image of FIG. 5 and the indication of the angle bisector are shown. [Figure 7] FIG. 7 shows the cross-sectional image of FIG. 6 rotated about the angle bisector. [Figure 8] FIG. 8 shows a spinal cage as a medical implant intended to be placed between two adjacent vertebrae. [Figure 9a] 1 shows a spinal sling and a spinal clamp as medical implants to be attached to the vertebrae. [Figure 9b] 1 shows a spinal sling and a spinal clamp as medical implants to be attached to the vertebrae. [Figure 9c] 1 shows a spinal sling and a spinal clamp as medical implants to be attached to the vertebrae. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] Exemplary embodiments will now be described with reference to the drawings, in which the same reference numbers are used to denote the same or similar structural features.

[0032] FIG. 1 shows a schematic diagram of a system 100 of the present disclosure. The system 100 comprises a computing unit 2 comprising at least one processor 4 communicatively connected to at least one memory 6 and at least one wired and / or wireless interface 8. The system 100 or the computing unit 2 may be generally referred to as a "computing system." It is also possible that individual components of the computing unit 2 are part of a cloud computing platform, e.g., as virtual functions. The computing unit 2 may be part of a surgical navigation system.

[0033] The system 100 further comprises a display unit 10, a server or data storage 12, a tracking unit 14 and a medical image acquisition unit 16, each connected to the computing unit 2 via a wired or wireless connection. The display unit 10 may be mounted on a stand in the operating room or may be part of a head-mounted augmented reality device. The data storage 12 may be part of a picture archiving and management system (PACS) of a hospital and may store medical image data such as X-ray images, CT image data and / or MR image data. The tracking unit 14 may comprise a (e.g. stereo) camera or an electromagnetic field generator and may be configured to track (e.g. locate) a user and / or a device 18 (e.g. equipped with a tracking marker) that is in the field of view of the tracking unit 14. The tracking unit 14 may be configured to track a patient marker 20 having a fixed spatial relationship with respect to the patient's body 22. This allows the computing unit 2 to determine the relative pose of the tracked instrument 18 and the patient's body 22. The medical image acquisition unit 16 may be a fluoroscopic imager, a C-arm scanner, or an MR scanner and may be configured to acquire or generate medical image data of at least a portion of a patient's body 22. The display 10 may be configured as a touch screen for acquiring user input. User input may also be acquired via the tracking unit 14, for example based on a pose of the tracked instrument 18. The patient's body 22 includes a number of anatomical elements 24, for example bones such as vertebrae.

[0034] 2 shows a flowchart of a method of the present disclosure. The method can be executed by the system 100, for example, by the at least one processor 4. The at least one memory 6 (e.g., configured as a non-transitory computer storage medium) can store a computer program including instructions that, when executed by the at least one processor 4, cause the at least one processor 4 to perform the methods described herein.

[0035] The method illustrated in FIG. 2 is a method for generating an image that includes a depiction of an anatomical element 24 of a patient's body 22 .

[0036] The method includes acquiring 202 medical image data of at least one anatomical element 24 (eg, including the anatomical element 24) of a patient's body 22.

[0037] The medical image data may be pre-operative medical image data. The medical image data may be referred to as (e.g., pre-operative) patient image data. The medical image data may include or consist of X-ray image data, magnetic resonance (MR) image data, or computed tomography (CT) image data. The medical image data may include or consist of two-dimensional and / or three-dimensional image data. The medical image data may include or consist of volumetric image data.

[0038] The at least one anatomical element 24 may include a limb, a bone, or an organ. Each of the at least one anatomical element 24 may have the same physical and / or biological properties. The physical properties may include one or more of a transmittance (e.g., of radiation used to generate the medical image data), an absorption rate (e.g., of radiation used to generate the medical image data), a water or hydrogen concentration. The biological properties may include one or more of a type of biological material (e.g., bone, tissue, or body fluid), a type of tissue (e.g., nervous tissue or muscle tissue), or a biological function (e.g., vascular function or lymphatic function). In one variation, each of the at least one anatomical element 24 may include or be composed of a bone, such as a vertebra.

[0039] The medical image data may be acquired from a medical image acquisition unit 16 (e.g., a C-arm scanner, an MR scanner, or an X-ray device). The medical image data may be acquired from a storage unit 12, which may be part of a PACS. Alternatively, the medical image data may be acquired from a portable storage device.

[0040] The method further includes the step of obtaining 204 planning data.

[0041] The planning data may be obtained from at least one memory 6, the data storage device 12, a PACS system and / or a portable storage device. The planning data may be part of a dataset that includes both medical image data and planning data. Thus, the step 202 of acquiring medical image data and the step 204 of acquiring planning data may be performed simultaneously. It is also possible to change the order of steps 202 and 204 compared to FIG. 2.

[0042] The planning data indicates at least three planning positions 25 (eg, spatial, two-dimensional or three-dimensional positions) for at least one anatomical element 24 .

[0043] The at least three planning locations 25 can be associated with at least one anatomical element 24 by being located on or inside the at least one anatomical element 24, by being a distance to the at least one anatomical element 24 that is less than a predetermined maximum value, and / or by being virtually linked to the at least one anatomical element 24 (a virtual link indicated by the medical image data and / or the planning data, e.g., a tag).

[0044] One or more (eg, all) of the (eg, at least three) planned locations 25 are associated with at least one planned medical implant 26 .

[0045] In general, one or more (e.g., all) of the at least three planned locations 25 may be associated with at least one anatomical element 24 by being associated with one or more medical implants 26 that are embedded in, attached to, and / or positioned in contact with the at least one anatomical element 24 (e.g., according to planning data). One of the planned locations 25 associated with a medical implant 26 may be located on the medical implant 26, e.g., at a distal end, a proximal end, or a tip of the medical implant 26. Alternatively, or in addition, one of the planned locations 25 associated with a medical implant 26 may be located on an axis or plane (e.g., a longitudinal axis, an axis of symmetry, a planar contact surface, or a plane of symmetry) defined by the medical implant 26.

[0046] The at least three planning positions 25 may be defined in an image coordinate system of the medical image data or in a planning coordinate system that has a known correlation with the image coordinate system. The known correlation may be defined by what is referred to as image registration and / or a transformation between the two coordinate systems (e.g., including rotational and / or translational components). The at least three planning positions 25 may include multiple subsets of planning positions 25, each subset consisting of three or more planning positions 25 and associated with a different one of the at least one anatomical element 24.

[0047] The method further includes step 208 of generating an image based on the medical image data and the planning data, the image including a representation (e.g., a drawn or rendered image) of at least one anatomical element 24 present in a posture (e.g., at least one position and orientation) defined by the at least three planning positions.

[0048] The image may include only one representation of the at least one anatomical element 24. The pose may also be referred to as the alignment of the at least one anatomical element 24 in the coordinate system of the generated image, e.g., in the vertical and / or horizontal image axis of the generated image. The pose may be determined without the need to segment the at least one anatomical element 24. The pose of the at least one anatomical element may be defined exclusively, i.e., only by, at least three planned positions 25 associated with the at least one anatomical element depicted in the generated image.

[0049] The images are generated such that two or more of the at least three planned locations 25 lie in the same plane as the generated image or in a (e.g., virtual) plane parallel to it. The image plane corresponds to a plane onto which one or more objects (e.g., at least one anatomical element 24 and / or medical implant 26) are projected.

[0050] Two or more planned locations 25 are associated with the same planned medical implant 26 .

[0051] At least two of the planned locations 25 associated with a same planned medical implant 26 are located on a straight line that defines (e.g., in at least two or three dimensions) an orientation of the same planned medical implant 26. This straight line is identical to the longitudinal axis, the axis of symmetry, and / or the insertion trajectory of the same planned medical implant 26. The orientation of the same planned medical implant defined by the straight line may correspond to a longitudinal orientation, a main axis orientation, an axis of symmetry orientation, and / or an implantation orientation.

[0052] The at least three planned locations 25 associated with the same planned medical implant 26 may be located (e.g., in at least two or three dimensions) within a plane that defines an orientation of the same planned medical implant 26. The plane may correspond to or be parallel to an outer surface portion of the same planned medical implant 26, a central plane of the same planned medical implant 26, a symmetry plane of the same planned medical implant 26, and / or a contact surface of the same planned medical implant 26. The orientation of the same planned medical implant 26 defined by the plane corresponds to an alignment or orientation (e.g., angular or rotational) of the same medical implant 26 (e.g., the plane).

[0053] The images are generated by adjusting (e.g., rotating or aligning) or including (e.g., generating or projecting) the orientation of the representation of at least one anatomical element 24 such that (i) an angle between a line (e.g., the straight line) indicating the orientation of the same planned medical implant 26 and (ii) a vertical or horizontal image axis of the generated image satisfies at least one predefined criterion. The at least one predefined criterion may be that the angle is within a predefined range and / or is smaller than a predefined maximum angle (e.g., an angle of 10°, 8°, 5°, 2°, 1.5° or 1°). The at least one predefined criterion may be that the angle is minimized and / or is zero. This results in the generation of images in which the planned medical implant has a desired orientation relative to the vertical and horizontal image axes and in which the associated at least one anatomical element is depicted in a desired orientation.

[0054] The images can be generated such that multiple (e.g., all) planned locations 25 associated with the same planned medical implant 26 lie in a plane that is the same as or parallel to the image plane of the generated image. The image plane can include multiple (e.g., all) planned locations associated with the same planned medical implant.

[0055] The at least three planned positions 25 may also include at least two pairs of planned positions 25, each pair associated with a different planned medical implant 26. The planned positions 25 of each pair of planned positions 26 may be located on a (e.g., respective) line that defines an orientation of the planned medical implant 26 associated with that pair. The line may correspond to a longitudinal axis, an axis of symmetry, and / or an insertion trajectory of the planned medical implant 26 associated with that pair. The images may be generated such that the planned positions 25 of at least two pairs (e.g., all pairs) of planned positions 25 are located in the same image plane as the generated image. The image plane may include at least two pairs of planned positions 25.

[0056] The images may be generated by orienting (e.g., rotating or aligning) or including a representation of at least one anatomical element such that an angle between (i) an angle bisector that bisects an angle between lines (e.g., straight lines) indicating the orientation of the different medical implants 26 and (ii) a vertical or horizontal image axis of the generated image satisfies at least one predefined condition. The at least one predefined condition may be that the angle is less than a predefined maximum angle (e.g., an angle of 10°, 8°, 5°, 2°, 1.5° or 1°). The at least one predefined condition may be that the angle is minimized and / or zero. The at least one predefined condition may be different from or the same as the at least one predefined criterion. Instead of an angle bisector, an alignment line may be used, which is determined such that the distance between the planned position, optionally weighted by a respective priority value, is minimized. The alignment line may be said to be close to the planned position. Either approach provides images in which multiple planned implants are positioned in desired orientations relative to the vertical and horizontal image axes, and in which at least one associated anatomical element can be depicted in a desired orientation.

[0057] The medical image data may include volumetric image data. The image may be generated as a two-dimensional image representing a cross-section (e.g., along an image plane) of the volumetric image data. The image may be generated as a rendered image representing a (e.g., virtual) plane extending through the patient's body. The image may be a digitally rendered radiograph (DRR).

[0058] The generated image can include a representation of at least a portion (e.g., a contour) of the at least one (e.g., each) planned medical implant 26. The generated image can include a representation of a portion of the at least one planned medical implant 26 that intersects with the image plane. The generated image can include a representation of an intersection area or intersection contour of the at least one (e.g., each) planned medical implant 26 with the image plane.

[0059] The medical implant 26 can include at least one component selected from (i) a spinal cage, (ii) a bone screw, such as a pedicle fixation screw, (iii) a pedicle fixation hook, and (iv) a pedicle fixation band. The at least one anatomical element can include a bone, such as a vertebra.

[0060] The method may further include saving the generated image. The generated image may be stored in at least one memory 6, data storage unit 12, or another storage device. The method may include transmitting the generated image to a receiver (e.g., a PACS system, a server, or a user device such as a mobile phone).

[0061] The method may further include the optional step 210 of initiating display of the generated image. The image may be initiated to be displayed on a display unit 10, such as a screen, an augmented reality (AR) display, a head-mounted (e.g., augmented reality) display (HMD), or a tablet computer.

[0062] The method may further include an optional step 206 of obtaining a user input indicating a selected one of the at least one anatomical element. The user input may be obtained from a user interface (e.g., a touch screen, a computer mouse, a joystick, a keyboard or a microphone). The user interface may be part of the display unit 10 or may be realized by the tracking unit 14. That is, the user input may also be obtained from the tracking unit 14. The user input may correspond to a tracked pose of the instrument or pointer 18. For example, to select this anatomical element 24, the user may point to the anatomical element 24 using the pointer 18. As another example, to select the anatomical element 24 associated with one of the planned medical implants 26, the user adjusts the orientation of the tracking instrument or pointer 18 to a pose associated with one of the planned medical implants (e.g., to a pose corresponding to an insertion trajectory of a planned pedicle screw).

[0063] The image may be generated based on (and only on) the at least three planned positions 25 associated with (and only on) the selected anatomical element 24. That is, planned positions associated with other anatomical elements 24 may not be considered when generating the image.

[0064] An individual image may be generated for each of two or more of the at least one anatomical element 24. Each of these images is generated based on the medical image data and the planning positions 25 associated with the respective anatomical element 24. A plurality of images (e.g., respective images) are generated based on the medical image data and the planning data (e.g., during or by the repetition of the image generation step), each image being generated based on at least three planning positions 25 associated with the same respective anatomical element 24. Only the images generated based on at least three planning positions 25 associated with the selected anatomical element 24 can be activated for display. That is, selection of an anatomical element 24 not only activates the corresponding image for display, but also selects one of the plurality of generated images for activation for display.

[0065] The method may also include updating the images displayed (e.g., triggered to be displayed) in response to user input (e.g., obtained in step 210). For example, a first generated image including a representation of a first vertebra is triggered to be displayed in step 210 based on a first tracked pose of a pointer or surgical instrument as user input obtained in step 206. Thereafter, a second generated image including a representation of a different second vertebra is triggered to be displayed in a subsequent iteration of step 210 based on a different second pose of the pointer of the surgical instrument obtained as user input at a later time point (e.g., a subsequent iteration of step 206).

[0066] Next, the method will be described based on a specific embodiment with reference to FIG. 3 to FIG.

[0067] Figure 3 shows a rendered image of medical image data of a portion of a patient's body 22, in this example a portion of the patient's spine. The medical image data in this example is pre-operative CT image data acquired from a CT scanner, and the rendered image represents an anterior-posterior view. The image plane of the rendering shown in Figure 3 may be said to correspond to a coronal or frontal plane. In the example of Figure 3, the medical image data includes a number of vertebrae of the patient's body 22 as anatomical elements 24.

[0068] FIG. 3 also shows pre-planned positions 25a-25d. The pre-planned positions 25a, 25b are associated with a first medical implant, a planned first pedicle screw 26a, and the pre-planned positions 25c, 25d are associated with a second medical implant, a planned second pedicle screw 26b. Both implants 26a, 26b are planned to be implanted in the same vertebra 24. Therefore, both implants 26a, 26b are associated with the same vertebra 24, and the pre-planned positions 25a-25d are also associated with this same vertebra 24. In the example of FIG. 3, the planned position 25a corresponds to the head of the planned pedicle screw 26a, and the planned position 25b corresponds to the tip of the same pedicle screw 26a. Thus, both positions 25a, 25b are located on the central longitudinal screw axis of the pedicle screw 26a. The same is true for the intended positions 25c, 25d lying on the central axis of the pedicle screw 26b. The positions 25a, 25b form a first pair and the positions 25c, 25d form a second pair.

[0069] 4 shows a rendered image representing FIG. 3 and a plane 28. The plane 28 is defined by pre-planned positions 25a-25d. In the illustrated example, all pre-planned positions 25a-25d lie within the plane 28.

[0070] At least three pre-planned positions 25 are required to define the plane 28. If the two medical implants 26a, 26b are not in the same plane, two pre-planned positions (e.g., 25a, 25b) of one of the implants (e.g., 26a) can be used together with one pre-planned position (e.g., 25c) of the other implant (e.g., 26b). Alternatively, two pre-planned positions associated with one and the same medical implant 26 can be used together with one additional pre-planned position 25 associated with the anatomical element 24 associated with the same medical implant 26. That is, all of the pre-planned positions used to define the plane 28 may be associated with the same anatomical element 24, and may or may not be associated with one medical implant 26. The additional pre-planned position 25 can be a planned point located on an anatomical landmark, for example, a point on the spinous process of the vertebra where the same medical implant 26 is to be implanted, or a point located on the planned trajectory. Other combinations of pre-planned locations are possible. Alternatively, the plane 28 can be defined such that none or only some of the pre-planned locations 25 lie within the plane 28. For example, the plane 28 can be defined to be equally distant from all pre-planned locations. Locations can also be correlated priority values ​​and distances to the plane 28 according to these priority values. Other variables defining the plane 28 can also be used.

[0071] The plane 28 defines a cross section through the volumetric CT image data of the patient's body 22 and corresponds to the image plane of the generated image. FIG. 5 shows a DRR generated based on the CT image data when the plane 28 is the image plane. In this example, the two pedicle screws 26a, 26b and their associated pre-planned positions 25a-25d are all in the image plane. FIG. 5 also shows the outlines 27a, 27b of the pedicle screws 26a, 26b corresponding to the intersection of the individual screws 26a, 26b with the plane 28. The generated image shown in FIG. 4 is useful to the user because it not only depicts the vertebrae, but also the associated implants 26a, 26b. Nevertheless, the vertebrae in this image may not be oriented as the surgeon would normally desire. It may be desired to be able to generate or rotate the image to an orientation of the vertebrae with the spinous processes extending vertically.

[0072] Instead of manually rotating the image of FIG. 5, the present technique allows the generation of images in which the vertebrae are depicted in a pose defined by the pre-planned positions. As shown in FIG. 6, the straight lines 30, 32 extending through one of the pairs of positions 25a, 25b and 25c, 25d, respectively, can be used for this purpose. That is, an angle bisector 34 between the two straight lines 30, 32 can be determined. This angle bisector is also shown in FIG. 6. As shown in FIG. 7, the image can then be rotated or generated so that the angle bisector 34 is aligned with the vertical image axis "y", i.e., the angle between the angle bisector 34 and the vertical image axis "y" is zero. This approach is particularly useful in the case of spinal procedures involving planned pedicle screws, since the screws will generally be aligned at similar angles to the spinous processes due to the symmetry of the vertebrae.

[0073] The final image obtained with the method described herein is the same as the image shown in Figure 7, but the display of lines 30, 32 and angle bisector 34 can be omitted. Instead of the angle bisector, a weighted average can be used, giving more weight to more reliable planned positions compared to less reliable planned positions. The reliability of a planned position (e.g., indicated as its priority value) can also be defined or determined based on the type of planned position (e.g., associated with a planned implant, associated with a landmark, associated with a planned trajectory, manually planned, or automatically planned).

[0074] In the example of FIG. 8, the planned positions 25e-25g are associated with the spinal cage 26c. The planned positions 25e-25g are in the central symmetry plane 36a of the spinal cage 26c, which is parallel to the outer contact surfaces 38, 40 configured to contact the adjacent vertebrae 24. The cage 26c has a predefined orientation in the central symmetry plane, which is defined by the longitudinal extension of the cage 26c and also by the planned positions 25e-25g. In the illustrated example, the planned cage 26c has one end associated with the position 25g oriented in a predefined and known anatomical direction. Thus, the orientation of the adjacent vertebrae 24 can be derived from the planned orientation of the cage 26c, in particular based on the pre-planned positions 25e-25g. This allows the image to be generated so that the depiction of an anatomical element (e.g., one of the vertebrae 24 adjacent to the cage 26c) has a desired orientation (e.g., the spinous process faces upward) in the image, which can be defined by the pre-planned positions 25e-25g and the known orientation of the plane 36a, i.e., a predetermined known anatomical direction. This shows that the technology disclosed in the present invention is applicable not only to pedicle screws but also to spinal cages as medical implants 26.

[0075] 9a-9c show further examples of medical implants 26 that can be used as medical implants in association with pre-planned locations in the presently disclosed technology.

[0076] FIG. 9a shows a band or sling 26d configured to be attached to the vertebrae. In this case, pre-planned positions 25h-25j may be placed on the sling to define the symmetry plane 36b of the sling. The sling may extend in a pre-defined known anatomical direction, meaning that the symmetry plane 36b may have a pre-defined alignment with respect to the vertebrae to which it is attached. As with the spine cage 26c, this pre-defined alignment may be used together with the symmetry plane 36b defining the image plane and the desired rotation of the vertebrae so that the spinous processes of the vertebrae to be attached are vertically oriented in the generated image. Also shown in FIG. 9a is a spinal rod 38 configured to be attached to the sling 26d.

[0077] 9b shows two pedicle hooks 26e, each associated with a different vertebra. The hooks 26e are connected via a spinal rod 38. Again, each hook 26e can be associated with a pre-planned position (not shown) that indicates the orientation of the vertebra associated with the respective hook 26e. These positions can then be used to generate different images for each of the vertebrae, depicting each vertebra in a desired orientation with the spinous process facing upward.

[0078] Fig. 9c shows a combination of pedicle hook 26e and pedicle screw 26a associated with different vertebrae, where hook 26e is attached to screw 26a via rod 38. The technique described in the present invention allows for the generation of different images according to the medical implants associated with each vertebra, even if the implant types are different as shown in Fig. 9c.

[0079] A user can move the tracked instrument 18 along the patient's spine. Based on the current position of the instrument 18, one of the vertebrae can be selected and the corresponding image displayed. This allows the instrument 18 to be navigated relative to the vertebrae based on the image where the individual vertebrae always have the desired orientation, even if the patient's actual vertebrae are misaligned relative to one another due to scoliosis.

[0080] Generally, a medical condition such as scoliosis is a deformation of the normal curvature of the spine by twisting it and causing an abnormal sideways curvature. The most common surgery for scoliosis is spinal fusion, which treats the curved or misaligned vertebrae by realigning and fusing them into one solid bone. To do so, the surgeon may plan two pedicle screws 26a, 26b, pedicle slings 26d, or pedicle hooks 26e for each vertebra to serve as a pathway for rods 38 that help to restore the spinal curvature during the healing process. Alternatively, or in addition, a spinal cage 26c may be planned to be inserted between the vertebrae to be fused. At a later point in time, when using a navigation system to navigate the tracking instrument 18, the surgeon may struggle with anatomically unusual orientations, because the general screw planning and placement rules are defined and planned with the spine viewed in a desired and familiar orientation. Essentially, the posterior aspect of the vertebrae should be displayed facing upwards in the image, with the spinous processes extending vertically. This is how a healthy spine looks with a patient lying prone on the operating bed. Aligning the views of each vertebra in this ideal orientation allows the user to quickly see the desired anatomy in a familiar alignment, allowing for smoother, more efficient planning and navigation.

[0081] The present disclosure can reduce the complexity of this alignment step in the procedure by predicting the preferred orientation based on pre-planned items (e.g., medical implants such as screws or K-wires, procedure information such as trajectories, or user-defined points of interest), so that the user does not have to imagine or spend time manually reorienting the vertebrae to their preferred anatomical orientation.

[0082] As explained above, a set of planning features (e.g., screws, K-wires, trajectories, points of interest) are planned by an automated process and / or manual user definition. Then, a plane is constructed based on the orientation and position of these planning features or a subset thereof. A rotational orientation is constructed based on the orientation of these planning features or a subset thereof. A planning system orientation is defined that orients the world / patient to the constructed planning plane and rotation. This orientation allows the user to explore the patient data by maintaining a preferred view orientation relative to the plane and controlling the view rotation, e.g., controlling the view rotation so that the planned rotation is pointing upwards in the view. Multiple groups of these planning features can be constructed and grouped by an automated process and / or manual user definition. For example, planning features can be assigned to vertebral levels even without anatomical information about the vertebrae. For each of these groups, a planning system orientation can be constructed (e.g., plane and rotation). The user can adjust the orientation of these planning systems in one direction or another and the view direction, switching between orientation via an automated process (e.g., by bringing the tracked instrument 18 close to the item being planned) or manually.

[0083] As is evident from the above, the present disclosure provides a technique that allows generating an image of at least one anatomical element of a patient's body in a preferred orientation. Since the orientation is derived from the planned position indicated by the planning data, there is no need to employ computationally expensive segmentation or image recognition algorithms to place the anatomical element in a preferred orientation. The image generated by the technique disclosed in the present invention is also indicative of medical implants of interest to the user, in particular medical implants that are planned for at least one anatomical element depicted in the image. By selecting the generated image based on user input, for example based on the current pose of a tracked pointer or a surgical tool relative to the patient's body, it can be ensured that the image displayed is of real interest to the user. Further modifications and advantages to the technique disclosed in the present invention will be apparent to those skilled in the art.

Claims

1. 1. A method for generating, by a computing system, an image including a depiction of an anatomical element of a patient's body, comprising: acquiring medical image data of at least one anatomical element of a patient's body; acquiring planning data indicative of at least three planned locations associated with the at least one anatomical element, where one or more of the planned locations are associated with at least one planned medical implant; generating an image based on the medical image data and the planning data, the image including a representation of the at least one anatomical element in a pose defined by the at least three planning positions; The method includes:

2. The method of claim 1 , wherein the images are generated such that two or more of the at least three planned locations lie in the same plane that corresponds to or is parallel to an image plane of the generated images.

3. The method of claim 1 , wherein two or more of the planned locations are associated with the same planned medical implant.

4. The method of claim 3 , wherein at least two of said planned locations associated with said same planned medical implant lie on a line that defines an orientation of said same planned medical implant.

5. The method of claim 3 , wherein at least three of the planned locations associated with the same planned medical implant lie within a plane that defines an orientation of the same planned medical implant.

6. by orienting a representation of the at least one anatomical element; (i) a line indicating the orientation of said same planned medical implant; (ii) the vertical or horizontal image axis of the generated image is The method of claim 4 , wherein the images are generated such that the angle satisfies at least one predetermined criterion.

7. 4. The method of claim 3, wherein the images are generated such that multiple planned locations associated with the same planned medical implant lie in the same plane corresponding to or parallel to the image plane of the generated images.

8. The method of claim 1 , wherein the at least three planned locations include at least two pairs of planned locations, each pair associated with a different planned medical implant.

9. The method of claim 8 , wherein the planned locations of each planned location pair lie on a straight line that defines an orientation of the planned medical implant associated with that pair.

10. The method of claim 8 , wherein the images are generated such that the planning positions of the at least two pairs of planning positions are in the same plane that corresponds to or is parallel to an image plane of the generated images.

11. by orienting a representation of the at least one anatomical element; (i) the bisector of the angle between the straight lines indicating the orientation of the different medical implants; (ii) the vertical or horizontal image axis of the generated image is 9. The method of claim 8, wherein the images are generated such that the angle satisfies at least one predetermined condition.

12. The method of claim 1 , wherein the medical image data includes volumetric image data, and the image is generated as a two-dimensional image representing a cross-section of the volumetric image data.

13. The method of claim 1 , wherein the generated image includes a depiction of at least a portion of the at least one planned medical implant.

14. The medical implant comprises at least one component selected from: (i) a spinal cage; (ii) a bone screw, such as a pedicle fixation screw; (iii) a pedicle fixation hook; and (iv) a pedicle fixation band; and / or The method of claim 1 , wherein the at least one anatomical element comprises a bone, such as a vertebra.

15. The method of claim 1 , further comprising initiating a display of the generated image.

16. obtaining a user input indicating a selected one of the at least one anatomical element; The method of claim 1 , wherein the image is generated based on the at least three planned positions associated with the selected anatomical element.

17. 17. The method of claim 16, wherein a plurality of images are generated based on the medical image data and the planning data, each image being generated based on at least three planned positions associated with a same anatomical element, and display of only the images generated based on the at least three planned positions associated with the selected anatomical element is initiated.

18. 1. A system including at least one processor configured to execute a method for generating an image including a representation of an anatomical element of a patient's body, the method comprising: acquiring medical image data of at least one anatomical element of a patient's body; acquiring planning data indicative of at least three planned locations associated with the at least one anatomical element, where one or more of the planned locations are associated with at least one planned medical implant; generating an image based on the medical image data and the planning data, the image including a representation of the at least one anatomical element in a pose defined by the at least three planning positions; A system for performing image generation by

19. 20. The system of claim 18, further comprising at least one of the following components: a medical image acquisition unit configured to generate said medical image data A user input device configured to obtain user input. a display unit configured to display at least said generated image;

20. 1. A computer program comprising instructions that, when executed on at least one processor, cause the at least one processor to perform a method for generating an image including a representation of an anatomical element of a patient's body by: Acquiring medical image data of at least one anatomical element of a patient's body acquiring planning data indicative of at least three planned locations associated with the at least one anatomical element, where one or more of the planned locations are associated with at least one planned medical implant; generating an image based on the medical image data and the planning data, the image including a representation of the at least one anatomical element in a pose defined by the at least three planning positions;

Images