Select the cursor position on the medical image using the direction from the distal end of the probe

Abstract

A medical probe (21) includes a tubular distal end segment (22) configured to be inserted into a cavity of a patient and comprising: (a) a visual guide object (32) disposed above a periphery of the distal end segment; and (b) a magnetic field sensor (34) comprising two sensor coils (34a, 34b) aligned non-parallel to each other, the sensor being attached to the distal end segment (22) and having: (i) a first axis of symmetry of one of the coils, the first axis of symmetry being aligned perpendicular to a central longitudinal axis of the distal end segment, and (ii) a second axis of symmetry of the remaining coil, the second axis of symmetry being aligned perpendicular to the central longitudinal axis of the distal end segment and non-parallel to the first axis of symmetry.

Description

Technical Field

[0001] The present invention relates generally to medical probes, and particularly to tools for use in ear, nose and throat (ENT). Background Art

[0002] Techniques for guiding invasive probes to target tissue within the cavity of an organ have been previously proposed in the patent literature. For example, U.S. Patent Application Publication 2019 / 0090959 describes a number of improvements related to computer-assisted surgery (CAS) utilizing an on-board tool tracking (OTT) system. Some of the improvements relate to methods for providing feedback during a procedure to improve the efficiency or quality of the procedure, or both, including the rate and type of data processed according to the CAS mode. In one embodiment, to provide navigation assistance during an OTT CAS procedure, the OTT device monitors the position of an associated surgical tool within the surgical field. Depending on the requirements of the OTT CAS procedure being performed, the OTT CAS system may use none or one or more reference frames, including one or more position sensors or one or more fiducial markers.

[0003] As another example, U.S. Patent Application Publication 2016 / 0183841 describes a method for guiding an interventional instrument within a patient's anatomy, the method comprising processing a target position within the patient's anatomy and receiving a position of a distal portion of the interventional instrument at a first position within the patient's anatomy. The method also comprises determining a three-dimensional distance between the first position and the target position, and displaying a symbol representing the target position and a symbol representing the distal portion of the interventional instrument. In one embodiment, the rotational orientation of a feature of the distal distal portion may also be displayed by a navigation aid image having a rotational aid symbol. For example, if the biopsy instrument has a side opening, the side having the opening may be indicated on the navigation aid image having the rotational aid symbol.

[0004] U.S. Patent Application Publication 2007 / 0208252 describes apparatus, systems, and methods for performing image-guided interventional and surgical procedures, including various procedures for treating sinusitis and other conditions of the paranasal sinuses, ear, nose, or throat. In some applications, a preoperative tomographic scan (e.g., a CT scan) may be obtained, and the image guidance system may be programmed to display the tomographic image on a video monitor along with a real-time indication (e.g., crosshairs, a glowing dot, etc.) of the position of the working device relative to the anatomical structures displayed on the tomographic image. Summary of the Invention

[0005] One embodiment of the present invention includes a medical probe comprising a tubular distal end segment configured to be inserted into a cavity of a patient and comprising: (a) a visual guide object disposed above a periphery of the distal end segment; and (b) a magnetic field sensor comprising two sensor coils aligned non-parallel to each other, the sensor being attached to the distal end segment and having: (i) a first axis of symmetry of one of the coils, the first axis of symmetry being aligned perpendicular to a central longitudinal axis of the distal end segment, and (ii) a second axis of symmetry of the remaining coil, the second axis of symmetry being aligned perpendicular to the central longitudinal axis of the distal end segment and non-parallel to the first axis of symmetry.

[0006] In some embodiments, the visual guide object comprises a guide bump.In other embodiments, the visual guide object comprises one or more colored angled portions of the perimeter of the distal end segment.

[0007] In one embodiment, the two sensor coils are orthogonal to each other.

[0008] According to another embodiment of the present invention, there is further provided a system comprising a probe and a processor of a magnetic tracking system. The probe comprises a tubular distal end segment configured to be inserted into a cavity of a patient and comprising (a) a visual guide object disposed above a periphery of the distal end segment; and (b) a magnetic field sensor comprising two sensor coils aligned non-parallel to each other, the sensor being attached to the distal end segment and having: (i) a first axis of symmetry of one of the coils, the first axis of symmetry being aligned perpendicular to a central longitudinal axis of the distal end segment, and (ii) a second axis of symmetry of the remaining coil, the second axis of symmetry being aligned perpendicular to the central longitudinal axis of the distal end segment and non-parallel to the first axis of symmetry. The processor of the magnetic tracking system is configured to: (a) calculate the position, direction, and rotational orientation of the distal end in the patient's cavity using signals received from the magnetic field sensor coils, (b) align the measured position with a medical image, (c) find a first position in the medical image along a direction of a central longitudinal axis and a second position in a direction from the calculated position to the object using the calculated direction and rotational orientation, and (d) switch a cursor between the first position and the second position on the medical image.

[0009] In some embodiments, the system further includes a shading angle segment located above the periphery of the distal edge of the distal end segment, wherein based on the known orientation of the shading angle segment relative to the second axis of symmetry, the processor is further configured to define the object as any one of the shading angle segments observed using an endoscope inserted into the cavity, and to switch the cursor between the first position and the second position on the medical image accordingly.

[0010] According to another embodiment of the present invention, a method for switching a cursor on a medical image of an organ of a patient is further provided, the method comprising inserting a tubular distal end segment of a probe into a cavity of the patient's organ, wherein the distal end segment comprises: (a) a visual guide object disposed above a periphery of the distal end segment; and (b) a magnetic field sensor comprising two sensor coils aligned non-parallel to each other, the sensor being attached to the distal end segment and having: (i) a first symmetry axis of one of the coils, the first symmetry axis being aligned perpendicular to a central longitudinal axis of the distal end segment, and (ii) a second symmetry axis of the remaining coil, the second symmetry axis being aligned perpendicular to the central longitudinal axis of the distal end segment and non-parallel to the first symmetry axis. Using signals received from the magnetic field sensor coils, a position, orientation, and rotational orientation of the distal end segment in the patient's cavity is calculated. The measured position is registered with the medical image. Using the calculated orientation and rotational orientation, a first position along the central longitudinal axis and a second position along a direction from the calculated position to the object are found in the medical image. The cursor is switched between the first and second positions on the medical image.

[0011] In some embodiments, the method further includes defining the object as a colored angular segment observed using an endoscope inserted into the cavity within the colored angular segment above a periphery of a distal edge of the distal end segment, and switching the cursor between a first position and a second position on the medical image accordingly based on a known orientation of the colored angular segment relative to the second axis of symmetry.

[0012] The present invention will be more fully understood through the following detailed description of embodiments of the present invention in conjunction with the accompanying drawings, in which: BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 is a schematic illustration of an ear-nose-throat (ENT) system according to an embodiment of the present invention;

[0014] Figure 2 According to an embodiment of the present invention Figure 1 A side view of a distal end of an ear, nose, and throat (ENT) tool used in an ENT procedure;

[0015] Figure 3 is a top view of a distal end portion of an ear-nose-throat (ENT) tool according to another embodiment of the present invention;

[0016] Figure 4 is a perspective view of the distal end of an ear-nose-throat (ENT) tool according to an embodiment of the present invention, showing Figure 2 and Figure 3 A specific embodiment of the elements of the ENT tool; and

[0017] Figure 5 is for use according to an embodiment of the present invention Figure 2 A flow chart of a method for switching a cursor between locations on a medical image at the distal end of an ear-nose-throat (ENT) tool. DETAILED DESCRIPTION

[0018] Overview

[0019] The distal end section of a probe, such as an ear-nose-throat (ENT) probe used with a guidance system, can be tracked to visually serve as a cursor (i.e., a pointer) of a position in a 3D view (e.g., a medical image) of a patient's cavity. For example, TruDi can be utilized in this manner. TM The ENT tracking system (manufactured by Acclarent, Irvine, California) is used to use ENT aspiration tools or cutters.For example, medical images can be generated from CT or MRI images.

[0020] A magnetic sensor attached to the distal end can be used to track the distal end section of a probe (e.g., an ENT suction device), wherein the tracked position is projected onto a position on a medical image along the central longitudinal axis of the distal end (e.g., the center of the suction orifice of a suction tool). In this way, the physician can observe the cursor position on the medical image (on a display) as if viewed from the distal side of the tool itself.

[0021] However, for some clinical procedures, it may be preferred that the user to switch the image cursor between an image position projected along the central longitudinal direction and a different image position corresponding to a visual guide object disposed on the periphery of the distal edge of the distal end of the probe. The different image positions can be viewed interchangeably as if viewed from the distal side of the tool via virtual crosshairs, for example, as viewed by a physician using a user interface of the position tracking system at central and peripheral tracking positions on the distal edge of the distal end of the probe.

[0022] Embodiments of the present invention described below provide a means for allowing a user to switch a displayed cursor on a 3D view (e.g., a medical image) between medical image positions received by projecting a tracking position along two different directions as described above. In one embodiment, as described below, the tracked object is a guide bump. In another embodiment, the distal edge of a tubular distal end segment (e.g., a nosepiece) is shaded to illustrate several angular segments (e.g., four quadrants), each of which can be tracked based on a user's decision as to which segment to place the crosshairs on.

[0023] Using a video image from an endoscope (e.g., an otoscope) inserted into a cavity, a physician can visualize in real time at least a portion of the bump or angle segment, as well as the target tissue (e.g., a polyp) and nearby tissue not affected by the tool (e.g., brain tissue). Based on the known orientation of the colored angle segment relative to the object, the processor redefines the object to any of the colored angle segments viewed using the endoscope and switches the cursor on the medical image accordingly.

[0024] Typically, at the beginning of a medical procedure, the medical image and the reference frame of the magnetic tracking system are registered. As described above, the position, direction, and angular orientation of the sensor are tracked by the system to enable placement of a crosshair at different tracking locations, thereby enabling switching a cursor on the medical image between a centered and tilted orientation.

[0025] The disclosed technology allows a physician to guide the distal edge of an ENT tool to a target in vivo location where the distal edge of the tool is optimally aligned in position, direction, and rotational orientation to perform, for example, a therapeutic procedure such as ENT aspiration.

[0026] System Description

[0027] Figure 1 is a schematic illustration of an ear-nose-throat (ENT) system 20 according to an embodiment of the present invention. In the following description, it is assumed that the ENT tool 21 in the system 20 is used to perform a suction procedure in the sinuses of a patient 28, but it should be understood that the tool can be used to perform other procedures on the patient.

[0028] As described below, in one embodiment, the tool 21 includes a distal end ( Figure 22 and 3. A magnetic field sensor 34 (a tilted dual-axis magnetic sensor) is provided at the distal end of the distal end (described in conjunction with the sensor) that is tracked by the magnetic tracking system 23 during the procedure. To enable tracking in the system 20, a medical image 60 (e.g., a computed tomography (CT) image) of the patient 28 is registered with the reference frame of the magnetic tracking system 23. Although the medical image 60 may typically include a magnetic resonance imaging (MRI) image or a fluoroscopic image, in the description herein, by way of example, the image is assumed to include a fluoroscopic CT image.

[0029] Before and during the sinus procedure, a magnetic radiator assembly 24 included in the magnetic tracking system is positioned under the patient's head. Magnetic radiator assembly 24 includes a magnetic field radiator 26 that is fixed in place and transmits an alternating magnetic field into a region 30 where the patient's 28 head is located. The potential generated by a magnetic field sensor 34 in region 30 in response to the magnetic field enables its position, direction, and angular orientation to be measured in the reference frame of the magnetic tracking system.

[0030] By way of example, the five radiators 26 of the magnetic radiator assembly 24 are arranged in a generally horseshoe shape around the head of the patient 28. However, alternative configurations of the radiators of the magnetic radiator assembly 24 may also be used, and all such configurations are considered to be within the scope of the present invention.

[0031] Prior to the procedure, registration of the magnetic tracking system's frame of reference with the CT image may be performed by positioning the magnetic sensor at a known location in the image, such as the end of the patient's nose. However, any other convenient system for registering the frame of reference may be used.

[0032] The elements of system 20 are under the overall control of a system processor 40. Processor 40 may be mounted in a console 50 that includes operating controls 58, which typically include a keypad and / or a pointing device, such as a mouse or trackball. Console 50 is connected to radiator 26 and magnetic field sensor 34 wirelessly and / or via one or more cables. A physician 54 uses operating controls 58 to interact with the processor while using system 20 to perform an ENT procedure. While performing the procedure, the processor displays a cursor 15 on a medical image 60 on screen 56 to help the physician guide the distal tip to the target tissue location in the sinus.

[0033] Processor 40 operates system 20 using software stored in memory 42. The software may be downloaded to processor 40 in electronic form, for example, over a network, or alternatively or additionally, the software may be provided and / or stored on non-transitory tangible media such as magnetic, optical, or electronic memory.

[0034] Toggle the cursor between positions on the medical image based on the direction and center of the bump

[0035] Figure 2 According to an embodiment of the present invention Figure 1 1 is a side view of the distal end section 22 of the ear, nose and throat (ENT) tool 21 used in the present invention. The distal end section 22 includes a magnetic field sensor 34 (a dual-axis coil sensor) whose two coils (34a, 34b) are aligned non-parallel to each other. Both coils 34a and 34b have their axes of symmetry (340a, 340b) aligned perpendicular to the direction 44 of the central axis of the distal end. For any given orientation of the distal end relative to the magnetic field direction of the system 20, and for any roll angle about the axis 44, the magnetic field sensor 34 (a dual-axis sensor) allows the system 20 to find the tilt direction 33 and the central longitudinal direction 44 and use the orientation as described below.

[0036] When the tool 21 is inserted, the distal end section 22 of the tool is typically in air, i.e., in a schematically illustrated cavity region 200 of the anatomical structure 100, which corresponds to a zero Hounsfield Unit (HU) value in the 3-plane of a medical image, such as a CT image 205 of the anatomical structure. During a medical procedure, the nosepiece is typically viewed with an endoscope (not shown), which is typically operated by a physician to acquire and display video images so that the physician can see the position of the nosepiece relative to the anatomical structure 100. Figure 2 As shown, anatomical structure 100 includes anatomical features at surface locations 62 and 64 that a physician desires to view with an endoscope.

[0037] In the illustrated embodiment, the processor projects the position of the magnetic field sensor 34 onto the anatomy in a direction defined by the tracked center position 11 and a bump position 32 located above the perimeter of the distal edge of the distal tip segment 22. In the illustrated embodiment, the position 11 and the bump position 32 define directions 33 and 44, respectively. The reference frames of the CT 205 image and the magnetic tracking system are registered so that the processor 40 can use the anatomical location actually targeted by the distal tip 22 to mark the matching location with a cursor on the image 205. Thus, the tracking system associates the visually observed locations 62 and 64 (the locations that the physician targeting these locations with the ENT tool desires to resolve) with the corresponding locations 202 and 204 in the three planes of the CT image 205.

[0038] To select the direction 33 or 44 of the tool relative to the anatomy, the physician uses the user interface to place virtual crosshairs 102 and 104 at positions such as position 11 and bump position 32, respectively. The physician can move the crosshairs to any other arbitrary tilted position on the distal periphery, which causes the cursor to mark another position on the CT image 205 that is different from position 62. Thus, the physician can toggle the cursor on the medical image between a first position 302 and a second position 304 (which match the preselected crosshair position 102 or 104 on the tool) to view the anatomy position 62 or 64 from directions 33 and 44, respectively.

[0039] Switching the cursor between positions 302 and 304 on the plane of the CT image 205 corresponding thereto actual anatomical locations 62 and 64 pointed to by different portions of the distal end section 22 , respectively, allows the physician to better control the use of tools on the marked tissue locations.

[0040] Note that only a single cursor is always presented on the plane of the CT image 205, and the cursor for Figure 2 The cursors in both positions 302 and 304 are purely for purposes of describing the switching of the cursors to place the crosshairs 102 and 104 (by software) according to the selected location on the medical tool.

[0041] The magnetic navigation system can further inform the physician how far the nearest tissue location (e.g., location 62 or 64) is from the bump 32 or center location 11. The processor can display the distance from the selected tracking location on the tool to the nearest tissue region (the region with a non-zero HU value) to help the physician assess proximity.

[0042] Toggles the cursor between locations on the medical image based on the direction of the angle segment

[0043] Figure 3 FIG. 1 is a top view of a distal end section 122 of an ear-nose-throat (ENT) tool according to another embodiment of the present invention. In the embodiment shown, the magnetic field sensor 34 (a dual-axis magnetic sensor) is coupled to Figure 2 Same as in.

[0044] like Figure 3As shown, the nosepiece of the distal end 122 is visually marked (e.g., colored) into quadrants 48. In the illustrated embodiment, one of the colored quadrants 48 defines direction 55a, while another of the colored quadrants 48 defines direction 55b. Based on the known geometry of the distal end, and by using the magnetic field sensor 34, a crosshair can be placed on any of the position-tracking quadrants 48, where in the illustrated embodiment, the physician has placed crosshairs 112 and 114 on the quadrant positions defining directions 55a and 55b, respectively. As described above, a cursor appearing on a registered medical image (such as a 3-plane CT image 305) can be switched between corresponding positions 302 and 304, respectively. Note again that only a single cursor is always presented on each plane of the medical image.

[0045] When viewing the nosepiece with the endoscope, the physician can switch between different quadrants and, accordingly, select the cursor for the 3D view to be at a position and orientation corresponding to the angular segment at which the physician selects the aiming crosshair. For example, based on the physician selection, the processor 40 can select one of the quadrants 48 to point the cursor to a position 302 on the medical image corresponding to an anatomical structure position 67 in a region 301 of the anatomical structure 101, projected along direction 55a via the crosshairs positioned (102) on that quadrant, or to point the cursor to a position 304 on the medical image corresponding to an anatomical structure position 68 in a region 301 of the anatomical structure 101 having a non-zero HU, projected along direction 55b via the crosshairs 104 positioned (104), as viewed on the other quadrant.

[0046] Hardware implementation of the probe

[0047] Figure 4 is a perspective view of a distal end section 222 of an ear-nose-throat (ENT) tool 211, showing Figure 2 and Figure 3 Such a perspective view of the distal end section 222 may be part of a video image taken by the aforementioned endoscope.

[0048] In the embodiment shown, the coils 34a and 34b of the transverse dual-axis sensor 134 are formed so that their axes of symmetry 340a and 340b have an angle α between them. The axes are not parallel to each other and are generally closer to being orthogonal (α is about 120 degrees in the embodiment shown). The magnetic field sensor 34 (dual-axis sensor) is configured to generate a magnetic field according to the direction of the distal end 22 about the axis 44 (e.g., Figure 2 ) provide different sets of voltage signals.

[0049] Forming a multi-axis magnetic sensor on a distal end, such as the transverse dual-axis sensor 134, is described in U.S. Patent Application Publication 2018 / 0228392, which is assigned to the assignee of the present patent application and describes a position sensor comprising a flexible substrate formed into a three-dimensional (3D) shape. At least first and second field sensing coils are formed in respective first and second layers of the flexible substrate such that, in the 3D shape, the first and second field sensing coils have respective first and second axes that are not parallel to one another.

[0050] Figure 4 Also visualized are the aforementioned guide nubs 32 and angled segments 48 (eg, quadrants 48 ), which are visually marked (eg, colored) on the distal end 22 (ie, nosepiece).

[0051] Switching Cursor Position Procedure

[0052] Figure 5 According to another embodiment of the present invention, Figure 2 Flowchart of a method for switching a cursor between positions on a medical image using the distal end section 22 of an ear, nose, and throat (ENT) tool 21. The process begins with an initial step 70 in which the magnetic tracking system 23 and the reference frame of a medical image (such as a CT image of a patient 28) are registered, as described above. To perform the registration with the medical image, the magnetic tracking system 23 is activated and used to track the position, direction, and angular orientation of the magnetic field sensor 34 (a dual-axis sensor), as described above. It is assumed that the tracking is updated in real time.

[0053] In an inserting step 72, physician 54 inserts distal end section 22 of tool 21 into the nostril of patient 28. Once inserted, in a ranging step 74, processor 40 finds the location of the nearest internal element of patient 28 on the medical image using a virtual crosshair located on distal end section 22 of tool 21 using signals from magnetic field sensor 34.

[0054] Next, at a cursor placement step 76 , the processor 40 places a cursor on the medical image so as to point to the internal element of the patient 28 closest to the designated location of the distal end section 22 of the tool 21 .

[0055] At a cursor switching step 78, the physician 54 switches the cursor on the medical image between two imaging positions corresponding to the crosshairs placed at two tracking positions on the distal end section 22 of the tool 21. As the physician moves the distal end, this process repeats itself, as indicated by the dashed directional lines: the cursor position on the medical image changes as the physician continues to move the device or switch the cursor.

[0056] Figure 5 The exemplary flow charts shown in FIG. 5 are chosen solely for conceptual clarity. Figure 5 Only steps relevant to embodiments of the present invention are shown. Other steps are omitted, such as selecting a tracking position on the distal end section 22 of the tool 21 other than the center 11 and the bump 32, placing the crosshairs on the newly selected corresponding position on the medical image, and then switching the cursor between the newly selected corresponding positions.

[0057] Although the embodiments described herein are primarily directed to ENT applications, the methods and systems described herein may also be used in other applications, such as cardiac, neurological, or ophthalmic applications.

[0058] It will therefore be understood that the embodiments described above are cited by way of example, and that the present invention is not limited to what has been particularly shown and described hereinabove. On the contrary, the scope of the present invention includes combinations and subcombinations of the various features described hereinabove, as well as variations and modifications thereof, which will occur to those skilled in the art upon reading the foregoing description and which are not disclosed in the prior art.

Claims

1. A medical probe comprising a tubular distal end section configured to be inserted into a cavity of a patient, wherein the tubular distal end section terminates distally at a periphery, wherein the tubular distal end section comprises: a visual guide object protruding distally from a distal edge of the tubular distal end section, wherein the tubular distal end section extends along a central longitudinal axis; as well as a magnetic field sensor comprising two magnetic field sensor coils aligned non-parallel to each other, the magnetic field sensor being attached to the tubular distal end section and having: a first axis of symmetry of one of the magnetic field sensor coils, the first axis of symmetry being aligned perpendicular to a central longitudinal axis of the tubular distal end section; and A second axis of symmetry of the residual magnetic field sensor coil is aligned perpendicular to the central longitudinal axis of the tubular distal end section and is non-parallel to the first axis of symmetry.

2. The probe according to claim 1, wherein The visual guide object includes a guide bump.

3. The probe according to claim 1, wherein The visual guide object comprises one or more shaded angular segments of the periphery of the tubular distal end segment. The probe according to claim 1 , wherein: The two magnetic field sensor coils are orthogonal to each other.

5. A medical system comprising: A probe comprising a tubular distal end section configured to be inserted into a cavity of a patient, wherein the tubular distal end section terminates distally at a periphery, wherein the tubular distal end section comprises: a visual guide object protruding distally from a distal edge of the tubular distal end section, wherein the tubular distal end section extends along a central longitudinal axis; and a magnetic field sensor comprising two magnetic field sensor coils aligned non-parallel to each other, the magnetic field sensor being attached to the tubular distal end section and having: a first axis of symmetry of one of the magnetic field sensor coils, the first axis of symmetry being aligned perpendicular to a central longitudinal axis of the tubular distal end section; and a second axis of symmetry of a residual magnetic field sensor coil, the second axis of symmetry being aligned perpendicular to the central longitudinal axis of the tubular distal end section and non-parallel to the first axis of symmetry; and A processor of the magnetic tracking system, the processor being configured to: calculating a position, direction, and rotational orientation of the tubular distal end segment within the cavity of the patient using signals received from the magnetic field sensor coil; registering the measured positions with the medical image; Using the calculated direction and rotation orientation, find in the medical image: a first position in the direction of the central longitudinal axis; and a second position along a direction from the calculated position to the vision guide object; and A cursor is switched between the first position and the second position on the medical image.

6. The system according to claim 5, wherein: The visual guide object is a guide bump.

7. A system according to claim 5, and including a shading angle segment located above the periphery of the distal edge of the tubular distal end segment, wherein based on the known orientation of the shading angle segment relative to the second axis of symmetry, the processor is further configured to limit the visual guide object to any shading angle segment among the shading angle segments observed using an endoscope inserted into the cavity, and to switch a cursor between the first position and the second position on the medical image accordingly.

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