System and method for cavity imaging in organ of patient based on position of 4D ultrasound catheter

Abstract

A system is disclosed that includes a display and a processor display and a processor. The display is configured to display a plurality of pixels of an image of an organ having a cavity and tissue surrounding the cavity. The processor is configured to: (1) receive ultrasound (US) signals of at least the lumen and the tissue, and one or more position signals in the organ indicative of one or more positions of one or more catheters having a known geometry, respectively, and (2) based on the one or more position signals, the known geometry, and the US signal: (i) identifying a given pixel in the image at a given position, and (ii) displaying the given pixel as (a) indicating a first pixel of the cavity or (b) indicating a second pixel of the tissue in response to identifying that the given position corresponds to the one or more positions.

Description

Technical Field

[0001] The present invention relates generally to medical imaging, and in particular to methods and systems for imaging using a four-dimensional (4D) ultrasound catheter. Background Art

[0002] Various techniques have been published for imaging a cavity in an organ of a patient.

[0003] For example, U.S. Patent Application Publication 2019 / 0053708 describes a catheterization procedure that is performed by inserting a probe having a position sensor into a body cavity and responding to a plurality of position measurements identifying corresponding mapping regions of the body cavity. Using the position measurements, a simulated three-dimensional surface of the body cavity is constructed. One or more unmapped regions are depicted by rotating the simulated three-dimensional surface around an axis. The simulated three-dimensional surface of the body cavity is configured to indicate the position of the unmapped region based on the position measurements.

[0004] U.S. Patent 10,163,252 describes a system and method for automatically controlling a displayed view of an anatomical structure of a patient on a graphical user interface used by a physician. Such a system and method for automatically controlling a displayed view of an anatomical structure of a patient can facilitate visualization of the position of a medical device relative to the anatomical structure during a medical procedure for the anatomical structure. In certain implementations, the system and method of the present disclosure provides an automatic displayed view of a cardiac catheter relative to a three-dimensional model of a patient's heart chamber during a medical procedure such as cardiac ablation.

[0005] The present invention will be more fully understood through the following detailed description of examples of the present disclosure in conjunction with the accompanying drawings, in which: BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 is a schematic illustration of a catheter-based ultrasound imaging system according to an example of the present invention;

[0007] Figure 2A and Figure 2B For use according to the example of the present invention Figure 1 A schematic illustration of an ultrasound image produced by system 20; and

[0008] Figure 3 is a flow chart schematically illustrating a method for improving the quality of a displayed ultrasound image according to an example of the present invention. DETAILED DESCRIPTION

[0009] Overview

[0010] Ultrasound imaging can be performed in vivo by inserting a four-dimensional (4D) ultrasound catheter into the organ in question, such as a chamber of a patient's heart. In principle, a 4D US catheter can provide real-time US images of a volume within the field of view (FOV) of the ultrasound (US) image. For example, in response to applying ultrasound (US) waves to a cardiac chamber (e.g., atrium and / or ventricle),

[0011] The applied ultrasound waves penetrate the hollow cavity of the chamber and reflect from the chamber walls and surrounding organs within the field of view. Therefore, when a US image of a cardiac chamber is displayed, the tissue of the desired chamber wall appears gray, and the desired chamber appears black. In other words, gray is assigned to pixels (e.g., two-dimensional pixels or volume pixels referred to herein as voxels) of the US image at locations corresponding to the chamber walls.

[0012] When the cavity is filled with blood, blurring occurs. Blood includes cellular components suspended in an extracellular matrix. The cellular components can reflect US waves, so that pixels in the portion of the cavity where blood is present can appear gray. These gray pixels may not be easily distinguished from pixels representing the cavity walls and are therefore considered noise.

[0013] Examples of the invention described below provide improved techniques for reducing noise in US images while visualizing a patient's organs (eg, from within a cavity of the patient's heart).

[0014] In some examples, a system includes one or more catheters for insertion into an organ of a patient, and a processor.

[0015] In some examples, the catheter may include at least one of: (i) a mapping catheter configured to sense electrocardiogram (ECG) signals in the patient's heart, and (ii) an ablation catheter having one or more ablation electrodes configured to apply ablation signals to cardiac tissue. The system also includes a catheter having a distal end, the distal end including a (4D) ultrasound catheter having an ultrasound transducer (UT) configured to apply US waves to the organ in question (e.g., a cardiac chamber), and to generate one or more US signals indicating the shape and morphology of the chamber in question and surrounding tissue based on the US waves returned (e.g., reflected) from the chamber in question.

[0016] In some examples, the UTs are arranged in a two-dimensional (2D) array. Note that when using 4D ultrasound imaging techniques, the processor is configured to generate a three-dimensional (3D) ultrasound-based image that is presented over time corresponding to the location accessed by the distal tip of the catheter in the organ in question (e.g., the right atrium of the heart).

[0017] In some examples, the distal end of each catheter and / or the distal end of the catheter shaft described above typically includes a position sensor that is configured to generate one or more position signals indicative of one or more respective positions of the respective distal end within the lumen in question.

[0018] In some examples, the processor is configured to receive and record US signals and position signals received from the distal end of at least one of the inserted catheters, and generate an ultrasound (US) image of the cavity and tissue surrounding the cavity (e.g., tissue surrounding the wall of the cavity). Note that the 4D catheter is configured to travel or position within the cavity, and is therefore not expected to cut through tissue surrounding the cavity (in other cases, the 4D US catheter may be used in conjunction with a tool for cutting through tissue, such as in a procedure requiring the formation of a transseptal channel). In addition, the geometry (i.e., physical dimensions) of the distal end of each catheter is known and stored in the system.

[0019] In some examples, based on the recorded position signals received from each catheter and the known geometry of each catheter, the processor is configured to identify a given pixel (or a given group of pixels) in the US image that corresponds to a given position accessed by one or more of the distal tips of the corresponding catheters (including the distal tip assembly of the 4D ultrasound catheter) (e.g., when the US signal is applied). In such examples, the processor is configured to mark the given pixel (or given group of pixels) as a pixel of the cavity.

[0020] In the event that one or more of the given pixels of the cavity are erroneously rendered as gray (as described above), the processor checks whether the position signal indicates that one or more corresponding distal ends have visited a given position corresponding to the given pixel. In the event that one or more corresponding distal ends have visited the given position, the processor is configured to mark the one or more given pixels as pixels of the cavity. For example, in the event that a given pixel is erroneously marked as a tissue pixel and rendered as gray, the processor is configured to assign black to the given pixel. In addition, the processor is configured to display a modified US image, for example on a display of the system, in which the marking of the one or more pixels is corrected based on the disclosed technology.

[0021] In the context of the present disclosure and in the claims, the terms "distal tip" and "distal tip assembly" and grammatical variations thereof are used interchangeably and refer to the distal tip of one or more respective catheters.

[0022] The disclosed techniques improve the quality of ultrasound images of organs obtained using 4D ultrasound catheters and additional catheters used during medical procedures. In addition, the disclosed techniques can be used, with appropriate modifications, in imaging using other kinds of imaging sensors coupled to one or more distal ends of one or more corresponding catheters together with one or more position sensors.

[0023] System Description

[0024] Figure 1 is a schematic illustration of a catheter-based ultrasound imaging system 20 according to an example of the present invention.

[0025] Now refer to illustration 45. In some examples, the system 20 includes one or more catheters, such as but not limited to a catheter 21 having a distal tip assembly 40, the distal tip assembly including an ultrasonic transducer (UT) 53, which is arranged in the form of a two-dimensional (2D) ultrasonic array in this example, and the two-dimensional ultrasonic array is also referred to herein as a 2D array of UT 50. The distal tip assembly 40 also includes a position sensor 52 coupled at a known position relative to the 2D array 50.

[0026] In some examples, 2D array 50 is configured to apply ultrasound (US) waves to an organ (in this example, heart 26 of patient 28 ) and generate one or more US signals indicative of surface topography and morphology of corresponding tissue of heart 26 .

[0027] In some examples, position sensor 52 is integrated with 2D array 50 of catheter 21 and pre-calibrated.

[0028] In some examples, position sensor 52 is configured to generate one or more position signals that indicate one or more respective positions of distal tip assembly 40 within heart 26 of patient 28 lying on operating table 29 , as will be described in greater detail herein.

[0029] Now return to see Figure 1 In some examples, system 20 includes a processor 39 configured to estimate the direction and orientation of distal tip assembly 40 based on position signals received from position sensor 52, and more specifically estimate the direction and orientation of 2D array 50 of UT within (the cavity of) heart 26.

[0030] In some examples, based on the position signals received from position sensor 52 , processor 39 is configured to generate a US image of the heart tissue by performing registration between ultrasound images acquired by 2D array 50 in corresponding slices of the tissue of heart 26 .

[0031] In some examples, the distal tip assembly 40 is mounted at the distal end of the shaft 22 of the catheter 21, which is inserted into the heart 26 through the sheath 23. The proximal end of the catheter 21 is connected to the console 24. In the examples described herein, the catheter 21 is used for ultrasound-based diagnostic procedures. In other examples, the catheter can also be used in therapeutic procedures, such as electrical sensing and ablation of tissue in the heart 26, using the tip electrode 56 shown in the inset 45.

[0032] See now Inset 25. In some examples, system 20 includes an additional catheter 17 having a position sensor 18 and an electrode 19, both coupled to the distal end of catheter 17 at known respective locations.

[0033] In some examples, position sensor 18 is configured to generate one or more position signals indicative of one or more respective positions of the distal end of catheter 17 within heart 26 .

[0034] In some examples, electrode 19 comprises a sensing electrode configured to sense electrocardiogram (ECG) signals at one or more locations accessed by the distal end of catheter 17 in heart 27. In other embodiments, electrode 19 comprises an ablation electrode configured to apply an ablation signal to tissue at a predefined location in heart 26.

[0035] In some examples, physician 30 navigates distal tip assembly 40 of catheter 21 and the distal tip of catheter 17, respectively, to respective target locations in cavity 33 of heart 26 by manipulating shaft 22 using manipulator 32 positioned near the proximal end of catheter 21. It should be noted that cavity 33 is surrounded by tissue 35 and orifices of the vascular system connected to cavity 33. Figure 1 In the example of , the physician 30 navigates the distal tip assembly 40 and the distal tip of the catheter 17 into the cavity 33 (eg, the right atrium of the heart 26 ) and applies UT of the 2D array 50 to generate a US image of the right atrium.

[0036] Reference is now made again to Illustrations 25 and 45. In some examples, the physician 30 navigates the 2D array 50 in the cavity 33. In this example, the 2D array 50 includes approximately 2048 UTs 53 arranged in an array of approximately 64 columns and approximately 32 rows, and is configured to generate one or more US images of one or more corresponding slices of the cavity 33 and tissue 35. Note that based on the position signal received from the position sensor 52, the spatial coordinates of each pixel in the imaged slice are known and calibrated to generate a full US image of the slice in question. It should be noted that the number of UTs in the 2D array 50 and their arrangement are presented by way of example, and in other examples, the 2D array 50 may include any other suitable number of UTs 53 arranged in any similar or different suitable configuration.

[0037] In the context of the present disclosure and claims, the terms "about" or "approximately" for any numerical values ​​or ranges indicate a suitable dimensional tolerance that allows the part or collection of components to function for the intended purpose described herein.

[0038] Now return to see Figure 1 In some examples, console 24 includes: a processor 39, typically a general purpose computer, having a suitable front end; and interface circuitry 38 for receiving signals from catheter 21, and optionally for administering therapy to tissue in heart 26 via catheter 21, and for controlling other components of system 20. Console 24 also includes drive circuitry 34 configured to drive magnetic field generator 36.

[0039] In some instances, during navigation of distal tip assembly 40 in heart 26, console 24 receives position signals from position sensor 52 in response to a magnetic field from external field generator 36. Similarly, during navigation of catheter 17 in heart 26, console 24 receives position signals from position sensor 18 in response to a magnetic field applied by external field generator 36. In some examples, magnetic field generator 36 is placed at a known location external to patient 28, such as beneath table 29 on which the patient lies. The position signals indicate the position and orientation of 2D array 50 in a coordinate system of a position tracking system that is calibrated with the coordinate system of system 20. In the context of the present disclosure and claims, the terms "calibrated" and "registered" and grammatical variations thereof are used interchangeably.

[0040] Position sensing methods using external magnetic fields are implemented in various medical applications, for example, in the CARTO TMThe system is implemented in the US Pat. Nos. 6,618,612 and 6,332,089, PCT Patent Publication No. WO 96 / 05768, and US Patent Application Publications Nos. 2002 / 0065455, 2003 / 0120150, and 2004 / 0068178.

[0041] In some examples, the processor 39 is configured to operate the 2D array 50 by applying ultrasound to corresponding slices of the heart 26 including at least the cavity 33 and the tissue 35, and sensing US waves returning from the corresponding slices for imaging the cavity 33 (e.g., the right atrium) and / or surrounding tissue (e.g., tissue 35) of the heart 26. In an example, the processor 39 is configured to display at least a portion of the imaged cavity 33 to the physician 30 on the display 27, for example, as an ultrasound image (referred to herein as image 55), or using any other suitable presentation. Examples related to image 55 are described below. Figure 2A and Figure 2B Described in more detail in .

[0042] In some examples, processor 39 typically includes a general purpose computer that is programmed in software to perform the functions described herein. The software may be downloaded to the computer in electronic form over a network, for example, or it may alternatively or additionally be provided and / or stored on a non-transitory tangible medium such as magnetic, optical, or electronic memory.

[0043] Figure 1 The example configurations shown are chosen by way of example for conceptual clarity. The disclosed techniques may be applied mutatis mutandis using other components and configurations of the system 20. For example, the system 20 may include additional components and be configured to perform catheterization procedures other than the heart.

[0044] Visualizing tissue and cavity using 4D ultrasound catheter

[0045] Figure 2A is the use of an example according to the present invention Figure 1 Schematic illustration of an ultrasound image 55 produced by system 20.

[0046] In some examples, the physician 30 applies a four-dimensional (4D) ultrasound catheter, in this example, a distal tip assembly 40, which is configured to generate 4D ultrasound data about the tissue 35 and the cavity 33. In the context of the present disclosure and in the claims, the term "4D ultrasound" refers to one or more ultrasound transducers, usually arranged in an array, configured to apply ultrasound (US) waves to an organ and generate one or more US signals indicating three-dimensional (3D) features of the corresponding organ, and the processor 39 is configured to generate US images based on the US signals. It should be noted that each US image is a 2D image (of a slice of the organ in question), and the processor 39 is configured to generate a 3D US image by integrating the 2D slices into a volumetric image with volume pixels (voxels). The fourth dimension is time. When the physician 30 moves the 2D array 50, the processor 39 is configured to generate a video clip including the aforementioned 3D US images displayed over time based on the corresponding positions of the 2D array 50 moving within the organ in question (e.g., the cavity 33 of the heart 26 and the tissue 35).

[0047] In this example, physician 30 wants to perform anatomical mapping of cavity 33 and tissue 35, for example, for treating arrhythmias in heart 26 by applying radiofrequency (RF) ablation signals (e.g., pulses) to slices of tissue (not shown) that are intended to be ablated, or for any other suitable medical application. It should be understood that RF ablation is only one of a large number of treatments for which US imaging may be useful. Pulsed field ablation (sometimes referred to as irreversible electroporation (IRE)) is another exemplary treatment for which US imaging is useful.

[0048] In some examples, during RF ablation, a catheter (such as catheter 17) having one or more ablation electrodes (eg, electrode 19) is inserted into the organ in question, and the ablation electrodes are placed in contact with the tissue desired to be ablated.

[0049] After obtaining sufficient contact force between each ablation electrode and the corresponding tissue, the user of the ablation system (e.g., physician 30) applies an RF ablation signal to the tissue. It should be noted that during RF ablation, it is important to produce continuous lesions along the entire slice of tissue that is expected to be ablated. In some cases, the topography in the surface of the slice may result in insufficient contact between one or more ablation electrodes and the tissue that is expected to be ablated. Therefore, it is very important to select the appropriate position of the ablation electrode when performing RF ablation.

[0050] In the present example, the organ in question is a cavity 33 and tissue 35 of the heart 26. In some examples, prior to performing an ablation procedure, the physician 30 inserts: (i) a distal tip of a catheter 17 for performing anatomical mapping and (ii) a distal tip assembly 40 into the cavity 33, and then uses the 2D array 50 to apply US waves and generate one or more US signals indicative of the morphology (e.g., shape and surface topography) of at least a selected slice of the cavity 33 and tissue 35.

[0051] In some examples, US signals are generated using a 2D array 50 for applying a 3D wedge (not shown) acquisition mode that enables simultaneous acquisition of ultrasound images of the cavity 33 and selected slices of the tissue 35. Figure 1 As described in , 2D array 50 may include approximately 2048 UTs 53 arranged in an array of approximately 64 columns and approximately 32 rows, or any other suitable configuration.

[0052] In some examples, when physician 30 moves catheter 17 within lumen 33 (e.g., during anatomical mapping and / or ablation of tissue 35 ), position sensor 18 generates position signals at corresponding visited 3D locations, and processor 39 is configured to record and store these positions, for example, in a memory device of system 20 and / or in processor 39 .

[0053] In some examples, based on position signals from position sensor 52 , processor 39 is configured to record the 3D position of the 4D US catheter (e.g., distal tip assembly 40 ) as physician 30 moves the 4D US catheter within lumen 33 and acquires US signals using 2D array 50 .

[0054] In some examples, based on the position signals from the position sensors 18 and 52, the known dimensions of the distal tip assemblies of the catheters 21 and 17, and the US signals, the processor 39 is configured to calibrate between the coordinate systems of the position sensors 52 and the 2D array 50, and identify the visited 3D locations as locations within the cavity 33. Note that because the catheters 17 and 21 cannot penetrate the tissue 33, each 3D location that has been visited by the distal tip assemblies of the catheters 17 and 21 is necessarily within the cavity 33. Subsequently, the processor 39 is configured to generate a US image 55. Based on the 3D locations, the known dimensions of the respective distal tips, and the ultrasound signals, the processor 39 is configured to identify voxels in the US image 55 of the heart 26 that correspond to the additional 3D locations, and associate these voxels with the tissue 33. In other words, based on the known visited locations and geometric dimensions, the distal tip and shaft of the catheter can be used as an erasing tool that erases all gray areas that are not part of the cavity wall. The processor 39 is further configured to display one or more US images 55 so that the distal tip assembly 40 and, when applicable, the distal tip of the catheter 17 are positioned within the field of view of the US image 55. Thus, the physician 30 can see the US image at the location currently accessed by the distal tip assembly 40 and the distal tip of the catheter 17.

[0055] In some examples, based on the US signals of the 2D array 50, the known dimensions of the distal ends of the catheters 17 and 21, and the corresponding position signals of the position sensors 18 and 52, the processor 39 is configured to visualize the shape of the cavity 33 and the surface of the selected slice of tissue 35. Methods of applying US signals and position sensors for producing anatomical images, particularly based on ultrasound, are described in the applicant's other patent applications (e.g., in U.S. patent applications 17 / 357,231 and 17 / 357,303).

[0056] In some examples, processor 39 is configured to generate image 55 indicating the shape of at least a portion of cavity 33 and the topography and shape of a corresponding slice of tissue 33. Figure 1 As described in , the processor 39 is configured to display the image 55 having a wedge shape to the physician 30 on the display 27 .

[0057] In some examples, the image 55 includes one or more pixels, in this example, volume pixels (voxels) 77, indicating imaging of the cavity 33. In this example, a first color is assigned to the pixel 77. For example, the processor 39 is configured to present the pixel 77 in black, which is obtained based on the interaction between the US wave and the blood filling the cavity 33 at the maximum expansion position of the cavity 33 (e.g., in the maximum expansion of the right atrium). It should be noted that when the 2D array 50 applies the US wave, almost no US wave returns from the cavity 33 to the US sensor of the 2D array 50. Therefore, the processor 39 typically assigns black to the pixel 77. Figure 2A In the example of , because black pixels may not appear as a pixel grid, pixel 77 is shown in white only for clarity in presenting the example of the present invention.

[0058] In some examples, the image 55 includes one or more pixels 66 indicating imaging of the tissue 35. In this example, some of the applied US waves are returned from the tissue 35 to the 2D array 50 (e.g., more than from the cavity 33), and therefore, a second different color (e.g., gray) is assigned to the pixel 66. The image 55 also includes a line 37 (shown in bold for conceptual clarity) representing the surface shape of the tissue 35, which also represents the interface between the cavity 33 and the tissue 35. Any suitable color (e.g., white, light gray, or black) can be assigned to the line 37. For example, if the line 37 returns (e.g., reflects) more US waves back to the 2D array 50 than the tissue 35, the line 37 can appear in light gray or white.

[0059] In some examples, pixels 66 and 77 (as well as any other pixels of image 55 ) may include 2D pixels or volumetric pixels (voxels) for imaging the volumes of tissue 35 and cavity 33 , respectively.

[0060] In some examples, processor 39 is configured to gate the visualization of the slices of cavity 33 and tissue 35 to the appropriate phase of the cardiac cycle of beating heart 26, such as to a cardiac phase when heart 26 is fully dilated or fully contracted. This gating is necessary to provide physician 30 with the most accurate shape and surface topography of cavity 33 and tissue 35 without producing imaging artifacts associated with the different phases of systole of heart 26.

[0061] In some examples, processor 39 is configured to generate image 55 as physician 30 moves distal tip assembly 40 (and the distal tip of catheter 17) within lumen 33. In some cases, the color assigned to one or more of pixels 66 and 77 may be incorrect, for example, due to the presence of solid particles (e.g., fat or clots) within blood or another substance, or due to the systolic phase of heart 26. In the example of image 55, pixels 77a, 77b of lumen 33 are incorrectly assigned a gray color, and pixel 66a of tissue 35 is incorrectly assigned a white color.

[0062] Improving the quality of ultrasound images based on position signals received from position sensors

[0063] Figure 2B is a schematic illustration of an ultrasound image 55a according to an example of the present invention, the image being generated using the system 20 and being similar to the above Figure 2A The image 55 has improved quality compared to the image 55.

[0064] In some examples, based on position signals from position sensors 19 and 52, processor 39 is configured to record the 3D position of the distal end of catheter 17 and the 4D US catheter (e.g., distal end assembly 40) as physician 30 moves catheter 17 and the 4D US catheter within cavity 33 and acquires US signals using 2D array 50.

[0065] Based on the above Figure 2A According to the techniques described in the previous section, based on the position signals received from the position sensors 19 and 52, the known physical dimensions of the distal ends of the catheters 17 and 21, and the US signals acquired by the 2D array 50, the processor 39 is configured to calibrate between the coordinate systems of the position sensors 19 and 52 and the 2D array 50. Subsequently, the processor 39 is configured to generate Figure 2A and Figure 2B Based on the calibration, the processor 39 is configured to display the US image 55a so that the distal tip assembly 40 (and, where applicable, the distal tip of the catheter 17) is positioned within the field of view of the US image 55a.

[0066] In some examples, based on the fact that the distal tip assembly 40 and the distal end of the catheter 17 cannot perforate (e.g., cut through) the tissue 35 of the heart 26 (or any other tissue), the processor 39 is configured to assign a white color to each voxel corresponding to the position signal received from the position sensors 19 and 52. In other words, each location within the heart 26 accessed by the distal tip assembly 40 and the distal end of the catheter 17 is considered a cavity (because the distal tip assembly 40 cannot pass through the tissue 35). Therefore, the processor 39 is configured to classify all voxels corresponding to the visited locations as cavity voxels and assign a white color to these corresponding voxels. The color assignment is used to mark each voxel so that the physician 30 can immediately identify the cavity on the US image 55a (and in the above-mentioned Figure 2A The position of each voxel can be seen on the US image 55 of the image 55) as corresponding to the tissue 35 or the cavity 33. In the context of the present disclosure and in the claims, the terms "marking" and "displaying the voxel as" and their grammatical variations are used interchangeably and refer to presenting one or more voxels on the corresponding US map (e.g., on the display 27).

[0067] Similarly, in some cases, physician 30 is unable to position distal tip assembly 40 at a location having one or more voxels classified as cavity voxels (i.e., indicating cavity 33). In some examples, processor 39 is configured to reclassify at least one of these one or more voxels as a tissue voxel and mark them by assigning a gray color to the corresponding one or more voxels.

[0068] In the context of the present disclosure, the terms "cavity pixel" and "cavity voxel" refer to pixels and voxels, respectively, whose locations correspond to the locations of cavities (e.g., cavity 33) of heart 26. Similarly, the terms "tissue pixel" and "tissue voxel" refer to pixels and voxels, respectively, whose locations correspond to the locations of tissues (e.g., tissue 35) of heart 26.

[0069] exist Figure 2B In some examples, physician 30 moves distal tip assembly 40 and / or the distal tip of catheter 17, particularly at locations corresponding to pixels 77a and 77b. In some examples, in response to (i) identifying that pixels 77a and 77b correspond to the aforementioned visited locations, and (ii) identifying that gray is assigned to pixels 77a and 77b (as described above), physician 30 moves distal tip assembly 40 and / or the distal tip of catheter 17, particularly at locations corresponding to pixels 77a and 77b. Figure 2A ), processor 39 is configured to reclassify pixels 77a and 77b as cavity pixels and assign white (instead of the gray shown in image 55 above) to both pixels 77a and 77b.

[0070] In some examples, in response to (i) identifying that pixel 66a corresponds to a location that is not accessible by distal tip assembly 40 and / or the distal tip of catheter 17, and (ii) identifying that white is assigned to pixel 66a (as described above), Figure 2A ), the processor 39 is configured to reclassify the pixel 66a as a tissue pixel and assign a gray color to the pixel 66a.

[0071] In such examples, based on one or more locations received from position sensors 19 and 52, processor 39 is configured to reclassify one or more pixels or voxels on image 55 and generate image 55a that assigns different colors to the reclassified pixels. In other words, in response to receiving a location signal accessed by distal tip assembly 40 and / or the distal end of catheter 17, and identifying that a given pixel in the image corresponds to the accessed location, processor 39 is configured to display the given pixel as a lumen pixel on display 27. Similarly, processor 39 may identify additional locations that cannot be accessed (by distal tip assembly 40 and / or by the distal end of catheter 17) as tissue, and may classify one or more pixels corresponding to the additional locations as tissue pixels, and display the classified pixels as tissue pixels with an assigned gray color.

[0072] Figure 2A and Figure 2B The images 55 and 55a are shown by way of example and are simplified for conceptual clarity. For example, the images 55 and 55a each include approximately 200 pixels, while a typical ultrasound image may include millions of pixels. Therefore, at least one (typically each) of the pixels 66, 66a, 77, 77a, and 77b includes any suitable number of pixels, such as approximately 10,000 pixels. In addition, the processor 39 is configured to process the image at the position of Figure 2A and / or Figure 2B The processor 39 may be configured to reclassify or change the color of a single pixel or pixel group at any position of the image 55 and 55a. In addition, the processor 39 is configured to display the pixels or voxels in the images 55 and 55a on the display 27.

[0073] In other examples, each pixel or voxel of images 55 and / or 55a may include more than one lumen pixel or tissue pixel. For example, where an organ includes several types of tissues having characteristics that differ from one another, each tissue type may have a different classification. In such examples, processor 39 is configured to use the above Figure 2A and Figure 2B In the example described in , each pixel is classified according to the US signal received from the 2D array and based on the position of each pixel or voxel. In addition, the processor 39 is configured to assign different colors to each pixel corresponding to different tissue types.

[0074] In an alternative example, instead of or in addition to assigning a color code according to the classification of each pixel, the processor 39 is configured to display pixels or voxels using any other technique that visually distinguishes pixels of different categories. For example, different textures and / or different icons are assigned to one or more pixels having common characteristics or different characteristics, such as tissue pixels and cavity pixels.

[0075] In some examples, when the physician 30 moves the distal tip assembly 40 between a first position in the cavity 33 and a second position different from the first position, the processor 39 is configured to receive: (i) a first position signal and a second position signal indicating the first position and the second position, respectively, and (ii) a first US signal and a second US signal indicating the cavity 33 and / or tissue 35 at the first position and the second position, respectively. In some examples, based on the first position signal and the second position signal and the corresponding US signals, the processor 39 is configured to present at least a first US image and a second US image of the first position and the second position, respectively, on the display 27. In some examples, the pixels include voxels, and the processor 39 is configured to present a 3D ultrasound image. In addition, the processor 39 is configured to present, for example, a video clip including at least the first and second 3D US images on the display 27, and typically, the video clip includes US imaging of at least the cavity 33 and / or tissue 35 located between the first position and the second position.

[0076] Improving the quality of 4D ultrasound images displayed to the user

[0077] Figure 3 is a flow chart schematically illustrating a method for improving the quality of an ultrasound image 55 displayed to a physician 30 according to an example of the present invention.

[0078] The method begins with a catheterization step 100, which inserts a plurality of catheters, in this example, distal tip assembly 40 and the distal end of catheter 17, into the right atrium of heart 26. Note that the geometry (i.e., physical dimensions) of the distal ends of both catheters are known and stored in system 20, such as in processor 39. As described above, for example, Figure 1 As described in , the distal end of the catheter 17 includes a magnetic position sensor 18 and an electrode 19, and the distal end assembly 40 includes a 2D array 50 of UT and a position sensor 52. In some examples, the 2D array 50 is configured to: (i) apply US waves to the tissue in question (e.g., tissue 35) and (ii) generate US signals indicating the surface topography of the cardiac tissue in question. The position sensors 18 and 52 are configured to generate position signals indicating the respective positions of the distal end of the catheter 17 and the distal end assembly 40 in the right atrium (i.e., cavity 33) of the heart 26.

[0079] In some examples, processor 39 is configured to perform calibration between the coordinate systems of 2D array 50 and position sensor 52. Note that this calibration is typically performed prior to catheter insertion (e.g., during the production and / or certification of catheters 17 and 21) to reduce the time of the diagnostic procedure, but in other examples, calibration or verification of the catheter may be performed after the distal tip of catheter 17 and / or distal tip assembly 40 is inserted into cavity 33.

[0080] In ultrasound application step 102, when the physician moves distal tip assembly 40 within cavity 33, processor 39 controls 2D array 50 to apply US waves to tissue 35 and / or cavity 33. In some examples, processor 39 receives US signals (from 2D array 50) and position signals (from position sensor 52), as described above. Figure 1 , Figure 2A and Figure 2B Described in detail in .

[0081] At a first visualization step 104, based on the received US signals, the known geometry of the distal ends of catheters 17 and 21, and the position signals received from position sensors 18 and 52, processor 39 generates a US image 55 having: (i) tissue pixels, such as pixel 66, and (ii) lumen pixels, such as pixel 77, as described above in Figure 2A It is noted that each pixel may include a 2D pixel or a volume pixel (voxel) and may be classified and labeled as a tissue voxel (or pixel) or a cavity voxel (or pixel) in the US image 55. Furthermore, in the context of the present disclosure and in the claims, the term "pixel" may refer to a 2D pixel or a volume (3D) pixel (i.e., voxel).

[0082] At the pixel verification step 106, based on the position signals received from the position sensors 18 and 52, the processor 39 is configured to identify at least a given pixel in the US image 55 corresponding to a given position in the cavity 33, which is accessed by the distal end of the catheter 17 and / or the distal end assembly 40 when sensing ECG signals and / or acquiring US signals.

[0083] At a first decision step 108 , the processor 39 is configured to check whether a given pixel is classified and marked as a cavity pixel.

[0084] Where a given pixel of the US image 55 (e.g., pixel 77) is marked as a cavity pixel, the method loops back to step 106 and the processor 39 checks another pixel of the US image 55, and at step 108, the processor 39 checks whether the other pixel is classified and marked as a cavity pixel.

[0085] In the event that a given pixel of the US image 55 (e.g., pixel 77a) is labeled as a tissue pixel, the method proceeds to a labeling step 110. In some examples, at step 110, the processor 39 verifies that the position signal corresponding to the position of pixel 77a received from one or both of the position sensors 18 and 52 means that the distal end of the catheter 17 and / or the distal end assembly 40 has accessed a position corresponding to the position of pixel 77a. In such examples, at step 110, in response to the verification, the processor 39 is configured to reclassify pixel 77a as a lumen pixel and change the label of pixel 77a from a tissue pixel to a lumen pixel, as described above in Figure 2B Detailed description and illustration in FIG.

[0086] In other examples, processor 39 is configured to apply steps 106 to 110, with appropriate modifications, to locations that cannot be accessed by distal tip assembly 40. For example, processor 39 is configured to check whether the distal tip of catheter 17 and / or distal tip assembly 40 has already accessed the location corresponding to pixel 66a. In the event that the distal tip of catheter 17 and / or distal tip assembly 40 has not yet accessed and / or cannot access the location corresponding to pixel 66a, processor 39 is configured to reclassify pixel 66a as a tissue pixel and change the label of pixel 66a from a cavity pixel to a tissue pixel, as described above in Figure 2B Note that the same techniques are applied to pixel 77b as described above in Figure 2B Described in detail in .

[0087] At a second decision step 112, processor 39 checks whether additional pixels of the US image (eg, image 55) must be checked. In the event that there are additional pixels that must be checked, the method loops back to step 106.

[0088] In the case where it is not necessary to examine additional pixels of the US image 55, the method proceeds to a second visualization step 114 and then ends the method. In step 114, the processor 39 is configured to display the image 55a to the physician 30, for example on the display 27, wherein the image 55a is visualized using the method described above. Figure 2B The techniques described in steps 106 to 110 are used to correct the labels of pixels 66a, 77a, and 77b.

[0089] Figure 3 The method is intended to improve the quality of US images displayed to the physician 30 and may be performed during mapping of the heart 26 (or any other organ) as well as during therapeutic medical procedures such as during tissue ablation. Note that the processor 39 may reclassify and relabel the pixels of the US image at any suitable time (e.g., even offline) as long as the position signal is recorded.

[0090] In addition, for the sake of conceptual clarity, Figure 3 The methods are simplified and typically include additional steps necessary to perform visualization of the heart or any other suitable organ in question.

[0091] Example 1

[0092] A system includes a display (27) and a processor (39). The display (27) is configured to display a plurality of pixels (66, 66a, 77, 77a, 77b) of an image (55, 55a) of an organ (26) having a cavity (33) and tissue (35) surrounding the cavity (33). The processor (39) is configured to: (1) receive ultrasound (US) signals of at least the cavity (33) and the tissue (35), and one or more position signals in the organ (26) indicating one or more positions of one or more catheters (22, 17) having known geometries, respectively, and (2) based on the one or more position signals, the known geometries and the US signals: (i) identify a given pixel (77a) at a given position in the image (55, 55a), and (ii) display the given pixel (77a) as: (a) a first pixel indicating the cavity (33) in response to identifying that the given position corresponds to the one or more positions, or (b) a second pixel indicating the tissue (35).

[0093] Example 2

[0094] A system as in embodiment 1, wherein the plurality of pixels, the given pixel, and the first pixel and the second pixel comprise volume pixels (voxels).

[0095] Example 3

[0096] A system as in embodiment 1 wherein the processor is configured to assign a first color to the first pixel and a second color different from the first color to the second pixel.

[0097] Example 4

[0098] According to the system of Example 1, in response to identifying that the distal end of the catheter in the catheter has failed to reach an additional position, the processor is configured to identify additional pixels corresponding to the additional position and assign the second color to the additional pixels.

[0099] Example 5

[0100] The system of Example 1, wherein the one or more catheters include one or both of: (i) a mapping catheter configured to sense electrical signals in the tissue, and (ii) an ablation catheter configured to apply an ablation signal to the tissue.

[0101] Example 6

[0102] A system according to embodiments 1 to 5, wherein at least one of the catheters comprises a distal end having a known geometry and comprises an ultrasonic transducer (UT), wherein the UT is configured to apply US waves to the organ and generate the US signal at a corresponding position of the distal end.

[0103] Example 7

[0104] According to the system of Example 6, the catheter comprises a four-dimensional (4D) ultrasound catheter, wherein the UTs are arranged in a two-dimensional (2D) array at the distal end, and wherein the position sensor is coupled to the distal end at a known position relative to the 2D array.

[0105] Example 8

[0106] A system according to Example 7, wherein the processor is configured to calibrate between a first coordinate system of the 2D array and a second coordinate system of the position sensor, and identify the given pixel in the image based on the calibrated first coordinate system and second coordinate system.

[0107] Example 9

[0108] A system according to Example 6, wherein, when the distal end moves between a first position in the cavity and a second position different from the first position, the processor is configured to receive: (i) a first position signal and a second position signal indicating the first position and the second position, respectively, and (ii) a first US signal and a second US signal indicating the cavity at the first position and the second position, respectively, and based on the first position signal and the second position signal and the US signals, present at least a first US image and a second US image of the first position and the second position, respectively, on the display.

[0109] Example 10

[0110] A system as in embodiment 9, wherein the first US image and the second US image comprise a first three-dimensional (3D) US image and a second 3D US image, respectively.

[0111] Embodiment 11

[0112] A method, the method comprising: displaying a plurality of pixels (66, 66a, 77, 77a, 77b) of an image (55, 55a) of an organ (26), the organ having a cavity (33) and tissue (35) surrounding the cavity (33). Receiving an ultrasound (US) signal of at least the cavity (33) and the tissue (35), and one or more position signals in the organ (26) indicating one or more positions of one or more catheters (22, 17) having known geometries, respectively. Based on the one or more position signals, the known geometries, and the US signals: (i) identifying a given pixel (77a) at a given position in the image (55, 55a), and (ii) displaying the given pixel (77a) as: (a) a first pixel indicating the cavity (33) in response to identifying that the given position corresponds to the one or more positions, or (b) a second pixel indicating the tissue (35).

[0113] Although the embodiments described herein primarily address electroanatomical mapping, tissue ablation, and 4D US imaging of a patient's heart, the methods and systems described herein may also be used in other patient organs and / or in other applications.

[0114] It should therefore be understood that the above embodiments are cited by way of example, and the present invention is not limited to what is specifically shown and described above. On the contrary, the scope of the present invention includes combinations and sub-combinations of the various features described above, as well as variations and modifications thereof, which will occur to those skilled in the art upon reading the above description, and which are not disclosed in the prior art.

Claims

1. A system, comprising: a display configured to display a plurality of pixels of an image of an organ having a cavity and tissue surrounding the cavity; and A processor, the processor being configured to: receiving ultrasound (US) signals of at least the cavity and the tissue, and one or more position signals in the organ respectively indicating one or more positions of one or more conduits having known geometries; as well as Based on the one or more position signals, the known geometry and the US signal: (i) identifying a given pixel at a given location in the image, and (ii) displaying the given pixel as: (a) a first pixel indicating the cavity in response to identifying that the given location corresponds to the one or more locations, or (b) a second pixel indicating the tissue.

2. The system according to claim 1, wherein: The plurality of pixels, the given pixel, and the first and second pixels include volume pixels (voxels).

3. The system according to claim 1, wherein: The processor is configured to assign a first color to the first pixel and to assign a second color different from the first color to the second pixel.

4. The system according to claim 3, wherein: In response to identifying that the distal end of one of the catheters has failed to reach an additional location, the processor is configured to identify additional pixels corresponding to the additional location and assign the second color to the additional pixels.

5. The system according to claim 1, wherein: The one or more catheters include one or both of: (i) a mapping catheter configured to sense electrical signals in the tissue, and (ii) an ablation catheter configured to apply an ablation signal to the tissue.

6. The system according to claim 1, wherein: At least one of the catheters comprises a distal end having the known geometry and comprises an ultrasonic transducer (UT) configured to apply US waves to the organ and generate the US signal at a corresponding position of the distal end.

7. The system according to claim 6, wherein: The catheter comprises a four-dimensional (4D) ultrasound catheter, wherein the UTs are arranged in a two-dimensional (2D) array at the distal end, and wherein the position sensor is coupled to the distal end at a known position relative to the 2D array.

8. The system according to claim 7, wherein: The processor is configured to calibrate between a first coordinate system of the 2D array and a second coordinate system of the position sensor, and to identify the given pixel in the image based on the calibrated first and second coordinate systems.

9. The system according to claim 6, wherein: When the distal end moves between a first position in the cavity and a second position different from the first position, the processor is configured to receive: (i) a first position signal and a second position signal indicating the first position and the second position, respectively, and (ii) a first US signal and a second US signal indicating the cavity at the first position and the second position, respectively, and based on the first position signal and the second position signal and the US signals, present at least a first US image and a second US image of the first position and the second position, respectively, on the display.

10. The system according to claim 9, wherein: The first US image and the second US image include a first three-dimensional (3D) US image and a second three-dimensional (3D) US image, respectively.

11. A method comprising: a plurality of pixels displaying an image of an organ having a cavity and tissue surrounding the cavity; receiving ultrasound (US) signals of at least the cavity and the tissue, and one or more position signals in the organ respectively indicating one or more positions of one or more conduits having known geometries; as well as Based on the one or more position signals, the known geometry and the US signal: (i) identifying a given pixel at a given location in the image, and (ii) displaying the given pixel as: (a) a first pixel indicating the cavity in response to identifying that the given location corresponds to the one or more locations, or (b) a second pixel indicating the tissue.

12. The method according to claim 11, wherein: The plurality of pixels, the given pixel, and the first and second pixels include volume pixels (voxels).

13. The method according to claim 11, wherein: Displaying the image includes assigning a first color to the first pixel and assigning a second color different from the first color to the second pixel.

14. The method according to claim 13, wherein: In response to identifying that the distal end has failed to reach an additional position, the processor is configured to identify additional pixels corresponding to the additional position and assign the second color to the additional pixels.

15. The method according to claim 11, wherein: The one or more catheters include one or both of: (i) a mapping catheter configured to sense electrical signals in the tissue, and (ii) an ablation catheter configured to apply an ablation signal to the tissue.

16. The method according to claim 11, wherein: At least one of the catheters comprises a distal end having the known geometry and comprises an ultrasonic transducer (UT) for applying US waves to the organ and generating the US signal at a corresponding position of the distal end.

17. The method according to claim 16, wherein: The catheter comprises a four-dimensional (4D) ultrasound catheter, wherein the UTs are arranged in a two-dimensional (2D) array at the distal end, and wherein the position sensor is coupled to the distal end at a known position relative to the 2D array.

18. The method of claim 17, and comprising calibrating between a first coordinate system of the 2D array and a second coordinate system of the position sensor, and identifying the given pixel in the image based on the calibrated first and second coordinate systems.

19. The method according to claim 16, wherein: When the distal end moves between a first position in the cavity and a second position different from the first position, receiving: (i) a first position signal and a second position signal indicating the first position and the second position, respectively, and (ii) a first US signal and a second US signal indicating the cavity at the first position and the second position, respectively, and based on the first position signal and the second position signal and the US signals, presenting at least a first US image and a second US image of the first position and the second position, respectively, on the display.

20. The method according to claim 19, wherein: The first US image and the second US image include a first three-dimensional (3D) US image and a second three-dimensional (3D) US image, respectively.

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