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

Abstract

The system includes a 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 at least an ultrasonic (US) signal of the cavity and the tissue and one or more position signals within the organ indicating one or more positions of one or more catheters having a known geometric shape; and (2) based on the one or more position signals, the known geometric shape, and the US signal, (i) identify a given pixel at a given position in the image and (ii) display the given pixel as either (a) a first pixel indicating the cavity in response to identifying that the given position corresponds to one or more of the one or more positions, or (b) a second pixel indicating the tissue.

Description

Technical Field

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

Background Art

[0002] Various techniques for imaging the lumen within a patient's organ have been disclosed.

[0003] For example, U.S. Patent Application Publication No. 2019 / 0053708 describes a catheter procedure that is performed by inserting a probe having a position sensor into a body cavity and identifying each mapped region of the body cavity according to a plurality of position measurements. Using these position measurements, a simulated three-dimensional surface of the body cavity is constructed. One or more unmapped regions are delineated by rotating the simulated three-dimensional surface of the body cavity about an axis. The simulated three-dimensional surface of the body cavity is configured to indicate the position of unmapped regions based on the position measurements.

[0004] U.S. Patent No. 10,163,252 describes a system and method for automatically controlling a display view of a patient's anatomical structure on a graphical user interface used by a physician. Such a system and method for automatically controlling a display view of a patient's anatomical structure can facilitate visualizing the position of a medical device relative to the anatomical structure during a medical procedure directed at the anatomical structure. In certain implementations, the systems and methods of the present disclosure provide an automatically displayed view of a cardiac catheter relative to a three-dimensional model of a patient's heart cavity during a medical procedure such as cardiac ablation.

[0005] The present invention will be more fully understood from the following detailed description of embodiments of the disclosure in conjunction with the drawings.

Brief Description of the Drawings

[0006]

Figure 1

Figure 2A

Figure 2B

Figure 3

Mode for Carrying Out the Invention

[0007] Overview Ultrasonic imaging can be performed in vivo by inserting a four-dimensional (4D) ultrasonic catheter into an organ in question, such as the atrium and ventricle of a patient's heart. In principle, a 4D US catheter can provide real-time ultrasonic (US) images of a volume within the field-of-view (FOV) of a US image. For example, in response to the application of ultrasonic (US) waves to a heart cavity (e.g., an atrium and / or ventricle), The applied ultrasonic waves penetrate the hollow cavity of the atrium and ventricle and are reflected from the atrium wall and surrounding organs within the field of view. Thus, when displaying a US image of the heart cavity, the tissue of the atrium wall is expected to appear in gray, and the cavity is expected to appear in black. In other words, gray is assigned to the pixels (e.g., two-dimensional pixels or volume pixels, referred to herein as voxels) of the US image at positions corresponding to the atrium wall.

[0008] Ambiguity occurs when the cavity is filled with blood. Blood contains cellular elements suspended in the extracellular matrix. The cellular elements can reflect US waves such that the pixels of a portion of the cavity where blood was present can appear in gray. These gray pixels cannot be easily distinguished from the pixels representing the atrium wall and are thus considered noise.

[0009] The embodiments of the present invention described below provide an improved technique for reducing noise from US images while visualizing a patient's organ, such as from within the cavity of the patient's heart.

[0010] In some embodiments, the system comprises one or more catheters for insertion into a patient's organ and a processor.

[0011] In some embodiments, the catheter may include at least one of (i) a mapping catheter configured to sense an electrocardiogram (ECG) signal in a patient's heart, and (ii) an ablation catheter having one or more ablation electrodes configured to apply an ablation signal to heart tissue. The system further comprises a catheter having a distal end with an (4D) ultrasound catheter having an ultrasound transducer (UT), the ultrasound transducer (UT) being configured to apply US waves to the organ in question (e.g., a heart cavity) and generate one or more US signals indicative of the shape and morphology of the cavity in question and the surrounding tissue based on the US waves returned (e.g., reflected) from the cavity in question.

[0012] In some embodiments, the UT is arranged in a two-dimensional (2D) array. When using 4D ultrasound imaging technology, the processor is configured to generate a three-dimensional (3D) ultrasound-based image, which is presented over time corresponding to the location accessed by the distal end of the catheter within the organ in question (e.g., the right atrium of the heart). Note that.

[0013] In some embodiments, the distal end of each of the catheters described above and / or the distal end of the catheter shaft typically comprises a position sensor configured to generate one or more position signals indicative of the respective position of one or more of the respective distal ends within the cavity in question.

[0014] In some embodiments, the processor is configured to receive and record US signals and position signals received from at least one distal end of the inserted catheter, and generate an ultrasonic (US) image of a cavity and the tissue surrounding the cavity (e.g., the tissue of the wall surrounding the cavity). The 4D catheter is configured to travel within or be positioned within a heart chamber, and it should be noted that it is not intended to incise the tissue surrounding the cavity (in other cases, the 4D US catheter can be used in combination with a tool for incising tissue, such as in a procedure that requires the formation of a transseptal access). Further, the geometric shape (i.e., physical dimensions) of the distal end of each catheter is known and stored within the system.

[0015] In some embodiments, based on the recorded position signals received from each catheter and the known geometric shape of each catheter, the processor is configured to identify a given pixel (or a group of given pixels) corresponding to a given position accessed by one or more than one of the distal ends of each catheter, including the distal end assembly of the 4D ultrasonic catheter, within the US image (e.g., while applying the US signal). In such embodiments, the processor is configured to tag a given pixel (or a group of given pixels) as a pixel of the cavity.

[0016] If one or more of the given pixels of the lumen appear erroneously gray (as described above), the processor checks whether the position signal indicates that one or more respective distal ends accessed a given position corresponding to the given pixel. If one or more respective distal ends accessed the given position, the processor is configured to tag one or more of the given pixels as lumen pixels. For example, if a given pixel is erroneously tagged as a tissue pixel and appears gray, the processor is configured to assign black to the given pixel. Further, the processor is configured to display, for example, on a display of the system, a revised US image in which the tagging of one or more pixels has been corrected, based on the disclosed technique.

[0017] In the context of the present disclosure and claims, the terms "distal end" and "distal end assembly" and their grammatical variations are used interchangeably and refer to the distal tip of one or more respective catheters.

[0018] The disclosed technique improves the quality of ultrasonic images of organs obtained using a 4D ultrasonic catheter and additional catheters used during a medical procedure. Further, the disclosed technique can be used with the necessary modifications in imaging using other types of imaging sensors coupled to one or more distal ends of one or more respective catheters, along with one or more position sensors.

[0019] Description of the System FIG. 1 is a schematic pictorial diagram of a catheter-based ultrasonic imaging system 20 according to an embodiment of the present invention.

[0020] Here, refer to the inserted Figure 45. In some embodiments, the system 20 includes one or more catheters, such as catheter 21 having a distal end assembly 40 that includes, but is not limited to, an ultrasonic transducer (UT) 53. The UT 53 is, in this embodiment, arranged in a two-dimensional (2D) ultrasonic array, which is also referred to herein as the 2D array 50 of the UT. The distal end assembly 40 further includes a position sensor 52 coupled to the 2D array 50 at a known position.

[0021] In some embodiments, the 2D array 50 is configured to apply ultrasonic (US) waves to an organ, in this embodiment, the heart 26 of patient 28, and generate one or more US signals indicating the surface topography and morphology of the respective tissues of the heart 26.

[0022] In some embodiments, the position sensor 52 is integrated with the 2D array 50 of the catheter 21 and pre-calibrated.

[0023] In some embodiments, the position sensor 52 is configured to generate one or more position signals indicating one or more respective positions of the distal end assembly 40 within the heart 26 of the patient 28 lying on the operating table 29, as described in more detail herein.

[0024] Here, refer again to the overall view of FIG. 1. In some embodiments, the system 20 includes a processor 39 configured to estimate the direction and orientation of the distal end assembly 40, more specifically, the direction and orientation of the 2D array 50 of the UT within the heart 26 (chamber), based on the position signals received from the position sensor 52.

[0025] In some embodiments, based on the position signals received from the position sensor 52, the processor 39 is configured to generate a US image of the heart tissue by aligning the ultrasonic images acquired by the 2D array 50 in each respective section of the heart 26 tissue.

[0026] In some embodiments, the distal end assembly 40 is attached to the distal end of the catheter 21 shaft 22 that is inserted into the heart 26 through the sheath 23. The proximal end of the catheter 21 is connected to the control console 24. In the embodiments described herein, the catheter 21 is used for ultrasonic-based diagnostic procedures. In other embodiments, the catheter may also be used in therapeutic procedures such as electrical sensing and ablation of tissue within the heart 26 using the tip electrode 56 shown in the insertion figure 45.

[0027] Now, referring to the insertion figure 25. In some embodiments, the system 20 includes an additional catheter 17 having a position sensor 18 and an electrode 19, both of which are coupled to the distal end of the catheter 17 at their respective known positions.

[0028] In some embodiments, the position sensor 18 is configured to generate one or more position signals indicating one or more respective positions of the distal end of the catheter 17 inside the heart 26.

[0029] In some embodiments, the electrode 19 includes a sensing electrode, which is configured to sense an electrocardiogram (ECG) signal at one or more positions where the distal end of the catheter 17 accesses within the heart 27. In other embodiments, the electrode 19 includes an ablation electrode configured to apply an ablation signal to the tissue at a defined position within the heart 26.

[0030] In some embodiments, physician 30 navigates the distal end assembly 40 of catheter 21, and separately the distal end of catheter 17, to respective target positions within the chamber 33 of the heart 26, by manipulating the shaft 22 using a manipulator 32 located near the proximal end of the catheter 21. Note that the chamber 33 is surrounded by tissue 35 and small holes of the vasculature connected to the chamber 33. In the embodiment of FIG. 1, physician 30 navigates the distal end assembly 40 and the distal end of catheter 17 into the chamber 33, such as the right atrium of the heart 26, and applies the UT of the 2D array 50 to generate a US image of the right atrium.

[0031] Now referring again to insertion diagrams 25 and 45. In some embodiments, physician 30 navigates the 2D array 50 within the chamber 33. In this embodiment, the 2D array 50 comprises 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 respective sections of the chamber 33 and the tissue 35. Note that based on the position signals received from the position sensor 52, the spatial coordinates of all pixels within the imaged section are known and are calibrated to generate a complete US image of the section in question. The number and arrangement of the UTs in the 2D array 50 are presented as examples, and note that in other embodiments, the 2D array 50 may comprise any other suitable number of UTs 53 arranged in any similar or different suitable configuration.

[0032] In the context of the present disclosure and the claims, the term "about" or "approximately" used with any numerical value or range indicates a suitable dimensional tolerance that enables a component or a set of components to function for its intended purpose as described herein.

[0033] Referring again to the overall view of FIG. 1, in some embodiments, the control console 24 includes a processor 39, typically a general-purpose computer, with suitable front-end and interface circuitry 38 for receiving signals from the catheter 21 and, optionally, for delivering therapy to tissue within the heart 26 via the catheter 21 and for controlling other components of the system 20. The console 24 also includes a driver circuit 34 configured to drive the magnetic field generator 36.

[0034] In some embodiments, during navigation of the distal end assembly 40 within the heart 26, the console 24 receives a position signal from the position sensor 52 in response to the magnetic field from the external magnetic field generator 36. Similarly, during navigation of the catheter 17 within the heart 26, the console 24 receives a position signal from the position sensor 18 in response to the magnetic field applied by the external magnetic field generator 36. In some embodiments, the magnetic field generator 36 is placed at a known location external to the patient 28, for example, under the table 29 on which the patient is lying. The position signal indicates the position and orientation of the 2D array 50 in a coordinate system of a position tracking system calibrated to the coordinate system of the system 20. In the context of the present disclosure and the claims, the terms “calibrated” and “aligned” and their grammatical variations are used interchangeably.

[0035] This method of position sensing using an external magnetic field has been implemented in various medical applications, for example, in the CARTO™ system manufactured by Biosense Webster, and is described in detail in U.S. Pat. Nos. 6,618,612, 6,332,089, International Publication No. WO 96 / 05768, and U.S. Patent Application Publication Nos. 2002 / 0065455, 2003 / 0120150, and 2004 / 0068178.

[0036] In some embodiments, the processor 39 is configured to operate the 2D array 50 by applying ultrasonic waves to respective sections of the heart 26 including at least the chamber 33 and the tissue 35, and sensing the US waves returning from the respective sections to image the chamber 33 (e.g., the right atrium) and / or the surrounding tissue (e.g., the tissue 35) of the heart 26. In one embodiment, the processor 39 is configured to display at least a portion of the imaged chamber 33 on the display 27 for the physician 30 as, for example, an ultrasonic image, referred to herein as the image 55, or using any other suitable presentation. Embodiments related to the image 55 are described in more detail in FIGS. 2A and 2B below.

[0037] In some embodiments, the processor 39 typically includes a general-purpose computer programmed in software to perform the functions described herein. The software can be downloaded to the computer in electronic form, for example, via a network, or alternatively or additionally, provided and / or stored on a non-transitory tangible medium such as magnetic memory, optical memory, or electronic memory.

[0038] The exemplary configuration shown in FIG. 1 is chosen by way of example to make the concepts easy to understand. The disclosed technology can be applied with the necessary modifications using other components and settings of the system 20. For example, the system 20 may include additional components and be configured to perform catheter procedures other than on the heart.

[0039] Visualization of Tissue and Chambers Using a 4D Ultrasound Catheter FIG. 2A is a schematic pictorial view of an ultrasonic image 55 generated using the system 20 of FIG. 1, according to an embodiment of the invention.

[0040] In some embodiments, physician 30 applies a distal end assembly 40, in this embodiment, a 4D ultrasound catheter configured to generate four-dimensional (4D) ultrasound data regarding tissue 35 and cavity 33. In the context of the present disclosure and the claims, the term "4D ultrasound" typically refers to one or more ultrasound transducers arranged in an array, which are configured to apply ultrasound (US) to an organ and generate one or more US signals indicative of three-dimensional (3D) features of each organ, and a processor 39 is configured to generate a US image based on the US signals. Each US image is a 2D image (of a slice of the organ in question), and it should be noted that the processor 39 is configured to generate a 3D US image by integrating the 2D slices into a volume image having 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 respective positions of the 2D array 50 as it is moved within the organ in question (e.g., cavity 33 and tissue 35 of the heart 26).

[0041] In this embodiment, physician 30 intends to perform an anatomical mapping of cavity 33 and tissue 35, for example, to treat an arrhythmia in the heart 26 by applying a radiofrequency (RF) ablation signal (e.g., a pulse) to a section of tissue (not shown) intended to be ablated, or for any other suitable medical use. It will be understood that RF ablation is just one of numerous therapeutic procedures for which US imaging may be useful. Pulse field ablation, also sometimes referred to as irreversible electroporation (IRE), is another exemplary therapeutic procedure for which US imaging is useful.

[0042] In some embodiments, during an RF ablation procedure, a catheter such as catheter 17 having one or more ablation electrodes (e.g., electrode 19) is inserted into the organ in question, and the ablation electrodes are placed in contact with the tissue intended to be ablated.

[0043] After obtaining sufficient contact force between each ablation electrode and the respective 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 an RF ablation procedure, it is important to create continuous lesions along the entire section of the tissue intended to be ablated. In some cases, the topography on the surface of the section can cause insufficient contact between one or more of the ablation electrodes and the tissue intended to be ablated. Therefore, it is important to select the appropriate position of the ablation electrodes when performing an RF ablation procedure.

[0044] In this embodiment, the organ in question is the chamber 33 and tissue 35 of the heart 26. In some embodiments, prior to performing the ablation procedure, physician 30 inserts (i) the distal end of catheter 17 for performing anatomical mapping, and (ii) distal end assembly 40 into chamber 33 and uses 2D array 50 to apply US waves and generate one or more US signals indicating the morphology (e.g., shape and surface topography) of at least a selected section of chamber 33 as well as tissue 35.

[0045] In some embodiments, the US signals are generated by using 2D array 50 to apply a 3D wedge (not shown) acquisition mode that enables simultaneous acquisition of ultrasonic images of selected sections of chamber 33 and tissue 35. As described in FIG. 1 above, 2D array 50 can comprise approximately 2048 UT53s arranged in an array of approximately 64 columns and approximately 32 rows, or any other suitable configuration.

[0046] In some embodiments, 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 each accessed 3D position, 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.

[0047] In some embodiments, based on position signals from position sensor 52, processor 39 is configured to record the 3D position of a 4D US catheter (e.g., distal end assembly 40) while physician 30 moves the 4D US catheter within lumen 33 and to acquire US signals using 2D array 50.

[0048] In some embodiments, based on the position signals from position sensors 18 and 52, the known dimensions of the distal end assemblies of catheters 21 and 17, and the US signals, processor 39 is configured to calibrate between the coordinate system of position sensor 52 and the coordinate system of 2D array 50 and identify the accessed 3D position as a position within chamber 33. Note that since catheters 17 and 21 cannot penetrate tissue 33, all 3D positions accessed by the distal end assemblies of catheters 17 and 21 must be within chamber 33. Thereafter, processor 39 is configured to generate US image 55. Based on the 3D positions, the known dimensions of the respective distal ends, and the ultrasonic signals, processor 39 is configured to identify voxels within US image 55 of heart 26 corresponding to additional 3D positions and associate these voxels with tissue 33. In other words, based on the known accessed positions and geometric dimensions, the distal ends and shafts of the catheters can be used as erasing tools to erase all gray areas that are not part of the atrioventricular wall. Processor 39 is further configured to display one or more US images 55 such that distal end assembly 40, and, if applicable, the distal end of catheter 17, are positioned within the field of view of US image 55. Thus, physician 30 can view the US image at the position currently accessed by distal end assembly 40 and the distal end of catheter 17.

[0049] In some embodiments, based on the US signals of 2D array 50, the known dimensions of the distal ends of catheters 17 and 21, and the corresponding position signals of position sensors 18 and 52, processor 39 is configured to visualize the shape of chamber 33 and the surface of a selected section of tissue 35. In particular, the method of applying US signals and position sensors to generate ultrasound-based anatomical images is described in the applicant's additional patent applications, for example, U.S. Patent Application Nos. 17 / 357,231 and 17 / 357,303.

[0050] In some embodiments, the processor 39 is configured to generate an image 55 that shows the shape of at least a section of the cavity 33 and the topography and shape of each section of the tissue 33. As described in FIG. 1 above, the processor 39 is configured to display the wedge-shaped image 55 on the display 27 to the physician 30.

[0051] In some embodiments, the image 55 includes one or more pixels, in this embodiment volume pixels (voxels) 77, that represent an image of the cavity 33. In this embodiment, 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., maximum expansion of the right atrium). Note that when the 2D array 50 applies the US wave, there is little US wave returning from the cavity 33 to the US sensor of the 2D array 50. Thus, the processor 39 typically assigns black to the pixel 77. In the embodiment of FIG. 2A, since the black pixels may not appear as a grid of pixels, the pixel 77 is shown in white merely for clarity when presenting embodiments of the present invention.

[0052] In some embodiments, the image 55 includes one or more pixels 66 that represent an image of the tissue 35. In this embodiment, a portion of the applied US wave is returned from the tissue 35 to the 2D array 50 (e.g., more than from the cavity 33), and thus a second, different color (e.g., gray) is assigned to the pixel 66. The image 55 further includes a line 37 (shown in bold for conceptual clarity) that represents the shape of the surface of the tissue 35, and this line 37 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 wave to the 2D array 50 than the tissue 35, the line 37 can appear in light gray or white.

[0053] In some embodiments, pixels 66 and 77 (and any other pixels of image 55) may each comprise 2D pixels or volume pixels (voxels) used to image the volumes of tissue 35 and lumen 33, respectively.

[0054] In some embodiments, processor 39 is configured to gate the visualization of sections of lumen 33 and tissue 35 to an appropriate phase of the cardiac cycle of the beating heart 26, e.g., a cardiac phase in which the heart 26 is fully dilated or fully contracted. Gating is essential to provide the physician 30 with the most accurate shape and surface topography of lumen 33 and tissue 35 without generating imaging artifacts associated with different stages of cardiac contraction of the heart 26.

[0055] In some embodiments, processor 39 is configured to generate image 55 as the physician 30 moves the distal end assembly 40 (and the distal end of catheter 17) within lumen 33. In some cases, the color assigned to one or more of pixels 66 and 77 may be incorrect, e.g., due to the presence of solid particles (e.g., fat or blood clots) in blood or another substance, or due to the systolic phase of the heart 26. In an example of image 55, gray is incorrectly assigned to pixels 77a, 77b of lumen 33 and white is incorrectly assigned to pixel 66a of tissue 35.

[0056] Improvement in Quality of Ultrasonic Images Based on Position Signals Received from Position Sensors FIG. 2B is a schematic pictorial diagram of an ultrasonic image 55a generated using system 20 in accordance with an embodiment of the present invention and having improved quality as compared to image 55 of FIG. 2A above.

[0057] In some embodiments, based on position signals from position sensors 19 and 52, processor 39 records the 3D positions of the distal end of catheter 17 and the 4D US catheter (e.g., distal end assembly 40) as the physician 30 moves catheter 17 and the 4D US catheter within lumen 33 and is configured to acquire US signals using 2D array 50.

[0058] Based on the technique described in FIG. 2A above, based on the position signals received from position sensors 19 and 52, the known physical dimensions of the distal ends of catheters 17 and 21, and the US signals acquired by 2D array 50, processor 39 is configured to calibrate between the coordinate systems of position sensors 19 and 52 and 2D array 50. Thereafter, processor 39 is configured to generate images 55 and 55a of FIGS. 2A and 2B, respectively. Based on the calibration, processor 39 is configured to display US image 55a such that distal end assembly 40 (and, when applicable, also the distal end of catheter 17) is positioned within the field of view of US image 55a.

[0059] In some embodiments, based on the fact that the distal end assembly 40 and the distal end of catheter 17 cannot puncture (e.g., cut) the tissue 35 of the heart 26 (or any other tissue), processor 39 is configured to assign white to all voxels corresponding to the position signals received from position sensors 19 and 52. In other words, any position within the heart 26 accessed by the distal end assembly 40 and the distal end of catheter 17 is considered a cavity (since distal end assembly 40 cannot pass through tissue 35). Thus, processor 39 is configured to classify all voxels corresponding to the accessed positions as cavity voxels and assign white to each of these voxels. The color assignment is used to tag each voxel so that physician 30 can immediately see on US image 55a (and on US image 55 of FIG. 2A above) whether the position of each voxel corresponds to tissue 35 or cavity 33. In the context of the present disclosure and the claims, the terms "tag" and "display as a voxel" and their grammatical variations are used interchangeably and refer to presenting one or more voxels on each US map, e.g., on display 27.

[0060] Similarly, in some cases, the physician 30 may not be able to position the distal end assembly 40 at a location having one or more voxels classified as lumen voxels (i.e., indicating lumen 33). In some embodiments, the processor 39 is configured to reclassify at least one of these one or more voxels as tissue voxels and tag them by assigning gray to each of the one or more voxels.

[0061] In the context of the present disclosure, the terms "lumen pixel" and "lumen voxel" refer to a pixel and a voxel, respectively, whose position corresponds to the position of a lumen (e.g., lumen 33) of the heart 26. Similarly, the terms "tissue pixel" and "tissue voxel" refer to a pixel and a voxel, respectively, whose position corresponds to the position of tissue (e.g., tissue 35) of the heart 26.

[0062] In the embodiment of FIG. 2B, the physician 30 moves the distal end of the distal end assembly 40 and / or the catheter 17 to a position corresponding, among other things, to pixels 77a and 77b. In some embodiments, in response to (i) identifying that pixels 77a and 77b correspond to the previously accessed positions, and (ii) identifying the gray assigned to pixels 77a and 77b (as shown in FIG. 2A above), the processor 39 is configured to reclassify pixels 77a and 77b as lumen pixels and assign white to both pixels 77a and 77b (instead of the gray shown in image 55 above).

[0063] In some embodiments, in response to (i) identifying that pixel 66a corresponds to a position that cannot be accessed by the distal end of the distal end assembly 40 and / or the catheter 17, and (ii) identifying that white is assigned to pixel 66a (as shown in FIG. 2A above), the processor 39 is configured to reclassify pixel 66a as a tissue pixel and assign gray to pixel 66a.

[0064] In such an embodiment, based on one or more positions received from position sensors 19 and 52, processor 39 is configured to reclassify one or more pixels or voxels on image 55 and generate an image 55a having different colors assigned to the reclassified pixels. In other words, in response to receiving position signals accessed by distal end assembly 40 and / or the distal end of catheter 17, and identifying that a given pixel within the image corresponds to the accessed position, processor 39 is configured to display the given pixel as a lumen pixel on display 27. Similarly, processor 39 may identify additional positions that (the distal end of distal end assembly 40 and / or catheter 17) cannot access as tissue, classify one or more pixels corresponding to the additional positions as tissue pixels, and display the classified pixels as tissue pixels having the gray color assigned thereto.

[0065] Images 55 and 55a of FIGS. 2A and 2B are shown as examples and are simplified for clarity. For example, images 55 and 55a each include approximately 200 pixels, although a typical ultrasound image may include millions of pixels. Thus, at least one of pixels 66, 66a, 77, 77a, and 77b, typically each of them, includes any suitable number of pixels, such as approximately 10,000 pixels. Further, processor 39 is configured to reclassify and change the color for a single pixel or group of pixels located at any position in FIGS. 2A and / or 2B. Further, processor 39 is configured to display pixels or voxels within images 55 and 55a on display 27.

[0066] In other embodiments, each pixel or voxel of image 55 and / or 55a may contain more than a lumen pixel or a tissue pixel. For example, if an organ contains several types of tissue having different characteristics from one another, each tissue type may have a different classification. In such embodiments, processor 39 is configured to classify each pixel according to the US signals received from the 2D array and based on the position of each pixel or voxel using the embodiments described above with reference to FIGS. 2A and 2B. Further, processor 39 is configured to assign a different color to each pixel corresponding to a different tissue type.

[0067] In an alternative embodiment, instead of or in addition to assigning a color code according to the classification of each pixel, processor 39 is configured to display the pixels or voxels using any other technique that visually differentiates between different classes of pixels. For example, different textures and / or different icons are assigned to one or more pixels having common or different characteristics such as tissue pixels and lumen pixels.

[0068] In some embodiments, when the physician 30 moves the distal end assembly 40 within the lumen 33 between a first position 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 respectively indicating the first position and the second position, and (ii) a first US signal and a second US signal respectively indicating the lumen 33 and / or the tissue 35 at the first position and the second position. In some embodiments, based on the first position signal and the second position signal and the corresponding US signals, the processor 39 is configured to present on the display 27 at least a first US image and a second US image of the first position and the second position respectively. In some embodiments, a pixel includes a voxel, and the processor 39 is configured to present a 3D ultrasound image. Further, the processor 39 is configured to present, for example, on the display 27, a video clip including at least a first 3D ultrasound image and a second 3D US image, and typically, the video clip includes US imaging of at least the lumen 33 and / or the tissue 35 located between the first position and the second position.

[0069] Improvement in the quality of 4D ultrasound images displayed to the user FIG. 3 is a flowchart generally showing a method for improving the quality of the ultrasound image 55 displayed to the physician 30 according to an embodiment of the present invention.

[0070] The method begins with a catheter insertion step 100, where a plurality of catheters are inserted into the right atrium of the heart 26. In this embodiment, the distal end assembly 40 and the distal end of the catheter 17 are inserted into the right atrium of the heart 26. Note that the geometric shapes (i.e., physical dimensions) of the distal ends of both catheters are known and stored within the system 20, for example, within the processor 39. For example, as described in FIG. 1 above, the distal end of the catheter 17 comprises a magnetic position sensor 18 and an electrode 19, and the distal end assembly 40 comprises a 2D array 50 of UTs and a position sensor 52. In some embodiments, the 2D array 50 is configured to (i) apply US waves to the tissue in question (e.g., tissue 35) and (ii) generate a US signal indicative of the surface topography of the heart tissue in question. The position sensors 18 and 52 are configured to generate position signals indicative of the respective positions of the distal end of the catheter 17 and the distal end assembly 40 within the right atrium of the heart 26 (i.e., the chamber 33).

[0071] In some embodiments, the processor 39 is configured to calibrate between the coordinate system of the 2D array 50 and the coordinate system of the position sensor 52. Calibration is typically performed prior to catheter insertion (e.g., during the manufacturing and / or certification process of the catheters 17 and 21) to shorten the time of the diagnostic procedure, but note that in other embodiments, calibration or its verification can be performed after insertion of the distal end of the catheter 17 and / or the distal end assembly 40 into the chamber 33.

[0072] In an ultrasonic application step 102, while the physician is moving the distal end assembly 40 within the chamber 33, the processor 39 controls the 2D array 50 to apply US waves to the tissue 35 and / or the chamber 33. In some embodiments, the processor 39 receives a US signal (from the 2D array 50) and a position signal (from the position sensor 52), as described in detail in FIGS. 1, 2A, and 2B above.

[0073] In the first visualization step 104, based on the received US signal, the known geometric shapes 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 in detail in FIG. 2A above. It should be noted that each pixel may include a 2D pixel or a volume pixel (voxel), and can be classified and tagged as a tissue voxel (or pixel) or a lumen voxel (or pixel) in US image 55. Further, in the context of the present disclosure and the claims, the term "pixel" may refer to a 2D pixel or a volume (3D) pixel, i.e., a voxel.

[0074] In pixel verification step 106, based on the position signals received from position sensors 18 and 52, processor 39 is configured to identify at least a given pixel in US image 55 corresponding to a given position within lumen 33 accessed by the distal end of catheter 17 and / or by distal end assembly 40 while sensing the ECG signal and / or while acquiring the US signal.

[0075] In the first determination step 108, processor 39 is configured to check whether a given pixel is classified and tagged as a lumen pixel.

[0076] If a given pixel (e.g., pixel 77) of US image 55 is tagged as a lumen pixel, the method loops back to step 106, and processor 39 checks another pixel of US image 55 and, in step 108, processor 39 checks whether the other pixel is classified and tagged as a lumen pixel.

[0077] If a given pixel of the US image 55 (e.g., pixel 77a) is tagged as a tissue pixel, the method proceeds to the tagging step 110. In some embodiments, at step 110, the processor 39 verifies that the position signals received from one or both of the position sensors 18 and 52 correspond to the position of pixel 77a, which 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 embodiments, at step 110, in response to the verification, the processor 39 reclassifies pixel 77a as a lumen pixel and is configured to change the tagging of pixel 77a from a tissue pixel to a lumen pixel, as detailed and described in FIG. 2B above.

[0078] In other embodiments, the processor 39 is configured to apply steps 106 - 110 with the necessary modifications to positions that the distal end assembly 40 cannot access. For example, the processor 39 is configured to check whether the distal end of the catheter 17 and / or the distal end assembly 40 has accessed a position corresponding to pixel 66a. If the distal end of the catheter 17 and / or the distal end assembly 40 has not accessed and / or cannot access a position corresponding to pixel 66a, the processor 39 reclassifies pixel 66a as a tissue pixel and is configured to change the tagging of pixel 66a from a lumen pixel to a tissue pixel, as detailed and described in FIG. 2B above. Note that the same technique is applied to pixel 77b as detailed in FIG. 2B above.

[0079] In a second decision step 112, the processor 39 checks whether additional pixels of the US image (e.g., image 55) need to be checked. If there are additional pixels that need to be checked, the method loops back to step 106.

[0080] If additional pixels of the US image 55 do not need to be checked, the method proceeds to a second visualization step 114 that ends the method. In step 114, the processor 39 is configured to display the corrected image 55a with the tagging of pixels 66a, 77a, and 77b to the physician 30, for example, on the display 27, using the techniques described in FIG. 2B and steps 106-110 above.

[0081] The method of FIG. 3 is intended to improve the quality of the US image displayed to the physician 30 and can be performed during mapping of the heart 26 (or any other organ) and during therapeutic medical procedures such as during a tissue ablation procedure. Note that as long as the position signal is recorded, the processor 39 can reclassify and retag the pixels of the US image at any appropriate time, for example, even offline.

[0082] Furthermore, the method of FIG. 3 is simplified for clarity and typically includes additional steps essential to performing visualization of the heart or any other appropriate organ of interest.

Example

[0083] The 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 at least an ultrasonic (US) signal of the cavity (33) and the tissue (35) and one or more position signals within the organ (26) indicating one or more positions of one or more catheters (22, 17) having a known geometric shape, respectively; (2) based on the one or more position signals, the known geometric shape, and the US signal, (i) identify a given pixel (77a) at a given position within 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 one or more positions, or (b) a second pixel indicating the tissue (35).

Example

[0084] The system according to Example 1, wherein the plurality of pixels, the given pixel, and the first and second pixels include volume pixels (voxels).

Example

[0085] The system according to Example 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.

Example

[0086] The system according to Example 1, wherein in response to identifying that a distal end of one of the catheters does not reach an additional position, the processor is configured to identify an additional pixel corresponding to the additional position and assign a second color to the additional pixel.

Example

[0087] One or more catheters include one or both of (i) a mapping catheter configured to sense electrical signals within tissue and (ii) an ablation catheter configured to apply an ablation signal to tissue, the system of Example 1.

Example

[0088] At least one of the catheters includes a distal end, the distal end having a known geometric shape and including an ultrasonic transducer (UT) configured to apply US waves to an organ and generate a US signal at each respective position of the distal end, the system of any one of Examples 1-5.

Example

[0089] The catheter includes a four-dimensional (4D) ultrasonic catheter, the UT being arranged in a two-dimensional (2D) array at the distal end, and the position sensor being coupled to the distal end at a known position relative to the 2D array, the system of Example 6.

Example

[0090] 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 a given pixel in the image based on the calibrated first and second coordinate systems, the system of Example 7.

Example

[0091] When the distal end is moved within the cavity between a first position and a second position different from the first position, the processor receives (i) a first position signal and a second position signal respectively indicating the first position and the second position, and (ii) a first US signal and a second US signal respectively indicating the cavity at the first position and the second position, and is configured to present on a display at least a first US image and a second US image of the first position and the second position respectively based on the first position signal and the second position signal, and the first US signal and the second US signal, the system described in Example 6.

Example

[0092] The first US image and the second US image respectively include a first three-dimensional (3D) US image and a second 3D US image, the system described in Example 9.

Example

[0093] The method includes displaying a plurality of pixels (66, 66a, 77, 77a, 77b) of images (55, 55a) of an organ (26) having a cavity (33) and tissue (35) surrounding the cavity (33). At least an ultrasonic (US) signal of the cavity (33) and the tissue (35) and one or more position signals within the organ (26) indicating one or more positions of one or more catheters (22, 17) having a known geometric shape are respectively received. Based on the one or more position signals, the known geometric shape, and the US signal, (i) a given pixel (77a) is identified at a given position within the image (55, 55a), and (ii) the given pixel (77a) is displayed as a first pixel indicating the cavity (33) in response to identifying that the given position corresponds to one or more positions, or as a second pixel indicating the tissue (35).

[0094] The embodiments described herein mainly address electroanatomical mapping, tissue ablation, and 4D US imaging of a patient's heart, but the methods and systems described herein can also be used in other patient organs and / or other applications.

[0095] Accordingly, the above-described embodiments are cited by way of example, and it will be understood that the present invention is not particularly shown and is not limited to what has been described above. Rather, the scope of the present invention includes both various combinations and sub-combinations of the features described in the above specification, as well as those variations and modifications thereof that are not disclosed in the prior art and would be contemplated by those skilled in the art upon reading the foregoing description.

[0096] [Embodiment] (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; a processor, wherein the processor receives at least an ultrasonic (US) signal of the cavity and the tissue and one or more position signals within the organ indicating one or more positions of one or more catheters having a known geometric shape; and based on the one or more position signals, the known geometric shape, and the US signal, (i) identifies a given pixel at a given position in the image, and (ii) configures the given pixel to be displayed as (a) a first pixel indicating the cavity in response to identifying that the given position corresponds to the one or more positions, or (b) a second pixel indicating the tissue. (2) The system according to embodiment 1, wherein the plurality of pixels, the given pixel, and the first and second pixels include volume pixels (voxels). (3) The system according to 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. (4) In response to identifying that a distal end of one of the catheters does not reach an additional position, the processor is configured to identify an additional pixel corresponding to the additional position and assign the second color to the additional pixel, the system according to Embodiment 3. (5) The one or more catheters include one or both of (i) a mapping catheter configured to sense electrical signals within the tissue and (ii) an ablation catheter configured to apply an ablation signal to the tissue, the system according to Embodiment 1.

[0097] (6) At least one of the catheters has a distal end, the distal end has the known geometric shape, and includes an ultrasonic transducer (UT) configured to apply US waves to the organ and generate the US signal at each position of the distal end, the system according to Embodiment 1. (7) The catheter includes a four-dimensional (4D) ultrasonic catheter, the UT is arranged in a two-dimensional (2D) array at the distal end, and the position sensor is coupled to the distal end at a known position with respect to the 2D array, the system according to Embodiment 6. (8) 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 the second coordinate system, the system according to Embodiment 7. (9) When the distal end is moved within the cavity between a first position and a second position different from the first position, the processor: (i) receives a first position signal and a second position signal respectively indicating the first position and the second position; and (ii) receives a first US signal and a second US signal respectively indicating the cavity at the first position and the second position. Based on the first position signal, the second position signal, the first US signal, and the second US signal, the processor 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. The system according to embodiment 6. (10) The system according to embodiment 9, wherein the first US image and the second US image each include a first three-dimensional (3D) US image and a second 3D US image.

[0098] (11) A method comprising: displaying a plurality of pixels of an image of an organ having a cavity and tissue surrounding the cavity; receiving at least an ultrasonic (US) signal of the cavity and the tissue, and one or more position signals within the organ indicating one or more positions of one or more catheters having a known geometric shape; Based on the one or more position signals, the known geometric shape, and the US signal: (i) identifying a given pixel at a given position within the image; and (ii) displaying the given pixel as a first pixel indicating the cavity or a second pixel indicating the tissue in response to identifying that the given position corresponds to the one or more positions. A method. (12) The method according to embodiment 11, wherein the plurality of pixels, the given pixel, and the first pixel and the second pixel include volume pixels (voxels). (13) The method according to embodiment 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) In response to identifying that the distal end does not reach an additional position, the processor is configured to identify an additional pixel corresponding to the additional position and assign the second color to the additional pixel, the method according to embodiment 13. (15) The one or more catheters include one or both of (i) a mapping catheter configured to sense an electrical signal within the tissue and (ii) an ablation catheter configured to apply an ablation signal to the tissue, the method according to embodiment 11.

[0099] (16) At least one of the catheters has a distal end, the distal end having the known geometric shape and comprising an ultrasonic transducer (UT) for applying US waves to the organ and generating the US signal at each position of the distal end, the method according to embodiment 11. (17) The catheter includes a four-dimensional (4D) ultrasonic catheter, the UT being arranged in a two-dimensional (2D) array at the distal end, and the position sensor being coupled to the distal end at a known position with respect to the 2D array, the method according to embodiment 16. (18) 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 coordinate system and the second coordinate system, the method according to embodiment 17. (19) When the distal end is moved within the cavity between a first position and a second position different from the first position, receiving (i) a first position signal and a second position signal respectively indicating the first position and the second position, and (ii) a first US signal and a second US signal respectively indicating the cavity at the first position and the second position, and presenting on a display at least a first US image and a second US image of the first position and the second position respectively based on the first position signal and the second position signal, and the first US signal and the second US signal, the method according to embodiment 16. (20) The method according to embodiment 19, wherein the first US image and the second US image each include a first three-dimensional (3D) US image and a second 3D US image.

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, wherein the processor: receives at least an ultrasonic (US) signal of the cavity and the tissue, and one or more position signals within the organ indicating one or more positions of one or more catheters having a known geometric shape; based on the one or more position signals, the known geometric shape, and the US signal, (i) identifies a given pixel at a given position in the image, and (ii) configures the given pixel to be displayed as (a) a first pixel indicating the cavity in response to identifying that the given position corresponds to the one or more positions, or (b) a second pixel indicating the tissue, the system.

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

3. The system of claim 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.

4. In response to identifying that a distal end of one of the catheters does not reach an additional position, the processor is configured to identify an additional pixel corresponding to the additional position and assign the second color to the additional pixel, the system of claim 3.

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

6. The system of claim 1, wherein at least one of the catheters has a distal end, the distal end has the known geometric shape, and includes an ultrasonic transducer (UT) configured to apply US waves to the organ and generate the US signal at each respective position of the distal end.

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

8. 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 based on the calibrated first coordinate system and the second coordinate system, identify the given pixel in the image. The system according to claim 7.

9. When the distal end is moved within the cavity between a first position and a second position different from the first position, the processor (i) receives a first position signal and a second position signal respectively indicating the first position and the second position, and (ii) a first US signal and a second US signal respectively indicating the cavity at the first position and the second position, and based on the first position signal and the second position signal, and the first US signal and the second US signal, at least a first US image and a second US image of the first position and the second position are respectively presented on the display. The system according to claim 6.

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

11. A method comprising: displaying a plurality of pixels of an image of an organ having a cavity and tissue surrounding the cavity; receiving at least the ultrasonic (US) signals of the cavity and the tissue and one or more position signals within the organ indicating one or more positions of one or more catheters having a known geometric shape; based on the one or more position signals, the known geometric shape, and the US signals, (i) identifying a given pixel at a given position in the image, and (ii) displaying the given pixel as (a) a first pixel indicating the cavity in response to identifying that the given position corresponds to the one or more positions, or (b) a second pixel indicating the tissue. A method.

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

13. The method of 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. In response to identifying that the distal end does not reach an additional position, the processor is configured to identify an additional pixel corresponding to the additional position and assign the second color to the additional pixel, the method of claim 13.

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

16. At least one of the catheters has a distal end, the distal end having the known geometric shape and comprising an ultrasonic transducer (UT) for applying US waves to the organ and generating the US signal at each position of the distal end, the method of claim 11.

17. The method of claim 16, wherein the catheter includes a four-dimensional (4D) ultrasonic catheter, the UT is arranged in a two-dimensional (2D) array at the distal end, and the position sensor is coupled to the distal end at a known position relative to the 2D array.

18. The method of claim 17, including 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. When the distal end is moved within the cavity between a first position and a second position different from the first position, (i) a first position signal and a second position signal respectively indicating the first position and the second position, and (ii) a first US signal and a second US signal respectively indicating the cavity at the first position and the second position are received, and based on the first position signal and the second position signal, and the first US signal and the second US signal, at least a first US image and a second US image of the first position and the second position are respectively presented on a display. The method according to claim 16.

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

Images