Patent Publication Number: US-11647966-B2

Title: Flattened organ display

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 16/443,531, filed on Jun. 17, 2019, which is a continuation of U.S. patent application Ser. No. 15/388,029, filed on Dec. 22, 2016, the contents of which are incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to medical ablation procedures, and particularly to the display of a medical ablation procedure. 
     BACKGROUND 
     Catheter ablation is a minimally invasive procedure used to remove or terminate a faulty electrical pathway from sections of the heart of a patient who is prone to developing cardiac arrhythmias. 
     U.S. Patent Application 2013/0123598 describes an MRI-compatible catheter, which includes an elongated flexible shaft having opposite distal and proximal end portions. A handle is attached to the proximal end portion and includes an actuator in communication with the shaft distal end portion that is configured to articulate the shaft distal end portion. The distal end portion of the shaft may include an ablation tip and includes at least one RF tracking coil positioned adjacent the ablation tip that is electrically connected to an MRI scanner. The at least one RF tracking coil is electrically connected to a circuit that reduces coupling when the at least one RF tracking coil is exposed to an MRI environment. Each RF tracking coil is a 1-10 turn solenoid coil, and has a length along the longitudinal direction of the catheter of between about 0.25 mm and about 4 mm. 
     U.S. Patent Application 2012/0189178 describes a method and an apparatus for automatically generating an optimal 2-dimensional (2D) medical image from a 3D medical image, at least one virtual plane crossing a 3D volume is generated from 3D volume image data for showing part of a patient&#39;s body in a 3D manner, at least one 2D image representing a cross section of the part of the patient&#39;s body is generated by applying the 3D volume image data to the virtual plane, and a 2D image suitable for diagnosis of the patient having a feature most similar to a target feature from among the at least one 2D image is output. 
     U.S. Pat. No. 8,135,185 describes a method of finding the location of an occluded portion of a blood vessel relative to a three-dimensional angiographic image of a subject&#39;s vasculature includes identifying the location of the occluded portion of the blood vessel on each of a series of displayed two dimensional images derived from the three dimensional image data in planes substantially transverse to direction of the occluded portion of the vessel. The identified locations in the occluded portion of the vessel can then be used to determine the path of the occluded portion of the vessel. 
     U.S. Pat. No. 7,961,924 describes a method and system for determining the three-dimensional location and orientation of a medical device distal end using a single-plane imaging system, using a computational model of the medical device and a transfer function for the medical device describing local device shape and orientation in response to user or computer determined inputs. The method allows guidance of an interventional medical system to a set of target points within the patient using a single-projection imaging system. 
     SUMMARY 
     Embodiments of the present invention that are described hereinbelow provide a method for viewing a lumen of a patient. 
     There is therefore provided, in accordance with an embodiment of the present invention, a method for data display, including acquiring a three-dimensional (3D) map of a lumen inside a body of a subject, transforming the 3D map of the lumen into a two-dimensional (2D) image by projecting the 3D map onto an annulus, and presenting the 2D image on a display screen. 
     In a disclosed embodiment, presenting the 2D image includes presenting a stationary 2D image. 
     In some embodiments a 3D image of the 3D map and the stationary 2D image are simultaneously presented on adjacent parts of the display screen. Additionally or alternatively, the 2D image may be kept stationary while manipulating the 3D image. 
     In a disclosed embodiment acquiring the 3D map includes acquiring a 3D map of a lumen undergoing an ablation procedure, wherein the ablation procedure may include ablating a pulmonary vein of a heart. Additionally or alternatively, the method includes calculating a path for the ablation procedure for a given starting point on the pulmonary vein, and displaying an image of the path on a 3D image of the 3D map and on the 2D image. 
     In some embodiments a calculated location and an extent of an ablation lesion are displayed on a 3D image of the 3D map and on the 2D image. Additionally or alternatively, a recommended starting point for a further ablation is calculated based on at least one of the calculated location and the extent of the ablation lesion, and the method includes displaying the recommended starting point as a mark on the 3D image and on the 2D image. 
     In a further embodiment a completion of the ablation procedure is determined in response to presenting an image of a contiguous closed lesion on the 2D image. 
     There is also provided, in accordance with an embodiment of the present invention, an apparatus for displaying data, including a display screen and a processor which is configured to acquire a 3D map of a lumen inside a body of a subject, transform the 3D map of the lumen into a 2D image by projecting the 3D map onto an annulus and present the 2D image on the display screen. 
     In another embodiment the 2D image is stationary. 
     In yet another embodiment the processor is configured to present a 3D image of the 3D map and the 2D image simultaneously on adjacent parts of the display screen. Additionally or alternatively, the processor is configured to keep the 2D image stationary while manipulating the 3D image. 
     In still other embodiments the 3D map includes a 3D map of a lumen undergoing an ablation procedure, and the ablation procedure may include ablating a pulmonary vein of a heart. Additionally or alternatively, the processor is configured to calculate a path for the ablation procedure for a given starting point on the pulmonary vein, and to display an image of the path on a 3D image of the 3D map and on the 2D image. 
     In another embodiment the processor is configured to display a calculated location and an extent of an ablation lesion on a 3D image of the 3D map and on the 2D image. Additionally or alternatively, the processor is configured to calculate a recommended starting point for a further ablation based on at least one of the calculated location and the extent of the ablation lesion, and to display the recommended starting point as a mark on the 3D image and on the 2D image. 
     In an embodiment the processor is configured to determine a completion of the ablation procedure in response to presenting an image of a continuous closed lesion on the 2D image. 
     The present invention will be more fully understood from the following detailed description of the embodiments thereof, taken together with the drawings in which: 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a schematic illustration of an ablation procedure of a pulmonary vein, according to an embodiment of the present invention; and 
         FIGS.  2 - 8    show a display screen as seen by a surgeon during an ablation procedure of a pulmonary vein of a subject, in accordance with an embodiment of the invention. 
     
    
    
     OVERVIEW 
     One of the problems during a catheter ablation procedure, such as ablation of the pulmonary vein, is visualization of the procedure. Typically, the pulmonary vein is presented as a three-dimensional (3D) image, and as a surgeon performs the ablation he/she re-positions and/or rotates and/or changes the magnification of the image to observe the progress of the procedure. Surgeons using this method for tracking the procedure have found the use and manipulation of a 3D image, typically while ablating, both complicated and difficult to execute efficiently. 
     An embodiment of the present invention solves this problem by acquiring a 3D map of a lumen, such as the pulmonary vein, that is inside a body of a subject. The 3D map is transformed into a two-dimensional (2D) image by projecting the 3D map onto an annulus, and the 2D image is presented to the surgeon on a display screen. 
     Using this method, the surgeon is able to view and manipulate a 3D image of a region of an ablation, as described above, while being simultaneously presented with a stationary two-dimensional (2D) image of the region. 
     In one embodiment, in the ablation of a pulmonary vein, the region of ablation comprises a cylindrical structure. A processor acquiring the 3D image transforms this cylindrical structure into a 2D annulus, with the two edges of the cylindrical structure transformed into the inner and outer circumferences of the annulus, and the area of the cylindrical structure transformed into the area of the annulus. The display screen that the surgeon observes during the ablation procedure, is divided into two areas: The manipulable 3D image of the region of ablation, together with other parts of the heart, is displayed in one area of the display screen, whereas the stationary 2D annulus is displayed in the other area. 
     In another embodiment, once the surgeon has determined the starting point of the ablation, the processor calculates, based on this starting point and on the known geometry of the pulmonary vein, a recommended path for the ablation procedure. This path is marked both in the 3D image and in the 2D annulus in order to guide the surgeon. The recommended path is a path around the pulmonary vein, such that, when the ablation procedure has been completed, a heartbeat activation wave will be blocked. 
     In yet another embodiment, while an ablation lesion is growing during the procedure, the processor calculates the locations where the surgeon should start the next ablation lesion in order to ensure the elimination of any gaps between the ablation lesions. There will usually be two such locations, one on either side of the existing ablation lesions. These locations are marked on both the 3D image and the 2D annulus, and they are re-calculated and moved as the ablation lesions grow. 
     In a disclosed embodiment, the dimensions of any given ablation lesion is calculated by the processor, using measurements of force exerted by the tip of the catheter, the radio-frequency power emitted from the tip of the catheter, and the elapsed time for the lesion. In a successful ablation procedure, the surgeon sees a contiguous chain of calculated images of ablation lesions growing around the pulmonary vein, until a complete ring of ablation lesions has been formed. The visualization of both the progress and the completeness of the ring of calculated images of ablation lesions is greatly facilitated by the display of the 2D annulus, as the entire ablated region can be seen at once. 
     System Description 
       FIG.  1    is a schematic illustration of an invasive medical procedure using apparatus  12 , according to an embodiment of the present invention. The procedure is performed by a surgeon  14 , and, by way of example, the procedure in the description hereinbelow is assumed to comprise ablation of a portion of a pulmonary vein  16  of a heart  46  of a human patient  18 . However, it will be understood that embodiments of the present invention are not just applicable to this specific procedure, and may include substantially any procedure on biological tissue. 
     In order to perform the ablation, surgeon  14  inserts a probe  20 , typically a catheter, into a lumen of the patient, so that a distal end  22  of the probe enters pulmonary vein  16  of the patient. Distal end  22  comprises electrodes  24  mounted on the outside of the distal end, the electrodes contacting respective locations of pulmonary vein  16 . A proximal end  28  of probe  20  is coupled to a console  32  of apparatus  12 . 
     Apparatus  12  is controlled by a processor  30 , which is located in console  32 . Console  32  comprises controls  34  which are used by surgeon  14  to communicate with processor  30 . During the procedure, processor  30  typically tracks a location and an orientation of distal end  22  of the probe, using any method known in the art. For example, processor  30  may use a magnetic tracking method, wherein magnetic transmitters external to patient  18  generate signals in coils positioned in distal end  22 . The Carto® system produced by Biosense Webster, of Diamond Bar, Calif., uses such a tracking method. 
     The software for processor  30  may be downloaded to the processor in electronic form, over a network, for example. Alternatively or additionally, the software may be provided on non-transitory tangible media, such as optical, magnetic, or electronic storage media. Processor  30  is coupled to a display screen  36 , which is divided into a left display  38  and a right display  40 , as is detailed below. While for simplicity the description herein assumes that the screen is divided into a left and a right display, it will be understood that the scope of the present invention includes any other convenient method for screen division and image display, such as an upper and lower display, or a first screen and a separate second screen. 
     In order to operate apparatus  12 , processor  30  communicates with electronics  42 , which has a number of modules used by the processor to operate the apparatus. Thus, electronics  42  comprises modules such as an ablation module  43 , a force module  45  for measuring the force on distal end  22 , and a tracking module  47  for operating the tracking method used by processor  30 . The modules may comprise hardware as well as software elements. Proximal end  28  of probe  20 , coupled to console  32 , is further coupled to the modules of electronics  42 . 
     Processor  30  uses results of measurements from the modules, such as a force exerted by tip  44  of distal end  22 , a radio-frequency power emitted from the tip, an elapsed time of the ablation, and a location of the tip, to calculate and to display graphically the progress of the ablation procedure on display screen  36 , as is detailed below. 
       FIGS.  2 - 8    show, with reference to  FIG.  1   , display screen  36  as seen by surgeon  14  during an ablation procedure of pulmonary vein  16  of patient  18 , in accordance with embodiments of the invention. Left display  38  shows 3D images of pulmonary vein  16  and heart  46  of patient  18 , and right display  40  shows a 2D image of a selected portion of pulmonary vein  16 . As is described below, the 3D image in left display  38  is typically manipulable, while the 2D image in right display  40  is typically stationary. Corresponding items in left display  38  and right display  40  are labelled with the same number, with letter “L” and “R” indicating left and right display, respectively. Display screen  36  may display additional information relating to the ablation procedure, for example, an elapsed time, and a power dissipated by electrodes performing the ablation. For simplicity, such additional information is not presented in the figures. 
       FIG.  2    illustrates in left display  38  a 3D image  50  of heart  46  and a 3D image  52  of pulmonary vein  16  of heart  46 . A cylindrical region  54  of image  52  corresponds to the region of pulmonary vein  16  where surgeon  14  implements the ablation procedure. During the procedure, processor  30  projects cylindrical region  54  to a 2D annulus  56  in right display  40 , with an edge  58 , proximal to image  50 , of cylindrical region  54 , projected to an inner circumference  60  of annulus  56 , and an edge  62 , distal to image  50 , projected to an outer circumference  64  of annulus  56 . Surgeon  14  has positioned tip  44  of probe  20  to touch pulmonary vein  16 , with the position indicated in left display  38  by a fiducial  66 L, and in right display  40  by a fiducial  66 R. Fiducials  66 L and  66 R, and the other fiducials referred to hereinbelow, are typically presented on screen  36  as icons corresponding to tip  44 . 
       FIG.  3    illustrates display screen  36  after surgeon  14  has selected a starting point for tip  44  to begin ablation, but before initiating the ablation. Fiducials  68 L and  68 R indicate the selected starting point of the ablation in left display  38  and right display  40 , respectively. Once the starting point is selected, processor  30  calculates a recommended closed ablation path based on the starting point and the known 3D dimensions of pulmonary vein  16 . The recommended closed path is calculated based on criteria chosen by surgeon  14 , with the criteria being, for example, that the closed path is a shortest path around the pulmonary vein, or that the closed path is a fixed distance from the base of the pulmonary vein. The recommended closed path is displayed as regions  70 L and  70 R in left display  38  and right display  40 , respectively. Region  70 L is a band within image  54 , corresponding to a recommended path around pulmonary vein  16 , and region  70 R is a ring within annulus  56 . Within each of regions  70 L and  70 R there is marked a narrower ring  71 L and  71 R further assisting surgeon  14  in directing the ablation procedure. Ring  71 L and  71 R are optimal paths for the ablation, and the width of regions  70 L and  70 R are typically set by surgeon  14  based on the maximum distance he/she is willing to deviate from rings  71 L and  71 R. The recommended ablation path is a closed path around pulmonary vein  16 , such that, when the ablation procedure has been completed, a heartbeat activation wave is blocked. 
       FIG.  4    illustrates display screen  36  at the start of the ablation. Left display  38  and right display  40  show calculated ablation lesion images  72 L and  72 R for the first ablation growing, with reference to  FIG.  3   , from starting point fiducials  68 L and  68 R, respectively. On screen  36  images of different elements are typically differentiated by different colors. In the figures of the present application, images of different elements are differentiated by different types of shading. Thus, completed ablation lesion regions may be imaged as red on screen  36 , and are shown has cross-hatched in the figures. 
     The dimensions of lesion images  72 L and  72 R are calculated by processor  30 , using measurements of force exerted by tip  44 , radio-frequency power emitted from the tip, and elapsed ablation time. In addition, processor  30  calculates two next recommended ablation positions in regions  70 L and  70 R and shows them as marks  74 L and  76 L on left display  38  and as marks  74 R and  76 R on right display  40 . The next recommended ablation positions provide the surgeon with two optional starting positions for a subsequent ablation. In a disclosed embodiment these positions are calculated to be a fixed distance from the edge of outermost ablations. The fixed distance may be chosen by surgeon  14 . In one embodiment the fixed distance has a default value of 3 mm, but the distance may be smaller or larger than this value. 
     The next recommended positions depend on the location and size of the ablation lesion. Surgeon  14  may slide tip  44  along the pulmonary vein, and simultaneously ablate using the tip. Alternatively or additionally, the surgeon may keep the tip stationary while ablating. In either case, as the ablation lesion grows, the next recommended positions are re-calculated and “pushed out.” The images presented on screen  36  are generated in real-time, and surgeon  14  is aided by the real-time presentation of the lesion images  72 L and  72 R on the two displays. Surgeon  14  terminates the ablation based on his/her judgment and the images on screen  36 , but no later than when the ablation lesion images on screen  36  reach the edge of regions  70 L and  70 R. Both the real-time visualization of the ablation lesions and the indication of next ablation positions are applied continuously in the ablation procedure. 
     Referring back to  FIGS.  2  and  3   , it is apparent in left display  38  that surgeon  14  has rotated, using controls  34 , the 3D image as the ablation procedure progresses. However, during this rotation, processor  30  ensures that annulus  56  in right display  40  remains stationary, thus aiding surgeon  14  in an easy and fast observation of the progress of the ablation procedure. It is of great help for surgeon  14  to be able to rotate or otherwise manipulate the 3D image at will in left display  38 , while at the same time observing a fully stationary 2D image in right display  40 . 
       FIG.  5    illustrates display screen  36  at the completion of the first ablation lesion, displayed as lesion images  72 L and  72 R, and the start of a second ablation lesion, shown as lesion images  78 L and  78 R. The second ablation is implemented at the “upper” recommended next position, shown as marks  76 L and  76 R, respectively, in  FIG.  4   . Since the ablation procedure is continuing, processor  30  calculates new recommended next positions. Thus, processor  30  calculates a new, shifted upper recommended next position to reflect the presence of a second ablation lesion, and displays it as marks  80 L and  80 R. The “lower” recommended next position  74 L,  74 R is not changed. 
       FIG.  6    illustrates display screen  36  after the first ablation lesion, shown as lesion images  72 L and  72 R, and the second ablation lesion, shown as lesion images  78 L and  78 R, have reached their final sizes, melding into each other, and a third ablation lesion, shown as lesion images  82 L and  82 R, has started forming. In this case processor  30  changes the position of the lower recommended position to a new position  83 L,  83 R, while leaving the position of the upper recommended position  80 L,  80 R unchanged. 
       FIG.  7    illustrates on display screen  36  the progress of the ablation procedure, when over half of the circumference of pulmonary vein  16  has been covered by a contiguous ablation lesion, shown as lesion images  84 L and  84 R, respectively. The advantage of displaying the 2D image on right display  40 , as compared with the 3D image on left display  38 , for a rapid and easy assessment of the progress of the ablation procedure, is clearly seen. As is illustrated in the figure, 2D image lesion  84 R displays the complete contiguous lesion, position  83 R and another recommended ablation position  85 R, whereas in 3D image  84 L only a portion of the lesion, and one of the recommended ablation positions  85 L, are visible. 
       FIG.  8    illustrates the completed ablation lesion, shown as lesion images  86 L and  86 R. Both images display as closed paths, corresponding to the closed recommended path around the pulmonary vein illustrated in  FIG.  3   . However, the contiguity of the lesion is immediately visible and verifiable in the 2D image of right display  40 , whereas the 3D image of left display  38  requires manipulation in order to verify the lesion contiguity. 
     It will be appreciated that the embodiments described above are cited by way of example, and that the present invention is not limited to what has been particularly shown and described hereinabove. Rather, the scope of the present invention includes both combinations and subcombinations of the various features described hereinabove, as well as variations and modifications thereof which would occur to persons skilled in the art upon reading the foregoing description and which are not disclosed in the prior art.