KR20110078274A - Position tracking method for vascular treatment micro robot using image registration - Google Patents

Abstract

PURPOSE: A position tracking method of a vascular treatment micro robot using image matching is provided to match and display two images of different modality, thereby tracking the position of the micro robot using two displayed images. CONSTITUTION: Two images of different modality are prepared. The two images are arranged and matched. The matched images are displayed. The position of a micro robot is tracked using the displayed two images.

Description

Position tracking method of micro robot for vascular treatment using image registration {POSITION TRACKING METHOD FOR VASCULAR TREATMENT MICRO ROBOT USING IMAGE REGISTRATION}

The present disclosure relates to a method for tracking a location of a micro robot for vascular treatment using image registration as a whole.

This section provides background information related to the present disclosure which is not necessarily prior art.

The present disclosure relates to sensing the position and orientation of an object disposed within a living human body. More specifically, the present disclosure relates to fixing the position and orientation of intravascular probes in the moving internal organs of a living human body. Extensive medical procedures involve placing objects such as sensors, tubes, catheters, dispensing devices, and implants in the human body. Real-time imaging methods are often used to help operators in visualizing objects and their surroundings during medical procedures. In most situations, however, real-time three-dimensional imaging is impossible or unnecessary. Instead, a system is often used to obtain real time spatial coordinates of an internal object. Many such position sensing systems have been previously developed or planned. Such systems involve attaching sensors to internal objects in the form of transducers or antennas capable of sensing magnetic, electric or ultrasonic fields generated outside of the human body. For example, US Pat. No. 5,983,126, to Wittkampf, the disclosure of which is incorporated herein by reference, discloses a system in which substantially three orthogonal alternating signals are applied through an object. The catheter has at least one measuring electrode and the voltage is sensed between the catheter tip and the reference electrode. The voltage signal has a component corresponding to three orthogonally applied current signals from which calculations are made for the determination of the three-dimensional local position of the catheter chip in the human body. A similar method for sensing the potential between the electrodes has been proposed by US Pat. No. 5,899,860 to Pfeiffer, which is incorporated herein by reference. In these two systems, it is necessary to ensure a separate calibration procedure to adjust for discrepancies between the clear position of the catheter tip as measured and its actual position. Hybrid catheters are now known to perform ultrasound imaging in connection with position sensing. Such devices are disclosed, for example, in US Pat. Nos. 6,690,963, 6,716,166, and 6,773,402, which are incorporated herein by reference. Medical applications include the measurement of atrial wall thickness, wall velocity, and electrical activity as well as three-dimensional mapping of the cavity of the human body. In medical applications, it is common to obtain maps and images of human organs in different ways that can be interpreted for each other. One example is the correlation of electronic anatomical maps of the heart and images, such as three-dimensional ultrasound images. Commercial electrophysiological and physical mapping systems based on detecting the position of the probe inside the human body are currently available. Of these, the Carto-Biosense® Navigation System, available from Biosence Webster Inc., 91765 Diamond Canyon Road Diamond Bar 3333, California, has a catheter local location. A system for automated coupling and mapping of local electrical activity.

This will be described later in the Specification for Implementation of the Invention.

SUMMARY OF THE INVENTION Herein, a general summary of the present disclosure is provided, which should not be construed as limiting the scope of the present disclosure. of its features).

According to one aspect of the present disclosure (According to one aspect of the present disclosure), a method for tracking the position of a microrobot for vascular treatment using image matching, comprising: preparing two images having different modalities; Matching two images having different modalities through alignment; Displaying the two matched images; And, tracking the position of the micro robot using the matched and displayed two images are provided, the method for tracking the position of the micro-robot for blood vessel treatment using the image registration, characterized in that it comprises a.

This will be described later in the Specification for Implementation of the Invention.

The present disclosure will now be described in detail with reference to the accompanying drawing (s).

With reference to the drawings, a reference is made with reference to FIG. 1, which shows a system 20 for imaging and mapping a patient's heart 24, the system comprising a heart 24 in accordance with embodiments of the present disclosure. It is suitable for carrying out diagnostic or therapeutic procedures. The system typically includes a catheter 28 that is percutaneously inserted into the vascular structure of the ventricle or heart by an operator 43, a physician. Catheter 28 typically includes a handle 29 for operation of the catheter by a physician. Proper control on the handle allows the surgeon to steer, position, and orient the distal end of the catheter as necessary for the physician to perform the medical procedure. The second catheter 27 is used to image the heart and to determine the position of the catheter 28 relative to the target as described below.

do. The catheter 27 has a steering mechanism 41 which is selectively controlled by the robot manipulator 31 and by the operator 43. Manipulator 31 receives control signals from positioning processor 36 located in console 34.

System 20 includes a positioning subsystem that measures the local position and azimuth coordinate of catheter 28. Throughout this patent application, the term "local location" refers to the spatial coordinates of the catheter, and the term "orientation" refers to the angular coordinates. The term “position” refers to the overall position information of the catheter, including both local position and azimuth coordinates.

In one embodiment, the positioning subsystem includes a magnetic position tracking system that determines the position and orientation of the catheter 28 and the catheter 27. The positioning subsystem generates a magnetic field at a predefined working volume in its vicinity, which detects the magnetic field in the catheter. The positioning subsystem typically includes a set of external radiators, such as the magnetic field generating coil 30, which is located at a known fixed external location of the patient. The coil 30 generates a magnetic field, such as an electromagnetic field, entirely in the vicinity of the heart 24.

In an alternative embodiment, a radiator in a catheter, such as a coil, generates an electromagnetic field, which is received by a sensor (not shown) outside the patient's body.

The position sensor transmits a position related electrical signal to the console 34 via a cable 33 that passes through the catheter in response to the sensed magnetic field. Optionally, the position sensor may send a signal to the console via a wireless connection. Positioning processor 36 calculates the local position and orientation of catheter 28 based on the signal sent by position sensor 32. Positioning processor 36 typically receives, amplifies, filters, digitizes, and otherwise processes the signal from catheter 28. Positioning processor 36 also provides a signal input to manipulator 31 for manipulating catheter 28.

Some location tracking systems that can be used for this purpose are described, for example, in US Pat. Nos. 6,690,963, 6,618,612, US Patent Application Publication Nos. 2002/0065455 A1, 2004/0147920 A1, and 2004/0068178 A1. Described. Although the positioning subsystem shown in FIG. 1 uses a magnetic field, the method described below may be implemented using any suitable positioning subsystem, such as a system based on electromagnetic, acoustic and ultrasonic measurements.

Optionally, the system 20 can be realized as the above-described cato-biosense navigation system, which is suitably modified to carry out the procedure described below. For example, system 20 may employ (with the necessary modifications) the catheter disclosed in US Pat. Nos. 6,716,166 and 6,773,402 described above to obtain ultrasound images for display in near real time.

In accordance with an embodiment of the present disclosure, a description is made with reference to FIG. 2, which schematically illustrates the distal end of the catheter 28 (FIG. 1). The magnetic field generated by the magnetic field generating coil 30 (FIG. 1) is sensed by the position sensor 32 inside the catheter 28. Catheter 28 also includes an ultrasonic imaging sensor that is typically realized by an array of ultrasonic transducers 40. In one embodiment, the transducer is a piezo-electric transducer, the ultrasonic transducer being located in or adjacent the window 41 defining an opening in the human body or in the wall of the catheter. Typically has at least one lumen 37, which can enter the guide wire and the guide tube to assist in the deployment of the treatment device.

Transducer 40 acts as a tuned array that jointly transmits an ultrasonic beam from the array aperture through window 23. Although the transducers are shown arranged in a linear array configuration, other array configurations may be used, such as circular or convex configurations. In one embodiment, the array transmits a short burst of ultrasound energy and then from the surrounding tissue

Switch to the receive mode to receive the reflected ultrasonic signal. Typically, the transducers 40 are individually driven in a controlled manner to steer the ultrasound beam in the required direction. By proper timing of the transducer, the generated ultrasonic beam can be given a wave front that is concentrically curved to focus the beam at a given distance from the transducer array. Therefore, system 20 (FIG. 1) uses the transducer array as a tuned array and implements a transmit / receive scanning mechanism that enables steering and focusing of the ultrasound beam to produce two-dimensional ultrasound images.

In one embodiment, the ultrasonic sensor comprises 16 to 64 transducers 40, preferably 48 to 64 transducers. Typically, the transducer generates ultrasonic energy at a center frequency in the range of 5-10 MHz with a typical penetration depth of 14 cm. The penetration depth is typically in the range of several millimeters to 16 cm, depending on the ultrasonic sensor characteristics, the surrounding tissue characteristics and the operating frequency. In alternative embodiments, other suitable frequency ranges and penetration depths may be used.

After receiving the reflected ultrasonic echo, the reflected sound wave signal or electrical signals based on the echo are passed through the catheter 28 to the image processor 42 (FIG. 1) in the console 34 over the cable 33. 40, and the image processor transforms it into a two-dimensional, typically sector-shaped ultrasound image. Positioning processor 36, in cooperation with image processor 42, typically computes or determines position and orientation information to display an ultrasound image in real time, and to perform three-dimensional or volumetric reconstruction and other functions, which are described below. It is explained in detail.

Position sensors and ultrasound transducers in the catheter 27 (FIG. 1) are those in the catheter 28 except that the transducer of the catheter 27 is suitable for imaging the application rather than delivering therapeutic ultrasound energy to the target. Similar to

In some embodiments, image processor 42 uses ultrasound images and location information to create a three-dimensional model of the target structure of the patient's heart. The three-dimensional model is presented to the physician as a two-dimensional projection on the display 44.

In some embodiments, the distal end of catheter 28 also includes at least one electrode 46 for performing diagnostic functions, such as electrophysiological mapping and radio frequency (RF) ablation, therapeutic functions, or both. In one embodiment, electrode 46 is used to sense localized potential. The potential measured by electrode 46 is used to map local electrical activity at the point of contact of the endocardial surface. When electrode 46 is in contact with or adjacent a point on the inner surface of the heart 24 (FIG. 1), it measures the local potential at that point. The measured potential is converted into an electrical signal and sent through the catheter to the image processor for display as a map reflecting the functional data or activity at each contact point. In other embodiments, the local potentials are all obtained from other catheters including appropriate electrodes and position sensors connected to the console 34. In some applications, because the potential is weaker there than in the myocardial layer, electrode 46 can be used to determine when the catheter contacts the valve.

Although electrode 46 is shown as being a single ring electrode, the catheter may include any number of electrodes in any form. For example, the catheter may include two or more electrodes, an array of multiple or point electrodes, a tip electrode, or any combination of these types of electrodes to perform the diagnostic and therapeutic functions of the above summary.

The position sensor 32 is typically located within the distal end of the catheter 28 adjacent to the electrode 46 and the transducer 40. Typically, the mutual position and azimuth offset between the position sensor 32, the electrode 46 and the transducer 40 of the ultrasonic sensor is constant. This deviation is typically a positioning pro- gram to derive the coordinates of the ultrasonic sensor and electrode 46 given the measured position of the position sensor 32.

Used by the parser 36. In yet another embodiment, the catheter 28 includes two or more position sensors 32, each having a constant position and orientation deviation with respect to the electrode 46 and the transducer 40. In some embodiments, the deviation (or equivalent calibration parameter) is precalibrated and stored in the positioning processor 36. Optionally, the deviation fits into the handle 29 (FIG. 1) of the catheter 28.

Loss of memory may be stored in a memory device (electrically programmable read-only memory, or EPROM).

The position sensor 32 typically includes three non-concentric coils (not shown) as disclosed in the above-mentioned US Pat. No. 6,690,963. Alternatively, any other suitable position sensor device may be used, such as sensors including any number of concentric or non-concentric coils, Hall-effect sensors or magneto resistive sensors.

Typically, ultrasound images and position measurements are synchronized with the cardiac cycle by gate controlling the signal and image capture for human surface electrocardiogram (ECG) signals or intra-cardiac electrocardiograms (in one embodiment, ECG signals). May be generated by electrode 46). Because the features of the heart change its shape and position during the periodic contraction and relaxation of the heart, a complete imaging process is typically performed at specific timing for this period. In some embodiments, additional measurements taken by the catheter, such as measurement of various tissue features, temperature and blood flow, are also synchronized to the ECG signal. These workpieces also relate to corresponding position measurements taken by the position sensor 32. Additional measurements are typically overlaid on the reconstructed three-dimensional model.

In some embodiments, the acquisition of the position measurement and ultrasound image is synchronized to an internally generated signal produced by the system 20. For example, a synchronization mechanism can be used to avoid interference in ultrasound signal images caused by a particular signal. In this example, the timing of the image acquisition and position measurement is set to a specific deviation with respect to the interfering signal, so that the images are obtained without interference. Deviation can be adjusted from time to time to maintain image acquisition without interference. Optionally, the measurement and acquisition can be synchronized to an externally supplied synchronization signal.

In one embodiment, the system 20 includes an ultrasonic driver 25 (not shown) that drives the ultrasonic transducer 40. One example of a suitable ultrasonic driver that can be used for this purpose is the trademark AN2300 ultrasonic system manufactured by Analogic Corp. (Perbodi, Mass., USA). In this embodiment, the ultrasonic driver is an ultrasonic sensor

Drives some of the functions of the image processor 42 to create a two-dimensional ultrasound image. The ultrasonic driver may support different imaging modes such as B-mode, M-mode, CW Doppler and color flow Doppler as known in the art.

Typically, positioning processor 36 and image processor 42 are implemented using a general purpose computer, which is programmed in software to carry out the functions described in the specification. The software may be downloaded to the computer in electronic form, for example, throughout the network, or may be optionally supplied to the computer on a specific medium such as a CD-ROM. The positioning processor and the image processor may be implemented using a separate computer or using a single computer or may be integrated with other computing functions of the system 20. Additionally or alternatively, positioning and image processing functions may be implemented using dedicated hardware.

2D anatomical imaging

Referring to FIG. 1, using a catheter 27, a gated gated image, for example an ultrasound image, of the core is generated and registered as local position data of the catheter 28. Suitable registration techniques are disclosed in US Pat. No. 6,650,927.

3, which is a schematic exploded view of a diagnostic image 56 of the heart 24 (FIG. 1), in accordance with an embodiment of the present disclosure. Drawings are generated using bullseye rendition techniques. Image 56 includes a stack of parallel slices 58, the slices perpendicular to axis 60. Slices are typically taken in fixed slice increments along axis 60.

Each slice shows an area 62.

3D Anatomical Imaging

Referring to FIG. 1, a three-dimensional image is disclosed in commonly assigned US patent application Ser. No. 11 / 115,002, filed April 26, 2005, entitled "Three-dimensional Cardiac Imaging Using Ultrasound Appearance Reconstruction."

In essence, the three-dimensional image is constructed by combining multiple two-dimensional ultrasound images obtained at different locations of the catheter 27 into a single three-dimensional model of the target structure. The catheter 27 may operate in a scanning mode and move between different positions inside the ventricles of the heart 24. At each catheter position, image processor 42 obtains and generates a two-dimensional ultrasound image. In one embodiment, catheter 27 is side-looking, and partial three-dimensional reconstruction of the heart is obtained by shaking the catheter using manipulator 31 to change its rolling angle with pendulum motion. do. Optionally, the catheter 27 can be shaken to change its pitch or yaw angle. In either case, the result is a shim comprising catheter 28 and its current target structure.

It is displayed as a three-dimensional piece of yarn.

Optionally, the catheter 28 swivets the beam in a pendulum fashion, provided by a two-dimensional array of transduces 40 (FIG. 2) that can be modulated to obtain different two-dimensional images of the target structure in one plane. On the other hand, the catheter 28 is maintained in a fixed position.

Tracking and display

Referring to FIG. 1, during the medical procedure, the system 20 continuously tracks the three-dimensional position of the catheter 28 using the catheter 27 to produce an image of the catheter 28 and its target area in near real time. Can be displayed. The positioning subsystem of system 20 iteratively measures and calculates the current position of catheter 28. The calculated position is stored with the corresponding slice or slices 58 (FIG. 3). Typically, each position of the catheter 28 is represented in the form of coordinates, such as six-dimensional coordinates (pitch, yaw and rolling angle of the X, Y, Z axis position and orientation).

Image processor 42 then assigns three-dimensional coordinates to important contours of interest, such as the identified feature in the set of images. The local position and orientation of the plane of these images in three-dimensional space is known by the position information stored with the images. Therefore, the image processor can determine the three-dimensional coordinates of any pixel in the two-dimensional image. When assigning coordinates, the image processor typically uses stored calibration data, including position and orientation deviations between the position sensor and the ultrasonic sensor as described above.

Optionally, system 20 can be used for three-dimensional display and projection of two-dimensional ultrasound images without reconstructing the three-dimensional model. For example, the doctor may acquire a single two-dimensional ultrasound image. Important contours of such images can be tagged using the procedure described below. System 20 may then orient and project the ultrasound image in three-dimensional space.

4, which is a schematic illustration of a mechanism used by the system 20 (FIG. 1) to perform real-time control of an imaging catheter during a medical procedure in accordance with an embodiment of the present disclosure. Positioning processor 36 uses the signal developed by position sensor 32 (FIG. 2) to determine the local position of catheter 28, and changes the signal sent to manipulator 31. Catheter

27 is then automatically manipulated by the manipulator 31 so that the current position of the catheter 28 is always included in the field of view 35 of the catheter 27. Positioning processor 36 may also receive a signal from a position sensor (not shown) in catheter 27 to determine the relative local position of the catheter 27, 28.

Using the information obtained from the catheter 27, 28, the position sensing system determines the current appropriate local position and orientation of the catheter 27 and measures any deviations. It then automatically sends a signal to the manipulator 31 to perform compensatory control of the catheter 27. Optionally, an indicator 39, audibly or visually, directs the operator to change the manipulator 31 to manually adjust the position of the catheter 27.

In some embodiments, when the target is in the vicinity with the catheter 28, enhanced mode of operation is possible. Using the image developed by the image processor 42 (FIG. 1), the target 38 is generally identified by the operator, but may optionally be identified using information obtained from a knowledge base or previously obtained map as described below. Can be. The positioning processor 36 then instructs the manipulator 31 to include the target 38 as well as include the catheter 28 in the field of view 35. The system 20 (FIG. 1) then displays the catheter 28 and the target 38 on the display 44 in a perspective view that is most helpful to the operator. For example, in endoscope applications, display 44 may provide an angular view of compensation as requested by the operator.

Optional embodiment

The technique of the present disclosure may also be used to maintain an ultrasound catheter aimed towards a target that is not equipped with a position sensor. Referring again to FIG. 1, the catheter 27 may be controlled to aim the ultrasound beam continuously towards the marker on the heart. There is an alternative method of fixing the local position and orientation of the ultrasound beam to include the marking.

The operator 43 indicates fixed reference coordinates on the previously acquired map. Suitable maps may be prepared using the method described in US Pat. No. 6,226,542. In essence, the processor reconstructs a three-dimensional map of volume and cavity in the patient's human body from a number of sampled points on the weld whose position coordinates are determined. In the case of a moving structure, such as the heart, the sampled point relates to a frame of reference obtained by gating imaging data at a point in the cardiac cycle. When obtaining the maps, the reference catheter is fixedly located in the heart and the sampled points are determined along with the location of the reference catheter used to register that point.

5, which schematically illustrates a control mechanism used by the system 20 (FIG. 1) to perform real-time tracking and control of an imaging catheter during a medical procedure in accordance with an optional embodiment of the present disclosure. 5 is similar to FIG. 4 except that the positioning processor 36 now does not receive signals from the position sensor of the catheter 27. Instead, the position of the catheter 27 is automatically determined by the positioning processor 36 with reference to the appropriately modified coordinates of the map 70 shown in FIG. 5 as the reconstructed heart volume. Map 70 has a number of sampled points 72 that are used to reconstruct surface 74. A grid (not shown) is adjusted to form the surface 74, where each point on the grid receives a reliability value that indicates the accuracy of the decision. When the map 70 is displayed for the operator 43, the areas of the surface 74 covered with relatively less certain grid points may be displayed translucently. Alternatively or additionally, different levels of translucency are used with multiple levels of reliability measures.

Optionally, the map 70 may indicate the coordinates of the target used as the reference point.

The embodiment illustrated by FIG. 5 may be used to aim the ultrasound catheter toward important markers such as left atrial appendages or mitral valves. This may be for example to confirm that the area has not been damaged by medical procedures and that the embolism has not developed. As an additional example, embodiments may be used to confirm the depth of ablation injury.

6 and 7 are views illustrating a method for tracking the position of a micro robot for vascular treatment using image registration according to the present disclosure. According to the present disclosure, a method for tracking the position of a micro robot for vascular treatment using image registration, comprising: preparing two images having different modalities; Matching two images having different modalities through alignment; Displaying the two matched images; And, tracking the position of the micro robot using the matched and displayed two images are provided, the method for tracking the position of the micro-robot for blood vessel treatment using the image registration, characterized in that it comprises a.

1 illustrates a system for imaging and mapping a patient's heart in accordance with an embodiment disclosed herein.

 2 schematically illustrates an embodiment of the distal end of an S (s) catheter used in the system shown in FIG. 1, in accordance with an embodiment disclosed herein.

3 is a schematic exploded view of a diagnostic image of the heart, in accordance with an embodiment disclosed in the present invention.

4 schematically illustrates a control mechanism used by the system shown in FIG. 1 to steer an imaging catheter during a medical procedure in accordance with an embodiment disclosed herein.

5 schematically illustrates a control mechanism used by the system shown in FIG. 1 to steer an imaging catheter during a medical procedure in accordance with an alternative embodiment of the present invention.

6 to 7 are views illustrating a method for tracking the position of a micro robot for vascular treatment using image registration according to the present disclosure.

Claims (1)

In the location tracking method of a micro robot for blood vessel treatment using image registration, Preparing two images having different modalities; Matching two images having different modalities through alignment; Displaying the two matched images; And, Tracking the position of the micro robot using the matched and displayed two images; Position tracking method of a micro-robot for blood vessel treatment using the image registration comprising a.

Images