# Patent

## Title
System and method of combining ultrasound image acquisition with fluoroscopic image acquisition

## Abstract

A system and method to image an imaged subject is provided. The system comprises an ultrasound imaging system including an imaging probe operable to move internally and acquire ultrasound image data of the imaged subject, a fluoroscopic imaging system operable to acquire fluoroscopic image data of the imaged subject during image acquisition by the ultrasound imaging system, and a controller in communication with the ultrasound imaging system and the fluoroscopic imaging system. A display can be illustrative of the ultrasound image data acquired with the imaging probe in combination with a fluoroscopic imaging data acquired by the fluoroscopic imaging system.

## Background
RELATED APPLICATIONS
This application claims priority to U.S. Provisional Application No. 60/938,602 filed on May 17, 2007, and is hereby incorporated herein by reference in its entirety.


BACKGROUND
The subject matter herein generally relates to tracking or delivery of medical instruments, and in particular, systems and methods to track and deliver medical instruments using ultrasound.
Image-guided surgery is a developing technology that generally provides a surgeon with a virtual roadmap into a patient's anatomy. This virtual roadmap allows the surgeon to reduce the size of entry or incision into the patient, which can minimize pain and trauma to the patient and result in shorter hospital stays. Examples of image-guided procedures include laparoscopic surgery, thorasoscopic surgery, endoscopic surgery, etc. Types of medical imaging systems, for example, computerized tomography (CT), magnetic resonance imaging (MRI), positron emission tomography (PET), ultrasound (US), radiological machines, etc., can be useful in providing static image guiding assistance to medical procedures. The above-described imaging systems can provide two-dimensional or three-dimensional images that can be displayed to provide a surgeon or clinician with an illustrative map to guide a tool (e.g., a catheter) through an area of interest of a patient's body.
One example of application of image-guided surgery is to perform an intervention procedure to treat cardiac disorders or arrhythmias. Heart rhythm disorders or cardiac arrhythmias are a major cause of mortality and morbidity. Atrial fibrillation is one of the most common sustained cardiac arrhythmia encountered in clinical practice. Cardiac electrophysiology has evolved into a clinical tool to diagnose these cardiac arrhythmias. As will be appreciated, during electrophysiological studies, probes, such as catheters, are positioned inside the anatomy, such as the heart, and electrical recordings are made from the different chambers of the heart.
A certain conventional image-guided surgery technique used in interventional procedures includes inserting a probe, such as an imaging catheter, into a vein, such as the femoral vein. The catheter is operable to acquire image data to monitor or treat the patient. Precise guidance of the imaging catheter from the point of entry and through the vascular structure of the patient to a desired anatomical location is progressively becoming more important. Current techniques typically employ fluoroscopic imaging to monitor and guide the imaging catheter within the vascular structure of the patient.
BRIEF SUMMARY
A technical effect of the embodiments of the system and method described herein includes enhancement in monitoring and/or treating regions of interest. Another technical effect of the subject matter described herein includes enhancement of placement and guidance of probes (e.g., catheters) traveling through an imaged subject. Yet, another technical effect of the system and method described herein includes reducing manpower, expense, and time to perform interventional procedures, thereby reducing health risks associated with long-term exposure of the subject to radiation.
According to one embodiment, a system to image an imaged subject is provided. The system comprises an ultrasound imaging system including an imaging probe operable to move internally and acquire ultrasound image data of the imaged subject, a fluoroscopic imaging system operable to acquire fluoroscopic image data of the imaged subject during image acquisition by the ultrasound imaging system, and a controller in communication with the ultrasound imaging system and the fluoroscopic imaging system. A display can be illustrative of the ultrasound image data acquired with the imaging probe in combination with a fluoroscopic imaging data acquired by the fluoroscopic imaging system.
According to another embodiment of the subject matter described herein, a method of image acquisition of an imaged subject is provided. The method comprises the steps of providing an ultrasound imaging system including an imaging probe in communication with a controller; providing a fluoroscopic imaging system operable to acquire fluoroscopic image data of the imaged subject; acquiring the ultrasound image data simultaneously with acquiring fluoroscopic image data of the imaged subject; and displaying a combination of the ultrasound image data and the fluoroscopic image data.
Systems and methods of varying scope are described herein. In addition to the aspects of the subject matter described in this summary, further aspects of the subject matter will become apparent by reference to the drawings and with reference to the detailed description that follows.



BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 illustrates a schematic diagram of an embodiment of a system of the subject matter described herein to perform imaged guided medical procedures on an imaged subject.
FIG. 2 illustrates a picture of a tool to travel through the imaged subject.
FIG. 3 illustrates a more detailed schematic diagram of a tracking system in combination with an imaging system as part of the system described in FIG. 1.
FIG. 4 shows an embodiment of a method of performing an image-guided procedure via the system of FIG. 1.
FIG. 5 shows an embodiment of an illustration of a display created with the system of FIG. 1.



DETAILED DESCRIPTION
In the following detailed description, reference is made to the accompanying drawings that form a part hereof, and in which is shown by way of illustration specific embodiments, which may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the embodiments, and it is to be understood that other embodiments may be utilized and that logical, mechanical, electrical and other changes may be made without departing from the scope of the embodiments. The following detailed description is, therefore, not to be taken in a limiting sense.
FIG. 1 illustrates an embodiment of a system 100 operable to create a full-view three- or four-dimensional (3D or 4D) image or model from a series of generally real-time, acquired 3D or 4D image data 102 relative to a tracked position information of a probe (e.g., an imaging catheter 105) traveling through the imaged subject 110. According to one embodiment, the system 100 can be operable to acquire a series of general real-time, partial view, 3D or 4D image data 102 while simultaneously rotating and tracking a position and orientation of the catheter 105 through the imaged subject 110. From the acquired general real-time, partial views of 3D or 4D image data 102, a technical effect of the system 100 includes creating an illustration of a general real-time 3D or 4D model 112 of a region of interest (e.g., a beating heart) so as to guide a surgical procedure.
An embodiment of the system 100 generally includes an image acquisition system 115, a steering system 120, a tracking system 125, an ablation system 130, and an electrophysiology system 132 (e.g., a cardiac monitor, respiratory monitor, pulse monitor, etc. or combination thereof), and a controller or workstation 134.
The image acquisition system 115 is generally operable to generate the 3D or 4D image or model 112 corresponding to an area of interest of the imaged subject 110. Examples of the image acquisition system 115 can include, but is not limited to, computed tomography (CT), magnetic resonance imaging (MRI), x-ray or radiation, positron emission tomography (PET), computerized tomosynthesis (CT), ultrasound (US), angiographic, fluoroscopic, and the like or combination thereof. The image acquisition system 115 can be operable to generate static images acquired by static imaging detectors (e.g., CT systems, MRI systems, etc.) prior to a medical procedure, or real-time images acquired with real-time imaging detectors (e.g., angioplastic systems, laparoscopic systems, endoscopic systems, etc.) during the medical procedure. Thus, the types of images acquired by the acquisition system 115 can be diagnostic or interventional.
One embodiment of the image acquisition system 115 includes a general real-time, intracardiac echocardiography (ICE) imaging system 140 that employs ultrasound to acquire general real-time, 3D or 4D ultrasound image data of the patient's anatomy and to merge the acquired image data to generate a 3D or 4D model 112 of the patient's anatomy relative to time, generating herein referred to as the 4D model or image 112. In accordance with another embodiment, the image acquisition system 115 is operable to fuse or combine acquired ultrasound image data 102 or model 112 using above-described ICE imaging system 140 with an intra-operative image data or image models (e.g., 2D image data) generated by a fluoroscopic imaging system 142. One embodiment of the fluoroscopic imaging system 142 generally includes an X-ray source in combination with an image intensifier to acquire fluoroscopic image data 144 of the imaged subject 110. The acquired image data 102, 112, or 144 can be further combined with other pre-operative or intra-operative image data (e.g., MRI, PET, endoscopic, CT, etc.) and is not limiting on the invention.
FIG. 2 illustrates one embodiment of the catheter 105, herein referred to as an ICE catheter 105. The illustrated embodiment of the ICE catheter 105 includes a transducer array 150, a micromotor 155, a drive shaft or other mechanical connection 160 between the micromotor 155 and the transducer array 150, an interconnect 165, and a catheter housing 170.
According to the illustrated embodiment in FIG. 3, the micromotor 155 via the drive shaft 160 generally rotates the transducer array 150. The rotational motion of the transducer array 150 is controlled by a motor control 175 of the micromotor 155. The interconnect 165 generally refers to, for example, cables and other connections coupling so as to receive and/or transmit signals between the transducer array 150 with the ICE imaging system (shown in FIG. 1) 105. An embodiment of the interconnect 165 is configured to reduce its respective torque load on the transducer array 150 and the micromotor 155.
Still referring to FIG. 2, an embodiment of the catheter housing 170 generally encloses the transducer array 150, the micromotor 155, the drive shaft 160, and the interconnect 165. The catheter housing 170 may further enclose the motor control 175 (illustrated in dashed line). The catheter housing is generally of a material, size, and shape adaptable to internal imaging applications and insertion into regions of interest of the imaged subject 110. At least a portion of the catheter housing 170 that intersects the ultrasound imaging volume or scanning direction is comprised of acoustically transparent (e.g., low attenuation and scattering, acoustic impedance near that of the blood and tissue (Z ̃1.5M Rayl) material. An embodiment of the space between the transducer array 150 and the housing 170 is filled with acoustic coupling fluid (e.g., water) having an acoustic impedance and sound velocity near those of blood and tissue (e.g., Z ̃1.5M Rayl, V ̃1540 m/sec).
An embodiment of the transducer array 150 is a 64-element one-dimensional array having 0.110 mm azimuth pitch, 2.5 mm elevation, and 6.5 MHz center frequency. The elements of the transducer array 150 are electronically phased in order to acquire a sector image generally parallel to a longitudinal axis 180 of the catheter housing 170. In operation, the micromotor 155 mechanically rotates the transducer array 150 about the longitudinal axis 180. The rotating transducer array 150 captures a plurality of two-dimensional images for transmission to the ICE imaging system 140 (shown in FIG. 1). The ICE imaging system 140 is generally operable to assemble the sequence or succession of acquired 2D images so as to generally produce or generate 3D image or reconstructed model 112 of the imaged subject 110.
The motor control 175 via the micromotor 155 generally regulates or controls the rate of rotation of the transducer array 150 about the longitudinal axis 180 of the ICE catheter 105. For example, the motor control 175 can instruct the micromotor 155 to rotate the transducer array 150 relatively slowly to produce the 3D reconstructed image or model 112. Also, the motor control 175 can instruct the micromotor 155 to rotate the transducer array 150 relatively faster to produce the general real-time, 3D or 4D reconstructed image or model. The 4D reconstructed image or model 112 can be defined to include a 3D reconstructed image or model correlated relative to an instant or instantaneous time of image acquisition. The motor control 175 is also generally operable to vary the direction of rotation so as to generally create an oscillatory motion of the transducer array 150. By varying the direction of rotation, the motor control 175 is operable to reduce the torque load associated with the interconnect 165, thereby enhancing the performance of the transducer array 150 to focus imaging on specific regions within the range of motion of the transducer array 150 about the longitudinal axis 180.
Referring back to FIG. 1, an embodiment of the steering system 120 is generally coupled in communication to control maneuvering (including the position or the orientation) of the ICE catheter 105. The embodiment of the system 100 can include synchronizing the steering system 120 with gated image acquisition by the ICE imaging system 140. The steering system 120 may be provided with a manual catheter steering function or an automatic catheter steering function or combination thereof. With selection of the manual steering function, the controller 134 and/or steering system 120 aligns an imaging plane vector 181 relative to the ICE catheter 105 shown on the 3D ICE reconstructed image or model 112 per received instructions from the user, as well as directs the ICE catheter 105 to a target anatomical site. An embodiment of the imaging plane vector 181 represents a central direction of the plane that the transducer array 150 travels, moves or rotates through relative to the longitudinal axis 180. With selection of the automatic steering function, the controller 134 and/or steering system 120 or combination thereof estimates a displacement or a rotation angle 182 at or less than maximum (See FIG. 2) relative to a reference (e.g., imaging plane vector 181), passes position information of the ICE catheter 105 to the steering system 120, and automatically drives or positions the ICE catheter 105 to continuously follow movement of a second object (e.g., delivery of an ablation catheter 184 of the ablation system 130, moving anatomy, etc.). The reference (e.g., imaging plane vector 181) can vary.
Referring to FIGS. 1 and 3, the tracking system 125 is generally operable to track or detect the position of the tool or ICE catheter 105 relative to the acquired image data or 3D or 4D reconstructed image or model 112 generated by the image acquisition system 115, or relative to delivery of a second instrument or tool (e.g., ablation system 130, electrophysiology system 132).
As illustrated in FIG. 3, an embodiment of the tracking system 125 includes an array or series of microsensors or tracking elements 185, 190, 195, 200 connected (e.g., via a hard-wired or wireless connection) to communicate position data to the controller 134 (See FIG. 1). Yet, it should be understood that the number of tracking elements 185, 190, 195, 200 can vary. An embodiment of the system 100 includes intraoperative tracking and guidance in the delivery of the at least one catheter 184 of the ablation system 130 by employing a hybrid electromagnetic and ultrasound positioning technique.
An embodiment of the hybrid electromagnetic/ultrasound positioning technique can facilitate dynamic tracking by locating tracking elements or dynamic references 185, 190, 195, 200, alone in combination with ultrasound markers 202 (e.g., comprised of metallic objects such brass balls, wire, etc. arranged in unique patterns for identification purposes). The ultrasonic markers 202 may be active (e.g., illustrated in dashed line located at catheters 105 and 184) or passive targets (e.g., illustrated in dashed line at imaged anatomy of subject 110). An embodiment of the ultrasound markers 202 can be located at the ICE catheter 105 and/or ablation catheter 184 so as to be identified or detected in acquired image data by supplemental imaging system 142 and/or the ICE imaging system 140 or controller 134 or combination thereof. As image data is acquired via the ICE catheter 105, an image-processing program stored at the controller 134 or other component of the system 100 can extract or calculate a voxel position of the ultrasonic markers 202 in the image data. In this way, the controller 134 or tracking system 125 or combination thereof can track a position of the ultrasonic markers 202 with respect to the ICE catheter 105, or vice versa. The tracking system 125 can be configured to selectively switch between tracking relative to electromagnetic tracking elements 185, 190, 195, 200 or ultrasound markers 202 or simultaneously track both.
For sake of example, assume the series of tracking elements 185, 190, 195, 200 includes a combination of transmitters or dynamic references 185 and 190 in communication or coupled (e.g., RF signal, optically, electromagnetically, etc.) with one or more receivers 195 and 200. The number and type transmitters in combination with receivers can vary. Either the transmitters 185 and 190 or the receivers 195 and 200 can define the reference of the spatial relation of the tracking elements 185, 190, 195, 200 relative to one another. An embodiment of one of the receivers 195 represents a dynamic reference at the imaged anatomy of the subject 110. An embodiment of the system 100 is operable to register or calibrate the location (e.g., position and/or orientation) of the tracking elements 185, 190, 195, 200 relative to the acquired imaging data by the image acquisition system 115, and operable to generate a graphic representation suitable to visualize the location of the tracking elements 185, 190, 195, 200 relative to the acquired image data.
The tracking elements 185, 190, 195, 200 generally enable a surgeon to continually track the position and orientation of the catheters 105 or 182 during surgery. The tracking elements 185, 190, 195 may be passively powered, powered by an external power source, or powered by an internal battery. One embodiment of one or more of the tracking elements or microsensors 185, 190, 195 include electromagnetic (EM) field generators having microcoils operable to generate a magnetic field, and one or more of the tracking elements 185, 190, 195, 200 include an EM field sensor operable to detect an EM field. For example, assume tracking elements 185 and 190 include a EM field sensor operable such that when positioned into proximity within the EM field generated by the other tracking elements 195 or 200 is operable to calculate or measure the position and orientation of the tracking elements 195 or 200 in real-time (e.g., continuously), or vice versa, calculate the position and orientation of the tracking elements 185 or 190.
For example, tracking elements 185 and 190 can include EM field generators attached to the subject 110 and operable to generate an EM field, and assume that tracking element 195 or 200 includes an EM sensor or array operable in combination with the EM generators 185 and 190 to generate tracking data of the tracking elements 185, 190 attached to the patient 110 relative to the microsensor 195 or 200 in real-time (e.g., continuously). According to one embodiment of the series of tracking elements 185, 190, 195, 200, one is an EM field receiver and a remainder are EM field generators. The EM field receiver may include an array having at least one coil or at least one coil pair and electronics for digitizing magnetic field measurements detected by the receiver array. It should, however, be understood that according to alternate embodiments, the number of combination of EM field receivers and EM field generators can vary.
The field measurements generated or tracked by the tracking elements 185, 190, 195, 200 can be used to calculate the position and orientation of one another and attached instruments (e.g., catheters 105 or 184) according to any suitable method or technique. An embodiment of the field measurements tracked by the combination of tracking elements 185, 190, 195, 200 are digitized into signals for transmission (e.g., wireless, or wired) to the tracking system 125 or controller 134. The controller 134 is generally operable to register the position and orientation information of the one or more tracking elements 185, 190, 195, 200 relative to the acquired imaging data from ICE imaging system 140 or other supplemental imaging system 142. Thereby, the system 100 is operable to visualized or illustrate the location of the one or more tracking elements 185, 190, 195, 200 or attached catheters 105 or 184 relative to pre-acquired image data or real-time image data acquired by the image acquisition system 115.
Referring now to FIG. 3, an embodiment of the tracking system 125 includes the tracking element 200 located at the ICE catheter 105. The tracking element 200 is in communication with the receiver 195. This embodiment of the tracking element 200 includes a transmitter that comprises a series of coils that define the orientation or alignment of the ICE catheter 105 about the rotational axis (generally aligned along the longitudinal axis 180) of the ICE catheter 105. Referring to FIG. 2, the tracking element 200 can be located integrally with the ICE catheter 105 and can be generally operable to generate or transmit a magnetic field 205 to be detected by the receiver 195 of the tracking system 125. In response to passing through the magnetic field 205, the receiver 195 generates a signal representative of a spatial relation and orientation of the receiver 195 or other reference relative to the transmitter 200. Yet, it should be understood that the type or mode of coupling, link or communication (e.g., RF signal, infrared light, magnetic field, etc.) operable to measure the spatial relation varies. The spatial relation and orientation of the tracking element 200 is mechanically pre-defined or measured in relation relative to a feature (e.g., a tip) of the ICE catheter 105. Thereby, the tracking system 125 is operable to track the position and orientation of the ICE catheter 105 navigating through the imaged subject 110.
An embodiment of the tracking elements 185, 190, or 200 can include a plurality of coils (e.g., Hemholtz coils) operable to generate a magnetic gradient field to be detected by the receiver 195 of the tracking system 125 and which defines an orientation of the ICE catheter 105. The receiver 195 can include at least one conductive loop operable to generate an electric signal indicative of spatial relation and orientation relative to the magnetic field generated by the tracking elements 185, 190 and 200.
Referring back to FIG. 1, an embodiment of the ablation system 130 includes the ablation catheter 184 that is operable to work in combination with the ICE catheter 105 of the ICE imaging system 140 to delivery ablation energy to ablate or end electrical activity of tissue of the imaged subject 110. An embodiment of the ICE catheter 105 can include or be integrated with the ablation catheter 184 or be independent thereof. An embodiment of the ablation catheter 184 can include one of the tracking elements 185, 190 of the tracking system 125 described above to track or guide intra-operative delivery of ablation energy to the imaged subject 110. Alternatively or in addition, the ablation catheter 184 can include ultrasound markers 202 (illustrated in dashed line in FIG. 1) operable to be detected from the acquired ultrasound image data generated by the ICE imaging system 140. The ablation system 130 is generally operable to manage the ablation energy delivery to an ablation catheter 184 relative to the acquired image data and tracked position data.
An embodiment of an electrophysiological system(s) 132 is connected in communication with the ICE imaging system 140, and is generally operable to track or monitor or acquire data of the cardiac cycle 208 or respiratory cycle 210 of imaged subject 110. Data acquisition can be correlated to the gated acquisition or otherwise acquired image data, or correlated relative to generated 3D or 4D models 112 created by the image acquisition system 115.
Still referring FIG. 1, the controller or workstation computer 134 is generally connected in communication with and controls the image acquisition system 115 (e.g., the ICE imaging system 140 or supplemental imaging system 142), the steering system 120, the tracking system 125, the ablation system 130, and the electrophysiology system 132 so as to enable each to be in synchronization with one another and to enable the data acquired therefrom to produce or generate a full-view 3D or 4D ICE model 112 of the imaged anatomy.
An embodiment of the controller 134 includes a processor 220 in communication with a memory 225. The processor 220 can be arranged independent of or integrated with the memory 225. Although the processor 220 and memory 225 is described located the controller 134, it should be understood that the processor 220 or memory 225 or portion thereof can be located at image acquisition system 115, the steering system 120, the tracking system 125, the ablation system 130 or the electrophysiology system 132 or combination thereof.
The processor 220 is generally operable to execute the program instructions representative of acts or steps described herein and stored in the memory 225. The processor 220 can also be capable of receiving input data or information or communicating output data. Examples of the processor 220 can include a central processing unit of a desktop computer, a microprocessor, a microcontroller, or programmable logic controller (PLC), or the like or combination thereof.
An embodiment of the memory 225 generally comprises one or more computer-readable media operable to store a plurality of computer-readable program instructions for execution by the processor 220. The memory 225 can also operable to store data generated or received by the controller 134. By way of example, such media may comprise RAM, ROM, PROM, EPROM, EEPROM, Flash, CD-ROM, DVD, or other known computer-readable media or combinations thereof which can be used to carry or store desired program code in the form of instructions or data structures and which can be accessed by a general purpose or special purpose computer or other machine with a processor. When information is transferred or provided over a network or another communications connection (either hardwired, wireless, or a combination of hardwired or wireless) to a machine or remote computer, remote computer properly views the connection as a computer-readable medium. Thus, any such a connection is properly termed a computer-readable medium.
The controller 134 further includes or is in communication with an input device 230 and an output device 240. The input device 230 can be generally operable to receive and communicate information or data from user to the controller 210. The input device 230 can include a mouse device, pointer, keyboard, touch screen, microphone, or other like device or combination thereof capable of receiving a user directive. The output device 240 is generally operable to illustrate output data for viewing by the user. An embodiment of the output device 240 can be operable to simultaneously illustrate or fuse static or real-time image data generated by the image acquisition system 115 (e.g., the ICE imaging system 140 or supplemental imaging system 142) with tracking data generated by the tracking system 125. The output device 240 is capable of illustrating two-dimensional, three-dimensional image and/or four-dimensional image data or combination thereof through shading, coloring, and/or the like. Examples of the output device 240 include a cathode ray monitor, a liquid crystal display (LCD) monitor, a touch-screen monitor, a plasma monitor, or the like or combination thereof.
Having provided a description of the general construction of the system 100, the following is a description of a method 300 (see FIG. 4) of operation of the system 100 in relation to the imaged subject 110. Although an exemplary embodiment of the method 300 is discussed below, it should be understood that one or more acts or steps comprising the method 300 could be omitted or added. It should also be understood that one or more of the acts can be performed simultaneously or at least substantially simultaneously, and the sequence of the acts can vary. Furthermore, it is embodied that at least several of the following steps or acts can be represented as a series of computer-readable program instructions to be stored in the memory 225 of the controller 210 for execution by the processor 220 or one or more of the image acquisition system 115, the steering system 120, the tracking system 125, the ablation system 130, the electrophysiology system 132, or a remote computer station connected thereto via a network (wireless or wired).
The controller 134 via communication with the tracking system 125 is operable to track movement of the ICE catheter 105 in accordance with known mathematical algorithms programmed as program instructions of software for execution by the processor 220 of the controller 134 or by the tracking system 125. An exemplary navigation software is INSTATRAK® as manufactured by the GENERAL ELECTRIC® Corporation, NAVIVISION® as manufactured by SIEMENS®, and BRAINLAB®.
The method 300 includes a step of registering 310 a reference frame 320 of the ICE imaging system 140 with one or more of the group comprising: a reference frame 325 of the tracking system 125, a reference frame 330 of the steering system 120, a reference frame 335 of the ablation system 130, or a reference time frame of the electrophysiological system(s) (e.g., cardiac monitoring system, respiratory monitoring system, etc.) 132.
The registering step 310 can further include registering the reference frame 320 of the ICE imaging system with a reference frame or coordinate system 340 that defines a spatial distribution of image data acquired by the fluoroscopic imaging system 142. The fluoroscopic system 142 can include a navigation calibration target 342 comprising an array of radio-opaque fiducials and one or more of the tracking elements 185, 190 of the tracking system 125.
According to one embodiment, the fluoroscopic imaging system 142 can acquire image data of a navigation calibration target to define the fluoroscopic reference frame 340 relative thereto. The ICE imaging system 140 can acquire ultrasound image data of the navigation calibration target 342 to define the imaging reference frame 320 relative thereto. By comparison to the same calibration target 342, mathematical modeling can be used to transform or register the fluoroscopic reference frame 340 relative to the imaging reference frame 320 (as well as one or more of the reference frames 325, 330, and 335 described above). Once reference frames 320 and 340 are registered relative to one another, the 4D ultrasound image data 102 and models 112 generated by the ICE imaging system 140 can be projected onto or combined with 2D generally real-time acquired fluoroscopic imaging data.
All reference frames 320, 325, 330, 335, and 340 can be registered to a common or world coordinate reference frame 345. One embodiment of the world reference frame 345 can be defined as a dynamic reference that includes one of the tracking elements 195 or an ultrasound marker 202 or both located at (e.g., rigidly attached with internally to the heart or externally to the chest) the imaged subject 110.
One embodiment of calibrating can include acquiring at least one fluoroscopic image containing both the fiducial markers (not shown) at the target 142 in combination with the position of the tracking elements 185, 190 at one or more of the fiducials markers at the target 142. The calibration estimates the intrinsic (or projection) fluoroscopic imaging parameters including focal length, piercing points, and 2D image scaling factor. The calibration step can also include calculating the extrinsic camera parameters including the calibration target fiducial positions relative to the fluoroscopic coordinate system 340. The fluoroscopic imaging parameters may be defined or transformed to any preferable coordinate reference frame. For example, given extrinsic fluoroscopic imaging parameter information and the calibration target sensor position information, a first transformation may be from the fluoroscopic image data defined in the intrinsic fluoroscopic imaging reference frame 340 relative to the sensor array coordinate reference frame 325, and then to the world coordinate system 345 as the dynamic reference at the imaged subject 110. Correspondingly, the 2D fluoroscopic reference frame 340 may be transformed to the world coordinate reference frame 345.
In another embodiment, the registering step 310 can further include registering a pre-operative 4D CT, MR, or PET image with the fluoroscopic reference frame 340 or one or more of the reference frames 320, 325, 330, and 335 described above.
An embodiment of the method 300 further includes a step 350 of acquiring image data (e.g., scan) of the anatomy of interest of the imaged subject 110. An embodiment of the step of acquiring image data includes acquiring the series of partial-views 102 of 3D or 4D image data while rotating the ICE catheter 105 around the longitudinal axis 180. The image acquisition step 350 can include synchronizing or gating a sequence of image acquisition relative to cardiac and respiratory cycle information 208, 210 measured by the electrophysiology system 132. One embodiment of the image acquiring step 350 can also include extracting a surface model of the imaged anatomy from the generated 4D ICE model according to the cardiac timing sequence, which may be denoted as [T(ice.3D.surf->wcs)].t1, [T(ice.3D.surf->wcs)].t2, . . . , and [T(ice.3D.surf->wcs)].tn.
The embodiment of step 350 can further include acquiring fluoroscopic imaging data of the imaged subject 110 during acquisition of the image data by the ICE catheter 105 of the ICE imaging system 140. The simultaneous acquisition of image data by the ICE imaging system 140 and the fluoroscopic imaging system 142 can be gated according to, or referenced to, the same time reference frame of the cardiac cycle or respiratory cycle information 208 and 210 acquired by the electrophysiology system 132. The illustration of the surface of the general real-time 4D ICE model 112 may be projected in combination with (e.g., overlapping) the two-dimensional (2D) fluoroscopic imaging data 144 at any given cardiac phase. Alternatively, projected general real-time 2D ultrasound image may be superimposed on the 2D fluoroscopic image data 144.
The embodiment of the method 300 further includes a step 355 of tracking a position or location of the at least one catheter 105 or 184 relative to the acquired image data. According to one embodiment of the method 300, at least one catheter 105 or 184 can be integrated with one or more ultrasonic markers 202 indicative of a unique identifier. The ultrasonic markers 202 can both be located and rigidly mounted on the at least one instrument catheter 105 or 184. A computer image-processing program is operable to detect and mark positions of the ultrasonic markers 202 relative to the generated 3D or 4D ICE image model 112.
The controller 134 can be generally operable to align positions of the ultrasonic markers 202 with a tracking coordinate reference frame or coordinate system 325. This registration information may be used for the alignment (calibration) between the tracking reference frame or coordinate system 325 relative to the imaging reference frame or coordinate system 320. This information may also be used for detecting the presence of electromagnetic distortion or tracking inaccuracy.
According to one embodiment, the controller 134 can process acquired partial views of 3D or 4D image data of the catheter 105 or 184 to extract the voxel positions of the ultrasonic markers 202. The controller 134 can also process the acquired partial views of 3D or 4D image data to extract or delineate a surface model of the imaged anatomy.
The embodiment of the ICE catheter 105 can include the tracking element 200 (e.g., electromagnetic coils or electrodes or other tracking technology) or ultrasound marker 202 operable such that the tracking system 125 can calculate the position and orientation (about six degrees of freedom) of the catheter 105. The tracking information may be used in combination with the registering step 310 described above to align the series of partial view 3D or 4D images 102 to create the larger 3D or 4D image or model 112 with an extended or larger FOV.
According to another embodiment, the tracking system 125 may not track the position or orientation of the ICE catheter 105. The controller 134 can assemble the series of acquired partial view 3D or 4D image data 102 by matching of speckle, boundaries, and other features identified in the image data.
An embodiment of step 380 can include creating a display 385 of the acquired real-time, partial views of 3D or 4D ultrasound image data 102 of the anatomical structure acquired by the ICE imaging system 140 in combination with the fluoroscopic image data 144 acquired with the fluoroscopic imaging system 142. One embodiment of step 380 includes combining the general-real-time 4D ultrasound surface model 112 generated by the ICE imaging system 140 in fused or superimposed relation with general real-time 2D fluoroscopic image data 144 acquired by the fluoroscopic imaging system 142 during movement of the catheter 105 or ablation catheter 184 through the imaged subject 110. The combination (e.g., overlapping, fusing, superposition, etc. or combination thereof) and order of combination (e.g., on top, on bottom, intermediate) can vary.
The above-described display 385 can further include one or more of the following: graphic representation(s) 390 of the locations (e.g., historical, present or future or combination thereof) and identifications of the ICE catheter 105 or ablation catheter 184 relative to the acquired 3D or 4D image data or 3D or 4D models 112 generated therefrom of the imaged anatomy; a graphic representation 400 of the imaging plane vector 181 representative of a general direction of the field of view (FOV) of the ICE catheter 105; selection of a target anatomical site 405 (e.g., via input instructions from the user) at the graphically illustrated surface 410 of the generated 3D or 4D model 390 of the imaged anatomy. An embodiment of step 380 can further include creating a graphic illustration of a distance 415 between the catheter 105 (or component thereof) relative to the illustrated anatomical surface 410, or a graphic illustration of a path 420 of the ICE catheter 105 or ablation catheter 184 delivery to the target anatomical site 405.
An embodiment of the displaying step 380 can also include illustrating the cardiac and respiratory cycles 208, 210 synchronized relative to point of time of acquisition or time of update of the displayed fluoroscopic and ultrasound image data 102, 112. One embodiment of the step 380 includes displaying of the 4D ICE model 112 synchronized with the cardiac or respiratory signals 208 and 210 can be represented as the following sequence of image frames [T(ice.3D->wcs)].t1, [T(ice.3D->wcs)].t2, . . . , and [T(ice.3D->wcs)].tn according to a cardiac phase t1, t2, . . . , and tn.
The technical effect of the subject matter described herein is to enable intraoperative tracking and guidance in the delivery of at least one instrument (e.g., ICE catheter 105 or ablation catheter 184) through an imaged subject 110 based on acquisition of ultrasound imaging information in combination with fluoroscopic imaging information. By integrating the 4D ICE ultrasound image data with the tracking system 125, the field of view of image data acquired by the imaging catheter 105 is enhanced. The subject matter described herein can accelerate the 4D ICE registration process with other pre-operative and intraoperative images, and can enable pre-operative surgical planning and intraoperative instrument catheter guidance. The hybrid of electromagnetic and ultrasound tracking system 125 described above can further improve reliability, usability, and accuracy. The system 100 can also provide the 4D view of anatomical structures, fast registration with other pre-operative and intraoperative images, surgical planning capability, and intraoperative surgical device guidance.
Embodiments of the subject matter described herein include method steps which can be implemented in one embodiment by a program product including machine-executable instructions, such as program code, for example in the form of program modules executed by machines in networked environments. Generally, program modules include routines, programs, objects, components, data structures, etc. that perform particular tasks or implement particular abstract data types. Machine-executable instructions, associated data structures, and program modules represent examples of computer program code for executing steps of the methods disclosed herein. The particular sequence of such computer- or processor-executable instructions or associated data structures represent examples of corresponding acts for implementing the functions described in such steps.
Embodiments of the subject matter described herein may be practiced in a networked environment using logical connections to one or more remote computers having processors. Logical connections may include a local area network (LAN) and a wide area network (WAN) that are presented here by way of example and not limitation. Such networking environments are commonplace in office-wide or enterprise-wide computer networks, intranets and the Internet and may use a wide variety of different communication protocols. Those skilled in the art will appreciate that such network computing environments will typically encompass many types of computer system configurations, including personal computers, hand-held devices, multi-processor systems, microprocessor-based or programmable consumer electronics, network PCs, minicomputers, mainframe computers, and the like. Embodiments of the subject matter described herein may also be practiced in distributed computing environments where tasks are performed by local and remote processing devices that are linked (either by hardwired links, wireless links, or by a combination of hardwired or wireless links) through a communications network. In a distributed computing environment, program modules may be located in both local and remote memory storage devices.
This written description uses examples to disclose the subject matter, including the best mode, and also to enable any person skilled in the art to make and use the subject matter described herein. Accordingly, the foregoing description has been presented for purposes of illustration and description, and is not intended to be exhaustive or to limit the subject matter to the precise form disclosed, and modifications and variations are possible in light of the above teachings or may be acquired from practice of the subject matter described herein. The patentable scope of the subject matter is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.

## Claims

1. A system to image an imaged subject, comprising:
an ultrasound imaging system including an imaging probe operable to move internally and acquire ultrasound image data of the imaged subject during an ultrasound image acquisition interval, the imaging probe including a first marker and a second marker, the first marker having a first pattern and the second marker having a second pattern that is different than the first pattern;
a fluoroscopic imaging system operable to acquire fluoroscopic image data of the imaged subject during the ultrasound image acquisition interval of the ultrasound imaging system;
a controller in communication with the ultrasound imaging system and the fluoroscopic imaging system, the controller configured to automatically track a location of the image probe using information received from the first and second markers; and
a display in communication with the controller, the display displaying during the ultrasound image acquisition interval, the ultrasound imaged data acquired with the imaging probe during the ultrasound image acquisition interval fused with the fluoroscopic imaging data acquired by the fluoroscopic imaging system during the ultrasound image acquisition interval.

2. The system of claim 1, wherein the imaging probe includes an intracardiac echocardiography (ICE) catheter having a transducer array rotational about a longitudinal axis of the catheter and operable to acquire the ultrasound image data of the imaged subject.

3. The system of claim 2, wherein the display includes a graphic representation of a location of a target site relative to the ultrasound and fluoroscopic image data per instructions received at the controller.

4. The system of claim 3, wherein the display includes a graphical illustration of a path of the imaging probe that leads to the target site of the imaged subject.

5. The system of claim 2, wherein the controller is operable to identify a location and an identification of a ablation tool marker in the acquired ultrasound image data, the ablation tool marker attached at an ablation catheter, and to generate a graphic representation of the identification and the location of the ablation catheter relative to the acquired fluoroscopic image data for illustration in the display.

6. The system of claim 5, wherein the display further includes a graphic illustration of a distance between the imaging probe relative to an anatomical surface of an imaged anatomy of the imaged subject.

7. The system of claim 6, wherein the display further includes an illustration of the cardiac cycle or the respiratory cycle synchronized relative to a point of time of acquisition of updates the ultrasound and fluoroscopic image data of the imaged anatomy continuously or periodically acquired and combined in the display.

8. The system of claim 7, wherein the marker is integrated in a construction of the imaging probe, and wherein the marker includes a metallic object representative of a unique identifier detectable in the fluoroscopic image data acquired by the fluoroscopic image system.

9. The system of claim 1, wherein an ultrasound reference frame defines a spatial relation of the ultrasound image data, and a fluoroscopic reference frame defines a spatial relation of the fluoroscopic image data, and the controller registers the ultrasound reference frame relative to fluoroscopic reference frame.

10. The system of claim 1, wherein the ultrasound image data and the fluoroscopic image data are acquired simultaneously.

11. The system of claim 1, wherein the fluoroscopic image data is acquired while the imaging probe is moved internally through the imaged subject.

12. The system of claim 1, wherein the imaging probe automatically follows a path of a second object located internally within the imaged subject.

13. The system of claim 1, wherein the first marker comprises a plurality of metallic objects arranged in the first pattern and the second marker comprises a plurality of metallic objects arranged in the second different pattern.

14. The system of claim 1, wherein the first and second markers comprise active targets.

15. The system of claim 1, further comprising at least one tracking element configured to receive a signal from the active targets, the controller configured to determine a location of the imaging probe based on the received signal.

16. The system of claim 1, wherein the first and second markers comprise passive targets.

17. A method of image acquisition of an imaged subject, the method comprising the steps of:
providing an ultrasound imaging system including an imaging probe in communication with a controller, the imaging probe including a first marker and a second marker, the first marker having a first pattern and the second marker having a second pattern that is different than the first pattern, the controller configured to automatically track a location of the image probe using information received from the first and second markers;
acquiring ultrasound image data of the imaged subject during an ultrasound image acquisition interval;
providing a fluoroscopic imaging system operable to acquire fluoroscopic image data of the imaged subject during the ultrasound image acquisition interval of the ultrasound imaging system; and
displaying the ultrasound imaged data acquired with the imaging probe during the ultrasound image acquisition interval fused with the fluoroscopic imaging data acquired by the fluoroscopic imaging system during the ultrasound image acquisition interval.

18. The method of claim 17, wherein the step of acquiring the ultrasound image data includes rotating a transducer array rotational about a longitudinal axis of the imaging probe, the imaging probe operable to acquire ultrasound image data of the imaged subject.

19. The method of claim 18, wherein step of displaying includes creating a graphic representation of a location of a target site relative to the ultrasound and fluoroscopic image data per instructions received at the controller.

20. The method of claim 19, wherein the step of displaying includes creating a graphical illustration of a path of the imaging probe that leads to the target site of the imaged subject.

21. The method of claim 18, wherein the controller is operable to identify a location and an identification of a marker attached at an ablation catheter in the acquired ultrasound image data, and to generate a graphic representation of the identification and the location of the ablation catheter relative to the acquired fluoroscopic image data for illustration in the display.

22. The method of claim 21, wherein the step of displaying further includes creating a graphic illustration of a distance between the imaging probe relative to an anatomical surface of the imaged anatomy of the imaged subject.

23. The method of claim 21, wherein the step of displaying further includes creating an illustration of a cardiac cycle or a respiratory cycle synchronized relative to a point of time of acquisition of updates continuously or periodically acquired and combined with the fluoroscopic image data of the imaged subject.

24. The method of claim 21, wherein the marker is integrated in a construction of the imaging probe, and wherein the marker includes a metallic object representative of a unique identifier detectable in the fluoroscopic image data acquired by the fluoroscopic imaging system.

25. The method of claim 17, wherein an ultrasound reference frame defines a spatial relation of the ultrasound image data, and wherein a fluoroscopic reference frame defines a spatial relation of the fluoroscopic image data, and further comprising the step of registering the ultrasound reference frame relative to fluoroscopic reference frame.

26. The method of claim 17 further comprising acquiring the fluoroscopic image data while the imaging probe is moved internally through the imaged subject.