Intracardiac echocardiography image reconstruction in combination with position tracking system

A system and method to display a four-dimensional (4D) model of an imaged anatomy is provided. The system comprises a controller, and an imaging system including an imaging probe in communication with the controller. The imaging probe can acquire generally real-time, 3D image data relative to a direction of image acquisition along an imaging plane. The system also includes a tracking system in communication with the controller. The tracking system includes at least one tracking element integrated with the imaging probe. The system is operable to process the generally real-time, 3D image data acquired by the imaging probe relative to generally real-time tracking information acquired by the tracking system so as to display the 4D model of the imaged anatomy.

BACKGROUND

The subject matter herein generally relates to medical imaging, and more specifically, to a system and method to navigate a tool through an imaged subject.

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, thoracoscopic 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.

When performing a medical procedure, it is desired to calibrate or align the acquired image data of the imaged subject with the tracked tool so as to navigate through the imaged subject. Yet, the sensors to the track the tool and the detectors to acquire the image data may not be precisely located due to manufacturing variation. 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 increasing the field of view of image data acquisition employed to generate three- or four-dimensional reconstruction of images to guide an interventional surgery procedure. In general, as a surgeon moves the medical instrument with respect to the patient's anatomy, virtual images of the instrument or object are displayed simultaneously relative to real-time acquired image data represented in the model of the patient's anatomy. Another technical effect of the system and method described herein of tracking includes readily tracking the spatial relationship of the medical instruments or objects traveling through an operating space of patient. 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 operable to generate a four-dimensional (4D) model of an imaged anatomy, the system comprising a controller and an imaging system including an imaging probe in communication with the controller. The 4D imaging probe is operable to acquire a real-time, 3D image data relative to a direction of image acquisition along an imaging plane. The system further includes a tracking system in communication with the controller. The tracking system includes at least one tracking element integrated with the 4D ultrasound imaging probe. The system is operable to process the real-time, 3D image data acquired by the imaging probe relative to generally real-time tracking information acquired by the tracking system to generate a 4D model of the imaged anatomy.

According to another embodiment, a method of image acquisition of an imaged anatomy is provided. The method comprises the steps of acquiring a series of partial view 3D image data with a 4D imaging probe defined by an image coordinate system and a time reference; tracking a position of the 4D imaging probe relative to the time reference and a tracking coordinate system; generating a 4D model of the imaged anatomy by merging the series of partial view 3D image data defined relative to the time reference; and displaying the 4D model in superposition with a representation of the tracked position of the imaging probe.

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.

DETAILED DESCRIPTION

FIG. 1generally illustrates an embodiment of a system100operable 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 (e.g., ultrasound) relative to tracked position information of an imaging probe (e.g., catheter105) traveling through the imaged subject110. Although the following description is in regard to a catheter, the type of probe (e.g., endoscope, laparoscope, etc. or combination thereof) can vary. One embodiment of the system100is operable to acquire the series of 3D or 4D ultrasound image data while simultaneously rotating and tracking a position and orientation of the catheter105through the imaged subject. From the acquired 3D or 4D ultrasound image data, a technical effect of the system100includes creating an illustration of a full-view, 4D model of a region of interest (e.g., a beating heart) so as to guide delivery of an instrument.

An embodiment of the system100generally includes an image acquisition system115, a steering system120, a tracking system125, an ablation system130, and an electrophysiology system132(e.g., a cardiac monitor, respiratory monitor, pulse monitor, etc. or combination thereof), and a controller or workstation134.

Still referring toFIG. 1, the image acquisition system115is generally operable to generate a three-dimensional, or four-dimensional image model corresponding to an area of interest of the imaged subject110. Examples of the image acquisition system115can include, but are not limited to, computed tomography (CT), magnetic resonance imaging (MRI), x-ray or radiation, positron emission tomography (PET), ultrasound (US), angiographic, fluoroscopic, and the like or combination thereof. The image acquisition system115can 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., angiographic systems, fluoroscopic systems, laparoscopic systems, endoscopic systems, etc.) during the medical procedure. Thus, the types of images acquired by the acquisition system115can be diagnostic or interventional.

An embodiment of the image acquisition system115includes a real-time, intracardiac echocardiography (ICE) imaging system140that employs ultrasound to acquire image data of the patient's anatomy and to merge acquired image data to generate a three-dimensional model of the patient's anatomy relative to time, generally herein referred to as a four-dimensional (4D) model or image. In accordance with another embodiment, the image acquisition system115is operable to fuse or combine acquired image data using above-described ICE imaging system140with pre-acquired or intra-operative image data or image models (e.g., two- or three-dimensional reconstructed image models) generated by another type of supplemental imaging system142(e.g., CT, MRI, PET, ultrasound, fluoroscopy, x-ray, etc. or combinations thereof).

FIG. 2illustrates one embodiment of the catheter105, herein referred to as an ICE catheter105. The illustrated embodiment of the ICE catheter105includes a transducer array150, a micromotor155, a drive shaft or other mechanical connection160between the micromotor155and the transducer array150, an interconnect165, and a catheter housing170.

According to the illustrated embodiment inFIG. 2, the micromotor155via the drive shaft160generally rotates the transducer array150. The rotational motion of the transducer array150is controlled by a motor control175of the micromotor155. The interconnect165generally refers to, for example, cables and other connections coupling so as to receive and/or transmit signals between the transducer array150with the ICE imaging system (shown inFIG. 1)105. An embodiment of the interconnect165is configured to reduce its respective torque load on the transducer array150and the micromotor155.

An embodiment of the catheter housing170generally encloses the transducer array150, the micromotor155, the drive shaft160, and the interconnect165. The catheter housing170may further enclose the motor control175(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 subject110. At least a portion of the catheter housing170that 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 array150and the housing170is 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 array150is 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 array150are electronically phased in order to acquire a sector image generally parallel to a longitudinal axis180of the catheter housing170. In operation, the micromotor155mechanically rotates the transducer array150about the longitudinal axis180. The rotating transducer array150captures a plurality of two-dimensional images for transmission to the ICE imaging system140(shown inFIG. 1). The ICE imaging system140(SeeFIG. 1) is generally operable to assemble the sequence or succession of acquired 2D images so as to generally produce or generate 3D image or reconstructed models of the imaged subject110.

Still referring toFIG. 2, the motor control175via the micromotor155generally regulates or controls the rate of rotation of the transducer array150about the longitudinal axis180of the ICE catheter105. For example, the motor control175can instruct the micromotor155to rotate the transducer array150relatively slowly to produce the 3D reconstructed image or model. Also, the motor control175can instruct the micromotor155to rotate the transducer array150relatively faster to produce a real-time, 3D reconstructed image or model, referred to as the 4D reconstructed image or model. The 4D reconstructed image or model can be defined to include the 3D reconstructed image or model correlated relative to a general instant in time or instantaneous time. The motor control175is also generally operable to vary the direction of rotation so as to generally create an oscillatory motion of the transducer array150. By varying the direction of rotation, the motor control175is operable to reduce the torque load associated with the interconnect165, thereby enhancing the performance of the transducer array150to focus imaging on specific regions within the range of motion of the transducer array150about the longitudinal axis180.

Referring back toFIG. 1, an embodiment of the steering system120is generally coupled in communication to control maneuvering (including the position or the orientation) of the ICE catheter105. The embodiment of the system100can include synchronizing the steering system120with gated image acquisition by the ICE imaging system140. The steering system120may be provided with a manual catheter steering function or an automatic catheter steering function or combination thereof. With selection of the manual steering function, a user manually aligns an imaging plane vector181(SeeFIG. 2) relative to a marker at the ICE catheter105shown on the 3D ICE reconstructed image or model, as well as directs the ICE catheter105to a target anatomical site. With selection of the automatic steering function, the controller134and/or steering system120or combination thereof estimates a displacement or a rotation angle182(SeeFIG. 2) relative to a reference (e.g., see ICE imaging reference frame discussed later) that is needed to aim the ICE imaging plane vector181(SeeFIG. 2) from the catheter105, passes position information of the ICE catheter105to the steering system120, and automatically drives or positions the ICE catheter105to continuously follow the delivery of a second instrument (e.g., an ablation catheter184of the ablation system130). The reference can vary.

Referring toFIGS. 1 and 3, the tracking system125is generally operable to track or detect the position of the tool or ICE catheter105relative to the acquired image data or 3D or 4D reconstructed image or model generated by the image acquisition system115, or relative to delivery of a second instrument or tool (e.g., ablation system130, electrophysiology system132).

As illustrated inFIG. 3, an embodiment of the tracking system125includes an array or series of microsensors or tracking elements185,190,195,200connected (e.g., via a hard-wired or wireless connection) to communicate position data to the controller134(SeeFIG. 1). Yet, it should be understood that the number of tracking elements185,190,195,200can vary. An embodiment of the system100includes intraoperative tracking and guidance in the delivery of the at least one catheter184of the ablation system130by employing a hybrid electromagnetic and ultrasound positioning technique. The hybrid electromagnetic/ultrasound positioning technique facilitates dynamic tracking by locating tracking elements or dynamic references185,190,195,200, alone or in combination with ultrasound markers202(e.g., comprised of metallic objects such brass balls, wire, etc.). The ultrasonic markers202may be active (e.g., illustrated in dashed line located at catheters105and184) or passive targets (e.g., illustrated in dashed line at imaged anatomy of subject110) (SeeFIG. 1). An embodiment of the ultrasound markers202can be located at the ICE catheter105and/or ablation catheter184(SeeFIG. 1) so as to be identified or detected in acquired image data by supplemental imaging system142and/or the ICE imaging system140. The tracking system125can be configured to selectively switch between tracking relative to electromagnetic tracking elements185,190,195,200or ultrasound markers202or simultaneously track both.

For sake of example and referring toFIG. 3, assume the series of tracking elements185,190,195,200includes a combination of transmitters or dynamic references185and190in communication or coupled (e.g., RF signal, optically, electromagnetically, etc.) with one or more receivers195and200. The number and type transmitters in combination with receivers can vary. Either the transmitters185and190or the receivers195and200can define the reference of the spatial relation of the tracking elements185,190,195,200relative to one another. An embodiment of one of the receivers195represents a dynamic reference at the imaged anatomy of the subject110. An embodiment of the system100(SeeFIG. 1) can be operable to register or calibrate the location (e.g., position and/or orientation) of the tracking elements185,190,195,200relative to the acquired imaging data by the image acquisition system115(SeeFIG. 1), and operable to generate a graphic representation suitable to visualize the location of the tracking elements185,190,195,200relative to the acquired image data.

The tracking elements185,190,195,200generally enable a surgeon to continually track the position and orientation of the catheters105or184(SeeFIG. 1) during surgery. The tracking elements185,190,195,200may 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 microsensors185,190,195,200include electromagnetic (EM) field generators having microcoils operable to generate a magnetic field, and one or more of the tracking elements185,190,195,200include an EM field sensor operable to detect an EM field. For example, assume tracking elements185and190include a EM field sensor operable such that when positioned into proximity within the EM field generated by the other tracking elements195or200is operable to calculate or measure the position and orientation of the tracking elements195or200in real-time (e.g., continuously), or vice versa, calculate the position and orientation of the tracking elements185or190.

For example, tracking elements185and190can include EM field generators attached to the subject110and operable to generate an EM field, and assume that tracking element195or200includes an EM sensor or array operable in combination with the EM generators185and190to generate tracking data of the tracking elements185,190attached to the patient110relative to the microsensor195or200in real-time (e.g., continuously). According to one embodiment of the series of tracking elements185,190,195,200, 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 and combination of EM field receivers and EM field generators can vary.

The field measurements generated or tracked by the tracking elements185,190,195,200can be used to calculate the position and orientation of one another and attached instruments (e.g., catheters105or184(SeeFIG. 1)) according to any suitable method or technique. In one embodiment, the field measurements tracked by the combination of tracking elements185,190,195,200can be digitized into signals for transmission (e.g., wireless, or wired) to the tracking system125or controller134. The controller134is generally operable to register the position and orientation information of the one or more tracking elements185,190,195,200relative to the acquired imaging data from ICE imaging system140or other supplemental imaging system142. Thereby, the system100is operable to visualize or illustrate the location of the one or more tracking elements185,190,195,200or attached catheters105or184(SeeFIG. 1) relative to pre-acquired image data or real-time image data acquired by the image acquisition system115(SeeFIG. 1).

Referring now toFIGS. 2 and 3, an embodiment of the tracking system125includes the tracking element200located at the ICE catheter105. The tracking element200is in communication with the receiver195. This embodiment of the tracking element200includes a transmitter that comprises a series of coils that define the orientation or alignment of the ICE catheter105about the rotational axis (generally aligned along the longitudinal axis180) of the ICE catheter105. The tracking element200can be located integrally with the ICE catheter105and can be generally operable to generate or transmit a magnetic field205to be detected by the receiver195of the tracking system125. In response to passing through the magnetic field205, the receiver195generates a signal representative of a spatial relation and orientation of the receiver195or other reference relative to the transmitter200. Yet, it should be understood that the type or mode of coupling, link or communication (e.g., RF signal, infrared light, magnetic field, electrical potential, etc.) operable to measure the spatial relation varies. The spatial relation and orientation of the tracking element200is mechanically pre-defined or measured in relation relative to a feature (e.g., a tip) of the ICE catheter105. Thereby, the tracking system125is operable to track the position and orientation of the ICE catheter105navigating through the imaged subject110.

Alternatively, the tracking elements185,190, or200can include a plurality of coils (e.g., Hemholtz coils) operable to generate a magnetic gradient field to be detected by the receiver195of the tracking system125and which defines an orientation of the ICE catheter105. An embodiment of the receiver195includes 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 elements185,190and200.

Referring back toFIG. 1, an embodiment of the ablation system130includes the ablation catheter184that is operable to work in combination with the ICE catheter105of the ICE imaging system140to deliver ablation energy to ablate or end electrical activity of tissue of the imaged subject110. An embodiment of the ICE catheter105can include or be integrated with the ablation catheter184or be independent thereof. An embodiment of the ablation catheter184can include one of the tracking elements185,190of the tracking system125described above to track or guide intra-operative delivery of ablation energy to the imaged subject110. Alternatively or in addition, the ablation catheter184can include ultrasound markers202operable to be detected from the acquired ultrasound image data generated by the ICE imaging system140. The ablation system130is generally operable to manage the ablation energy delivery to an ablation catheter184relative to the acquired image data and tracked position data.

Still referring toFIG. 1, an embodiment of an electrophysiological system(s)132is connected in communication with the ICE imaging system140, and is generally operable to track or monitor or acquire data of the cardiac cycle or respiratory cycle of imaged subject110. Data acquisition can be correlated to the gated acquisition or otherwise acquired image data, or correlated relative to generated 3D or 4D models created by the image acquisition system115.

An embodiment of the controller or workstation computer134can be generally connected in communication with and controls the image acquisition system115(e.g., the ICE imaging system140or supplemental imaging system142), the steering system120, the tracking system125, the ablation system130, and the electrophysiology system132so 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 of the imaged anatomy.

An embodiment of the controller134includes a processor220in communication with a memory225. The processor220can be arranged independent of or integrated with the memory225. Although the processor220and memory225are described located at the controller134, it should be understood that the processor220or memory225or portion thereof can be located at the image acquisition system115, the steering system120, the tracking system125, the ablation system130or the electrophysiology system132or combination thereof.

The processor220is generally operable to execute the program instructions representative of acts or steps described herein and stored in the memory225. The processor220can also be capable of receiving input data or information or communicating output data. Examples of the processor220can 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 memory225generally comprises one or more computer-readable media operable to store a plurality of computer-readable program instructions for execution by the processor220. The memory225can also be operable to store data generated or received by the controller134. 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, the remote computer properly views the connection as a computer-readable medium. Thus, any such a connection is properly termed a computer-readable medium.

As shown inFIG. 1, the controller134further includes or is in communication with an input device230and an output device240. The input device230can be generally operable to receive and communicate information or data from a user to the controller210. The input device230can include a mouse device, pointer, keyboard, touch screen, microphone, or other like device or combination thereof capable of receiving a user directive. The output device240is generally operable to illustrate output data for viewing by the user. An embodiment of the output device240can be operable to simultaneously illustrate or fuse static or real-time image data generated by the image acquisition system115(e.g., the ICE imaging system140or supplemental imaging system142) with tracking data generated by the tracking system125. The output device240is capable of illustrating two-dimensional, three-dimensional, and/or four-dimensional image data or combinations thereof through shading, coloring, and/or the like. Examples of the output device240include 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 system100, the following is a description of a method300(seeFIG. 4) of operation of the system100in relation to the imaged subject110. Although an exemplary embodiment of the method300is discussed below, it should be understood that one or more acts or steps comprising the method300could 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 memory225of the controller210for execution by the processor220or one or more of the image acquisition system115, the steering system120, the tracking system125, or the ablation system130or the remote computer station connected thereto via a network (wireless or wired).

Referring now toFIGS. 1 and 3and for sake of example, assume that the spatial relation and orientation of the image data acquired by the transducer array150of the ICE imaging system140is defined by an image coordinate system320referenced in predetermined spatial relation and orientation relative to the transducer array150(SeeFIG. 2) at the ICE catheter105. The image coordinate system320generally defines the spatial relation of voxels or pixels of image data relative to one another in the generated image frames or models generated by the ICE imaging system140in three-dimensions relative to time (i.e., four-dimensional model). Also, for sake of example, assume the tracking system125utilizes a tracking coordinate system325to define tracking spatial relation and orientation and movement of the tracking elements185,190,195, and200or respective catheters105and184relative to one another and to time. For example, the tracking coordinate system325references the orientation and spatial relation of the tracking element200at the ICE catheter105relative to one of the receiver or references185,190,195of the tracking system125. Also, for sake of example, assume the steering system130utilizes a mechanical or steering coordinate system330to define maneuvering and orientation of either or both of the catheters105and184relative to one another. The tracking system125may further employ an ultrasonic coordinate system332defined by ultrasonic markers202. Although these coordinate systems320and325and330can be described as Cartesian x-y-z coordinate systems, the type of coordinate systems320,325,330,332(e.g., polar, etc.) can vary. In addition, the location and orientation of the coordinate systems320,325,330,332can vary.

The controller134via the tracking system125is operable to track movement of the ICE catheter105in accordance with known mathematical algorithms programmed as program instructions of software for execution by the processor220of the controller134or by the tracking system125. An exemplary navigation software is INSTATRAK® as manufactured by the GENERAL ELECTRIC® Corporation, NAVIVISION® as manufactured by SIEMENS®, and BRAINLAB®.

Referring back toFIG. 1, having described registration of the ICE imaging system140with the tracking system125, the step of registering can further extend to registering the ICE imaging system140and tracking system125relative to other components of the system100, including the steering system120, ablation system130, or the electrophysiological system(s) (e.g., cardiac monitoring system, respiratory monitoring system, etc.)132, generally similar to the method of registering described above directed to the ICE imaging system140with the tracking system125.

Referring toFIGS. 1 through 4, the method300includes a step335of registering and/or calibrating the image acquisition system115(including the ICE imaging system140), the steering system120, the tracking system125, and the ablation system130with one another. An embodiment of the step335of calibrating and registering includes registering both an ICE imaging reference frame or ICE imaging catheter coordinate system (referred to later as “ice”)320relative to the mechanical reference frame or coordinate system330of the steering system (referred to later as “mcs”)130, and additionally registering the previous coordinate systems320,330relative to the electromagnetic microsensor or dynamic reference sensor frame or coordinate system (referred to later as “scs”)325. The above described registering events or coordinate transformations can be denoted as T(ice->scs) and T(mcs->scs), respectively.

An embodiment of the registering and/or calibrating step335includes the step of rigidly attaching at least one dynamic reference microsensor or tracking element185,190,195or200(SeeFIG. 2) at the imaged anatomy. An example of this step includes integrating the dynamic reference microsensor at the distal end of a (steerable) catheter (e.g., dynamic reference catheter)105(SeeFIG. 2), and delivering and anchoring the at least one dynamic reference tracking element185,190,195, or200(SeeFIG. 2) at the imaged organ, e.g. the heart. According to another embodiment, the dynamic reference can be independent and separate of the catheter105.

The dynamic reference microsensor185,190,195, or200establishes a so-called world coordinate system (world reference frame-dynamic reference microsensor) (wcs)340(SeeFIG. 3) that enables the system100to compensate for the respiratory and/or cardiac motion of the imaged organ in the display of the acquired generally real-time, 3D ultrasound image data or pre-operative or intra-operative image data acquired by the supplemental imaging system142. According to another example, the dynamic reference microsensor can be rigidly attached externally of the imaged subject110, e.g. the patient's chest such that the system100can compensate for motion of the imaged organ via synchronizing image acquisition relative to the respiratory and/or cardiac cycle of the imaged subject110tracked by the electrophysiology system132. The coordinate transformation from the tracking coordinate system325to the world coordinate system340can be denoted T(scs->wcs).

The embodiment of the method300further includes a step345of tracking (e.g., via the tracking system) a position or location of the at least one catheter105or184relative to the acquired image data. According to one embodiment of the method300, at least one instrument catheter105or184is integrated with a plurality of hybrid electromagnetic position microsensors185,190,195,200and ultrasonic markers202. The electromagnetic microsensors185,190,195,200and ultrasonic markers202can both be located and rigidly mounted on the at least one instrument catheter105or184. A computer image-processing program is operable to detect and mark positions of the ultrasonic markers202relative to the generated 3D or 4D ICE image model.

The controller134can be generally operable to align positions of the ultrasonic markers202with the tracking coordinate reference frame or coordinate system325. This registration information may be used for the alignment (calibration) between the tracking reference frame or coordinate system325and the ultrasonic marker reference frame or coordinate system332relative to the ICE imaging reference frame or coordinate system320. This information may also be used for detecting the presence of electromagnetic distortion or tracking inaccuracy.

An embodiment of the method300further includes a step355of acquiring image data (e.g., scan) of the anatomy of interest of the imaged subject110. An embodiment of the step of acquiring image data includes generating a series of partial-views358of 3D or 4D image data from real-time image data acquired while rotating the ICE catheter105around the longitudinal axis180(SeeFIG. 2) that extends through the center of the ICE catheter105. Image acquisition with the catheter105can include more general motion in addition to rotation of the transducer array150about axis180. The motor155can provide some range of rotation of the transducer array150to generate a 4D model112with an enhanced field of view. To image an entire “anatomy of interest” (e.g. an entire chamber of the heart), the imaging catheter105can be deflected, advanced, or retracted in addition to rotation of the transducer array150.

An embodiment of the image acquisition step355includes calculating positions or degree of rotation of the ICE catheter105about the longitudinal axis180. The image acquisition step355can further include synchronizing or gating a sequence of image acquisition relative to tracking data acquired by the hybrid tracking system125(e.g., tracking a location (e.g., position and/or orientation) relative to the acquired image data). In addition, the image acquisition step355can further include synchronizing or gating a sequence of image acquisition relative to measuring cardiac and respiratory signals by the electrophysiology system132.

According to one embodiment of the image acquisition step355, the ablation catheter184can be detected or is visible in the acquired image data by the ICE imaging system140. By “scribbling” the anatomical surface of the anatomy of interest with the at least one instrument catheter184relative to acquired tracking data of the location of the catheters105or184, the anatomical boundary may be enhanced to result in a more accurate surface model for image registration and surgical planning.

Referring toFIGS. 1 through 4, an embodiment of the method300further includes a step360of generating or reconstructing a full-view 3D or 4D model362from the sequence of generated partial-view 3D or 4D image views358relative to the world coordinate frame340established by the dynamic reference or tracking element185,190,195, or200. The 4D ICE imaging system140, the tracking system125, the steering system120, the cardiac and respiratory monitoring system132, and the 4D ICE imaging catheter105are generally involved in acquisition and reconstructing the full view 4D ICE model for the anatomy of the imaged subject110. The step360can include merging the series of partial 3D or 4D image views or views358(SeeFIG. 3) relative to acquired electrophysiology data (e.g., cardiac cycle, respiratory cycle) acquired by the electrophysiology system132. The step360can further include generating a display of the generated 3D or 4D model362(SeeFIG. 3) synchronized relative to electrophysiology signals364,366(seeFIG. 1).

An embodiment of the method300can further include a step370of acquiring or measuring location data of the ultrasonic markers202described above by detecting or identifying the voxels illustrative thereof in the acquired, real-time 3D or 4D ultrasound image data via the ICE imaging system140. An embodiment of the ultrasonic markers202can be configured to identify each of a series of tools or catheters105or184delivered through an imaged subject110. An embodiment of the pattern of the tracking elements185,190,195,200and/or ultrasonic markers202may be uniquely defined for different types of instrument catheters105or184for identification purposes. Dependent on the uniquely defined tracking elements185,190,195,200and/or ultrasonic markers202, the image acquisition system115, tracking system125or controller134or combination thereof can be operable to uniquely identify location and orientation of each of the tools or catheters105and184. An embodiment of the system100is operable to extract the location of voxels from the acquired image data correlated to the imaging of the ultrasonic markers202. In this way, the location of the ultrasonic markers202may be tracked with respect to the ICE catheter105or ablation catheter184, or vice versa.

An embodiment of the system100includes a software having image processing programs operable to extract the locations of the ultrasonic markers202from the acquired generally real-time, 3D or 4D ultrasound image data (e.g., partial views358), an electromagnetic distortion detection program using information from the 3D or 4D ultrasound image data, and the tracking program with instructions to execute steps of the hybrid tracking technique described above. According to one embodiment, the system100processes acquired 3D or 4D ICE image data to extract voxel positions of the ultrasonic markers202relative to the ablation catheter184. The system100also processes the acquired 3D or 4D ultrasound image data to generate a surface model of the imaged anatomy. The system100is also operable to calculate the vector181generally representative of a central direction of a field of view of the ICE imaging system140.

Referring toFIGS. 1 through 5, according to another embodiment, the system100includes a graphic user interface (GUI)371operable to facilitate image data acquisition and reconstruction of the 3D or 4D ICE model362, including display of a generally real-time 3D or 4D ICE image model362created from the acquired anatomical data; to display detected/identified locations or representations thereof of at least one instrument catheter105or184relative to the illustrated, real-time 3D or 4D ICE image model362; to display the vector181showing the general central direction of a field of view of the 3D or 4D ICE image model362; to receive an input of a selection of a target anatomical site relative to the 3D or 4D ICE image model362; to display a distance between the tip of the catheter105or184relative to an anatomical surface of the 3D or 4D ICE image model362; to display a path of delivery of the catheter105or184relative to a target anatomical site illustrated at the 3D or 4D ICE image model362; to display synchronization of image data acquisition to create the 3D or 4D ICE image model362relative to the signal of the tracked cardiac or respiratory cycle; and to receive input indicative of a selection between a manual and automatic steering function of the ICE catheter105.

According to one embodiment, the system100automatically conducts a 4D scan of the anatomy of interest of the imaged subject110. The controller134can calculate or estimate a number of the ICE scans needed to generate the full-view 4D model reconstruction. Based on the field of view (FOV) of the ultrasound transducer array150and a tracked starting position of the ICE catheter105, the system100is operable to calculate a set of orientations (e.g. T(mcs.p1->scs)T(scs->wcs), T(mcs.p2->scs)T(scs->wcs), . . . , T(mcs.pn->scs)T(scs->wcs) where p1, p2, and pn are different catheter orientations) of the ultrasound imaging plane181to conduct a full-view 4D scan in the dynamic reference sensor frame340. The controller134can also communicate signals representative of instructions to the steering system130that direct automatic maneuvering and rotating of the ICE catheter105to a series of imaging positions, e.g., T(mcs.p1->scs)T(scs->wcs), T(mcs.p2->scs)T(scs->wcs), . . . , and T(mcs.pn->scs)T(scs->wcs).

According to another embodiment, the ICE catheter105of the ICE imaging system140executes the full-view 3D or 4D ICE scan of the imaged anatomy according to received input instructions directed to manually drive the ICE catheter105into a series of imaging positions, as well as received input instructions directed to manually activate each event of image acquisition. Referring toFIG. 5, an embodiment of the GUI371facilitates the 3D or 4D ICE image acquisition via displaying representations372of a history of each position of the ICE catheter105or ablation catheter184at events of image acquisition, displaying a representation373of a current position of the ICE catheter105, and displaying a representation374of a next or future position or location of an image acquisition event by the ICE catheter105.

The 3D or 4D ICE image and catheter position acquisitions can be triggered at the preset cardiac and respiratory phase, e.g. t1, t2, . . . , tn. At a given catheter orientation (pi), the system100is operable to acquire and transform a series of ultrasound images relative to the world coordinate frame340, represented by [T(ice.pi->scs)T(scs->wcs)].t1, [T(ice.pi->scs)T(scs->wcs)].t2, . . . , and [T(mcs.pi->scs)T(ice->wcs)].tn.

Alternatively, the 3D or 4D ICE image acquisition may be conducted at a dynamic or variable rate optimized according to the imaged volume, desired ultrasound image quality, etc. With each acquired ultrasound image volume (or plane or beam), the system100records a current cardiac and respiratory phase (ti), and the current catheter or image position (pi).

Upon the completion of the full-view 3D or 4D scan, the system100can reconstruct the generated series of partial views358of 3D or 4D ultrasound image data at different catheter orientations and different cardiac cycle time or phase. By transforming or registering the partial views358of the acquired 3D or 4D ICE image data relative to the world coordinate frame340(seeFIG. 3), the system100can calculate the following transformations: [T(ice.p1->scs)T(scs->wcs)].t1, [T(ice.p1->scs)T(scs->wcs)].t2, [T(ice.p2->scs)T(scs->wcs)].t1, . . . , and [T(ice.pn->scs)T(scs->wcs)].tn.

To generate the full-view 3D or 4D ICE model362, an embodiment of the system100can group the partial views358of 3D or 4D ultrasound image data according the cardiac timing sequence, e.g. [T(ice.p1->scs)T(scs->wcs)].t1, [T(ice.p2->scs)T(scs->wcs)].t1, . . . , and [T(ice.pn->scs)T(scs->wcs)].t1at cardiac phase t1. A number of image processing techniques such as image smoothing, filtering, or averaging can be used to merge the series of partial views358to a full-view 3D or 4D ICE model362[T(ice.3D->wcs)].t1for the t1 cardiac phase or the respiratory phase.

The controller134is operable to repeat the above-described image reconstruction process to create a full-view 3D or 4D ICE model of the anatomic structure, denoted as [T(ice.3D->wcs)].t1, [T(ice.3D->wcs)].t2, . . . , and [T(ice.3D->wcs)].tn, for the rest of the cardiac phases or respiratory phases.

According to one embodiment of the system100and method300described herein, the controller134can control operation of the steering system120, the tracking system125, the ablation system130, and the electrophysiology monitoring system132, the ICE imaging system140and/or any supplemental imaging system142. Via the controller134, the system100is operable to process the acquired image data relative to the acquired real-time tracking information from the hybrid tracking system125and the cardiac and respiratory cycle information from the electrophysiology system132. The system100is further operable to generate full-view 3D or 4D ICE model of the imaged anatomy, register the acquired partial views358of the real-time 3D or 4D ICE image data with the generated full-view 3D or 4D model362or other pre-operative or intra-operative real-time non-ICE images375(e.g., MRI, CT, PET, etc.), and control the steering system120in maneuvering the ICE catheter105or ablation catheter184relative to the direction of the 3D or 4D ICE imaging plane181(or vice versa) (SeeFIG. 2).

Referring toFIGS. 1 through 5, the method300further includes a step380of generating a display385of the partial views358(SeeFIG. 3) of the general real-time 3D or 4D ICE image data superimposed or combined relative to one or more of the following: the full-view 4D ICE model362(SeeFIG. 3); one or more of an MRI, CT, PET, or other pre- or intra-operative images375; representations372,373,374(SeeFIG. 5) of the generally real-time tracked positions of the ICE catheter105or therapy catheter184(SeeFIG. 1); the cardiac and/or respiratory cycle data364,366(SeeFIG. 1) synchronized with a time of acquisition of the partial views358of the 3D or 4D ICE image data and positions of either catheter105or184; a preoperative surgical plan, including identifying and illustrating the surgical or ablation targets according to preoperative or intraoperative images375(e.g., EP information superimposed on the full-view 3D or 4D model362) (SeeFIG. 3); selection between manual and automatic catheter steering functions; and generating a display of the one or more locations of the surgical site on the full-view 3D or 4D ICE model362during delivery of the surgical treatment.

A technical effect of the embodiments of the system100and method300described above is to provide an image reconstruction algorithm that provides a full-view 4D image model of anatomic structure, fast registration of the acquired partial views358of the 3D or 4D ICE image data relative to other preoperative and intraoperative images375, capability to create the surgical plan that comprises graphic representations of historical locations, current locations, and future locations of image acquisition372,373,374(SeeFIG. 5), and intra-operative guidance to maneuver various devices, for example the diagnostic or therapeutic catheters105or184. The system100and method300also provide an integrated solution to create a full-view 3D or 4D ICE model362from the series of real-time partial 3D or 4D views358and catheter position information.

Another technical effect of the above-described system100and method300described above is an ability to register the 3D or 4D ICE imaging system140with the tracking system125or another type or supplemental imaging system142via execution of computer-readable program instructions stored and executable at the controller134. As described above, the controller134is operable to perform registration of the coordinate systems320,325,330,332,340relative to one another.

Another technical effect of the system100and method300described above is an ability to combine image data and models generated by the ICE imaging system140with a location of the ICE catheter105or ablation catheter184being tracked by tracking system125, all in combination with imaged data or models generated by another imaging system142, with an ability to compensate for deficiencies in the imaged data acquired with the ICE imaging system140. Accordingly, the system100and method300enhance tracking and guidance of the position and orientation of the catheter105or transducer array150navigating through the imaged subject110. The system100and method300also synchronize tracking and guidance of movement and orientation of the ICE catheter105or ablation catheter184associated with the ablation system130, with each other as well as with electrophysiological signals (e.g., respiratory cycle, cardiac cycle, etc.) as tracked by the electrophysiological system(s)132.

Technical effects of integrating the 4D ICE imaging system140with the tracking system125includes, inter alia, enhancement of the field of the view of the 4D ICE imaging catheter105, acceleration of the 4D ICE registration process with other pre-operative and intra-operative images, and enhancement of pre-operative surgical planning and intraoperative instrument catheter guidance.

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.