Patent Application
20090105579
This invention relates to methods, devices and systems for intra-operative three-dimensional image acquisition, the registration of a sequence of projection images to the three-dimensional reconstructed image data, and the display of diagnostic information registered to the three-dimensional reconstructed image data.
Interventional medicine is the collection of medical procedures in which access to the site of treatment is made by navigation through one of the subject's blood vessels, body cavities or lumens. Interventional medicine technologies have been applied to the manipulation of medical instruments such as guide wires and catheters which contact tissues during surgical navigation procedures, making these procedures more precise, repeatable, and less dependent on the device manipulation skills of the physician. Remote navigation of medical devices is a recent technology that has the potential to provide major improvements to minimally invasive medical procedures. Several presently available interventional medical systems for directing the distal end of a medical device use computer-assisted navigation and a display means for providing an image of the medical device within the anatomy. Such systems can display a projection or cross-section image of the medical device being navigated to a target location obtained from an imaging system such as x-ray fluoroscopy or computed tomography; the surgical navigation being effected through means such as remote control of the orientation of the device distal end and proximal advance of the medical device.
In a typical minimally invasive intervention diagnostic or functional data are collected from a catheter or other interventional devices that are of significant use in treatment planning, guidance, monitoring, and control. For example, in diagnostic applications right-heart catheterization enables pressure and oxygen saturation measure in the right heart chambers, and helps in the diagnosis of valve abnormalities; left-heart catheterization enables evaluation of mitral and aortic valvular defects and myocardial disease. In electrophysiology diagnostic applications, electrical signal measurements may be taken at a number of points within the cardiac cavities to map cardiac activity and determine the source of arrhythmias, fibrillations, and other disorders of the cardiac rhythm. For angioplasty therapeutic applications a number of interventional tools have been developed that are suitable for the treatment of vessel occlusions: guide wires and interventional wires may be proximally advanced and rotated to perform surgical removal of the inner layer of an artery when thickened and atheromatous or occluded by intimal plaque (endarterectomy). Reliable systems have evolved for establishing arterial access, controlling bleeding, and maneuvering catheters and catheter-based devices through the arterial tree to the treatment site.
Fluoroscopic x-ray imaging is the most widely used real-time imaging tool for minimally invasive medical interventions. Fluoroscopy allows immediate visualization of the interventional device progress within the patient's body lumens to the target volume. However significant limitations are associated with the use of x-ray projection imaging. Besides subjecting the patient and potentially the operator to possibly large radiation dose, fluoroscopy is limited by the noisy nature of the acquired images, and by the superimposition of three-dimensional anatomy onto a single plane inherent to projection imaging. The x-ray projection images present shadows of superimposed objects projected onto a single plane. To remedy these limitations, it is common to acquire pre-operative three-dimensional (3D) data by a modality such as computed tomography (CT) or ultrasound. While the pre-operative data provide an excellent 3D anatomical map of the region-of-interest at the time of the data acquisition, and therefore helps in planning the intervention, it is often difficult to register the projection information provided by the fluoroscopy to the pre-operative 3D reconstruction: the patient position with respect to the imaging chain might have changed; organs might have assumed a different shape or relative configuration as compared to the pre-operative acquisition; noise in the images renders the registration and registration evaluation difficult; and real-time demands put strict limits on the amount of computations that might be performed to bring two imaging modalities in registration. Additionally, both the pre-operative 3D CT or ultrasound data and the fluoroscopy images present anatomical information from which diagnostic information might be difficult or impossible to extract; changes due to disease processes might not appear conspicuously on an anatomical map such as provided by x-ray attenuation coefficients that depend mostly on electron density at diagnostic energies. Accordingly there is a need to develop techniques for intra-operative 3D imaging onto which clinical diagnostic data could be co-registered to guide the intervention more effectively and efficiently.
Techniques that have shown potential to help minimally invasive procedures include intra-operative x-ray CT, intra-operative 3D or 4D ultrasound imaging, including intravascular ultrasound (IVUS), optical imaging and optical tissue characterization, and magnetic resonance imaging (MRI). U.S. Pat. No. 6,351,513 issued to Bani-Hashemi et al. and assigned to Siemens Corporate Research, Inc., discloses a method of providing a high-quality representation of a volume having a real-time 3-D reconstruction therein of movement of an object, wherein the real-time movement of the object is determined using a lower-quality representation of only a portion of the volume. In particular U.S. Pat. No. 6,351,513 presents a method of determining the motion of a catheter from a low-quality fluoroscopic image by registering that projection data to a high-quality 3D angiographic reconstruction of the patients vessel. However it does not disclose nor suggest the use of intra-operative 3D data, nor the use of ultrasound imaging, nor the use of two modalities of similar image quality; nor does it teach or suggest the use of magnetic navigation or the co-registration of diagnostic information onto image data. U.S. Pat. No. 6,775,405 issued to Zhu and assigned to Koninkiijke Philips Electronics, N.V., discloses a method of performing image registration of images acquired by different modalities using cross-entropy optimization. U.S. Pat. No. 6,775,405 does not teach nor suggest the use of intra-operative 3D image data, nor does it teach or suggest the co-registration of diagnostic information onto image data.
The present invention addresses the need for intra-operative and preferably real-time 3D imaging of an interventional volume of interest, to which diagnostic and functional information of direct relevance to the intervention can be co-registered to help guide, monitor, and control surgery.
One object of the invention is to provide methods, devices and systems to perform a medical procedure utilizing diagnostically enhanced, intra-operative 3D image data set(s), the co-registered intra-operative data and diagnostic information being combined with a virtual or actual image of a remotely controlled navigation device into a real-time display. The 3D image data set can be acquired and reconstructed by various means including 3D X-ray rotational angiography, 3D/4D ultrasound, MRI or other appropriate imaging modality. The 3D reconstructed image data set is registered to the navigation system by various means and approaches depending on the imaging source. For example, a 3D X-ray image can be inherently registered due to a known, fixed mechanical alignment of the X-ray and navigation system, while a 3D ultrasound data set could be registered using a localization system that tracks the position and orientation of the imaging device tip relative to the navigation system. The remotely navigated interventional device is visualized directly by the 3D imaging device (e.g. ultrasound) or indirectly by a localization means and associated device model to derive the virtual appearance of the device in the reconstructed 3D data set. The 3D reconstruction can be a fused representation of the anatomy whereby a static or periodically refreshed volumetric anatomical reconstruction is formed using a sweep of the external or internal imaging device and then fused with a real-time representation of a portion (e.g. a wedge) of the anatomy. The 3D reconstruction presents regions or targets based upon diagnostic and functional information related to the anatomy, the diagnostic information having been acquired through various internal and external methods. For example, the navigation device can be advanced to positions along a vessel or cardiac chamber wall to gather diagnostic information which when processed can then be displayed as regions of activity or therapy targets on the organ wall. The imaging device in this case could be a 3D ultrasound catheter, the catheter location being directly extracted from the image. There are many types of diagnostic information that could be collected including but not limited to voltage, electrical timing, impedance, tissue content and characterization, and blood pressure and velocity. By combining a diagnostically enhanced 3D or 4D reconstructed data set with a rendition of a remotely controlled navigation device that can be displayed directly or virtually co-registered to the 3D or 4D image data, the methods and systems of the present invention enable an operator to efficiently diagnose conditions and deliver correspondingly appropriate therapy to a plurality of targeted points within the patient anatomy.
Corresponding reference numerals indicate corresponding points throughout the several views of the drawings.
As illustrated in
Sub-system 180 comprises controls and software necessary for the intra-operative acquisition of 3D images and the co-registered superposition of diagnostic and functional information onto the reconstructed 3D image data. In one embodiment of the invention, sub-system 180 processes commands from the user to trigger the acquisition of 3D image data, such as from a computed tomography scanner (not shown) or an IVUS ultrasound device. In one embodiment, an IVUS probe 128 is provided at or near the device distal end 124, and acquires a “wedge” of image data providing information regarding the condition of the vasculature and any existing wall or plaque condition; by rotating interventional IVUS probe 128, either by proximally rotating device 120 or through an IVUS probe rotation means provided within the device itself, a 3D map of ultrasound data may be acquired. The real-time “wedge” data may then be fused onto the 3D intra-operative image data, which in turn may be periodically refreshed by an additional scan image data acquisition. Three-dimensional image data are then processed by sub-system 180 and co-registered to interventional image data provided, for example, by fluoroscopy system 150. Additionally, sub-system 180 interfaces with navigation sub-system 170 such that diagnostic and/or functional information are displayed in co-registered fashion onto the intra-operative 3D data. For example, in electrophysiological applications, electrical activity measured by the interventional device can be displayed in a color rendition onto the 3D data; localization information acquired in real-time, together with co-registration of the interventional device to the imaging system 150 frame of reference, enables real-time display of a real or virtual device image co-registered with the intra-operative 3D image data and then co-registered to the diagnostic information. With respect to the present invention, it is convenient to distinguish intra-operative 3D image data from navigation image data. Although both sets of image data may be acquired by using a similar modality, as for example acquiring 3D intra-operative image data by use of an external probe sweep, and navigation image data by means of an IVUS probe, and although the navigation data may be reconstructed into part of a 3D image data set, the distinction allows separating the 3D image data specifically collected to represent the intra-operative anatomy and super-impose diagnostic data, while the navigation data provides direct and often real-time information with respect to the device distal end position, orientation, and immediate neighborhood. It is understood that implementation wherein both 3D intra-operative data and navigation image data are provided by the same instrument, as for example an external ultrasound system or a CT system, are included within the scope of the present invention.
Many other situations where co-registered diagnostic information presented on intra-operative 3D data will help improve intervention efficiency, success rates, and eventually patient outcomes, are not illustrated but are within the scope of this invention. For example, the intra-operative image data could be 3D or 4D; with a periodic 3D image data refresh, either driven by a predetermined time schedule or by intervention-specific events, such as the progress of the interventional device to pre-determined anatomical features or tissue targets; or changes in monitored diagnostic information. Availability of at least one 3D intra-operative data set ensures that better morphological information is obtained as compared to any pre-operative data acquired by a similar procedure. Data set matching and co-registration is aided by effective localization tools, as match image measures tend to be evaluated in a smaller neighborhood of the optimum, and therefore many local extrema in the registration algorithm may be avoided. For illustration, image matching techniques have been previously developed to co-register and co-represent ultrasound image frames acquired by a moving probe in an extended, seamless field of view: in this setting, the problem reduces to that of finding the similarity transformation (parameters: translation, rotation, scaling) that minimizes the mean-squared error between candidate match points; other image measures may include the minimum of the sum of absolute differences or similar mathematical distance measures. While registration methods of images from a similar modality, such as x-ray fluoroscopy projections to CT image data or ultrasound frame to frame have been known in the art for more than a decade, more recently specific techniques such a mutual image information have been proposed to effect co-registration of images acquired by different modalities. Mutual information or relative entropy measures the statistical dependence or information redundancy between the image intensities of corresponding voxels in both images, which is assumed to be maximal if the images are geometrically aligned. Initial results indicate that sub-voxel accuracy may be achieved completely automatically and without any prior segmentation, feature extraction, or other preprocessing steps.
Further, it is understood that a wide range of diagnostic functional information may be acquired in minimally invasive procedures and might be available to guide an intervention to specific target points representative of various types of dysfunctions. Electrophysiology depends critically on electrical mapping of the heart to determine areas of abnormally placed secondary pacemaker driving the heart at a higher rate than normal, re-entry circuits, or heart blocks. Arrhythmias can originate from an ectopic focus or center that may be located at any point within the heart. Disturbances in the cardiac rhythm also originate from the formation of a disorganized electrical circuit, called “re-entry” and resulting in a reentrant rhythm, usually located within the atrium, at the junction between an atrium and a ventricle, or within a ventricle. In a reentrant rhythm, an impulse circulates continuously in a local, damaged area of the heart, causing irregular heart stimulation at an abnormally high rate. Finally various forms of heart blocks can form, preventing the normal propagation of the electrical impulses through the heart, slowing down or completely stopping the heart. Heart blocks originate in a point of local heart damage, and can be located within a chamber, or at the junction of two chambers. The determination of tissue impedance as a guide to tissue ablation, and particularly left atrium ablation around the pulmonary vein ostia, has been shown to be of significant help in guiding the procedure and ensuring a higher success rate. In PCI applications, classification of plaque as for example using ultrasound imaging or optical imaging or characterization, are known to be predictor of interventional success.
Although the method has been illustrated for magnetic navigation applications, it is clear that it may also be applied in conjunction with other means of navigation. For example, the navigation means may comprise mechanical actuation, as per use of a set of pull-wires that enable distal device bending, by itself or in conjunction with proximal device advance and rotation. The navigation means may also comprise other techniques known in the art, such as electrostrictive device control. Further navigation means may comprise combination of the above methods, such as combination of magnetic and electrostrictive navigation, combination of mechanical and electrostrictive navigation, or combination of magnetic and mechanical navigation.
The advantages of the above described embodiments and improvements should be readily apparent to one skilled in the art, as to enabling intra-operative three-dimensional data acquisition and display, display of diagnostic or functional information co-registered to the three-dimensional intra-operative data, and real-time display of an actual or virtual image of the interventional device co-registered with the three-dimensional anatomical image showing diagnostic information. Additional design considerations may be incorporated without departing from the spirit and scope of the invention. Accordingly, it is not intended that the invention be limited by the particular embodiment or form described above, but by the appended claims.
This application claims priority to U.S. Provisional Patent Application Ser. No. 60/981,472 filed Oct. 19, 2007. The disclosure of the above-referenced application is incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 60981472 | Oct 2007 | US |
