Three Dimensional Co-Registration for Intravascular Diagnosis and Therapy
A method and system are disclosed for creating, in a coordinated manner, graphical images of a body including vascular features from a combination of image data sources. The method includes initially creating an angiographic image of a vessel segment. The angiographic image is, for example, either a two or three dimensional image representation. Next, a vessel image data set is acquired that is distinct from the angiographic image data. The vessel image data set comprises information acquired at a series of positions along the vessel segment. An example of such vessel image data is a set of intravascular ultrasound frames corresponding to circumferential cross-section slices taken at various positions along the vessel segment. The angiographic image and the vessel image data set are correlated by comparing a characteristic rendered independently from both the angiographic image and the vessel image data at positions along the vessel segment.
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This application claims priority of Walker et al. U.S. provisional application Ser. No. 60/694,014 filed on Jun. 24, 2005, entitled “Three-Dimensional Co-Registration for Intravascular Diagnosis and Therapy”, the contents of which are expressly incorporated herein by reference in their entirety including the contents and teachings of any references contained therein.
AREA OF THE INVENTIONThe present invention generally relates to imaging blood vessels. More particularly, the present invention is directed to methods and systems for generating composite displays generally including at least a first graphical image rendered from a first type of data and a second graphical image rendered from a second type of data. A particular example of such composite graphical display comprises a graphically displayed three dimensional angiogram that is displayed in combination with a second graphical image created from IVUS information.
BACKGROUND OF THE INVENTIONAtherosclerosis is treated in arteries of the heart, head, neck and peripheral portions of the body using many different methods. The most popular methods, such as angioplasty, bare metal stenting, drug eluting stenting (permanently implantable and biodegradable), various types of energy delivery and rotational atherectomy, all treat an artery equally around the circumference of a target length of the arterial lumen. These devices are generally circumferentially symmetric, and cannot selectively treat one circumferential sector of the targeted length of the artery any different from another. Almost always, the targeted length of the artery identified for treatment is determined using angiography, which graphically depicts a vessel lumen, or intravascular ultrasound (IVUS), which graphically depicts the atherosclerotic plaque itself. With IVUS, the thickness of the atherosclerotic plaque can be determined along the length of the diseased area and at specific radial positions around its circumference. More often than not, the plaque is eccentric and thus varies in thickness at particular positions of a circumferential cross-sectional of the vessel. Treatment of plaque using the aforementioned circumferentially symmetric methods can sometimes cause undesired results. For example, drug eluting stents deliver drugs that inhibit neo-intimal proliferation (known as restenosis). In the section of artery where the stent is expanded, any normal (non-diseased) portion of vessel may not benefit from getting the same dosage of drug as the diseased portion.
Some methods for treating atherosclerosis, such as directional athrectomy, needle aided drug injection or certain types of brachytherapy (radiation), can actually vary the treatment along different circumferential sectors of the artery. The catheters used for these treatment methods are typically circumferentially asymmetric and have at least a portion that is torquable (rotatable), and thus able to be steered into a desired circumferential orientation. However, effective use of the asymmetric treatments is difficult because of certain characteristics of current imaging methods. For example, because angiography only shows an image of the lumen of the blood vessel, it is impossible to identify exactly where, in a particular circumferential cross-section, the atherosclerotic plaque is located and the plaque's thickness. IVUS does make it possible to view the circumferential location and thickness of atherosclerotic plaque in a length of a vessel, but unless the ultrasonic transducer is attached to the actual treatment device, it is difficult to use the IVUS image to direct the treatment catheter with precision. This is especially difficult in coronary arteries, where heart motion adds error. Attempts to include transducers on the treatment catheter have been moderately successful (U.S. Pat. No. 6,375,615 to Flaherty) but the additional components make it more difficult to build a small catheter, which is flexible and can track easily in the artery. Some other catheters have been developed (U.S. Pat. Nos. 4,821,731 and 5,592,939, both to Martinelli) which can combine IVUS imaging with tip positioning technology. This enables displaying a three dimensional graphical representation of the plaque, including any tortuosity inherent in the artery. However, additional capital equipment is required in the procedure room to perform this type of imaging and adds cost to performing the procedure.
Most of the methods described above are predominantly used to improve blood flow in stenosed areas of the artery, thus allowing for better delivery of blood to downstream tissue. Recently, more attention has been paid to vulnerable plaque—plaque that is prone to rupture, even though it may not actually be a stenotic lesion that limits flow prior to rupture. This is especially critical in coronary arteries, where a lesion rupture, combined with thrombosis, can cause a serious or even fatal myocardial infarction (heart attack). The lesion rupture can actually cause material, such as tissue factor, to dump out of the plaque, into the bloodstream, forcing the blood into a hypercoagulable state. Currently, angiography is of limited value in identifying vulnerable plaque, because this plaque is often non-stenotic, and looks similar to the normal vessel on an angiogram. New tissue characterization methods associated with IVUS (U.S. Pat. No. 6,200,268 to Vince and U.S. Pat. No. 6,381,350 to Klingensmith, as well as U.S. patent application Ser. Nos. 10/647,977, 10/649,473 and 10/647,971) show promise for identifying vulnerable plaque, and a patient having a significant amount of vulnerable plaque. There are currently no standard methods to treat patients having vulnerable plaque once such patients are identified.
SUMMARY OF THE INVENTIONCreating, in a coordinated manner, graphical images of a body including vascular features from a combination of image data sources, in accordance with the present invention, comprises initially creating an angiographic image of a vessel segment. The angiographic image is, for example, either a two or three dimensional image representation. Next, a vessel image data set is acquired that is distinct from the angiographic image data. The vessel image data set comprises information acquired at a series of positions along the vessel segment. An example of such vessel image data is a set of intravascular ultrasound frames corresponding to circumferential cross-section slices taken at various positions along the vessel segment. The angiographic image and the vessel image data set are correlated by comparing a characteristic rendered independently from both the angiographic image and the vessel image data at positions along the vessel segment.
The aforementioned steps are performed in a variety of imaging environments/modalities to render a broad variety of graphical displays of three-dimensional image data for carrying out a variety of diagnostic and treatment regimens including, for example, balloon angioplasty and atherectomy procedures.
While the claims set forth the features of the present invention with particularity, the invention, together with its objects and advantages, may be best understood from the following detailed description taken in conjunction with the accompanying drawing of which:
In
In accordance with an aspect of an imaging system embodying the present invention, IVUS images are co-registered with the three-dimensional image depicted on the graphical display 160. Fiduciary points are selected when the imaging catheter is at one or more locations, and by combining this information with pullback speed information, a location vs. time (or circumferential cross-sectional image slice) path is determined for the imaging probe mounted upon the catheter. Co-registering cross-sectional IVUS with three-dimensional images of the type depicted in
Turning to
Turning to
In the case of live two-dimensional or three-dimensional co-registration, one or more fiduciary points are selected first, followed by alignment by the system, and then simultaneous pullback and angiography or fluoroscopy. Note that in both co-registration in playback mode and co-registration in “live” mode, the information used by the system includes both the specific pullback speed being used (for example 0.5 millimeters per second) and the time vector of the individual image frames (for example IVUS image frames). This information tells the system where exactly the imaging element is located longitudinally when the image frame is (or was) acquired, and allows for the creation of an accurate longitudinal map.
Automatic fiduciary points are used, for example, and are automatically selected by the system in any one of multiple potential methods. A radiopaque marker on the catheter, approximating the location of the imaging element, for example is identified by the angiography system, creating the fiduciary point. Alternatively, the catheter has an electrode, which is identified by three orthogonal pairs of external sensors whose relative locations are known. By measuring field strength of an electrical field generated by the probe, the location of the electrode is “triangulated”.
Arteries also have side branches which can be identified with imaging techniques such as standard IVUS imaging, or IVUS flow imaging (which identifies the dynamic element of blood). The side branches are potentially used as fiduciary points for axial, circumferential and even radial orientation of the IVUS information, with respect to an angiographic base image, which also contains side branch information.
Turning to
Furthermore, as those skilled in the art will readily appreciate, the line graphs in
A lumen border 380 is also shown in
The best axial fit for establishing co-registration between angiogram and IVUS data is obtained where the following function is a minimum.
with ALumen=IVUS lumen area for frames n=1, N and
AAngio angiography area for “frames” n=1, N (sections 1-N along the length of an angiographic image of a blood vessel). By modifying how particular portions of the angiographic image are selected, the best fit algorithm can perform both “skewing” (shifting all slices a same distance) and “warping” (modifying distances between adjacent samples).
Using the axial alignment of frames where the summation function is a minimum, a desired best fit is obtained.
Positioning an IVUS frame on a proper segment of a graphical representation of a three-dimensional angiographic image also involves ensuring proper circumferential (rotational) alignment of IVUS slices and corresponding sections of an angiographic image. Turning to
Having described an illustrative way to co-register angiographic and IVUS images for graphically representing a three-dimensional image of a vessel, attention is directed to
With continued reference to
Turning to
The catheter in
The invention described herein is not limited to intravascular applications or even intraluminal applications. Tissue characterization is also possible in cancer diagnostics, and it is conceivable that a probe that images for cancer can also be used in conjunction with a three-dimensional map to create a similar reconstruction as that described above. This can be used to guide biopsy or removal techniques. Such cancers include, but are not limited to: prostate, ovarian, lung, colon and breast. In the intravascular applications, both arterial and venous imaging is conceived. Arteries of interest include, by way of example: coronaries, carotids, superficial femoral, common femoral, iliac, renal, cerebral and other peripheral and non-peripheral arteries.
The intravascular ultrasound methods described can also be expected to be applicable for other ultrasound applications, such as intracardiac echocardiography (ICE) or transesophageal echocardiography (TEE). Therapeutic techniques that are guided by these techniques include, but are not limited to, patent foramen ovale closure, atrial septal defect closure, ventricular septal defect closure, left atrial appendage occlusion, cardiac biopsy, valvuloplasty, percutaneous valve placement, trans-septal puncture, atrial fibrillation ablation (of pulmonary veins or left atrium, for example) and TIPS (transjugular intrahepatic portosystemic shunt for pulmonary hypertension).
Similar to the selective use of directional atherectomy and stenting/drugs in the circumferential, radial and axial orientations, the other energy delivery methods can also be manipulated as such. For example, in a thicker plaque, a higher power can be used in a cryogenic cooling catheter, etc. In addition, image guided automatic feedback can be used to automatically determine when to apply energy and when to stop applying energy, based on the information in the reconstruction. This is particularly of use in radiofrequency ablation of pulmonary veins for treatment of atrial fibrillation.
All of the image guided therapy described in this invention, can be conceived to be a combination of imaging and therapy on the same catheter, or to be two or more different catheters, each specialized in its use.
All of the techniques described here can also be used in conjunction with external imaging technologies such as MRI, CT, X-ray/angiography and ultrasound. Three dimensional reconstructions, for example from CT or MRI, can be co-registered with the imaging information in the same way as angiography.
The three-dimensional mapping of imaging information can also be combined with a three dimensional mapping of the electrical activity of the heart, for example, from information obtained from catheter-based electrodes. This is of use in a patient that has had an acute myocardial infarction.
It is also conceivable to include three-dimensional fluid mechanics analysis in the reconstruction so that points of high stress are identified.
The structures, techniques, and benefits discussed above, for illustrative systems embodying the present invention, are exemplary. In view of the many possible embodiments to which the principles of this invention may be applied, it should be recognized that the embodiments described herein with respect to the drawing figures are meant to be illustrative only and should not be taken as limiting the scope of the invention. Therefore, the invention as described herein contemplates all such embodiments as may come within the scope of the following claims and equivalents thereof.
Claims
1-22. (canceled)
23. A method, comprising:
- obtaining angiographic image data of a vessel segment from an imaging device positioned external to the vessel segment;
- creating a three-dimensional image of the vessel segment based upon the obtained angiographic image data;
- obtaining intravascular ultrasound (IVUS) image data of the vessel segment from an imaging device positioned within the vessel segment, wherein the IVUS image data comprises a series of intravascular images acquired as the imaging device positioned within the vessel segment is moved through and along the vessel segment;
- correlating the IVUS image data to the three-dimensional image of the vessel such that each of the images of the series of intravascular images of the IVUS image data is correlated to a portion of the three-dimensional image of the vessel created based upon the obtained angiographic image data, wherein correlating the IVUS image data to the three-dimensional image of the vessel includes aligning the images of the series of intravascular images of the IVUS image data both axially and circumferentially to the corresponding portions of the three-dimensional image of the vessel; and
- rendering simultaneously on a display an image of the series of intravascular images of the IVUS image data and at least the correlated portion of the three-dimensional image of the vessel as determined by the correlating step.
24. The method of claim 23, wherein time vectors of the series of intravascular images and a pullback speed of the imaging device are utilized to axially align the images of the series of intravascular images of the IVUS image data with the three-dimensional image of the vessel.
25. The method of claim 23, wherein the lumen measurement is a cross-sectional area.
26. The method of claim 25, wherein determining the best fit between the cross-sectional area of the vessel segment as depicted in the images of the series of intravascular images of the IVUS image data and the cross-sectional area of the vessel segment as depicted in the three-dimensional image of the vessel segment based on the obtained angiographic image data comprises determining a minimum of the sum of the squared differences between the cross-sectional area of the vessel segment as depicted in the images of the series of intravascular images of the IVUS image data and the cross-sectional area of the vessel segment as depicted in the three-dimensional image of the vessel segment based on the obtained angiographic image data.
27. The method of claim 25, wherein determining the best fit between the cross-sectional area of the vessel segment as depicted in the images of the series of intravascular images of the IVUS image data and the cross-sectional area of the vessel segment as depicted in the three-dimensional image of the vessel segment based on the obtained angiographic image data comprises determining a minimum of ∑ n = 1 N ( A IVUS - A Angio ) 2, where AIVUS is the cross-sectional area of the vessel as depicted in images 1 to N of the series of intravascular images of the IVUS image data and AAngio is the cross-sectional area of the vessel as depicted in the three-dimensional image of the vessel segment based on the obtained angiographic image.
28. The method of claim 23, wherein the images of the series of intravascular images of the IVUS image data are axially aligned with the three-dimensional image of the vessel by applying a skewing displacement.
29. The method of claim 23, wherein the images of the series of intravascular images of the IVUS image data are axially aligned with the three-dimensional image of the vessel by applying a warping displacement.
30. The method of claim 31, wherein the images of the series of intravascular images of the IVUS image data are circumferentially aligned with the three-dimensional image of the vessel based on a best angular fit.
31. The method of claim 30, wherein the best angular fit is determined for a plurality of the images of the series of intravascular images of the IVUS image data.
32. The method of claim 30, wherein the best angular fit is determined for each of the images of the series of intravascular images of the IVUS image data.
33. The method of claim 30, wherein a degree of rotation between adjacent images of the series of intravascular images of the IVUS image data is limited.
34. The method of claim 33, wherein the degree of rotation between adjacent images of the series of intravascular images of the IVUS image data is limited by a spline fit.
35. The method of claim 33, wherein the degree of rotation between adjacent images of the series of intravascular images of the IVUS image data is limited by a cubic polynomial fit.
36. The method of claim 23, wherein each of the images of the series of intravascular images of the IVUS image data is correlated to a portion of the three-dimensional image of the vessel created based upon the obtained angiographic image data in a live mode.
37. The method of claim 36, wherein the angiographic image data and the IVUS image data are obtained simultaneously.
38. The method of claim 23, wherein each of the images of the series of intravascular images of the IVUS image data is correlated to a portion of the three-dimensional image of the vessel created based upon the obtained angiographic image data in a playback mode.
39. The method of claim 23, wherein the angiographic image data and the IVUS image data are obtained simultaneously.
40. The method of claim 39, further comprising aligning the imaging device positioned external to the vessel segment with the imaging device positioned within the vessel segment using at least one fiduciary point.
41. The method of claim 40, wherein the at least one fiduciary point is a marker associated with the imaging device positioned within the vessel segment.
42. A system, comprising:
- a processing system configured to: obtain angiographic image data of a vessel segment generated from an imaging device positioned external to the vessel segment; create a three-dimensional image of the vessel segment based upon the obtained angiographic image data; obtain intravascular ultrasound (IVUS) image data of the vessel segment generated from an imaging device positioned within the vessel segment, wherein the IVUS image data comprises a series of intravascular images acquired as the imaging device positioned within the vessel segment is moved through and along the vessel segment; correlate the IVUS image data to the three-dimensional image of the vessel such that each of the images of the series of intravascular images of the IVUS image data is correlated to a portion of the three-dimensional image of the vessel created based upon the obtained angiographic image data, wherein correlating the IVUS image data to the three-dimensional image of the vessel includes aligning the images of the series of intravascular images of the IVUS image data both axially and circumferentially to the corresponding portions of the three-dimensional image of the vessel; and outputting a signal to a display in communication with the processing system to render simultaneously on the display an image of the series of intravascular images of the IVUS image data and at least the correlated portion of the three-dimensional image of the vessel as determined by the correlating step.
Type: Application
Filed: Oct 1, 2012
Publication Date: Jan 31, 2013
Applicant: VOLCANO CORPORATION (SAN DIEGO, CA)
Inventor: VOLCANO CORPORATION (SAN DIEGO, CA)
Application Number: 13/632,916
International Classification: A61B 8/12 (20060101); A61B 6/00 (20060101);