Sensor guided catheter navigation system
A method and a system for producing images of a subject, such as the heart of a human being. The method may comprise acquiring ultrasound images of the subject with a catheter comprising a position sensor. The method may also comprise capturing a plurality of 4D surface registration points in the acquired ultrasound images corresponding to points on the subject. The method may also comprise registering, in space and time, a high-resolution 4D model of the subject with the plurality of 4D surface registration points. The method may also comprise displaying high resolution, real-time images of the subject during a medical procedure based on the registration of the high resolution 4D model to the 4D surface registration points. Embodiments of the present invention are especially useful in left atrium ablation procedures.
1. A computer-implemented method, comprising:
receiving scan data collected from a scan of a heart;
extracting a three-dimensional (3D) surface model from the scan data, wherein the 3D surface model corresponds to a particular phase of a cardiac cycle of the heart;
generating a four-dimensional (4D) heart model using the 3D surface model and a time associated with the particular phase of the cardiac cycle of the heart;
receiving a 4D surface registration of the heart, wherein the scan data and the 4D surface registration are obtained via different imaging modalities, wherein a plurality of points included in the 4D surface registration are captured from an ultrasound image of the heart, and wherein an error associated with each of the plurality of points is determined based on a distance between each one of the points and an image center of the ultrasound image;
registering the 4D heart model with the 4D surface registration with a transformation function; and
updating the transformation function until the transformation function does not change more than a defined threshold.
2. The computer-implemented method of claim 1 , wherein the 4D heart model and the 4D surface registration are synchronized with electrocardiogram signals as time coordinates.
3. The computer-implemented method of claim 1 , wherein registering the 4D heart model with the 4D surface registration further comprises creating a rigid global space-time registration between the 4D heart model and the points included in the 4D surface registration.
4. The computer-implemented method of claim 3 , wherein creating the rigid global space-time registration between the 4D heart model and the points included in the 4D surface registration comprises determining the transformation function that aligns the points included in the 4D surface registration with the 4D heart model.
5. The computer-implemented method of claim 4 , wherein the transformation function aligns the points included in the 4D surface registration with the 4D heart model, such that at least some of the points included in the 4D surface registration are located on an inner heart wall of the 4D heart model.
6. The computer-implemented method of claim 3 , wherein registering the 4D heart model with the 4D surface registration further comprises creating a local non-rigid registration to further improve the registration accuracy.
7. The computer-implemented method of claim 1 , wherein the scan of the heart is a computer tomography (CT) scan.
8. The computer-implemented method of claim 1 , wherein the scan of the heart is a magnetic resonance imaging (MRI) scan.
9. The computer-implemented method of claim 1 , wherein the ultrasound image of the heart is generated via a catheter comprising an ultrasound transducer and a position sensor.
10. A catheter navigation system, comprising:
a catheter comprising an ultrasound transducer and a magnetic position sensor;
a position tracking system for tracking the position of the catheter based on signals received by the magnetic position sensor; and
an image processor in communication with the catheter and the position tracking system for:
capturing a plurality of four-dimensional (4D) surface registration points from a plurality of ultrasound images of one or more inner heart walls of a subject's heart acquired by the ultrasound transducer, wherein a location error associated with each one of the 4D surface registration points is determined based on an error associated with the magnetic position sensor and a distance between each one of the points and an image center of a respective one of the plurality of ultrasound images;
registering a 4D heart model of the subject's heart with the plurality of 4D surface registration points with a transformation function, wherein the 4D heart model and the 4D surface registration points are obtained via different imaging modalities;
determining an alignment error between the 4D heart model and the 4D surface registration points; and
updating the transformation function until the alignment error is below a defined threshold.
11. The catheter navigation system of claim 10 , wherein the 4D surface registration points correspond to points on the heart and are captured without the catheter touching any of the points on the heart.
12. The catheter navigation system of claim 10 , wherein the 4D heart model is constructed from a series of three-dimensional (3D) models at successive time points.
13. The catheter navigation system of claim 12 , wherein the series of 3D models are generated prior to acquiring the ultrasound images.
14. The catheter navigation system of claim 12 , wherein the series of 3D models are generated after acquiring the ultrasound images.
15. The catheter navigation system of claim 10 , wherein the catheter is configured to be positioned within the subject's heart and a portion of the catheter comprising the ultrasound transducer and the magnetic position sensor does not touch the one or more inner heart walls when capturing the plurality of ultrasound images of the heart.
16. A non-transitory computer readable medium storing computer executable instructions, executable by a processor to:
receive scan data collected from a scan of a heart;
extract a three-dimensional (3D) surface model from the scan data, wherein the 3D surface model corresponds to a particular phase of a cardiac cycle of the heart from a series of 3D surface models at successive time points;
generate a four-dimensional (4D) heart model using the 3D surface model and a time associated with the particular phase of the cardiac cycle of the heart;
receive a 4D surface registration of the heart, the 4D surface registration being generated via a catheter comprising an ultrasound transducer, wherein the scan data and the 4D surface registration are obtained via different imaging modalities, wherein an error associated with each of a plurality of points in the 4D surface registration is determined based on a distance between each one of the points and an image center of an image captured by the ultrasound transducer;
determine a weight for each one of the 4D surface registration points, based on the determined error associated with each one of the plurality of points in the 4D surface registration;
register the 4D heart model with the 4D surface registration with a transformation function, using the weighted 4D registration points; and
update the transformation function until the transformation function does not change more than a defined threshold.
17. The non-transitory computer readable medium of claim 16 , further comprising instructions executable by the processor to receive position data acquired from a position sensor disposed on the catheter.
18. The non-transitory computer readable medium of claim 17 , further comprising instructions executable by the processor to determine an orientation of the catheter based on the received position data.
19. The non-transitory computer readable medium of claim 18 , wherein the position sensor comprises a magnetic positioning sensor.