Deformable motion correction for stent visibility enhancement
View Patent ↗A method for enhancing stent visibility includes acquiring a set of image frames including multiple test frames. A set of measurement points uniformly distributed within an image of a stent is defined in the test frames. A local image context is defined around each measurement point. A non-rigid deformation field relating the local image contexts of the test frames to local image contexts of a reference image is calculated. The non-rigid deformation field is optimized by maximizing a similarity function between the local image contexts of the test frames and the local image contexts of the reference image. The optimized non-rigid deformation field is used to deform images of a stent in the multiple test frames and combine the non-rigidly deformed images of the stent from the test frames. An image frame with the combined image of the stents superimposed thereon is displayed.
1. A method for enhancing stent visibility in a set of image frames, comprising:
acquiring a set of image frames including multiple test frames;
defining a set of measurement points uniformly distributed within an image of a stent in each of the multiple test frames;
defining a local image context around each measurement point of each of the multiple test frames;
calculating a non-rigid deformation field that relates the local image contexts of each of the multiple test frames to local image contexts of a reference image;
optimizing the non-rigid deformation field by maximizing a similarity function between the local image contexts of each of the multiple test frames and the local image contexts of the reference image;
using the optimized non-rigid deformation field to deform images of a stent in each of the multiple test frames and combine the non-rigidly deformed images of the stent from each of the multiple test frames; and
displaying an image frame of the set of image frames with the combined image of the stents superimposed thereon.
2. The method of claim 1 , wherein prior to calculating the non-rigid deformation field, the test frame is preliminarily aligned to a reference frame of the set of image frames based on markers visible within the test frame and the reference frame.
3. The method of claim 2 , wherein the reference frame is one of the multiple test frames.
4. The method of claim 2 , wherein the preliminary alignment is a rigid or affine alignment.
5. The method of claim 2 , wherein the markers include balloon markers.
6. The method of claim 1 , wherein prior to calculating the rigid deformation field, preprocessing is performed on the set of image frames.
7. The method of claim 1 , wherein preprocessing includes removing a static background from the set of image frames.
8. The method of claim 1 , wherein the reference image is defined as a test frame of the multiple test frames or an average of multiple rigidly aligned test frames of the multiple test frames.
9. The method of claim 1 , wherein after combining the stent image and prior to displaying the image frame, post processing is performed on the image frame with the combined image of the stents superimposed thereon.
10. The method of claim 9 , wherein post processing includes adding back a static background that had been removed from the set of image frames.
11. The method of claim 1 , wherein the set of image frames is acquired using a fluoroscope.
12. The method of claim 1 , wherein the displayed image frame with the combined image of the stents superimposed thereon is used to aid in assessment of stent deployment to a desired location.
13. The method of claim 12 , wherein the desired location is a coronary artery stenosis.
14. The method of claim 1 , wherein the local image contexts of the test frame are oriented approximately in the direction of stent expansion.
15. The method of claim 14 , wherein the direction of stent expansion is tangential to the long axis of the stent image.
16. A method for enhancing stent visibility in a set of image frames, comprising:
acquiring a set of image frames including a test frame and a reference frame;
detecting balloon markers within the test frame and the reference frame;
removing a static background from the test frame and the reference frame;
performing rigid image alignment of the test frame to the reference frame using the detected balloon markers;
performing non-rigid registration of the test frame to the reference frame based on local image contexts of stent imagery within the test frame and the reference frame; and
performing temporal integration of the stent imagery using the non-rigid registration.
17. The method of claim 16 , further including displaying the temporal integration.
18. The method of claim 17 , wherein the removed static background is reintroduced prior to displaying the temporal integration.
19. The method of claim 16 , wherein the local image contexts are defined uniformly within the stent imagery.
20. A computer system comprising:
a processor; and
a non-transitory, tangible, program storage medium, readable by the computer system, embodying a program of instructions executable by the processor to perform method steps for enhancing stent visibility in a set of image frames, the method comprising:
acquiring a set of image frames including a test frame and a reference frame;
preprocessing the test frame and the reference frame;
performing non-rigid registration of the test frame to the reference frame based on local image contexts of stent imagery within the test frame and the reference frame; and
performing temporal integration of the stent imagery using the non-rigid registration.
21. The computer system of claim 20 , wherein rigid or affine image alignment of the test frame to the reference frame is performed prior to using the detected balloon markers.
22. The computer system of claim 21 , wherein the rigid or affine image alignment is performed based on balloon marker images or guidewire images.