Calibration and image processing devices, methods, and systems
In part, the invention relates to systems and methods of calibrating a plurality of frames generated with respect to a blood vessel as a result of a pullback of an intravascular imaging probe being pullback through the vessel. A calibration feature disposed in the frames that changes between a subset of the frames can be used to perform calibration. Calibration can be performed post-pullback. Various filters and image processing techniques can be used to identify one or more feature in the frames including, without limitation, a calibration feature, a guidewire, a side branch, a stent strut, a lumen of the blood vessel, and other features. The feature can be displayed using a graphic user interface.
1. An intravascular image data processing system comprising:
one or more electronic memories; and
a processor in communication with the one or more memories, wherein the one or more memories comprises instructions executable by the processor to cause the processor to:
store intravascular image data in the one or more electronic memories, the image data obtained from a probe pulled back a distance D in an artery;
generate a set of frames of image data from the intravascular image data;
identify, on per frame basis, an elliptical calibration feature that changes position along the distance D;
calibrate a majority of frames of the set of frames using the elliptical calibration feature; and
track the elliptical calibration feature in a plurality of frames in the set of frames of image data.
2. The system of claim 1 wherein identifying the elliptical calibration feature is performed using one or more constraints selected from the group consisting of non-concentric positioning of calibration feature, a circular profile of calibration feature, a perimeter measure of calibration feature, an area measure of calibration feature, a thickness of a brighter annular subset of the calibration feature, a thickness of a brighter annular subset of the calibration feature and thickness of a doped region of the calibration feature.
3. The system of claim 1 further comprising instructions executable by the processor to cause the processor to: divide the plurality of frames into a plurality of windows and fit a curve relative to a measurement of the elliptical calibration feature across the plurality of windows.
4. The system of claim 1 further comprising instructions executable by the processor to cause the processor to:
align the calibration feature or probe on a per frame basis.
5. The system of claim 4 further comprising instructions executable by the processor to cause the processor to:
detect a lumen of a blood vessel on a per frame basis for continuously calibrated frames; and
display the lumen of the blood vessel in continuously calibrated frames.
6. The system of claim 4 further comprising instructions executable by the processor to cause the processor to:
detect a guide catheter on a per frame basis.
7. The system of claim 4 further comprising instructions executable by the processor to cause the processor to:
detect a stent strut; and
display a stent strut on one or more continuously calibrated frames.
8. The system of claim 4 further comprising instructions executable by the processor to cause the processor to:
detect one or more side branches on a per frame basis in continuously calibrated frames;
detect one or more stent struts in the continuously calibrated frames on a per frame basis;
detect a lumen of a blood vessel on a per frame basis for the continuously calibrated frames; and
display a side branch, one or more stents struts, and the lumen on one or more of the continuously calibrated frames.
9. The system of claim 1 wherein the elliptical calibration feature comprises a first border, wherein the first border changes between two or more frames.
10. The system of claim 9 wherein the elliptical calibration feature comprises a second border disposed within the first border, wherein the second border changes between the two or more frames.
11. The system of claim 9 wherein one or more continuously calibrated frames comprise one or more calibrated scan lines.
12. The system of claim 9 further comprising instructions executable by the processor to cause the processor to: generate an alert in response to a shape of the first border or a loss of calibration feature tracking.
13. The system of claim 9 further comprising instructions executable by the processor to cause the processor to: detect a guidewire in the plurality of frames.
14. The system of claim 1 wherein each frame comprises a plurality of scan lines.
15. A method of calibrating an intravascular imaging system, the method comprising:
generating a set of frames of image data, using an intravascular imaging probe, the intravascular imaging probe pulled back a distance D in an artery;
identifying, on per frame basis, an elliptical calibration feature that changes position along the distance D;
calibrating a majority of the frames of the set of frames using the elliptical calibration feature; and
tracking the elliptical calibration feature in a plurality of frames in the set of frames of image data.
16. The method of claim 15 further comprising aligning the calibration feature or intravascular imaging probe on a per frame basis.
17. The method of claim 16 wherein each frame comprises a plurality of scan lines, the method further comprising calibrating each scan line of one or more frames.
18. The method of claim 15 further comprising displaying a plurality of continuously calibrated frames.
19. The method of claim 15 wherein the intravascular probe is an optical coherence tomography imaging probe or an intravascular ultrasound imaging probe.
20. The method of claim 15 wherein identifying the elliptical calibration feature is performed using one or more constraints selected from the group consisting of non-concentric positioning of calibration feature, a circular profile of calibration feature, a perimeter measure of calibration feature, an area measure of calibration feature, a thickness of a brighter annular subset of the calibration feature, a thickness of a brighter annular subset of the calibration feature and thickness of a doped region of the calibration feature.
21. The method of claim 15 further comprising:
dividing the plurality of frames into a plurality of windows; and
fitting a curve relative to a measurement of the elliptical calibration feature across the plurality of windows.
22. The method of claim 15 further comprising:
detecting one or more side branches; and
displaying a side branch.
23. The method of claim 15 further comprising:
detecting a lumen of a blood vessel on a per frame basis.
24. The method of claim 15 wherein the elliptical calibration feature disposed in the artery comprises a first border, wherein the border changes between two or more frames.
25. The method of claim 24 wherein the elliptical calibration feature disposed in the artery comprises a second border disposed within the first border, wherein the second border changes between the two or more frames.
26. The method of claim 24 further comprising generating an alert in response to a shape of the first border imaged relative to a section of the artery.
27. The method of claim 24 further comprising generating an alert in response to tracking of the elliptical calibration feature imaged relative to section of the artery terminating.
28. The method of claim 15 , wherein each frame comprises a plurality of scan lines.