Catheter-based off-axis optical coherence tomography imaging system
A system for imaging a body lumen includes a controller and a display. The controller is configured to connect to a proximal end of a catheter having an optical fiber extending along the length of an elongate catheter body. The controller is further configured to rotate a distal end of the optical fiber from a location near a proximal end of the elongate catheter body, acquire optical coherence tomography (OCT) images using the optical fiber as the distal end of the optical fiber rotates, and determine a rotational lag of the distal end of the optical fiber. The display is configured to display one or more OCT images corrected for the rotational lag.
1. A method of imaging a body lumen with Optical Coherence Tomography (OCT), the method comprising:
inserting an elongate catheter into the body lumen, the elongate catheter having a distal portion comprising a cutter and an OCT sensor, wherein the OCT sensor includes an optical fiber that extends through a central lumen of the catheter along a path that is off-axis of a length of the catheter, wherein a distal end of the optical fiber is fixedly attached to a distal end region of the catheter;
rotating the cutter and the distal end of the optical fiber while acquiring OCT images of the body lumen, wherein a proximal portion of the optical fiber is allowed to wind helically within a proximal handle of the catheter during gathering of the OCT images;
displaying the OCT images as a toroidal mapping in which the OCT images are displayed around a center region corresponding to a location of the elongate catheter;
steering the elongate catheter towards an identified region of the body lumen based upon the toroidal mapping; and
cutting tissue or plaque at the identified region with the cutter.
2. The method of claim 1 , wherein displaying the OCT images comprises determining the toroidal mapping based on a radial position of the OCT sensor relative to a central axis of the elongate catheter.
3. The method of claim 1 , further comprising correcting radial distortion in the OCT images by scaling the OCT images.
4. The method of claim 1 , further comprising correcting radial distortion in the OCT images by multiplying radial positions of the OCT sensor by a correction factor.
5. The method of claim 1 , further comprising correcting radial distortion in the OCT images by adding a correction offset to radial positions of the OCT sensor.
6. The method of claim 1 , further comprising correcting radial distortion in the OCT images by applying a mapping table of correction offsets to radial positions of the OCT sensor.
7. The method of claim 1 , further comprising monitoring a cut progression and depth in real time using the OCT images.
8. The method of claim 1 , wherein the elongate catheter comprises a directional atherectomy catheter.
9. The method of claim 1 , further comprising collecting the cut tissue or plaque in an internal storage of the elongate catheter.
10. The method of claim 1 , further comprising providing fluid across the OCT sensor while rotating the OCT sensor.
11. The method of claim 1 , wherein acquiring the OCT images comprises:
acquiring a first plurality of OCT scan lines using the OCT sensor;
point-wise averaging of data in the first plurality of OCT scan lines; and
transforming the averaged data in the first plurality of OCT scan lines by Inverse Fourier Transform.
12. The method of claim 11 , further comprising repeating the steps of acquiring, point-wise averaging and transforming for multiple pluralities of OCT scan lines.
13. The method of claim 12 , further comprising point-wise averaging of the multiple pluralities of OCT scan lines to post-FFT average the OCT image.
14. The method of claim 1 , wherein acquiring the OCT images comprises acquiring the OCT images using a lens that is positioned so as to face radially outwards relative to a longitudinal axis of the elongate catheter.
15. The method of claim 1 , wherein rotating the cutter and the distal end of the optical fiber comprises simultaneously rotating the distal portion of the elongate catheter.
16. The method of claim 1 , wherein the proximal handle includes an encoder that encodes rotational position information of a side-facing window of the catheter.
17. The method of claim 1 , wherein displaying the OCT images comprises displaying an indicator indicating an orientation of the OCT sensor.
18. The method of claim 1 , further comprising determining a phase delay by determining differences between the OCT images generated by rotating the catheter in opposing directions, acquiring a real-time view of the distal portion of the catheter as it rotates, or distinguishing motion from non-motion from scan to scan.
19. The method of claim 1 , wherein the proximal portion of the optical fiber is allowed to wind and unwind as the catheter is rotated in clockwise and counterclockwise directions.