Correction of motion artifacts in endoscopic optical coherence tomography and autofluorescence images based on azimuthal en face image registration

Abstract

Abstract. We present a method for the correction of motion artifacts present in two-and three-dimensional in vivo endoscopic images produced by rotary-pullback catheters. This method can correct for cardiac/breathingbased motion artifacts and catheter-based motion artifacts such as nonuniform rotational distortion (NURD). This method assumes that en face tissue imaging contains slowly varying structures that are roughly parallel to the pullback axis. The method reduces motion artifacts using a dynamic time warping solution through a cost matrix that measures similarities between adjacent frames in en face images. We optimize and demonstrate the suitability of this method using a real and simulated NURD phantom and in vivo endoscopic pulmonary optical coherence tomography and autofluorescence images. Qualitative and quantitative evaluations of the method show an enhancement of the image quality.

Data Stream Stabilization for Optical Coherence Tomography Volumetric Scanning

“…A frequency analysis of the texture of the Intra-Vascular Ultrasound (IVUS) image was used in [6] to estimate the rotational velocity. Matching based algorithms by minimizing the Euler distance of warped neighboring frames [8], [9], or by maximizing the cross-correlation [10], [11], [14] have been proposed to track the shift error of A-lines. Specifically, in intravascular OCT imaging, intra-vascular stents may serve as landmarks that help to capture rotational distortion in pullback volumetric scanning [13].…”

“…An essential step of the NURD estimation is to search a continuous optimal path with large correlation value from the correlation map. Solutions applied in previous OCT stabilization studies [10], [11], [14] are mainly based on graph searching (GS), and rely on local features of gradients, maxima, textures and other prior information. This type of technique is also a traditional way of contour tracing [23].…”

“…In proximal rotation devices Non-Uniform Rotational Distortion (NURD) can be observed due to mechanical friction between rotating optical components and the protecting sheath, mostly caused by bending of the catheter inserted in the tortuous path of the digestive, cardiovascular or respiratory system. Miniaturization of motors enabled distal scanning and more compact [1] and more easily miniaturized designs [11], in which instabilities are only related to the quality of the motor itself. However, these designs require electrical connection of the distally located motor, which adds additional safety risks to the device and causes partial shadowing of the tissue by the wires.…”

“…We formulate the problem as finding a warping vector for each frame, to shift each individual scanning A-line to its correct position. This can be done based on computing the cross-correlation or Euler distance between A-lines in the new uncorrected frame and in previous stabilized frames [8]- [11]. However, in a real application it is hard to ensure that every Aline of OCT images can provide visible features for correlation because of the limited Field of View (FoV) of OCT catheters (part of the OCT image is filled with background noise when the tubular lumen is larger than the catheter FoV).…”

Submillimeter diameter rotary-pullback fiber-optic endoscope for narrowband red-green-blue reflectance, optical coherence tomography, and autofluorescence in vivo imaging

“…To reduce the amount of NURD in some of the images, a motion correction method developed by our group denoted "azimuthal en face image registration" was applied to some of the images during postprocessing. 26 3 Results and Discussion…”