An automated 3D registration method for optical coherence tomography volumes

Abstract

Optical coherence tomography (OCT) is able to provide high resolution volumetric data for biological tissues. However, the field of view (FOV) of OCT is sometimes smaller than the field of interest, which limits the clinical application of OCT. One way to overcome the drawback is to stitch multiple 3D volumes. In this paper, we propose a novel method to register multiple overlapped volumetric OCT data into a single volume. The relative positions of overlapped volumes were estimated on en face plane and at depth. On en face plane, scale invariant feature transform (SIFT) was implemented to extract the keypoints in each volume. Based on the invariant features, volumes were paired through keypoint matching. Then, we formulated the relationship between paired offsets and absolute positions as a linear model and estimated the centroid of each volume using least square method. Moreover, we calibrated the depth displacement in each paired volume and aligned the z coordinates of volumes globally. The algorithm was validated through stitching multiple volumetric OCT datasets of human cervix tissue and of swine heart. The experimental results demonstrated that our method is capable of visualizing biological samples over a wider FOV, which enhances the investigation of tissue structure such as fiber orientation.

Optical design and simulation of a cervical scanning probe for polarization-sensitive optical coherence tomography using Ansys Zemax OpticStudio

“…These changes led to the on-axis lateral resolution being improved to 12 μm and lateral resolution at +2° scanning mirror angle improved to 10 μm. However, the resulting probe's FOV was drastically reduced to 1.45 mm, much lower than the 4-5 mm FOV of other OCT systems [7,12,13].…”

“…This is due to the magnification of the GRIN Objective and allows the design to have a wider FOV not limited by the diameter of the optics used. The vertical FOV on the sample surface was 6.0 mm, which was 1-2 mm wider than previously cited for OCT systems used to image the cervix [7,12,13]. The lateral resolution of the probe was calculated from the full width half maximum (FWHM) of the cross-sectional Huygens PSF generated in OpticStudio.…”

Freeform robotic optical coherence tomography beyond the optical field-of-view limit

“…The integration of mechanical design and novel processing expands the CIV of OCT, enabling the reconstruction of complex non-planar anatomies. Nearly all existing OCT montaging algorithms register en-face projection images 39,40 . However, en-face projections become nonlinearly distorted relative to each other when their curvature relative to the incident beam is significantly different from each other, as in our situation.…”

Concept for Markerless 6D Tracking Employing Volumetric Optical Coherence Tomography

“…To overcome the limited size of the FOV, different approaches have been studied. They usually involve moving the OCT scan head-for example, by integration into a motorized microscope [29] or by mounting it to a robot [30], and some kind of volume stitching [31]. As an alternative which does not require moving the scanning system, we recently proposed a setup which uses a second pair of galvos to laterally move the FOV to different locations [32].…”