Microsurgeries involving blood vessels, nerves and tissue reparations are traditionally guided by surgical microscopes, which limits the surgeon’s operation view to the enface level. As a new method of microsurgical guidance, optical coherence tomography (OCT) has been proposed, which is a noninvasive biomedical imaging modality capable of providing real-time subsurface 3D intraoperative imaging with ultra-high resolution in the order of a few microns. This can lead to less iatrogenic injury and better patient outcome [1
]. Compared to other image-guiding modalities such as MRI, CT and ultrasound, OCT is inexpensive, compact, portable, and can be integrated with many kinds of surgical tools. Various OCT guided neurosurgical tools have been tried in small rodents by Jafri et. al [2
]. However, most OCT systems generally suffer from limited imaging depth range in the order of only 1~3mm, which restricts its clinical applications when a tissue surface’s topological variance is larger than the imaging depth range [3
]. Moreover, involuntary beat and motion of subject tissues may cause OCT imaging artifacts [4
] and can misguide surgical procedures. This is especially critical in surface operations such as cerebral cortex neurosurgery [5
] and retina vitreous surgery [6
]. In these operations, tissue’s axial involuntary motion is one of the primary concerns and high dexterity from an experienced surgeon is required since beating or motion even in hundreds of microns can cause serious complications. A simple and efficient way to deal with such issues is to use an adaptive ranging technique based on depth-tracking. This is achieved by first locating the subject tissue surface using an OCT system and then using this information to adjust the coherence gate and range on the reference arm [7
]. The topological variance and motion is thus compensated and the image is obtained on a virtually “plain and static” surface. Motion compensation of surgical tools has been also achieved in ultra-sound guided beating heart mitral valve surgery, which showed the benefits of requiring less dexterity and applied force compared to using solid tools [9
Common-path OCT (CPOCT) is a rational and reasonable approach for topology and motion compensation because the reference and sample signals share the same path [11
] thus the reference offset can be changed directly by adjusting the distance between the probe and the tissue surface. No additional synchronization control is needed in the reference arm as in prior work [7
]. In addition, the CPOCT approach requires no alignment and has higher imaging stability [13
]; it is relatively insensitive to vibration as well as fiber induced polarization and dispersion mismatch [14
]. These properties logically predict ideal features when implementing an all-fiber CPOCT probe for integration with different microsurgical tools, which then can be used to adjust the tools axial motion in real time to compensate for the topological variance and motion of the tissue.
In this work, we developed a CPOCT system capable of surface topology and motion compensation (STMC) in axial direction. In the CPOCT-STMC system, one-dimensional erosion based edge-searching algorithm and autoregressive predictive filter are applied to A-scan data for real-time depth-tracking. Images were obtained while utilizing the topological and motional compensation technique. In addition, the motion compensation properties was studied, which predicts high feasibility of better STMC performance.