Microscope-integrated Optical Coherence Tomography Research Articles

Microscope-integrated optical coherence tomography for image-aided positioning of glaucoma surgery.

Most glaucoma surgeries involve creating new aqueous outflow pathways with the use of a small surgical instrument. This article reported a microscope-integrated, real-time, high-speed, swept-source optical coherence tomography system (SS-OCT) with a 1310-nm light source for glaucoma surgery. A special mechanism was designed to produce an adjustable system suitable for use in surgery. A two-graphic processing unit architecture was used to speed up the data processing and real-time volumetric rendering. The position of the surgical instrument can be monitored and measured using the microscope and a grid-inserted image of the SS-OCT. Finally, experiments were simulated to assess the effectiveness of this integrated system. Experimental results show that this system is a suitable positioning tool for glaucoma surgery.

Intrasurgical Human Retinal Imaging With Manual Instrument Tracking Using a Microscope-Integrated Spectral-Domain Optical Coherence Tomography Device.

To characterize the first in-human intraoperative imaging using a custom prototype spectral-domain microscope-integrated optical coherence tomography (MIOCT) device during vitreoretinal surgery with instruments in the eye. Under institutional review board approval for a prospective intraoperative study, MIOCT images were obtained at surgical pauses with instruments held static in the vitreous cavity and then concurrently with surgical maneuvers. Postoperatively, MIOCT images obtained at surgical pauses were compared with images obtained with a high-resolution handheld spectral-domain OCT (HHOCT) system with objective endpoints, including acquisition of images acceptable for analysis and identification of predefined macular morphologic or pathologic features. Human MIOCT images were successfully obtained before incision and during pauses in surgical maneuvers. MIOCT imaging confirmed preoperative diagnoses, such as epiretinal membrane, full-thickness macular hole, and vitreomacular traction and demonstrated successful achievement of surgical goals. MIOCT and HHOCT images obtained at surgical pauses in two cohorts of five patients were comparable with greater than or equal to 80% correlation in 80% of patients. Real-time video-imaging concurrent with surgical manipulations enabled, for the first time using this device, visualization of dynamic instrument-retina interaction with targeted OCT tracking. MIOCT is successful for imaging at surgical pauses and for real-time image guidance with implementation of targeted OCT tracking. Even faster acquisition speeds are currently being developed with incorporation of a swept-source MIOCT engine. Further refinements and investigations will be directed toward continued integration for real-time volumetric imaging of surgical maneuvers. Ongoing development of seamless MIOCT systems will likely transform surgical visualization, approaches, and decision-making.

Microscope-integrated optical coherence tomography: A new surgical tool in vitreoretinal surgery.

Optical coherence tomography (OCT) has revolutionized imaging of ocular structures and various disease conditions. Though it has been used in the clinic for some decades, the OCT has only recently found its way into the operating theater. Early attempts at intraoperative OCT, hand-held and microscope mounted, have already improved our understanding of the surgical pathology and the role it might play in surgical decision-making. The microscope-integrated OCT now allows seamless, high-resolution, real-time imaging of surgical maneuvers from the incision to wound closure. Visualization of instruments and intraoperative tissue manipulation are possible with this in vivo modality and, therefore, help improve the outcome of surgery. In this article, we describe the advantages it offers during various vitreoretinal procedures.

Microscope-integrated intraoperative OCT with electrically tunable focus and heads-up display for imaging of ophthalmic surgical maneuvers.

We present novel optical and mechanical designs for a microscope-integrated intraoperative optical coherence tomography (iOCT) system with enhanced function and ergonomics for visualization of ophthalmic surgical maneuvers. Integration of an electrically tunable lens allows rapid focal plane adjustment and iOCT imaging of both anterior and posterior segment tissue microstructures while maintaining parfocality with the ophthalmic surgical microscope. We demonstrate novel visualization of instrument positions relative to tissue layers of interest as colormap overlays onto en face OCT data, which may provide integrative display of volumetric information during surgical maneuvers. Finally, we implement a heads-up display system to provide real-time feedback as proof-of-principle for iOCT-guided ophthalmic surgery.

T1853 Morphological Feature Quantification of Colonic Crypt Patterns Using Microscope-Integrated OCT

Background: Optical coherence tomography examination of the upper and lower GI tract has shown promising technological advances over the last decade. However one limitation preventing implementation in clinical settings is the difficulty in interpreting images with large amounts of information in a timeframe suitable to facilitate an endoscopist. Reliable analytic methodologies to rapidly process and interpret images obtained at endoscopy do not currently exist. A computerized model to accurately quantify OCT obtained architectural features of colonic crypts could serve as a proof of principle that this concept is viable. Aim: To demonstrate the use of computerized algorithms to quantify the morphological features of colonic crypts. Methods: Samples of fresh colon tissues (10 normal and 10 aberrant crypt focus (ACF)) were obtained from colectomies. The samples were stained with methylene blue and microscopic images were recorded to approximately simulate In Vivo imaging with magnification chromoendoscopy. In addition, 3D OCT volumes were recorded from the same sites using an integrated OCT scanner. The crypts within the micrographs were automatically segmented using marker-based watershed morphological processing. The morphological features of the segmented crypts were extracted and quantified. For the correlated 3D OCT volumes, the crypts were first segmented in each en-face plane of the stack. Then the segmented crypts were visualized in 3D by volume rending. Finally 3D central axes of the crypts, called skeletons, were extracted and the orientations of the skeletons were quantified by centroid-searching. Results: For typical grossly normal colonic tissues, the mean area of segmented crypts was 4213μm2; the mean major axis length was 89μm; the mean minor axis length was 60μm; the mean eccentricity was 0.67; the mean standard deviation angle between the en-face plane and the skeletons was 2.5 degree. For typical aberrant crypt foci (ACF) colonic tissues, the mean area of segmented crypts was 10267μm2; the mean major axis length was 145μm; the mean minor axis length was 88μm; the mean eccentricity was 0.74; the mean standard deviation angle between the en-face plane and the skeletons was 12.7 degree. There were significant morphological feature differences between normal and ACF colonic crypts. Conclusion: These methods can quantify morphological features of colonic crypts, and the results correspond well to known differences between the crypt features of normal and aberrant crypts. Further development of this approach to OCT derived data analysis may facilitate the evolution of this technology into clinical practice.

Quantification of cardiac fiber orientation using optical coherence tomography

Heterogeneity in cardiac tissue microstructure is a potential mechanism for the generation and maintenance of arrhythmias. Abnormal changes in fiber orientation increase the likelihood of arrhythmia. We present optical coherence tomography (OCT) as a method to image myofibers in excised intact heart preparations. Three-dimensional (3-D) image sets were gathered from the rabbit right ventricular free wall (RVFW) using a microscope-integrated OCT system. An automated algorithm for fiber orientation quantification in the plane parallel to the wall surface was developed. The algorithm was validated by comparison with manual measurements. Quantifying fiber orientation in the plane parallel to the wall surface from OCT images can be used to help understand the conduction system of the specific sample being imaged.