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We present a method for automated, depth-resolved extraction of the attenuation coefficient from Optical Coherence Tomography (OCT) data. In contrast to previous automated, depth-resolved methods, the Depth-Resolved Confocal (DRC) technique derives an invertible mapping between the measured OCT intensity data and the attenuation coefficient while considering the confocal function and sensitivity fall-off, which are critical to ensure accurate measurements of the attenuation coefficient in practical settings (e.g., clinical endoscopy). We also show that further improvement of the estimated attenuation coefficient is possible by formulating image denoising as a convex optimization problem that we term Intensity Weighted Horizontal Total Variation (iwhTV). The performance and accuracy of DRC alone and DRC+iwhTV are validated with simulated data, optical phantoms, and ex-vivo porcine tissue. Our results suggest that implementation of DRC+iwhTV represents a novel way to improve OCT contrast for better tissue characterization through quantitative imaging.

Abstract. We describe a combination of fabrication techniques and a general process to construct a threedimensional (3-D) phantom that mimics the size, macroscale structure, microscale surface topology, subsurface microstructure, optical properties, and functional characteristics of a cancerous bladder. The phantom also includes features that are recognizable in white light (i.e., the visual appearance of blood vessels), making it suitable to emulate the bladder for emerging white light þ optical coherence tomography (OCT) cystoscopies and other endoscopic procedures of large, irregularly shaped organs. The fabrication process has broad applicability and can be generalized to OCT phantoms for other tissue types or phantoms for other imaging modalities. To this end, we also enumerate the nuances of applying known fabrication techniques (e.g., spin coating) to contexts (e.g., nonplanar, 3-D shapes) that are essential to establish their generalizability and limitations. We anticipate that this phantom will be immediately useful to evaluate innovative OCT systems and software being developed for longitudinal bladder surveillance and early cancer detection. © The Authors.Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

No abstract

White light endoscopy is widely used for diagnostic imaging of the interior of organs and body cavities, but the inability to correlate individual 2D images with 3D organ morphology limits its utility for quantitative or longitudinal studies of disease physiology or cancer surveillance. As a result, most endoscopy videos, which carry enormous data potential, are used only for real-time guidance and are discarded after collection. We present a computational method to reconstruct and visualize a 3D model of organs from an endoscopic video that captures the shape and surface appearance of the organ. A key aspect of our strategy is the use of advanced computer vision techniques and unmodified, clinical-grade endoscopy hardware with few constraints on the image acquisition protocol, which presents a low barrier to clinical translation. We validate the accuracy and robustness of our reconstruction and co-registration method using cystoscopy videos from tissue-mimicking bladder phantoms and show clinical utility during cystoscopy in the operating room for bladder cancer evaluation. As our method can powerfully augment the visual medical record of the appearance of internal organs, it is broadly applicable to endoscopy and represents a significant advance in cancer surveillance opportunities for big-data cancer research.

We demonstrate a novel catheterscope, based on scanning fiber endoscopy, for volumetric imaging with optical coherence tomography (OCT), which possesses a high resonance frequency (>2  kHz) and a small outer diameter (OD) (1.07 mm). Our design is the fastest volumetric-scanning, forward-viewing catheterscope for OCT, and the scanning package has the smallest OD of any such OCT package published to date. Using a proof-of-operation catheterscope with commercial lenses, we demonstrate high-quality in vivo and ex vivo volumetric imaging and extend the 1.1 mm diameter field of view more than 200-fold by mosaicking. Due to its small OD, short rigid tip length, and fast scan rate, this scope is the leading candidate design to enable early detection and staging of bladder cancer during flexible white light cystoscopy.

Three-dimensional (3D) organ-mimicking phantoms provide realistic imaging environments for testing various aspects of optical systems, including for evaluating new probe designs, characterizing the diagnostic potential of new technologies, and assessing novel image processing algorithms prior to validation in real tissue. We introduce and characterize the use of a new material, Dragon Skin (Smooth-On Inc.), and fabrication technique, air-brushing, for fabrication of a 3D phantom that mimics the appearance of a real organ under multiple imaging modalities. We demonstrate the utility of the material and technique by fabricating the first 3D, hollow bladder phantom with realistic normal and multi-stage pathology features suitable for endoscopic detection using the gold standard imaging technique, white light cystoscopy (WLC), as well as the complementary imaging modalities of optical coherence tomography and blue light cystoscopy, which are aimed at improving the sensitivity and specificity of WLC to bladder cancer detection. The flexibility of the material and technique used for phantom construction allowed for the representation of a wide range of diseased tissue states, ranging from inflammation (benign) to high-grade cancerous lesions. Such phantoms can serve as important tools for trainee education and evaluation of new endoscopic instrumentation.

We demonstrate the first automated, volumetric mosaicing algorithm for optical coherence tomography (OCT) that both accommodates 6-degree-of-freedom rigid transformations and implements a bundle adjustment step amenable to generating large fields of view with endoscopic and freehand imaging systems. Our mosaicing algorithm exploits the known, rigid connection between a combined white light and OCT imaging system to reduce the computational complexity of traditional volumetric mosaicing pipelines. Specifically, the search for 3-D point correspondences is replaced by two, 2-D processing steps: We first coregister a pair of white light images in 2-D and then generate a surface map based on the volumetric OCT data, which is used to convert 2-D image homographies into 3-D volumetric transformations. A significant benefit of our dual-modality approach is its tolerance for feature-poor datasets such as bladder tissue; in contrast, approaches to mosaic feature-rich volumes with significant variations in the local intensity gradient (e.g., retinal data containing prolific vasculature) are not suitable for such feature-poor datasets. We demonstrate the performance of our algorithm using ex vivo bladder tissue and a custom tissue-mimicking phantom. The algorithm shows excellent performance over the range of volume-to-volume transformations expected during endoscopic examination and comparable accuracy with several orders of magnitude superior run times than an open-source gold-standard algorithm (N-SIFT). We anticipate the proposed algorithm can benefit bladder surveillance and surgical planning. Furthermore, its generality gives it broad applicability and potential to extend the use of OCT to clinical applications relevant to large organs typically imaged with freehand, forward-viewing endoscopes.