Jianping Su

In Vivo Optical Coherence Tomography of the Human Larynx: Normative and Benign Pathology in 82 Patients

Objectives: Optical coherence tomography (OCT) is an emerging imaging modality that combines low‐coherence light with interferometry to produce cross‐sectional images of tissue with resolution about 10 μm. Patients undergoing surgical head and neck endoscopy were examined using a fiberoptic OCT imaging probe to study and characterize microstructural anatomy and features of the larynx and benign laryngeal pathology in vivo.

Optical coherence tomography of laryngeal cancer.

Objectives: Optical coherence tomography (OCT) is a high‐resolution optical imaging technique that produces cross‐sectional images of living tissues using light in a manner similar to ultrasound. This prospective study evaluated the ability of OCT to identify the characteristics of laryngeal cancer and measure changes in the basement membrane, tissue microstructure, and the transition zone at the edge of tumors.

Design and implementation of fiber-based multiphoton endoscopy with microelectromechanical systems scanning

A multiphoton endoscopy system has been developed using a two-axis microelectromechanical systems (MEMS) mirror and double-cladding photonic crystal fiber (DCPCF). The MEMS mirror has a 2-mm-diam, 20-deg optical scanning angle, and 1.26-kHz and 780-Hz resonance frequencies on the x and y axes. The maximum number of resolvable focal spots of the MEMS scanner is 720 x 720 on the x and y axes, which indicates that the MEMS scanner can potentially support high-resolution multiphoton imaging. The DCPCF is compared with standard single-mode fiber and hollow-core photonic bandgap fiber on the basis of dispersion, attenuation, and coupling efficiency properties. The DCPCF has high collection efficiency, and its dispersion can be compensated by grating pairs. Three configurations of probe design are investigated, and their imaging quality and field of view are compared. A two-lens configuration with a collimation and a focusing lens provides the optimum imaging performance and packaging flexibility. The endoscope is applied to image fluorescent microspheres and bovine knee joint cartilage.

Miniaturized probe based on a microelectromechanical system mirror for multiphoton microscopy

A factor that limits the use of multiphoton microscopy (MPM) in clinical and preclinical studies is the lack of a compact and flexible probe. We report on a miniaturized MPM probe employing a microelectromechanical system (MEMS) scanning mirror and a double-clad photonic crystal fiber (DCPCF). The use of a MEMS mirror and a DCPCF provides many advantages, such as size reduction, rapid and precise scanning, efficient delivery of short pulses, and high collection efficiency of fluorescent signals. The completed probe was 1 cm in outer diameter and 14 cm in length. The developed probe was integrated into an MPM system and used to image fluorescent beads, paper, and biological specimens.

In vivo three-dimensional microelectromechanical endoscopic swept source optical coherence tomography.

In clinical applications, three-dimensional (3-D) microscopic image volume reveals tissue morphological changes, which are closely related to pre-cancer and early stage disease, much better than two-dimensional images. However, the traditional endoscope only achieves two-dimensional surface images. In this paper, a 3-D endoscopic microscope was developed based on a rotational microelectromechanical system (MEMS) probe [1]. The 3-D helix scan mode was realized by combining a MEMS motor rotational scan and linear stage transversal movement. In order to coordinate the high spin speed of MEMS motor inside the endoscope, an optical coherence tomography (OCT) system with a broadband fast swept laser was used. In vivo 3-D image volumes of rabbit esophagus and trachea were demonstrated.

Improved lateral resolution in optical coherence tomography by digital focusing using two-dimensional numerical diffraction method

This paper proposes a non-iterative, two-dimensional numerical method to eliminate the compromise between the lateral resolution and wide depth measurement range in optical coherence tomography (OCT). A two-dimensional scalar diffraction model was developed to simulate the wave propagation process from out-of-focus scatters within the short coherence gate of the OCT system. High-resolution details can be recovered from outside of the depth-of-focus region with minimum loss of lateral resolution. Experiments were performed to demonstrate the effectiveness of the proposed method.

Real-time swept source optical coherence tomography imaging of the human airway using a microelectromechanical system endoscope and digital signal processor.

A fast-scan-rate swept laser for optical coherence tomography (OCT) is suitable to record and analyze a 3-D image volume. However, the whole OCT system speed is limited by data streaming, processing, and storage. In this case, postprocessing is a common technique. Endoscopic clinical applications prefer onsite diagnosis, which requires a real-time technique. Parallel digital signal processors were applied to stream and process data directly from a data digitizer. A real-time system with 20-kHz axial line speed, which was limited only by our swept laser scan rate, was implemented. To couple with the system speed, an endoscope based on an improved 3-D microelectromechanical motor (diameter 1.5 mm, length 9.4 mm) was developed. In vivo 3-D imaging of the human airway was demonstrated.

Imaging of the Pediatric Airway Using Optical Coherence Tomography

Objectives: Optical coherence tomography (OCT) is an imaging modality that uses a broadband light source to produce high‐resolution cross‐sectional images in living tissue (8–20 μm). A prospective study of normal, benign, and pathologic tissues in the pediatric airway was conducted to assess the utility of OCT technology in characterizing the microanatomy of the pediatric upper aerodigestive tract in vivo.

Optical coherence tomography of the larynx in the awake patient

Objective To demonstrate the feasibility of performing optical coherence tomography of the human larynx on the awake patient with a novel flexible fiberoptic delivery system. Study Design Prospective clinical trial. Subjects and Methods Imaging was performed in 17 awake patients. A flexible optical coherence tomography probe was inserted through the nose and placed in near or gentle contact with laryngeal tissues under direct endoscopic visualization. Results Images were successfully obtained from all laryngeal subsites and clearly identified laryngeal mucosal microanatomy. Several critical probe design modifications improved rotational and angular control of the distal tip while allowing linear translation of the probe and allowing more accurate apposition of the probe onto target tissues, which is critical for transnasal laryngeal imaging. Conclusion This study demonstrates the feasibility of awake transnasal laryngeal optical coherence tomography and identifies key instrumentation needed to obtain useful images.

Optical coherence tomography-enhanced microlaryngoscopy: preliminary report of a noncontact optical coherence tomography system integrated with a surgical microscope.

Objectives: Optical coherence tomography (OCT) is a new imaging modality that uses near-infrared light to produce cross-sectional images of tissue with a resolution approaching that of light microscopy. We have previously reported use of OCT imaging of the vocal folds (VFs) during direct laryngoscopy with a probe held in contact or near-contact with the VFs. This aim of this study was to develop and evaluate a novel OCT system integrated with a surgical microscope to allow hands-free OCT imaging of the VFs, which could be performed simultaneously with microscopic visualization. Methods: We performed a prospective evaluation of a new method of acquiring OCT images of the VFs. Results: An OCT system was successfully integrated with a surgical microscope to permit noncontact OCT imaging of the VFs of 10 patients. With this novel device we were able to identify VF epithelium and lamina propria; however, the resolution was reduced compared to that achieved with the standard contact or near-contact OCT. Conclusions: Optical coherence tomography is able to produce high-resolution images of vocal fold mucosa to a maximum depth of 1.6 mm. It may be used in the diagnosis of VF lesions, particularly early squamous cell carcinoma, in which OCT can show disruption of the basement membrane. Mounting the OCT device directly onto the operating microscope allows hands-free noncontact OCT imaging and simultaneous conventional microscopic visualization of the VFs. However, the lateral resolution of the OCT microscope system is 50 μm, in contrast to the conventional handheld probe system (10 μm). Although such images at this resolution are still useful clinically, improved resolution would enhance the systems performance, potentially enabling real-time OCT-guided microsurgery of the larynx.