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MEMS-Based Handheld Fourier Domain Doppler Optical Coherence Tomography for Intraoperative Microvascular Anastomosis Imaging

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      Abstract

      PurposeTo demonstrate the feasibility of a miniature handheld optical coherence tomography (OCT) imager for real time intraoperative vascular patency evaluation in the setting of super-microsurgical vessel anastomosis.MethodsA novel handheld imager Fourier domain Doppler optical coherence tomography based on a 1.3-µm central wavelength swept source for extravascular imaging was developed. The imager was minimized through the adoption of a 2.4-mm diameter microelectromechanical systems (MEMS) scanning mirror, additionally a 12.7-mm diameter lens system was designed and combined with the MEMS mirror to achieve a small form factor that optimize functionality as a handheld extravascular OCT imager. To evaluate in-vivo applicability, super-microsurgical vessel anastomosis was performed in a mouse femoral vessel cut and repair model employing conventional interrupted suture technique as well as a novel non-suture cuff technique. Vascular anastomosis patency after clinically successful repair was evaluated using the novel handheld OCT imager.ResultsWith an adjustable lateral image field of view up to 1.5 mm by 1.5 mm, high-resolution simultaneous structural and flow imaging of the blood vessels were successfully acquired for BALB/C mouse after orthotopic hind limb transplantation using a non-suture cuff technique and BALB/C mouse after femoral artery anastomosis using a suture technique. We experimentally quantify the axial and lateral resolution of the OCT to be 12.6 µm in air and 17.5 µm respectively. The OCT has a sensitivity of 84 dB and sensitivity roll-off of 5.7 dB/mm over an imaging range of 5 mm. Imaging with a frame rate of 36 Hz for an image size of 1000(lateral)×512(axial) pixels using a 50,000 A-lines per second swept source was achieved. Quantitative vessel lumen patency, lumen narrowing and thrombosis analysis were performed based on acquired structure and Doppler images.ConclusionsA miniature handheld OCT imager that can be used for intraoperative evaluation of microvascular anastomosis was successfully demonstrated.

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      Most cited references 14

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      Laser speckle contrast imaging in biomedical optics.

      First introduced in the 1980s, laser speckle contrast imaging is a powerful tool for full-field imaging of blood flow. Recently laser speckle contrast imaging has gained increased attention, in part due to its rapid adoption for blood flow studies in the brain. We review the underlying physics of speckle contrast imaging and discuss recent developments to improve the quantitative accuracy of blood flow measures. We also review applications of laser speckle contrast imaging in neuroscience, dermatology and ophthalmology.
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        Doppler optical micro-angiography for volumetric imaging of vascular perfusion in vivo.

         K. Wang,  Lin-Kun An (2009)
        We propose a Doppler optical micro-angiography (DOMAG) method to image flow velocities of the blood flowing in functional vessels within microcirculatory tissue beds in vivo. The method takes the advantages of recently developed optical micro-angiography (OMAG) technology, in which the endogenous optical signals backscattered from the moving blood cells are isolated from those originated from the tissue background, i.e., the tissue microstructures. The phase difference between adjacent A scans of OMAG flow signals is used to evaluate the flow velocity, similar to phase-resolved Doppler optical coherence tomography (PRDOCT). To meet the requirement of correlation between adjacent A scans in using the phase resolved technique to evaluate flow velocity, an ideal tissue-sample background (i.e., optically homogeneous tissue sample) is digitally reconstructed to replace the signals that represent the heterogeneous features of the static sample that are rejected in the OMAG flow images. Because of the ideal optical-homogeneous sample, DOMAG is free from the characteristic texture pattern noise due to the heterogeneous property of sample, leading to dramatic improvement of the imaging performance. A series of phantom flow experiments are performed to evaluate quantitatively the improved imaging performance. We then conduct in vivo experiments on a mouse brain to demonstrate that DOMAG is capable of quantifying the flow velocities within cerebrovascular network, down to capillary level resolution. Finally, we compare the in vivo imaging performance of DOMAG with that of PRDOCT, and show that DOMAG delivers at least 15-fold increase over the PRDOCT method in terms of the lower limit of flow velocity that can be detected.
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          Handheld optical coherence tomography scanner for primary care diagnostics.

          The goal of this study is to develop an advanced point-of-care diagnostic instrument for use in a primary care office using handheld optical coherence tomography (OCT). This system has the potential to enable earlier detection of diseases and accurate image-based diagnostics. Our system was designed to be compact, portable, user-friendly, and fast, making it well suited for the primary care office setting. The unique feature of our system is a versatile handheld OCT imaging scanner which consists of a pair of computer-controlled galvanometer-mounted mirrors, interchangeable lens mounts, and miniaturized video camera. This handheld scanner has the capability to guide the physician in real time for finding suspicious regions to be imaged by OCT. In order to evaluate the performance and use of the handheld OCT scanner, the anterior chamber of a rat eye and in vivo human retina, cornea, skin, and tympanic membrane were imaged. Based on this feasibility study, we believe that this new type of handheld OCT device and system has the potential to be an efficient point-of-care imaging tool in primary care medicine.
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            Author and article information

            Affiliations
            [1 ]Department of Electrical and Computer Engineering, Johns Hopkins University, 3400 N. Charles Street, Baltimore, Maryland, 21218, United States of America
            [2 ]Department of Plastic and Reconstructive Surgery, Vascularized Composite Allotransplantation (VCA) Laboratory, Johns Hopkins University School of Medicine, 720 Rutland Avenue, Ross 749D, Baltimore, Maryland, 21205, United States of America
            [3 ]Department of Hand Surgery, Beijing Jishuitan Hospital, 31 Xinjiekou East Street, Xicheng District, Beijing, 10035, China
            [4 ]Peking Union Medical College and Chinese Academy of Medical Sciences, Department of Plastic and Reconstructive Surgery, Plastic Surgery Hospital, 3 Ba-Da-Chu Road, Shijingshan District, Beijing, 10044, China
            University of Manchester, United Kingdom
            Author notes

            Competing Interests: The authors have declared that no competing interests exist.

            Conceived and designed the experiments: YH DT SZ WPAL GB JUK. Performed the experiments: YH GJF. Analyzed the data: YH DT SZ GJF GB JUK. Contributed reagents/materials/analysis tools: YH GJF. Contributed to the writing of the manuscript: YH GJF DT SZ WPAL GB JUK.

            Contributors
            Role: Editor
            Journal
            PLoS One
            PLoS ONE
            plos
            plosone
            PLoS ONE
            Public Library of Science (San Francisco, USA )
            1932-6203
            2014
            4 December 2014
            : 9
            : 12
            25474742
            4256419
            PONE-D-14-30398
            10.1371/journal.pone.0114215
            (Editor)

            This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

            Counts
            Pages: 14
            Funding
            The research was supported by NIH/NEI 5R01EY021540-03. Yong Huang acknowledges China Scholarship Council (CSC) for partial support for his PhD study. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
            Categories
            Research Article
            Biology and Life Sciences
            Biotechnology
            Bioengineering
            Biomedical Engineering
            Medical Devices and Equipment
            Engineering and Technology
            Digital Imaging
            Grayscale
            Medicine and Health Sciences
            Diagnostic Medicine
            Research and Analysis Methods
            Microscopy
            Optical Microscopy
            Simple Microscopy
            Custom metadata
            The authors confirm that all data underlying the findings are fully available without restriction. All relevant data are within the paper and its Supporting Information files.

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