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Lotz S, Göb M, Böttger S, Ha-Wissel L, Hundt J, Ernst F, Huber R. Large area robotically assisted optical coherence tomography (LARA-OCT). BIOMEDICAL OPTICS EXPRESS 2024; 15:3993-4009. [PMID: 38867778 PMCID: PMC11166428 DOI: 10.1364/boe.525524] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/08/2024] [Revised: 05/16/2024] [Accepted: 05/16/2024] [Indexed: 06/14/2024]
Abstract
We demonstrate large-area robotically assisted optical coherence tomography (LARA-OCT), utilizing a seven-degree-of-freedom robotic arm in conjunction with a 3.3 MHz swept-source OCT to raster scan samples of arbitrary shape. By combining multiple fields of view (FOV), LARA-OCT can probe a much larger area than conventional OCT. Also, nonplanar and curved surfaces like skin on arms and legs can be probed. The lenses in the LARA-OCT scanner with their normal FOV can have fewer aberrations and less complex optics compared to a single wide field design. This may be especially critical for high resolution scans. We directly use our fast MHz-OCT for tracking and stitching, making additional machine vision systems like cameras, positioning, tracking or navigation devices obsolete. This also eliminates the need for complex coordinate system registration between OCT and the machine vision system. We implemented a real time probe-to-surface control that maintains the probe alignment orthogonal to the sample by only using surface information from the OCT images. We present OCT data sets with volume sizes of 140 × 170 × 20 mm3, captured in 2.5 minutes.
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Affiliation(s)
- Simon Lotz
- Institute of Biomedical Optics, Universität zu Lübeck, Peter-Monnik-Weg 4, 23562 Lübeck, Germany
| | - Madita Göb
- Institute of Biomedical Optics, Universität zu Lübeck, Peter-Monnik-Weg 4, 23562 Lübeck, Germany
| | - Sven Böttger
- Institute for Robotic and Cognitive Systems, Universität zu Lübeck, Ratzeburger Allee 160, 23562 Lübeck, Germany
- qtec Services GmbH, Niels-Bohr-Ring 3-5, 23568 Lübeck, Germany
| | - Linh Ha-Wissel
- Lübeck Institute of Experimental Dermatology, Universität zu Lübeck, Ratzeburger Allee 160, 23562 Lübeck, Germany
- Department of Dermatology, Allergology, Venerology, University Hospital of Schleswig-Holstein, Ratzeburger Allee 160, 23538 Lübeck, Germany
| | - Jennifer Hundt
- Lübeck Institute of Experimental Dermatology, Universität zu Lübeck, Ratzeburger Allee 160, 23562 Lübeck, Germany
| | - Floris Ernst
- Institute for Robotic and Cognitive Systems, Universität zu Lübeck, Ratzeburger Allee 160, 23562 Lübeck, Germany
| | - Robert Huber
- Institute of Biomedical Optics, Universität zu Lübeck, Peter-Monnik-Weg 4, 23562 Lübeck, Germany
- Medizinisches Laserzentrum Lübeck GmbH, Peter-Monnik-Weg 4, 23562 Lübeck, Germany
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Zhao Y, Kong R, Ma F, Qi S, Dai C, Meng J. ATN-Res2Unet: an advanced deep learning network for the elimination of saturation artifacts in endoscopy optical coherence tomography. OPTICS EXPRESS 2024; 32:17318-17335. [PMID: 38858918 DOI: 10.1364/oe.517587] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2024] [Accepted: 04/17/2024] [Indexed: 06/12/2024]
Abstract
Endoscopic optical coherence tomography (OCT) possesses the capability to non-invasively image internal lumens; however, it is susceptible to saturation artifacts arising from robust reflective structures. In this study, we introduce an innovative deep learning network, ATN-Res2Unet, designed to mitigate saturation artifacts in endoscopic OCT images. This is achieved through the integration of multi-scale perception, multi-attention mechanisms, and frequency domain filters. To address the challenge of obtaining ground truth in endoscopic OCT, we propose a method for constructing training data pairs. Experimental in vivo data substantiates the effectiveness of ATN-Res2Unet in reducing diverse artifacts while preserving structural information. Comparative analysis with prior studies reveals a notable enhancement, with average quantitative indicators increasing by 45.4-83.8%. Significantly, this study marks the inaugural exploration of leveraging deep learning to eradicate artifacts from endoscopic OCT images, presenting considerable potential for clinical applications.
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Schulte B, Göb M, Singh AP, Lotz S, Draxinger W, Heimke M, Pieper M, Heinze T, Wedel T, Rahlves M, Huber R, Ellrichmann M. High-resolution rectoscopy using MHz optical coherence tomography: a step towards real time 3D endoscopy. Sci Rep 2024; 14:4672. [PMID: 38409328 PMCID: PMC10897148 DOI: 10.1038/s41598-024-55338-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2023] [Accepted: 02/22/2024] [Indexed: 02/28/2024] Open
Abstract
Colonoscopy and endoscopic ultrasound play pivotal roles in the assessment of rectal diseases, especially rectal cancer and inflammatory bowel diseases. Optical coherence tomography (OCT) offers a superior depth resolution, which is a critical factor for individualizing the therapeutic concept and evaluating the therapy response. We developed two distinct rectoscope prototypes, which were integrated into a 1300 nm MHz-OCT system constructed at our facility. The rapid rotation of the distal scanning probe at 40,000 revolutions per minute facilitates a 667 Hz OCT frame rate, enabling real-time endoscopic imaging of large areas. The performance of these OCT-rectoscopes was assessed in an ex vivo porcine colon and a post mortem human in-situ colon. The OCT-rectoscope consistently distinguished various layers of the intestinal wall, identified gut-associated lymphatic tissue, and visualized a rectal polyp during the imaging procedure with 3D-reconstruction in real time. Subsequent histological examination confirmed these findings. The body donor was preserved using an ethanol-glycerol-lysoformin-based technique for true-to-life tissue consistency. We could demonstrate that the novel MHZ-OCT-rectoscope effectively discriminates rectal wall layers and crucial tissue characteristics in a post mortem human colon in-situ. This real-time-3D-OCT holds promise as a valuable future diagnostic tool for assessing disease state and therapy response on-site in rectal diseases.
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Affiliation(s)
- Berenice Schulte
- Interdisciplinary Endoscopy, Medical Department 1, University Hospital Schleswig-Holstein, Campus Kiel, Kiel, Germany
| | - Madita Göb
- Institute of Biomedical Optics, University of Luebeck, Luebeck, Germany
| | | | - Simon Lotz
- Institute of Biomedical Optics, University of Luebeck, Luebeck, Germany
| | | | - Marvin Heimke
- Center of Clinical Anatomy, Institute of Anatomy, Christian-Albrechts University Kiel, Kiel, Germany
| | - Mario Pieper
- Institute of Anatomy, University of Luebeck, Luebeck, Germany
- Airway Research Center North (ARCN), German Center for Lung Research (DZL), Luebeck, Germany
| | - Tillmann Heinze
- Center of Clinical Anatomy, Institute of Anatomy, Christian-Albrechts University Kiel, Kiel, Germany
| | - Thilo Wedel
- Center of Clinical Anatomy, Institute of Anatomy, Christian-Albrechts University Kiel, Kiel, Germany
| | - Maik Rahlves
- Institute of Biomedical Optics, University of Luebeck, Luebeck, Germany
| | - Robert Huber
- Institute of Biomedical Optics, University of Luebeck, Luebeck, Germany
| | - Mark Ellrichmann
- Interdisciplinary Endoscopy, Medical Department 1, University Hospital Schleswig-Holstein, Campus Kiel, Kiel, Germany.
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Singh AP, Göb M, Ahrens M, Eixmann T, Schulte B, Schulz-Hildebrandt H, Hüttmann G, Ellrichmann M, Huber R, Rahlves M. Virtual Hall sensor triggered multi-MHz endoscopic OCT imaging for stable real-time visualization. OPTICS EXPRESS 2024; 32:5809-5825. [PMID: 38439298 DOI: 10.1364/oe.514636] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2023] [Accepted: 01/18/2024] [Indexed: 03/06/2024]
Abstract
Circumferential scanning in endoscopic imaging is crucial across various disciplines, and optical coherence tomography (OCT) is often the preferred choice due to its high-speed, high-resolution, and micron-scale imaging capabilities. Moreover, real-time and high-speed 3D endoscopy is a pivotal technology for medical screening and precise surgical guidance, among other applications. However, challenges such as image jitter and non-uniform rotational distortion (NURD) are persistent obstacles that hinder real-time visualization during high-speed OCT procedures. To address this issue, we developed an innovative, low-cost endoscope that employs a brushless DC motor for scanning, and a sensorless technique for triggering and synchronizing OCT imaging with the scanning motor. This sensorless approach uses the motor's electrical feedback (back electromotive force, BEMF) as a virtual Hall sensor to initiate OCT image acquisition and synchronize it with a Fourier Domain Mode-Locked (FDML)-based Megahertz OCT system. Notably, the implementation of BEMF-triggered OCT has led to a substantial reduction in image jitter and NURD (<4 mrad), thereby opening up a new window for real-time visualization capabilities. This approach suggests potential benefits across various applications, aiming to provide a more accurate, deployable, and cost-effective solution. Subsequent studies can explore the adaptability of this system to specific clinical scenarios and its performance under practical endoscopic conditions.
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Hu Z, He B, Shi Y, Wang C, Chen Z, Yin Z, Liu X, Zhang X, Zhang N, Jing L, Wang G, Xue P. High-speed k-linear swept laser using acousto-optic deflectors with Doppler shift compensation for optical coherence tomography. OPTICS LETTERS 2024; 49:101-104. [PMID: 38134155 DOI: 10.1364/ol.513516] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2023] [Accepted: 11/30/2023] [Indexed: 12/24/2023]
Abstract
Swept laser based on the acousto-optic deflector (AOD) is a promising swept source in optical coherence tomography (OCT) applications for its high wavenumber linear sweep without mechanical motion. However, the poor coherence length and the elongated cavity of the laser imposed limitations on the acquisition of high-quality images with adequate imaging depth and high imaging speed. In this Letter, we demonstrate a compact high-speed wavenumber linear swept laser based on AOD using Doppler shift compensation, achieving a high linearity of Pearson's R of 0.999991, a duty cycle of ∼100%, an extended coherence length of 5.7 mm, an output power of 18 mW, and excellent phase stability at a sweep speed of 500 kHz. OCT structural images with a system sensitivity of 103.2 dB and OCT angiography (OCTA) of human palm in vivo have been successfully performed, serving as a compelling demonstration of the excellent performance of this swept laser. We believe that the proposed laser will be of high potential in various clinical and industrial applications in the future.
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Klufts M, Jiménez AM, Lotz S, Bashir MA, Pfeiffer T, Mlynek A, Wieser W, Chamorovskiy A, Bradu A, Podoleanu A, Huber R. 828 kHz retinal imaging with an 840 nm Fourier domain mode locked laser. BIOMEDICAL OPTICS EXPRESS 2023; 14:6493-6508. [PMID: 38420314 PMCID: PMC10898573 DOI: 10.1364/boe.504302] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Revised: 11/08/2023] [Accepted: 11/16/2023] [Indexed: 03/02/2024]
Abstract
This paper presents a Fourier domain mode locked (FDML) laser centered around 840 nm. It features a bidirectional sweep repetition rate of 828 kHz and a spectral bandwidth of 40 nm. An axial resolution of ∼9.9 µm in water and a 1.4 cm sensitivity roll-off are achieved. Utilizing a complex master-slave (CMS) recalibration method and due to a sufficiently high sensitivity of 84.6 dB, retinal layers of the human eye in-vivo can be resolved during optical coherence tomography (OCT) examination. The developed FDML laser enables acquisition rates of 3D-volumes with a size of 200 × 100 × 256 voxels in under 100 milliseconds. Detailed information on the FDML implementation, its challenging design tasks, and OCT images obtained with the laser are presented in this paper.
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Affiliation(s)
- Marie Klufts
- Institute of Biomedical Optics, University of Lübeck, Lübeck 23562, Germany
| | | | - Simon Lotz
- Institute of Biomedical Optics, University of Lübeck, Lübeck 23562, Germany
| | | | | | | | | | | | - Adrian Bradu
- School of Physical Sciences, University of Kent, Canterbury CT2 7NH, United Kingdom
| | - Adrian Podoleanu
- School of Physical Sciences, University of Kent, Canterbury CT2 7NH, United Kingdom
| | - Robert Huber
- Institute of Biomedical Optics, University of Lübeck, Lübeck 23562, Germany
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Wang C, Zhu J, Ma J, Meng X, Ma Z, Fan F. Optical coherence elastography and its applications for the biomechanical characterization of tissues. JOURNAL OF BIOPHOTONICS 2023; 16:e202300292. [PMID: 37774137 DOI: 10.1002/jbio.202300292] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Revised: 09/19/2023] [Accepted: 09/27/2023] [Indexed: 10/01/2023]
Abstract
The biomechanical characterization of the tissues provides significant evidence for determining the pathological status and assessing the disease treatment. Incorporating elastography with optical coherence tomography (OCT), optical coherence elastography (OCE) can map the spatial elasticity distribution of biological tissue with high resolution. After the excitation with the external or inherent force, the tissue response of the deformation or vibration is detected by OCT imaging. The elastogram is assessed by stress-strain analysis, vibration amplitude measurements, and quantification of elastic wave velocities. OCE has been used for elasticity measurements in ophthalmology, endoscopy, and oncology, improving the precision of diagnosis and treatment of disease. In this article, we review the OCE methods for biomechanical characterization and summarize current OCE applications in biomedicine. The limitations and future development of OCE are also discussed during its translation to the clinic.
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Affiliation(s)
- Chongyang Wang
- Key Laboratory of the Ministry of Education for Optoelectronic Measurement Technology and Instrument, Beijing Information Science and Technology University, Beijing, China
| | | | - Jiawei Ma
- Key Laboratory of the Ministry of Education for Optoelectronic Measurement Technology and Instrument, Beijing Information Science and Technology University, Beijing, China
| | - Xiaochen Meng
- Key Laboratory of the Ministry of Education for Optoelectronic Measurement Technology and Instrument, Beijing Information Science and Technology University, Beijing, China
| | - Zongqing Ma
- Key Laboratory of the Ministry of Education for Optoelectronic Measurement Technology and Instrument, Beijing Information Science and Technology University, Beijing, China
| | - Fan Fan
- Key Laboratory of the Ministry of Education for Optoelectronic Measurement Technology and Instrument, Beijing Information Science and Technology University, Beijing, China
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