All Articles from Hiroshi Mashimo -Optical Coherence Tomography News

Articles from Hiroshi Mashimo

1-24 of 42 1 2 »
1. Multi-MHz MEMS-VCSEL swept-source optical coherence tomography for endoscopic structural and angiographic imaging with miniaturized brushless motor probes
  
  Explore OSA | OSA Publishing Mar 30 2021 Gastroenterology , Probes
  
  Swept source optical coherence tomography (SS-OCT) enables volumetric imaging of subsurface structure. However, applications requiring wide fields of view (FOV), rapid imaging, and higher resolutions have been challenging because multi-MHz axial scan (A-scan) rates are needed. We describe a microelectromechanical systems vertical cavity surface-emitting laser (MEMS-VCSEL) SS-OCT technology for A-scan rates of 2.4 and 3.0 MHz. Sweep to sweep calibration and resampling are performed using dual channel acquisition of the OCT signal and a Mach Zehnder interferometer signal, overcoming inherent optical clock limitations and enabling higher performance. We demonstrate ultrahigh speed structural SS-OCT and OCT angiography (OCTA) imaging ...
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  Mentions: Brigham and Women’s Hospital Massachusetts Institute of Technology Thorlabs
2. Multi-MHz MEMS-VCSEL swept-source optical coherence tomography for endoscopic structural ...
  
  Explore OSA | OSA Publishing Mar 26 2021 Gastroenterology , Probes , Tunable Sources
  
  Swept source optical coherence tomography (SS-OCT) enables volumetric imaging of subsurface structure. However, applications requiring wide fields of view (FOV), rapid imaging, and higher resolutions have been challenging because multi-MHz axial scan (A-scan) rates are needed. We describe a microelectromechanical systems vertical cavity surface-emitting laser (MEMS-VCSEL) SS-OCT technology for A-scan rates of 2.4 and 3.0 MHz. Sweep to sweep calibration and resampling are performed using dual channel acquisition of the OCT signal and a Mach Zehnder interferometer signal, overcoming inherent optical clock limitations and enabling higher performance. We demonstrate ultrahigh speed structural SS-OCT and OCT angiography (OCTA) imaging ...
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  Mentions: Massachusetts Institute of Technology National Institutes of Health Thorlabs
3. Correction of circumferential and longitudinal motion distortion in high-speed catheter/endoscope-based optical coherence tomography
  
  Explore OSA | OSA Publishing Dec 9 2020 Gastroenterology
  
  Catheter/endoscope-based optical coherence tomography (OCT) is a powerful modality that visualizes structural information in luminal organs. Increases in OCT speed have reduced motion artifacts by enabling acquisition faster than or comparable to the time scales of physiological motion. However motion distortion remains a challenge because catheter/endoscope OCT imaging involves both circumferential and longitudinal scanning of tissue. This paper presents a novel image processing method to estimate and correct motion distortion in both the circumferential and longitudinal directions using a single en face image from a volumetric data set. The circumferential motion distortion is estimated and corrected using the ...
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  Mentions: Massachusetts Institute of Technology Harvard University
4. Advanced endoscopic imaging for detecting and guiding therapy of early neoplasias of the esophagus
  
  Explore The New York Academy of Sciences Nov 17 2020 Gastroenterology
  
  Esophageal cancers, largely adenocarcinoma in Western countries and squamous cell cancer in Asia, present a significant burden of disease and remain one of the most lethal of cancers. Key to improving survival is the development and adoption of new imaging modalities to identify early neoplastic lesions, which may be small, multifocal, subsurface, and difficult to detect by standard endoscopy. Such advanced imaging is particularly relevant with the emergence of ablative techniques that often require multiple endoscopic sessions and may be complicated by bleeding, pain, strictures, and recurrences. Assessing the specific location, depth of involvement, and features correlated with neoplastic progression ...
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  Mentions: Harvard University Boston University
5. Tethered capsule en face optical coherence tomography for imaging Barrett’s oesophagus in unsedated patients
  
  Explore BMJ Open Gastroenterology Sep 6 2020 Gastroenterology , Probes
  
  Objective Barrett’s oesophagus (BE) screening outside the endoscopy suite can identify patients for surveillance and reduce mortality. Tethered capsule optical coherence tomography (OCT) can volumetrically image oesophageal mucosa in unsedated patients and detect features of BE. We investigated ultrahigh-speed tethered capsule swept-source OCT (SS-OCT), improved device design, developed procedural techniques and measured capsule contact, longitudinal pullback non-uniformity and patient toleration. Design OCT was performed in 16 patients prior to endoscopic surveillance/treatment. Unsedated patients swallowed the capsule with sips of water and the tether was pulled back to image the oesophagus. SS-OCT at 1 000 000 A-scans/s enabled ...
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  Mentions: Thorlabs Massachusetts General Hospital
6. Tethered capsule en face optical coherence tomography for imaging Barrett’s esophagus in unsedated patients
  
  Explore arxiv.org May 26 2020 Gastroenterology
  
  Objective Detection of Barrett’s esophagus (BE) at points of care outside the endoscopy suite may improve screening access and reduce esophageal adenocarcinoma mortality. Tethered capsule optical coherence tomography (OCT) can volumetrically image esophageal mucosa and detect BE in unsedated patients. We investigated ultrahigh-speed tethered capsule, swept-source OCT (SS-OCT) in unsedated patients, improved device design, developed procedural techniques, measured how capsule contact and longitudinal pullback non-uniformity affect coverage, and assessed patient toleration. Design OCT was performed in 16 patients prior to endoscopic surveillance/treatment. Unsedated patients swallowed the capsule with small sips of water and the esophagus imaged by retracting ...
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  Mentions: Massachusetts Institute of Technology Thorlabs
7. Application of OCT in the Gastrointestinal Tract
  
  Explore MDPI Open Access Journals Platform Jul 25 2019 Gastroenterology
  
  Optical coherence tomography (OCT) is uniquely poised for advanced imaging in the gastrointestinal (GI) tract as it allows real-time, subsurface and wide-field evaluation at near-microscopic resolution, which may improve the current limitations or even obviate the need of superficial random biopsies in the surveillance of early neoplasias in the near future. OCT’s greatest impact so far in the GI tract has been in the study of the tubular esophagus owing to its accessibility, less bends and folds and allowance of balloon employment with optimal contact to aid circumferential imaging. Moreover, given the alarming rise in the incidence of Barrett ...
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8. Computer-Aided Analysis of Gland-Like Subsurface Hyposcattering Structures in Barrett’s Esophagus Using Optical Coherence Tomography
  
  Explore MDPI Open Access Journals Platform Nov 28 2018 Gastroenterology
  
  (1) Background: Barrett’s esophagus (BE) is a complication of chronic gastroesophageal reflux disease and is a precursor to esophageal adenocarcinoma. The clinical implication of subsurface glandular structures of Barrett’s esophagus is not well understood. Optical coherence tomography (OCT), also known as volumetric laser endomicroscopy (VLE), can assess subsurface glandular structures, which appear as subsurface hyposcattering structures (SHSs). The aim of this study is to develop a computer-aided algorithm and apply it to investigate the characteristics of SHSs in BE using clinical VLE data; (2) Methods: SHSs were identified with an initial detection followed by machine learning. Comprehensive SHS ...
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  Mentions: Massachusetts Institute of Technology Harvard University
9. Feature Of The Week 10/08/2018: Clinical Utility of Ultrahigh-Speed Endoscopic Optical Coherence Tomography in Gastroenterology
  
  Explore Optical Coherence Tomography News Oct 7 2018 Gastroenterology
  
  Barrett’s esophagus (BE) surveillance is limited by biopsy sampling error. Optical coherence tomography (OCT) enables microscopic resolution, high speed, volumetric imaging and is commercially available as volumetric laser endomicroscopy (VLE, NinePoint Medical). Studies investigated cross-sectional OCT dysplasia features, including a diagnostic algorithm (VLE-DA), however, many VLE studies used ex vivo specimens due to challenges in registering biopsy with OCT. We previously demonstrated ultrahigh-speed endoscopic OCT >10x faster than commercial instruments, enabling depth-resolved en face and cross-sectional imaging. This study investigated volumetric en face and cross-sectional OCT for identifying neoplasia. 74 OCT datasets with correlated biopsy/endoscopic mucosal resection histology ...
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  Mentions: Massachusetts Institute of Technology Thorlabs Harvard University
10. Assessment of Barrett’s esophagus and dysplasia with ultrahigh-speed volumetric en face and cross-sectional optical coherence tomography
  
  Explore thieme-connect.de Sep 30 2018 Gastroenterology
  
  Background This study aimed to evaluate the use of ultrahigh-speed volumetric en face and cross-sectional optical coherence tomography (OCT) with micromotor catheters for the in vivo assessment of Barrett’s esophagus and dysplasia. Methods 74 OCT datasets with correlated biopsy/endoscopic mucosal resection histology (49 nondysplastic Barrett’s esophagus [NDBE], 25 neoplasia) were obtained from 14 patients with Barrett’s esophagus and a history of dysplasia and 30 with NDBE. The associations between irregular mucosal patterns on en face OCT, absence of mucosal layering, surface signal > subsurface, and > 5 atypical glands on cross-sectional OCT vs. histology and treatment history were ...
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  Mentions: Massachusetts Institute of Technology Thorlabs Praevium Research
11. Cycloid scanning for wide field optical coherence tomography endomicroscopy and angiography in vivo
  
  Explore OSA | OSA Publishing Jan 16 2018 Gastroenterology , Probes
  
  Devices that perform wide field-of-view (FOV) precision optical scanning are important for endoscopic assessment and diagnosis of luminal organ disease such as in gastroenterology. Optical scanning for in vivo endoscopic imaging has traditionally relied on one or more proximal mechanical actuators, limiting scan accuracy and imaging speed. There is a need for rapid and precise two-dimensional (2D) microscanning technologies to enable the translation of benchtop scanning microscopies to in vivo endoscopic imaging. We demonstrate a new cycloid scanner in a tethered capsule for ultrahigh speed, side-viewing optical coherence tomography (OCT) endomicroscopy in vivo . The cycloid capsule incorporates two scanners: a ...
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  Mentions: Johns Hopkins University Massachusetts Institute of Technology Thorlabs
12. Optical coherence tomography in gastroenterology: a review and future outlook
  
  Explore SPIE Digital Library Dec 19 2017 Gastroenterology
  
  Optical coherence tomography (OCT) is an imaging technique optically analogous to ultrasound that can generate depth-resolved images with micrometer-scale resolution. Advances in fiber optics and miniaturized actuation technologies allow OCT imaging of the human body and further expand OCT utilization in applications including but not limited to cardiology and gastroenterology. This review article provides an overview of current OCT development and its clinical utility in the gastrointestinal tract, including disease detection/differentiation and endoscopic therapy guidance, as well as a discussion of its future applications.
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  Mentions: Columbia University Massachusetts General Hospital Harvard University
13. Ultrahigh-speed endoscopic optical coherence tomography and angiography enables delineation of lateral margins of endoscopic mucosal resection: a case report
  
  Explore SAGE Journals Nov 28 2017 Gastroenterology
  
  Endoscopic mucosal resection (EMR) is a common technique for resecting dysplastic lesions in Barrett’s esophagus (BE), stomach, and colon, 1 but precise delineation of dysplastic margins before resection and verification of complete removal after resection remain challenging. 2 , 3 Endoscopic optical coherence tomography (OCT) enables three-dimensional visualization of tissue microstructure and is commercially available as Volumetric Laser Endomicroscopy (NinePoint Medical, Bedford, MA, USA). 4 , 5 We recently developed an ultrahigh-speed endoscopic OCT system which operates more than 10 times faster than commercial instruments, generating volumetric images with higher transverse resolution and voxel density. 6 , 7 This allows visualization of ...
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  Mentions: Massachusetts Institute of Technology Thorlabs Praevium Research
14. Endoscopic forward-viewing optical coherence tomography and angiography with MHz swept source
  
  Explore OSA | OSA Publishing Aug 9 2017 Gastroenterology , Probes
  
  Endoscopic optical coherence tomography (OCT) instruments are mostly side viewing and rely on at least one proximal scan, thus limiting accuracy of volumetric imaging and en face visualization. Previous forward-viewing OCT devices had limited axial scan speeds. We report a forward-viewing fiber scanning 3D-OCT probe with 900 μm field of view and 5 μm transverse resolution, imaging at 1 MHz axial scan rate in the human gastrointestinal tract. The probe is 3.3 mm diameter and 20 mm rigid length, thus enabling passage through the endoscopic channel. The scanner has 1.8 kHz resonant frequency, and each volumetric acquisition takes ...
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  Mentions: Massachusetts Institute of Technology Thorlabs Harvard University
15. Assessment of the radiofrequency ablation dynamics of esophageal tissue with optical coherence tomography
  
  Explore SPIE | Journal Jul 10 2017 Gastroenterology
  
  Radiofrequency ablation (RFA) is widely used for the eradication of dysplasia and the treatment of early stage esophageal carcinoma in patients with Barrett’s esophagus (BE). However, there are several factors, such as variation of BE epithelium (EP) thickness among individual patients and varying RFA catheter-tissue contact, which may compromise RFA efficacy. We used a high-speed optical coherence tomography (OCT) system to identify and monitor changes in the esophageal tissue architecture from RFA. Two different OCT imaging/RFA application protocols were performed using an ex vivo swine esophagus model: (1) post-RFA volumetric OCT imaging for quantitative analysis of the coagulum ...
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  Mentions: Massachusetts Institute of Technology Harvard University
16. Endoscopic optical coherence tomography angiography microvascular features associated with dysplasia in Barrett's esophagus: a pilot study (with video)
  
  Explore Elsevier Health Feb 3 2017 Gastroenterology , Oncology
  
  Background and Aims Angiogenesis is associated with neoplastic progression of Barrett’s esophagus (BE). Volumetric optical coherence tomography angiography (OCTA) visualizes subsurface microvasculature without exogenous contrast agents. We investigated the association of OCTA microvascular features with low-grade dysplasia (LGD) and high-grade dysplasia (HGD). Methods Fifty-two patients undergoing BE surveillance or endoscopic eradication therapies for dysplasia were imaged using volumetric OCTA and corresponding histological diagnoses obtained, to yield 97 data sets (non-dysplastic BE (NDBE): N=74; LGD: N=10; HGD: N=13). After evaluating OCTA image quality, 54 datasets (NDBE: N=35; LGD: N=8; HGD: N=11) from 32 patients ...
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  Mentions: Massachusetts Institute of Technology Thorlabs
17. Depth-resolved imaging of colon tumor using optical coherence tomography and fluorescence laminar optical tomography
  
  Explore OSA | OSA Publishing Dec 27 2016 Gastroenterology
  
  Early detection of neoplastic changes remains a critical challenge in clinical cancer diagnosis and treatment. Many cancers arise from epithelial layers such as those of the gastrointestinal (GI) tract. Current standard endoscopic technology is difficult to detect the subsurface lesions. In this research, we investigated the feasibility of a novel multi-modal optical imaging approach including high-resolution optical coherence tomography (OCT) and high-sensitivity fluorescence laminar optical tomography (FLOT) for structural and molecular imaging. The C57BL/6J-Apc Min /J mice were imaged using OCT and FLOT, and the correlated histopathological diagnosis was obtained. Quantitative structural (scattering coefficient) and molecular (relative enzyme activity ...
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  Mentions: University of Maryland University of Rochester Harvard University
18. Volumetric Mapping of Barrett’s Esophagus and Dysplasia With en face Optical Coherence Tomography Tethered Capsule
  
  Explore Nature Publishing Group Nov 9 2016 Gastroenterology
  
  To the Editor: Dysplasia in Barrett’s Esophagus (BE) is patchy ( 1 ) and sometimes missed by random biopsies. Optical coherence tomography (OCT) can image large areas of the esophagus; however, slow imaging speeds in earlier studies limited visualization to cross-sections. Cross-sectional OCT detected high-grade dysplasia with sensitivity / specificity of ~80 % ( 2 , 3 ). Tethered OCT capsules were demonstrated for cross-sectional imaging in unsedated screening to detect BE ( 4 , 5 ). Our group recently developed ultrahigh-speed OCT for en face and angiographic imaging, using micromotor probes in patients ( 6 , 7 ) and large field-of-view tethered capsule devices in swine ( 8 ). Narrow-band imaging (NBI) visualizes ...
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  Mentions: Massachusetts Institute of Technology Thorlabs Praevium Research
19. Circumferential optical coherence tomography angiography imaging of the swine esophagus using a micromotor balloon catheter
  
  Explore OSA | OSA Publishing Jul 5 2016 Gastroenterology , Probes
  
  We demonstrate a micromotor balloon imaging catheter for ultrahigh speed endoscopic optical coherence tomography (OCT) which provides wide area, circumferential structural and angiographic imaging of the esophagus without contrast agents. Using a 1310 nm MEMS tunable wavelength swept VCSEL light source, the system has a 1.2 MHz A-scan rate and ~8.5 µm axial resolution in tissue. The micromotor balloon catheter enables circumferential imaging of the esophagus at 240 frames per second (fps) with a ~30 µm (FWHM) spot size. Volumetric imaging is achieved by proximal pullback of the micromotor assembly within the balloon at 1.5 mm/sec ...
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  Mentions: Brigham and Women’s Hospital Massachusetts Institute of Technology Thorlabs
20. Feature Of The Week 03/08/2015: Endoscopic Optical Coherence Angiography Enables Three Dimensional Visualization of Subsurface Microvasculature
  
  Explore Optical Coherence Tomography News Mar 7 2015 Gastroenterology
  
  Endoscopic imaging technologies such as confocal laser endomicroscopy (CLE) and narrowband imaging (NBI) have been used to investigate vascular changes as hallmarks of early cancer in the GI tract. However, the limited frame rate and field of view make CLE imaging sensitive to motion artifacts, whereas NBI has limited resolution and visualizes only the surface vascular pattern. Endoscopic optical coherence tomography (OCT) enables high speed volumetric imaging of subsurface features at near-microscopic resolution, and can image microvasculature without exogenous contrast agents such as fluorescein, which obliterates the image in areas of bleeding, or after biopsies and resections. OCT has been ...
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  Mentions: Massachusetts Institute of Technology Thorlabs Harvard University
21. Ultrahigh speed en face OCT capsule for endoscopic imaging
  
  Explore OSA | OSA Publishing Mar 5 2015 Gastroenterology , Probes
  
  Depth resolved and en face OCT visualization in vivo may have important clinical applications in endoscopy. We demonstrate a high speed, two-dimensional (2D) distal scanning capsule with a micromotor for fast rotary scanning and a pneumatic actuator for precision longitudinal scanning. Longitudinal position measurement and image registration were performed by optical tracking of the pneumatic scanner. The 2D scanning device enables high resolution imaging over a small field of view and is suitable for OCT as well as other scanning microscopies. Large field of view imaging for screening or surveillance applications can also be achieved by proximally pulling back or ...
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  Mentions: Massachusetts Institute of Technology Thorlabs Praevium Research
22. Endoscopic Optical Coherence Angiography Enables Three Dimensional Visualization of Subsurface Microvasculature
  
  Explore Gastroenterology Dec 1 2014 Gastroenterology
  
  Endoscopic imaging technologies such as confocal laser endomicroscopy1 and narrow band imaging (NBI)2 have been used to investigate vascular changes as hallmarks of early cancer in the gastrointestinal tract. However, the limited frame rate and field of view make confocal laser endomicroscopy imaging sensitive to motion artifacts, whereas NBI has limited resolution and visualizes only the surface vascular pattern. Endoscopic optical coherence tomography (OCT) enables high-speed volumetric imaging of subsurface features at near-microscopic resolution,3, 4 and can image microvasculature without exogenous contrast agents,5 such as fluorescein, which obliterates the image in areas of bleeding, or after ...
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  Mentions: Massachusetts Institute of Technology Thorlabs Praevium Research
23. Ultrahigh speed endoscopic optical coherence tomography for gastroenterology
  
  Explore opticsinfobase.org Nov 29 2014 Gastroenterology
  
  We describe an ultrahigh speed endoscopic swept source optical coherence tomography (OCT) system for clinical gastroenterology using a vertical-cavity surface-emitting laser (VCSEL) and micromotor imaging catheter. The system had a 600 kHz axial scan rate and 8 µm axial resolution in tissue. Imaging was performed with a 3.2 mm diameter imaging catheter at 400 frames per second with a 12 µm spot size. Three-dimensional OCT (3D-OCT) imaging was performed in patients with a cross section of pathologies undergoing upper and lower endoscopy. The use of distally actuated imaging catheters enabled OCT imaging with more flexibility, such as volumetric imaging ...
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  Mentions: Massachusetts Institute of Technology Thorlabs Harvard University
24. Correction of rotational distortion for catheter-based en face OCT and OCT angiography
  
  Explore opticsinfobase.org Oct 10 2014
  
  We demonstrate a computationally efficient method for correcting the nonuniform rotational distortion (NURD) in catheter-based imaging systems to improve endoscopic en face optical coherence tomography (OCT) and OCT angiography. The method performs nonrigid registration using fiducial markers on the catheter to correct rotational speed variations. Algorithm performance is investigated with an ultrahigh-speed endoscopic OCT system and micromotor catheter. Scan nonuniformity is quantitatively characterized, and artifacts from rotational speed variations are significantly reduced. Furthermore, we present endoscopic en face OCT and OCT angiography images of human gastrointestinal tract in vivo to demonstrate the image quality improvement using the correction algorithm.
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  Mentions: Massachusetts Institute of Technology Thorlabs Harvard University
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