1. Articles from Desmond C. Adler

    1-24 of 24
    1. Method for identifying malignancies in barrett's esophagus using white light endoscopy

      Method for identifying malignancies in barrett's esophagus using white light endoscopy

      A method is described for computing a statistically significant difference between dysplasia and Barrett's esophagus (both with and without inflammatory component) using a discriminate function with diffuse reflectance measurements performed at a minimum of four different wavelengths of 485, 513, 598, and 629 nm. The discriminate function found depends both on local blood fraction volume T.sub.HB and oxygenation SO.sub.2. A pull-back approach of spectral data acquisition is disclosed which takes into account tissue motility in esophagus and measurement geometry peculiarities. The pull-back approach provides a significant improvement of measurement reproducibility and reduction of data deviation ...

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    2. Fourier domain mode locking: method and apparatus for control and improved performance

      Fourier domain mode locking: method and apparatus for control and improved performance

      A control system for improving and stabilizing Fourier domain mode locking (FDML) operation. The control system may also provide regulation of FDML operational parameters such as filter tuning, laser gain, polarization, polarization chromaticity, elliptical polarization retardance, and/or dispersion. The control system may be located internal to or external from the FDML laser cavity.

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    3. Extended coherence length megahertz FDML and its application for anterior segment imaging

      Extended coherence length megahertz FDML and its application for anterior segment imaging
      We present a 1300 nm Fourier domain mode locked (FDML) laser for optical coherence tomography (OCT) that combines both, a high 1.6 MHz wavelength sweep rate and an ultra-long instantaneous coherence length for rapid volumetric deep field imaging. By reducing the dispersion in the fiber delay line of the FDML laser, the instantaneous coherence length and hence the available imaging range is approximately quadrupled compared to previously published MHz-FDML setups, the imaging speed is increased by a factor of 16 compared to previous extended coherence length results. We present a detailed characterization of the FDML laser performance. We demonstrate ...
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    4. Structural markers observed with endoscopic 3-dimensional optical coherence tomography correlating with Barrett's esophagus radiofrequency ablation treatment response (with videos)

      Structural markers observed with endoscopic 3-dimensional optical coherence tomography correlating with Barrett's esophagus radiofrequency ablation treatment response (with videos)

      Background Radiofrequency ablation (RFA) is effective for treating Barrett's esophagus (BE) but often involves multiple endoscopy sessions over several months to achieve complete response. Objective Identify structural markers that correlate with treatment response by using 3-dimensional (3-D) optical coherence tomography (OCT; 3-D OCT). Design Cross-sectional. Setting Single teaching hospital. Patients Thirty-three patients, 32 male and 1 female, with short-segment (<3 cm) BE undergoing RFA treatment. Intervention Patients were treated with focal RFA, and 3-D OCT was performed at the gastroesophageal junction before and immediately after the RFA treatment. Patients were re-examined with standard endoscopy 6 to 8 weeks later ...

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    5. Comparison of Tissue Architectural Changes between Radiofrequency Ablation and Cryospray Ablation in Barrett’s Esophagus Using Endoscopic Three-Dimensional Optical Coherence Tomography

      Comparison of Tissue Architectural Changes between Radiofrequency Ablation and Cryospray Ablation in Barrett’s Esophagus Using Endoscopic Three-Dimensional Optical Coherence Tomography

      Two main nonsurgical endoscopic approaches for ablating dysplastic and early cancer lesions in the esophagus have gained popularity, namely, radiofrequency ablation (RFA) and cryospray ablation (CSA). We report a uniquely suited endoscopic and near-microscopic imaging modality, three-dimensional (3D) optical coherence tomography (OCT), to assess and compare the esophagus immediately after RFA and CSA. The maximum depths of architectural changes were measured and compared between the two treatment groups. RFA was observed to induce 230~260 

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    6. Cervical inlet patch-optical coherence tomography imaging and clinical significance

      Cervical inlet patch-optical coherence tomography imaging and clinical significance

      AIM: To demonstrate the feasibility of optical coherence tomography (OCT) imaging in differentiating cervical inlet patch (CIP) from normal esophagus, Barrett’s esophagus (BE), normal stomach and duodenum. METHODS: This study was conducted at the Veterans Affairs Boston Healthcare System (VABHS). Patients undergoing standard esophagogastroduodenoscopy at VABHS, including one patient with CIP, one representative patient with BE and three representative normal subjects were included. White light video endoscopy was performed and endoscopic 3D-OCT images were obtained in each patient using a prototype OCT system. The OCT imaging probe passes through the working channel of the endoscope to enable simultaneous video ...

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    7. Characterization of buried glands before and after radiofrequency ablation by using 3-dimensional optical coherence tomography (with videos)

      Characterization of buried glands before and after radiofrequency ablation by using 3-dimensional optical coherence tomography (with videos)

      Background: Radiofrequency ablation (RFA) is an endoscopic technique used to eradicate Barrett's esophagus (BE). However, such ablation can commonly lead to neosquamous epithelium overlying residual BE glands not visible by conventional endoscopy and may evade detection on random biopsy samples.Objective: To demonstrate the capability of endoscopic 3-dimensional optical coherence tomography (3D-OCT) for the identification and characterization of buried glands before and after RFA therapy.Design: Cross-sectional study.Setting: Single teaching hospital.Patients: Twenty-six male and 1 female white patients with BE undergoing RFA treatment.Interventions: 3D-OCT was performed at the gastroesophageal junction in 18 patients before attaining complete ...

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    8. Extended coherence length Fourier domain mode locked lasers at 1310 nm

      Extended coherence length Fourier domain mode locked lasers at 1310 nm
      Fourier domain mode locked (FDML) lasers are excellent tunable laser sources for frequency domain optical coherence tomography (FD-OCT) systems due to their combination of high sweep rates, large tuning ranges, and high output powers. However, conventional FDML lasers provide coherence lengths of only 4–10 mm, limiting their use in demanding applications such as intravascular OCT where coherence lengths of >20 mm are required for optimal imaging of large blood vessels. Furthermore, like most swept lasers, conventional FDML lasers produce only one useable sweep direction per tunable filter drive cycle, halving the effective sweep rate of the laser compared to ...
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    9. Features of Sub-Epithelial Glandular Structures on Three-Dimensional Endoscopic Optical Coherence Tomography (3D-EOCT) After Endoscopic Mucosal Ablation

      Features of Sub-Epithelial Glandular Structures on Three-Dimensional Endoscopic Optical Coherence Tomography (3D-EOCT) After Endoscopic Mucosal Ablation

      Abstracts submitted to ASGE 2010. Endoscopic mucosal ablative therapies are becoming accepted as a treatment for Barrett's esophagus (BE) with high-grade dysplasia. Radiofrequency ablation (RFA) has been shown to be effective in achieving broad and superficial BE ablation and replacement with normal-appearing squamous epithelium. Endoscopic optical coherence tomography (EOCT) is an imaging technique that uniquely allows visualization of sub-surface structures. The new three-dimensional EOCT (3D-EOCT) provides both cross-sectional and en face images of examined structures. 3D-EOCT may represent a novel method for post-ablation BE surveillance by revealing different glandular structures underneath the post-ablative surface epithelium.

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    10. Endoscopic 3D-OCT reveals buried glands following radiofrequency ablation of Barrett's esophagus

      Endoscopic 3D-OCT reveals buried glands following radiofrequency ablation of Barrett's esophagus

      Barrett's esophagus (BE) with high-grade dysplasia is generally treated by endoscopic mucosal resection or esophagectomy. Radiofrequency ablation (RFA) is a recent treatment that allows broad and superficial ablation for BE. Endoscopic three-dimensional optical coherence tomography (3D-OCT) is a volumetric imaging technique that is uniquely suited for follow-up surveillance of RFA treatment. 3D-OCT uses a thin fiberoptic imaging catheter placed down the working channel of a conventional endoscope. 3D-OCT enables en face and cross-sectional evaluation of the esophagus for detection of residual BE, neo-squamous mucosa, or buried BE glands. Patients who had undergone RFA treatment with the BARRX HALO90 system ...

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    11. Photothermal optical coherence tomography in ex vivo human breast tissues using gold nanoshells

      Photothermal optical coherence tomography in ex vivo human breast tissues using gold nanoshells

      We demonstrate photothermal optical coherence tomography (OCT) imaging in highly scattering human breast tissue ex vivo. A 120 kHz axial scan rate, swept-source phase-sensitive OCT system at 1300 nm was used to detect phase changes induced by 830 nm photothermal excitation of gold nanoshells. Localized phase modulation was observed 300-600 μm deep in scattering tissue using an excitation power of only 22 mW at modulation frequencies up to 20 kHz. This technique enables integrated structural and molecular-targeted imaging for cancer markers using nanoshells.

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    12. Frequency comb swept lasers

      Frequency comb swept lasers
      We demonstrate a frequency comb (FC) swept laser and a frequency comb Fourier domain mode locked (FC-FDML) laser for applications in optical coherence tomography (OCT). The fiber-based FC swept lasers operate at a sweep rate of 1kHz and 120kHz, respectively over a 135nm tuning range centered at 1310nm with average output powers of 50mW. A 25GHz free spectral range frequency comb filter in the swept lasers causes the lasers to generate a series of well defined frequency steps. The narrow bandwidth (0.015nm) of the frequency comb filter enables a ~- 1.2dB sensitivity roll off over ~3mm range, compared to ...
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    13. Applications of Fourier Domain Mode Locked lasers for optical coherence tomography imaging (Thesis)

      Applications of Fourier Domain Mode Locked lasers for optical coherence tomography imaging (Thesis)
      Optical coherence tomography (OCT) is a micrometer-resolution imaging technique that produces cross-sectional images of sample microstructure by measuring the amplitude and echo time delay of backscattered light. OCT imaging is performed using low-coherence interferometry, typically with a fiber optic Michelson interferometer. OCT imaging has recently been performed by measuring the spectrum of the interference signal in the Fourier domain. In "swept source OCT" implementations, the interference spectra are generated with a wavelength-swept laser and photodetector. Axial image lines are obtained via Fourier transformation of the spectra. Fourier domain techniques have extended OCT imaging speeds from several thousand to hundreds of ...
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    14. Effective treatment of chronic radiation proctitis using radiofrequency ablation

      Effective treatment of chronic radiation proctitis using radiofrequency ablation

      Endoscopic argon plasma coagulation and bipolar electrocautery are currently preferred treatments for chronic radiation proctitis, but ulcerations and strictures frequently occur. Radiofrequency ablation (RFA) has been successful for mucosal ablation in the esophagus. Here we report the efficacy of RFA with the BarRx Halo90 system in three patients with bleeding from chronic radiation proctitis. In all cases, the procedure was well tolerated and hemostasis was achieved after 1 or 2 RFA sessions. Re-epithelialization of squamous mucosa was observed over areas of prior hemorrhage. No stricturing or ulceration was seen on follow-up up to 19 months after RFA treatment. Real-time endoscopic ...

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    15. Three-dimensional endomicroscopy of the human colon using optical coherence tomography

      Three-dimensional endomicroscopy of the human colon using optical coherence tomography

      Three-dimensional (3D) endomicroscopy imaging of the human gastrointestinal tract is demonstrated in vivo using a swept source optical coherence tomography (OCT) system. 3D datasets of normal and pathologic regions of the colon, rectum, and anal verge were obtained from seven volunteers undergoing ...

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    16. Ultrahigh-Speed Optical Coherence Tomography for Three-Dimensional and En Face Imaging of the Retina and Optic Nerve Head

      Ultrahigh-speed swept-source optical coherence tomography (OCT) imaging of the retina and optic nerve is demonstrated at 249,000 axial scans per second and 1060 nm, while methods for en face visualization of the retina, choroid, and lamina cribrosa are investigated.
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    17. Real time en face Fourier-domain optical coherence tomography with direct hardware frequency demodulation

      We demonstrate en face swept source optical coherence tomography (ss-OCT) without requiring a Fourier transformation step. The electronic optical coherence tomography (OCT) interference signal from a k-space linear Fourier domain mode-locked laser is mixed with an adjustable local oscillator, ... [Opt. Lett. 33, 2556-2558 (2008)]
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    18. Photothermal detection of gold nanoparticles using phase-sensitive optical coherence tomography

      Photothermal detection of gold nanoparticles using phase-sensitive optical coherence tomography
      The detection of a gold nanoparticle contrast agent is demonstrated using a photothermal modulation technique and phase sensitive optical coherence tomography (OCT). A focused beam from a laser diode at 808 nm is modulated at frequencies of 500 Hz – 60 kHz while irradiating a solution ... [Opt. Express 16, 4376-4393 (2008)]
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    19. High-resolution optical coherence tomography imaging of the living kidney

      Optical coherence tomography (OCT) is a rapidly emerging imaging modality that can provide non-invasive, cross-sectional, high-resolution images of tissue morphology in situ and in real-time. In the present series of studies, we used a high-speed OCT imaging system equipped with a frequency-swept laser light source (1.3 m wavelength) to study living kidneys in situ. Adult, male Munich–Wistar rats were anesthetized, a laparotomy was performed and the living kidneys were exposed for in situ observation. We observed the kidneys prior to, during and following exposure to renal ischemia induced by clamping the renal artery. The effects of intravenous mannitol ...
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    20. Three-dimensional endomicroscopy using optical coherence tomography

      Optical coherence tomography enables micrometre-scale, subsurface imaging of biological tissue by measuring the magnitude and echo time delay of backscattered light. Endoscopic optical coherence tomography imaging inside the body can be performed using fibre-optic probes. To perform three-dimensional optical coherence tomography endomicroscopy with ultrahigh volumetric resolution, however, requires extremely high imaging speeds. Here we report advances in optical coherence tomography technology using a Fourier-domain mode-locked frequency-swept laser as the light source. The laser, with a 160-nm tuning range at a wavelength of 1,315 nm, can produce images with axial resolutions of 5–7 m. In vivo three-dimensional optical coherence ...
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    21. In vivo endomicroscopy using three-dimensional optical coherence tomography and Fourier domain mode locked lasers

      We report an endoscopic optical coherence tomography (OCT) system based on a Fourier Domain Mode Locked (FDML) laser, a novel data acquisition (DAQ) system with optical frequency clocking, and a high-speed spiralscanning fiber probe. The system is capable of acquiring three-dimensional (3D) in vivo ... [Proc. SPIE Int. Soc. Opt. Eng. 6847, 684708 (2008)] published Tue Feb 19, 2008.
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    22. Comparison of three-dimensional optical coherence tomography and high resolution photography for art conservation studies

      Gold punchwork and underdrawing in Renaissance panel paintings are analyzed using both three-dimensional swept source / Fourier domain optical coherence tomography (3D-OCT) and high resolution digital photography. 3D-OCT can generate en face images with micrometer-scale resolutions at arbitrary ... [Opt. Express 15, 15972-15986 (2007)]
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    23. Digital signal processing techniques for optical coherence tomography: OCT and OCT image enhancement (Thesis)

      Digital signal processing techniques for optical coherence tomography: OCT and OCT image enhancement (Thesis)
      Digital signal processing (DSP) techniques were developed to improve the flexibility, functionality, and image quality of ultrahigh resolution optical coherence tomography (OCT) systems. To reduce the dependence of OCT research systems on fixed analog electronics and to improve overall system flexibility, a digital demodulation scheme implemented entirely in software was developed. This improvement allowed rapid reconfiguration of the OCT imaging speed and source center wavelength without having to construct new analog filters and demodulators. This demodulation scheme produced a highly accurate envelope and was immune to local variations in carrier frequency. To provide an alternative contrast modality to conventional intensity-based ...
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    1-24 of 24
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    1. (24 articles) Desmond C. Adler
    2. (21 articles) Massachusetts Institute of Technology
    3. (21 articles) James G. Fujimoto
    4. (14 articles) St. Jude Medical
    5. (12 articles) Joseph M. Schmitt
    6. (11 articles) Chao Zhou
    7. (11 articles) Tsung-Han Tsai
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    Three-dimensional endomicroscopy of the human colon using optical coherence tomography Frequency comb swept lasers Digital signal processing techniques for optical coherence tomography: OCT and OCT image enhancement (Thesis) Endoscopic 3D-OCT reveals buried glands following radiofrequency ablation of Barrett's esophagus Applications of Fourier Domain Mode Locked lasers for optical coherence tomography imaging (Thesis) Optical Coherence Tomography Angiography in Myopic Patients Quantification of retinal microvasculature and neurodegeneration changes in branch retinal vein occlusion after resolution of cystoid macular edema on optical coherence tomography angiography Machining head for a laser machining device Quantitative Comparison Of Microvascular Metrics On Three Optical Coherence Tomography Angiography Devices In Chorioretinal Disease Detection of and validation of shadows in intravascular images Automated intravascular plaque classification Detection of stent struts relative to side branches