Showing papers by "Brett E. Bouma published in 1996"
TL;DR: OCT represents a promising new technology for imaging vascular microstructure with a level of resolution not previously achieved with the use of other imaging modalities, and can be performed with a catheter integrated with a relatively inexpensive optical fiber.
Abstract: Background Optical coherence tomography (OCT) is a recently developed medical diagnostic technology that uses back-reflected infrared light to perform in situ micron scale tomographic imaging. In this work, we investigate the ability of OCT to perform micron scale tomographic imaging of the internal microstructure of in vitro atherosclerotic plaques. Methods and Results Aorta and relevant nonvascular tissue were obtained at autopsy. Two-dimensional cross-sectional imaging of the exposed surface of the arterial segments was performed in vitro with OCT. A 1300-nm wavelength, superluminescent diode light source was used that allows an axial spatial resolution of 20 μm. The signal-to-noise ratio was 109 dB. Images were displayed in gray scale or false color. Imaging was performed over 1.5 mm into heavily calcified tissue, and a high contrast was noted between lipid- and water-based constituents, making OCT attractive for intracoronary imaging. The 20-μm axial resolution of OCT allowed small structural details...
664 citations
02 Jun 1996
TL;DR: The design and performance of a prototype single-mode fiber-optic scanning OCT catheter with a diameter of 1 mm is described, which will permit micron scale, cross-sectional medical diagnostic imaging in tissues such as the vascular system, the gastrointestinal tract, the urinary tract, and the respiratory tract.
Abstract: Summary form only given. In order to apply OCT for imaging of internal organ systems, a flexible, small diameter, catheter/endoscope, which is capable of delivering, focusing, scanning, and collecting a single-spatial-mode optical beam, must be constructed. In this summary, we describe the design and performance of a prototype single-mode fiber-optic scanning OCT catheter with a diameter of 1 mm. OCT imaging may be performed at 1.3-micron wavelengths using either a superluminescent laser diode source or a Kerr-lens mode-locked Cr:forsterite laser, which provides high powers for high-speed imaging. This device is an enabling technology for OCT and will permit micron scale, cross-sectional medical diagnostic imaging in tissues such as the vascular system, the gastrointestinal tract, the urinary tract, and the respiratory tract.
491 citations
TL;DR: Dynamic, motion-artifact-free in vivo imaging of a beating Xenopus laevis (African frog) heart is demonstrated.
Abstract: The development of techniques for high-speed image acquisition in optical coherence tomography (OCT) systems is essential for suppressing motion artifacts when one is imaging living systems. We describe a new OCT system for performing micrometer-scale, cross-sectional optical imaging at four images/s. To achieve OCT image-acquisition times of less than 1 s, we use a piezoelectric fiber stretcher to vary the reference arm delay. A Kerr-lens mode-locked chromium-doped forsterite laser is employed as the low-coherence source for the highspeed OCT system. Dynamic, motion-artifact-free in vivo imaging of a beating Xenopus laevis (African frog) heart is demonstrated.
326 citations
TL;DR: In this article, an all-solidstate Kerr-lens mode-locked Cr:forsterite laser operating at 1.28 μm is demonstrated as a shortcoherence-length, high-average-power source for optical coherence tomographic (OCT) imaging.
Abstract: An all-solid-state Kerr-lens mode-locked Cr:forsterite laser operating at 1.28 μm is demonstrated as a shortcoherence-length, high-average-power source for optical coherence tomographic (OCT) imaging. We achieve ultrahigh resolution by spectrally broadening the laser pulses, using self-phase modulation in a dispersion-shifted single-mode fiber. OCT imaging with a resolution of 6 μm and a dynamic range of 115 dB is achieved.
266 citations
TL;DR: OCT achieves high-resolution and image differentiation of vascular tissues to a degree that has not been previously possible with any method except excisional biopsy as mentioned in this paper, thus, OCT represents a promising new diagnostic technology for intracoronary imaging.
Abstract: OCT achieves high-resolution and image differentiation of vascular tissues to a degree that has not been previously possible with any method except excisional biopsy. Thus, OCT represents a promising new diagnostic technology for intracoronary imaging, which could permit the in vivo evaluation of critical vascular pathology.
256 citations
TL;DR: The feasibility of using OCT for assessing atherosclerotic plaque microstructure at resolutions of 4 to 16 micrometer-scale cross-sectional images is demonstrated.
Abstract: Optical coherence tomography (OCT) is a recently developed technology that uses infrared light to generate micrometer-scale cross-sectional images ( Science. 1991;254:1178-1181). We recently demonstrated the feasibility of using OCT for assessing atherosclerotic plaque microstructure ( Circulation. 1996;93:1206-1213) at resolutions of 4 to 16 …
203 citations
TL;DR: The optical coherence tomography (OCT) technology as mentioned in this paper combines high-resolution in vivo imaging in a diode-based benchtop instrument capable of micron-scale resolution in transparent and non-transparent biological specimens.
179 citations
TL;DR: In this paper, the application of OCT for imaging developing structure in Rana pipiens, Xenopus laevis, and Brachydanio rerio was investigated, and images were compared to conventional histological baselines.
143 citations
TL;DR: A novel compact cavity design that uses an intracavity lens and shows that nonastigmatic modes can signif icantly increase Kerr-lens action and achieve self-starting mode locking is demonstrated.
Abstract: We present a comparison of compact three-element Ti:Al2O3 laser resonator designs for enhanced Kerr-lens mode locking. We demonstrate a novel compact cavity design that uses an intracavity lens and show that nonastigmatic modes can significantly increase Kerr-lens action and achieve self-starting mode locking. A new mechanism for group-velocity dispersion that arises from the chromatic aberration of the intracavity focusing elements is also demonstrated.
128 citations
02 Jun 1996
TL;DR: In this paper, the authors proposed a cavity-dumping scheme for short-pulse Ti:sapphire laser with a single-Pulse energy of 62 nJ, where the AO wave must traverse the beam waist in the round-trip time of the cavity, limiting the energy to roughly 30 /spl mu/m.
Abstract: Summary form only given. Acousto-optical cavity-dumping (AO) has been demonstrated with short-pulse Ti:sapphire lasers producing single-pulse energies of 62 nJ. However, AO cavity-dumping is inherently limited because the AO wave must traverse the beam waist in the round-trip time of the cavity limiting the beam waist to roughly 30 /spl mu/m. This limits the pulse energy as the intensity must be kept below the threshold for nonlinear processes in the AO crystal. Furthermore, the contrast in the pulse energy on either side of the main cavity-dumped pulse is rather low (30:1 or 20:1). Electro-optical (EO) cavity dumping has no such limitation and can be scaled to higher energies with high contrast. However, there are several difficulties associated with EO cavity dumping all of which have now been solved.
119 citations
TL;DR: A new design for chromium-doped forsterite lasers based on near-IR (700-800-nm) pumping of a thin (3-mm) crystal is described, which results in an increased effective figure of merit and tuning performance.
Abstract: We describe a new design for chromium-doped forsterite lasers based on near-IR (700–800-nm) pumping of a thin (3-mm) crystal. In contrast with pumping at 1.06 μm, near-IR pumping permits the use of shorter crystal lengths, which enable one to develop compact and diode-pumped laser geometries. Near-IR pumping also results in an increased effective figure of merit and tuning performance. Using a Ti:Al2O3 pump laser, we investigated cw laser characteristics over a range of pump wavelengths compatible with diode pumping. Room-temperature cw operation with a tuning range of 1175 to 1375 nm was achieved. Kerr-lens mode-locked operation of this laser was also demonstrated with pulse durations of ~50 fs.
Journal Article•
TL;DR: The optical coherence tomography technology combines high-resolution in vivo imaging in a diode-based benchtop instrument capable of micron-scale resolution in transparent and non-transparent biological specimens for the investigation of developing neural morphology.
Abstract: Imaging technologies offer numerous possibilities to investigate the processes involved in neural development. The optical coherence tomography (OCT) technology is analogous to ultrasound backscatter microscopy except reflections of light are detected rather than sound. The OCT technology combines high-resolution in vivo imaging in a diode-based benchtop instrument capable of micron-scale resolution in transparent and non-transparent biological specimens. In this paper, we examine the potential of using OCT for the investigation of developing neural morphology. To demonstrate the capabilities of this technique in assessing neural development, we have chosen to image early normal and abnormal neural morphology in a common developmental biology model, Xenopus laevis. In vivo images clearly identify gross and subtle differences in neural structure and may offer an alternative to the costly and time-consuming process of repeated histological preparation for neural developmental studies. Because imaging can be performed rapidly and repeatedly, the morphological changes of single specimens can be followed throughout development. To illustrate the future potential of this technique, a state-of-the-art Cr 4+ :forsterite modelocked laser is used as a broad bandwidth light source to image individual cells in a developing specimen.
01 Dec 1996
TL;DR: Advances in OCT technology are presented that will enable in vivo OCT imaging of internal organ systems such as the cardiovascular system, the urinary tract, and the gastrointestinal tract and the development of an OCT compatible catheter-endoscope for access tointernal organ systems.
Abstract: We present advances in OCT technology that will enable in vivo OCT imaging of internal organ systems such as the cardiovascular system, the urinary tract, and the gastrointestinal tract. These advances include improvements in image acquisition speed to avoid motion artifacts, and the development of an OCT compatible catheter-endoscope for access to internal organ systems. A fast scanning OCT system has recently been constructed. This system employs a high power (200 mW) chromium doped forsterite laser as the low coherence source and a piezoelectric fiber stretcher to induce reference arm optical path length delay. The fast scanning system acquires OCT images with an acquisition rate of four images per second, an axial resolution of 15 /spl mu/m, and a signal to noise ratio of 112 dB.
Proceedings Article•
02 Jun 1996
TL;DR: There are several difficulties associated with EO cavity dumping all of which have now been solved and the AO wave must traverse the beam waist in the round-trip time of the cavity limiting the pulse energy to roughly 30 /spl mu/m.
Abstract: Summary form only given. Acousto-optical cavity-dumping (AO) has been demonstrated with short-pulse Ti:sapphire lasers producing single-pulse energies of 62 nJ. However, AO cavity-dumping is inherently limited because the AO wave must traverse the beam waist in the round-trip time of the cavity limiting the beam waist to roughly 30 /spl mu/m. This limits the pulse energy as the intensity must be kept below the threshold for nonlinear processes in the AO crystal. Furthermore, the contrast in the pulse energy on either side of the main cavity-dumped pulse is rather low (30:1 or 20:1). Electro-optical (EO) cavity dumping has no such limitation and can be scaled to higher energies with high contrast. However, there are several difficulties associated with EO cavity dumping all of which have now been solved.
Proceedings Article•
02 Jun 1996TL;DR: OCT is an imaging modality that permits the in vivo investigation of biological specimens on the micron scale as discussed by the authors, which can be thought of as an analog to ultrasound B-mode imaging except backscattering of light from biological tissue layers is detected rather than acoustic reflections.
Abstract: Summary form only given Recent advances in molecular biology techniques have permitted the site specific insertion of predetermined mutations into embryos for the investigation of normal and abnormal development Currently, there are several imaging modalities available to observe the expression of genetic mutations, but these typically require small, transparent, or fixed specimens Optical coherence tomography (OCT) offers the ability to image in vivo developing morphology in many of the animal models used for genetic studies In addition, OCT has the potential to rapidly and repeatedly acquire optical histology to assess development and to identify the expression of normal and abnormal genes Optical coherence tomography is an imaging modality that permits the in vivo investigation of biological specimens on the micron scale The imaging technique can be thought of as an analog to ultrasound B-mode imaging except backscattering of light from biological tissue layers is detected rather than acoustic reflections OCT incorporates a fiber-optic-based Michelson interferometer using a 1300-nm low-coherent superluminescent diode (SLD) as its light source to measure the intensity of optical backscattering from within the specimen OCT images are shown of in vivo developing morphology from a leopard frog tadpole
Proceedings Article•
01 Jan 1996TL;DR: OCT as discussed by the authors is an imaging modality that permits the in-vivo investigation of biological specimens on the micron scale, which can be thought of as an analog to ultrasound B-mode imaging except backscattering of light from biological tissue layers is detected rather than acoustic reflections.
Abstract: Summary form only given. Recent advances in molecular biology techniques have permitted the site specific insertion of predetermined mutations into embryos for the investigation of normal and abnormal development. Currently, there are several imaging modalities available to observe the expression of genetic mutations, but these typically require small, transparent, or fixed specimens. Optical coherence tomography (OCT) offers the ability to image in vivo developing morphology in many of the animal models used for genetic studies. In addition, OCT has the potential to rapidly and repeatedly acquire optical histology to assess development and to identify the expression of normal and abnormal genes. Optical coherence tomography is an imaging modality that permits the in vivo investigation of biological specimens on the micron scale. The imaging technique can be thought of as an analog to ultrasound B-mode imaging except backscattering of light from biological tissue layers is detected rather than acoustic reflections. OCT incorporates a fiber-optic-based Michelson interferometer using a 1300-nm low-coherent superluminescent diode (SLD) as its light source to measure the intensity of optical backscattering from within the specimen. OCT images are shown of in vivo developing morphology from a leopard frog tadpole.