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Biomedical subjects

S A Boppart

Publications and source records attributed to S A Boppart.

At least 19 recordsLinked to original sources
PubMed1999

High-resolution optical coherence tomography-guided laser ablation of surgical tissue.

BACKGROUND: Optical coherence tomography (OCT) is a compact high-speed imaging technology which uses infrared light to acquire cross-sectional images of tissue on the micrometer scale. Because OCT images are based on the optical backscattering properties of tissue, changes in tissue optical properties due to surgical laser ablation should be detectable using this technique. In this work, we examine the feasibility of using real-time OCT imaging to guide the placement and observe the dynamics of surgical laser ablation in a variety of tissue types. MATERIALS AND METHODS: More than 65 sites on five ex vivo rat organ tissue types were imaged at eight frames per second before, during, and after laser ablation. Ablation was performed with a coincident continuous wave argon laser operating at 514-nm wavelength and varying exposure powers and durations. Following imaging, tissue registration was achieved using microinjections of dye followed by routine histologic processing to confirm the morphology of the ablation site. RESULTS: High-speed OCT imaging at eight frames per second permitted rapid tissue orientation and guided ablation in numerous organ specimens. Acquisition rates were fast enough to capture dynamic changes in optical backscatter which corresponded to thermal tissue damage during laser ablation. CONCLUSIONS: The ability of high-resolution high-speed OCT to guide laser ablation and image the dynamic changes suggests a role in image-guided surgical procedures, such as the ablation of neoplasms. Future in vivo studies are necessary to demonstrate performance intraoperatively.

Abdominal Muscles↗
PubMed1999

High resolution imaging of normal and osteoarthritic cartilage with optical coherence tomography.

OBJECTIVE: We describe optical coherence tomography (OCT), a high resolution micron scale imaging technology, for assessment of osteoarthritic articular cartilage microstructure. OCT is analogous to ultrasound, measuring the intensity of backreflected infrared light rather than acoustical waves. METHODS: OCT imaging was performed on over 100 sites on 20 normal and osteoarthritic cartilage specimens in vitro. RESULTS: Microstructures that were identified included fibrillations, fibrosis, cartilage thickness, and new bone growth at resolutions between 5 and 15 microm. In addition, the polarization sensitivity of imaging suggested a diagnostic role of polarization spectroscopy. CONCLUSION: OCT represents an attractive new technology for intraarticular imaging due to its high resolution (greater than any available clinical technology), ability to be integrated into small arthroscopes, compact portable design, and relatively low cost.

Arthrography↗
PubMed1999

High-resolution imaging of gynecologic neoplasms using optical coherence tomography.

BACKGROUND: A modality capable of imaging the female reproductive tract, at or near the cellular level, could lead to the detection of diseases at earlier stages than currently possible. Optical coherence tomography achieves high resolutions in the cellular range (4-20 microm) and could accomplish that level of detection. METHOD: Optical coherence tomography imaging of gynecologic tissue was studied in vitro on normal and neoplastic human cervical and uterine tissue. EXPERIENCE: The structures of the normal ectocervix and endocervix, including epithelium, basal membrane, and glands, were identified clearly. These findings were compared with changes associated with carcinoma in situ and invasive carcinoma. The optical coherence tomography images of the uterus also showed changes between microstructural features of normal tissue and endometrial adenocarcinoma. CONCLUSION: Optical coherence tomography of tissue microstructures showed potential for powerful, minimally invasive assessment of the female reproductive tract at a resolution greater than any current clinical imaging method.

Feasibility Studies↗
PubMed1998

Optical biopsy with optical coherence tomography.

A need exists in medicine for a technology capable of 'optical biopsy,' imaging at or near the resolution of histopathology without the need for excisional biopsy. Optical coherence tomography (OCT) is a recently developed imaging technology that uses infrared light to generate cross-sectional images on a micron scale. In this work, the feasibility of OCT for optical biopsy was confirmed with in vitro tissue from the skeletal and male reproductive systems. This work supports the hypothesis that OCT is an attractive technology for in vivo optical biopsy.

Biopsy↗
PubMed1998

New technology for high-speed and high-resolution optical coherence tomography.

Optical coherence tomography (OCT) is an optical imaging technique that is capable of performing micron-scale, cross-sectional imaging of internal microstructure in biological systems. OCT is analogous to ultrasound B mode imaging except that it uses light rather than sound and performs imaging by measuring the back-scattered intensity of light from structures in tissue. We describe recent advances in OCT technology including the application of short pulse solid state lasers based on Ti: Al2O3 and Cr: Mg2SiO4 to enable high-resolution, high-speed imaging as well as the development of OCT catheter/endoscope delivery to permit imaging of internal organ systems. OCT enables the nonexcisional, in situ, real-time imaging of tissue microstructure and is thus a powerful and promising technique for optical biopsy.

Animals↗
PubMed1998

Two- and three-dimensional high-resolution imaging of the human oviduct with optical coherence tomography.

OBJECTIVE: To evaluate the feasibility of optical coherence tomography, a new method of micron-scale imaging, for high-resolution assessment of the oviduct. Optical coherence tomography is analogous to ultrasound except that it measures the backreflection of infrared light rather than acoustical waves. DESIGN: The ampulla of a human fallopian tube was imaged in vitro using optical coherence tomography. Images were generated in 2 and 3 dimensions. SETTING: University. PATIENT(S): Samples were obtained from women who had undergone hysterectomy for leiomyomatosis. INTERVENTION(S): None MAIN OUTCOME MEASURE(S): The ability to perform imaging on a micron scale, which is a level of resolution higher than that of any currently available clinical technology. RESULT(S): Two- and three-dimensional data sets of the reflectance of a human fallopian tube were acquired. A volume of 5 x 5 x 2.5 mm (length x width x depth) was scanned. The axial resolution was 11 microm, and the lateral resolution at the focus was 20 microm. The data sets showed detailed structures of the fallopian tube. CONCLUSION(S): Our ability to obtain micron-scale two- and three-dimensional images of an in vitro oviduct suggests that it may be possible to identify and surgically treat tubal causes of infertility.

Diagnostic Imaging↗
PubMed1998

Optical biopsy in human pancreatobiliary tissue using optical coherence tomography.

Optical coherence tomography (OCT) is a new technique for performing high-resolution, cross-sectional tomographic imaging in human tissue. OCT is analogous to ultrasound B mode imaging except that it uses light rather than acoustical waves. As a result, OCT has over 10 times the resolution of currently available clinical high-resolution cross-sectional imaging technologies. In this work, we investigate the capability of OCT to differentiate the architectural morphology of pancreatobiliary tissues. Normal pancreatobiliary tissues, including the gallbladder, common bile duct, pancreatic duct, and pancreas were taken postmortem and imaged using OCT. Images were compared to corresponding histology to confirm tissue identity. Microstructure was delineated in different tissues, including tissue layers, glands, submucosal microvasculature, and pancreatic islets of Langerhans. The ability of OCT to provide high-resolution imaging of pancreatobiliary architectural morphology suggests the feasibility of using OCT as a powerful diagnostic endoscopic imaging technology to image early stages of pancreatobiliary disease.

Biliary Tract↗
PubMed1998

Optical coherence tomography for neurosurgical imaging of human intracortical melanoma.

OBJECTIVE: Intraoperative identification of brain tumors and tumor margins has been limited by either the resolution of the in vivo imaging technique or the time required to obtain histological specimens. Our objective was to evaluate the feasibility of using optical coherence tomography (OCT) as a high-resolution, real-time intraoperative imaging technique to identify an intracortical melanoma. INSTRUMENTATION: OCT is a new, noncontact, high-speed imaging technology capable of resolutions on the micrometer scale. OCT is analogous to ultrasound B-mode imaging, except that reflections of infrared light, rather than sound, are detected. OCT uses inherent tissue contrast, rather than enhancement with dyes, to differentiate tissue types. The compact, fiberoptic-based design is readily integrated with surgical instruments. METHODS: A portable handheld OCT surgical imaging probe has been constructed for imaging within the surgical field. Cadaveric human cortex with metastatic melanoma was harvested and imaged in two and three dimensions. Changes in optical backscatter intensity were used to identify regions of tumor and to locate tumor margins. Structures within the optical coherence tomographic images were compared with the histological slides. RESULTS: Two-dimensional images showed increased optical backscatter from regions of tumor, which was quantitatively used to determine the tumor margin. The images correlated well with the histological findings. Three-dimensional reconstructions revealed regions of tumor penetrating normal cortex and could be resectioned at arbitrary planes. Subsurface cerebral vascular structures could be identified and were therefore avoided. CONCLUSION: OCT can effectively differentiate normal cortex from intracortical melanoma based on variations in optical backscatter. The high-resolution, high-speed imaging capabilities of OCT may permit the intraoperative identification of tumor and the more precise localization of tumor margins.

Brain Neoplasms↗
PubMed1998

Intraoperative assessment of microsurgery with three-dimensional optical coherence tomography.

PURPOSE: To evaluate three-dimensional optical coherence tomography (OCT) for use in the assessment of the microsurgical anastomoses of vessels and nerves. MATERIALS AND METHODS: OCT is an optical analogue of ultrasonography and is capable of imaging nontransparent biologic tissue by detecting backscattered infrared light. Cross-sectional in vitro images of rabbit and human vessels and nerves were obtained in as little as 125 msec at 10-micron resolution by using a solid-state laser as a light source. A surgical microscope was integrated with OCT to perform simultaneous imaging with en face visualization. Cross-sectional images were assembled to produce three-dimensional reconstructions of microsurgical specimens. RESULTS: Three-dimensional OCT reconstructions depicted the structure within an arterial anastomosis and helped identify sites of luminal obstruction. The longitudinal spatial orientation of individual nerve fascicles was tracked in three dimensions to identify changes in position. In vitro human arteries and nerves embedded in highly scattering tissue and not visible at microscopy were located and imaged with OCT at eight frames per second. CONCLUSION: The three-dimensional, micrometer-scale, diagnostic imaging capabilities of OCT permit rapid feedback for assessment of microsurgical procedures. OCT technology can be readily integrated with surgical microscopes and has potential for intraoperative monitoring to improve patient outcome.

Anastomosis, Surgical↗
PubMed1997

Optical biopsy with optical coherence tomography: feasibility for surgical diagnostics.

BACKGROUND: Optical coherence tomography (OCT) is a recently developed compact technology which uses infrared light to perform cross-sectional imaging on a micrometer scale. Since OCT provides imaging at a resolution comparable to conventional histology and does not require direct contact with the tissue surface, a role in real-time surgical diagnostics represents a logical extension. In this work, we test the feasibility of OCT for surgical diagnostics by demonstrating imaging in tissue relevent to microsurgical intervention, a previously undescribed observation. MATERIALS AND METHODS: Over 50 sites on nervous, reproductive, and microvascular specimens from 10 patients were examined postmortem with OCT. After imaging, tissue was registered with microinjections of dye, under visible light laser guidance, followed by routine histologic processing to confirm the identity of microstructure. RESULTS: The 16 +/- 1 microm resolution allowed subsurface microstructure to be identified at unprecedented resolution. Structures identified included fascicles of peripheral nerves, the internal elastic membrane of microvessels, and the granular layer of the cerebellum. CONCLUSIONS: The ability of OCT to provide micrometer-scale definition of tissue microstructure suggests a role in surgical diagnostics. Future in vivo investigations are merited to establish its utility for morbidity reduction associated with surgical intervention.

Animals↗
PubMed1997

In vivo endoscopic optical biopsy with optical coherence tomography.

Current medical imaging technologies allow visualization of tissue anatomy in the human body at resolutions ranging from 100 micrometers to 1 millimeter. These technologies are generally not sensitive enough to detect early-stage tissue abnormalities associated with diseases such as cancer and atherosclerosis, which require micrometer-scale resolution. Here, optical coherence tomography was adapted to allow high-speed visualization of tissue in a living animal with a catheter-endoscope 1 millimeter in diameter. This method, referred to as "optical biopsy," was used to obtain cross-sectional images of the rabbit gastrointestinal and respiratory tracts at 10-micrometer resolution.

Anatomy, Cross-Sectional↗
PubMed1997

Noninvasive assessment of the developing Xenopus cardiovascular system using optical coherence tomography.

Studies investigating normal and abnormal cardiac development are frequently limited by an inability to assess cardiovascular function within the intact organism. In this work, optical coherence tomography (OCT), a new method of micron-scale, noninvasive imaging based on the measurement of backscattered infrared light, was introduced for the high resolution assessment of structure and function in the developing Xenopus laevis cardiovascular system. Microstructural details, such as ventricular size and wall positions, were delineated with OCT at 16-microm resolution and correlated with histology. Three-dimensional representation of the cardiovascular system also was achieved by repeated cross-sectional imaging at intervals of 25 microm. In addition to structural information, OCT provides high speed in vivo axial ranging and imaging, allowing quantitative dynamic activity, such as ventricular ejection fraction, to be assessed. The sensitivity of OCT for dynamic assessment was demonstrated with an inotropic agent that altered cardiac function and dimensions. Optical coherence tomography is an attractive new technology for assessing cardiovascular development because of its high resolution, its ability to image through nontransparent structures, and its inexpensive portable design. In vivo and in vitro imaging are performed at a resolution approaching that of histopathology without the need for animal killing.

Animals↗
PubMed1997

A comparison of retinal morphology viewed by optical coherence tomography and by light microscopy.

OBJECTIVE: To compare the cross-sectional images of primate retinal morphology obtained by optical coherence tomography (OCT) with light microscopy to determine the retinal components represented in OCT images. METHODS: Laser pulses were delivered to the retina to create small marker lesions in a Macaca mulatta. These lesions were used to align in vivo OCT scans and ex vivum histologic cross sections for image comparison. RESULTS: The OCT images demonstrated reproducible patterns of retinal morphology that corresponded to the location of retinal layers seen on light microscopic overlays. Layers of relative high reflectivity corresponded to horizontally aligned retinal components such as the nerve fiber layer and plexiform layers, as well as to the retinal pigment epithelium and choroid. In contrast, the nuclear layers and the photoreceptor inner and outer segments demonstrated relative low reflectivity by OCT. CONCLUSIONS: Retinal morphology and macular OCT imaging correlate well, with alignment of areas of high and low reflectivity to specific retinal and choroidal elements. Resolution of retinal structures by OCT depends on the contrast in relative reflectivity of adjacent structures. Use of this tool will enable expanded study of retinal morphology, both normal and pathologic, as it evolves in vivo.

Animals↗
PubMed1997

Argon laser retinal lesions evaluated in vivo by optical coherence tomography.

PURPOSE: To assess the in vivo evolution of argon laser retinal lesions by correlating the cross-sectional structure from sequential optical coherence tomography with histopathologic sectioning. METHODS: Argon laser lesions were created in the retinas of Macaca mulatta and evaluated by cross-section optical coherence tomography, which was compared at selected time points with corresponding histopathology. RESULTS: Argon laser lesions induced an optical coherence tomography pattern of early outer retinal relative high reflectivity with subsequent surrounding relative low reflectivity that correlated well with histopathologic findings. The in vivo optical coherence tomography images of macular laser lesions clearly demonstrated differences in pathologic response by retinal layer over time. CONCLUSION: The novel sequential imaging of rapidly evolving macular lesions with optical coherence tomography provides new insight into the patterns of acute tissue response by cross-sectional layer. This sequential imaging technique will aid in our understanding of the rapid evolution of retinal pathology and response to treatment in the research and clinical setting.

Animals↗
PubMed1997

Assessing atherosclerotic plaque morphology: comparison of optical coherence tomography and high frequency intravascular ultrasound.

BACKGROUND: OCT can image plaque microstructure at a level of resolution not previously demonstrated with other imaging techniques because it uses infrared light rather than acoustic waves. OBJECTIVES: To compare optical coherence tomography (OCT) and intravascular ultrasound (IVUS) imaging of in vitro atherosclerotic plaques. METHODS: Segments of abdominal aorta were obtained immediately before postmortem examination. Images of 20 sites from five patients were acquired with OCT (operating at an optical wavelength of 1300 nm which was delivered to the sample through an optical fibre) and a 30 MHz ultrasonic transducer. After imaging, the microstructure of the tissue was assessed by routine histological processing. RESULTS: OCT yielded superior structural information in all plaques examined. The mean (SEM) axial resolution of OCT and IVUS imaging was 16 (1) and 110 (7), respectively, as determined by the point spread function from a mirror. Furthermore, the dynamic range of OCT was 109 dB compared with 43 dB for IVUS imaging. CONCLUSIONS: OCT represents a promising new technology for intracoronary imaging because of its high resolution, broad dynamic range, and ability to be delivered through intravascular catheters.

Aorta, Abdominal↗
PubMed1997

Optical biopsy in human urologic tissue using optical coherence tomography.

Optical Coherence Tomography (OCT) is a recently developed non-invasive technique for obtaining high resolution, cross-sectional images of human tissue. This work investigated the capability of OCT to differentiate the architectural morphology of urologic tissue with the long term aim of using OCT as an adjunct to endoscopic imaging and to improve the efficiency of interventional procedures such as transurethral prostatectomy (TURP). Urologic tissues were taken postmortem, dissected, and imaged using OCT. Microstructure was delineated in different urologic tissues, including the prostatic urethra, prostate, bladder, and ureter, with an axial resolution of 16 +/- 1 microm., higher than any clinically available endoscopic intraluminal imaging technology. The ability of OCT to provide non-contact high resolution imaging of urologic tissue architectural morphology (i.e. optical biopsy), without the need for excisional biopsy, suggests the potential of using OCT to obtain information on tissue microstructure that could only previously be obtained with conventional biopsy.

Biopsy↗
PubMed1997

Optical biopsy in human gastrointestinal tissue using optical coherence tomography.

OBJECTIVES: Optical coherence tomography (OCT) is a new technique for performing high-resolution, cross-sectional tomographic imaging in human tissue. OCT is somewhat analogous to ultrasound B mode imaging except that it uses light rather than acoustical waves. OCT has over 10 times the resolution of currently available clinical high-resolution imaging technologies. In this work, we investigate the capability of OCT to differentiate the architectural morphology of gastrointestinal tissue with the long-term objective of extending OCT to endoscopic based diagnostics. METHODS: Normal and diseased gastrointestinal tissues were taken postmortem and imaged using OCT. Images were compared with corresponding histology to confirm tissue identity and suggest the mechanisms that produce tissue contrast. RESULTS: Microstructure was delineated in different tissues, including the esophagus and colon, at 16 +/- 1 microns resolution, higher than any clinically available cross-sectional imaging technology. Differentiation of tissue layers, such as the mucosa, submucosa, and muscularis were achieved because of their different optical properties. CONCLUSIONS: The ability of OCT to provide high-resolution in situ imaging of gastrointestinal microstructure, without the need for excisional biopsy, suggests the feasibility of using OCT as a powerful diagnostic imaging technology, which can be integrated with conventional endoscopy.

Biopsy↗