Showing papers on "Imaging technology published in 1998"

Optical Coherence Tomography for Neurosurgical Imaging of Human Intracortical Melanoma

Abstract: 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 1ight, 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. RESUL TS: 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. (Neurosurgery 43:834-841, 1998) Key )Nords: Imaging, Infrared, Margins, Microscopy, Optical, Stereotactic, Tumor

Clinical thermal imaging today

Abstract: In order to make thermal imaging a universally acceptable clinical technique, one must try to understand what is being observed, and what the observation signifies. One must also prove the validity of hypotheses about underlying causes of a given local hyper or hypothermia. Such an understanding is absolutely necessary before one can adapt the available technology to meet given clinical needs effectively. This paper demonstrates that such an understanding is now developing and will lead to a far better utilization of infrared imaging technology.

Optical Biopsy with Optical Coherence Tomographya

Abstract: 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.

Key paradigms of emerging imaging sensor technologies

Abstract: In this paper, key paradigms of emerging imaging technologies from different technological areas, are presented. Examples of transfer, utilization, and exchange of the imaging technology are offered and discussed. These phenomena, will create advanced solutions for potential development in different areas of science and technology. Overall, new imaging technologies will merge and are expected to play an ever-expanding role in the civilian and military applications of the next century.

Magnetic resonance imaging of renal masses

Abstract: Renal cancer is diagnosed in 27,000 Americans and accounts for 12,000 deaths per year. Fortunately, improvements in imaging technology have resulted in earlier detection and longer survival. Although computed tomography (CT) and ultrasound (US) have accounted for much of this success, magnetic resonance (MR) imaging can offer several improvements in renal cancer imaging. MR imaging has demonstrated increased detection of tumor thrombus in the renal vein and IVC with better delineation of the superior extent of the tumor thrombus in the IVC, especially in the region of the right atrium. This information potentially impacts the surgical approach in cases where CT or US is equivocal. Visualization of tumor extension to the liver, spleen, and psoas muscle is also improved with MR imaging, increasing staging accuracy in selected cases. In addition, because of the relatively low nephrotoxicity and allergic potential of gadolinium chelates, contrast-enhanced MR imaging remains the study of choice for patients who cannot tolerate iodinated contrast agents. Although the current role of MR in renal cancer imaging is complementary to that of CT and US, its future role has not yet been completely defined. Recent developments in rapid MR imaging techniques have suggested the possibility of improved detection and characterization of renal masses relative to CT. In addition, as MR spectroscopic imaging of the kidney evolves, the possibility of future identification and characterization of renal masses on a biochemical basis may provide completely new insight into our understanding of renal cancer.

Rectal imaging and cancer.

Abstract: Rectal imaging has evolved substantially during the past 25 years and now offers surgeons exquisite anatomic detail and physiologic information. Dynamic cystoproctography, helical computed tomography, endoscopic ultrasonography, endorectal magnetic resonance imaging, and immunoscintigraphy have become standards for the diagnosis of rectal disease, staging of neoplasia, and survey of therapeutic results. The indications, limitations, and relative costs of current imaging methods are reviewed, and advances in imaging technology that promise future benefits to colorectal surgeons are introduced. Semin. Surg. Oncol. 15:72–77, 1998. © 1998 Wiley-Liss, Inc.

Biomedical imaging using optical coherence tomography

Abstract: Optical coherence tomography (OCT) is a new and powerful technology that can overcome many of the limitations of excisional biopsy. OCT is a recently developed optical imaging technique for performing high-resolution cross-sectional imaging tomography of microstructures in biological systems. OCT performs imaging by using low-coherence interferometry to measure the optical backscattering of tissue as a function of echo delay and transverse position. The resulting two-dimensional data can be displayed as a gray scale or false color image. OCT functions as a type of "optical biopsy" to provide cross-sectional images of tissue structure on the micron scale. OCT is a powerful imaging technology because it can provide images of tissue in situ and in real time, without the need for tissue excision and processing. This presentation will review recent advances in OCT technology and possible future clinical applications such as arterial imaging, the detection of early neoplastic changes, and guiding surgical intervention.

Cellular and neoplastic tissue imaging with optical coherence tomography

Abstract: Optical coherence tomography (OCT) imaging can resolve many of the changes associated with neoplasia and may provide a tool for in vivo real-time evaluation of tissue and biopsy guidance to help improve the diagnosis of early neoplasias, resulting in more successful treatment. OCT is a new imaging technology that allows cross-sectional imaging of nontransparent tissue. A low-coherence Michelson interferometer is used to measure echo time delays of reflected light from scattering tissue. The light beam is scanned across the tissue to produce two- and three-dimensional data sets. This technique has been extensively applied to imaging in ophthalmology and more recently to nontransparent tissues. High-resolution and high-speed OCT imaging has been achieved using broad bandwidth mode-locked lasers as short-coherence light sources. Recently, in vivo catheter/endoscope based imaging of the gastrointestinal and pulmonary tracts has been demonstrated in a rabbit model. In order to evaluate the ability of OCT to image cellular morphology in vivo, an animal model was used. OCT imaging in vitro was also performed on a series of human tissues of varying degrees of neoplastic infiltration, including colon, cervix, uterus, and lung.

A common sense approach to TMJ and implant imaging.

Abstract: During the last two decades, computer-based imaging technology has contributed significantly to our assessment of patients with head and neck anomalies. For instance, magnetic resonance imaging has given us a modality for visualizing the hard and soft tissues of the temporomandibular joint. We are fortunate that this has led to the refinement of the concepts of normality and the characterization of non-normal conditions. In the pre-surgical assessment of alveolar bone prior to implant placement, tomography in its various forms has provided the possibility of three dimensional bony assessment thus potentially optimizing fixture placement and minimizing potential failure. Unfortunately, there has been a reluctance to employ these techniques as they are either not available or both the equipment and the cost of image acquisition time is too expensive. Until recently, there has been a lack of consensus as to the selection of imaging modalities appropriate to patient presentation and the clinical value of the information obtained. The more recent development of computer-controlled panoramic imaging has made available to us many special projections which are capable of producing hard tissue images of either the TMJ or a potential implant site in multiple dimensions at lower cost (both financially and in terms of X-ray dose) than the more advanced modalities. These projections can now be incorporated into a clinically determined patient-based protocol and thus provide the clinician with both an economical and common sense approach to diagnostic imaging.

Imaging all Visible Surfaces Or How many Reference Images are needed for Image-Based Modeling?

Abstract: Today many systems exist to generate geometric models of existing scenes and objects. However, no accurate data about surface appearance such as colors and textures is stored in this process. Such data can be captured as a series of images that, collectively, capture all surfaces of the object. This work introduces a method to compute a minimal set of camera positions for this purpose. Taking images from the computed positions can then be used to derive a complete set of surface appearance data. A slightly different application of the presented method is the computation of a minimal set of viewpoints for reference images to be used in image-based rendering methods. First a method to determine an optimal set of viewpoint regions for a given scene is introduced. It uses a hierarchical visibility method to preprocess the scene. Then a technique to find an optimal set of viewpoint regions is presented and the solution is used to derive an optimal set of viewpoints. Results and visualizations of the computed solutions are presented.

Newer Imaging Modalities: This regular feature will enhance your knowledge of imaging technology in oncologic diagnosis, treatment, and evaluation.

Abstract: The search for greater sensitivity for detecting small subclinical tumor deposits and improved specificity for distinguishing between malignant and benign masses has led to the development of techniques for linking radioactive labels to tumor-specific antibodies or tissue-specific biochemical agents. Major progress is occurring as well in the development of nonspecific physiologic nuclear medicine modalities, most prominent among them being positron emission tomography (PET) and the recently adapted cardiac imaging agents. The current status of these new approaches is discussed below.

Pearls and pitfalls in clinical neuroradiology.

Abstract: Imaging technology continues to advance at a rapid pace. Central nervous system imaging, in particular, is an invaluable tool for the practicing clinical neurologist. Although computed tomography (CT) was once the procedure of choice for neuroimaging, CT has been surpassed by magnetic resonance imaging (MRI) because of the latter's greater sensitivity. MRI exquisitely demonstrates brain and spine pathology by means of its multiplanar capability and its ability to generate different tissue contrast with various pulse sequences. However, artifacts as well as normal anatomic variants can mimic significant CNS pathology. An understanding of the technology involved in producing and interpreting these images is necessary in order that protocols can be tailored for each individual patient and that unimportant findings are not misinterpreted as being pathologic. This article will present cases illustrating some of the common neuroimaging artifacts and normal variants as well as important differential diagnoses of certain imaging findings.

High frequency ultrasound B-scan imaging

Abstract: High frequency B-scan imaging or ultrasound biomiocroscopy (UBM) is a recent extention of the powerful methods of diagnostic ultrasound imaging. Operting in te 30 to 200 MHz range provides microscopic resolution but is limited to depths of penetration on the order of several millimetres. In spite of its' limited penetration, high frequency ultrasound B-scan imaging is finding clinical applictions in a number of areas where critical structures lie within the limited field of view. Imaging of the anterior segment of the eye, intraluminal imaging, skin imaging and imaging of cartilage are examples of UBM applications. In this paper, the physical principles applications of UBM imaging are explored with an emphasis on areas of current research and clinical applications. High frequency transducers and beamforming will be described together with basic system instrumentation. Resolution on the order of 50 microns laterally and 30 to 40 microns axially are readily achieved in the 60 MHz range. This permits visualization of disease processes in the very early stages. Examples of glaucauma an skin melanoma are used to illustrate this potential. The fundamental trade off between resolution and penetration is discussed and speculation on the development of new high frequency imaging technology such as high frequency Doppler techniques is presented.

Wide viewing angle floating 3-D display system (with no 3-D glasses)

Abstract: Previously, the author has described a new 3-D imaging technology entitled Real-Depth . with several different configurations and methods of implementation 1,2 . Included were several methods to float images in free space. Viewers can pass their hands through the image or appear to hold it in their hands. Most implementations provide an angle of view of approximately 45°. The technology produces images at different depths from any display, such as CRT and LCD, for television, computer, projection, and other formats. Unlike stereoscopic 3-D imaging, no glasses, headgear or other viewing aids are used. In addition to providing traditional depth cues, such as perspective and background image occlusion, the technology also provides both horizontal and vertical binocular parallax producing visual accommodation and convergence which coincide. Consequently, viewing these images don't produce headaches, fatigue, or eyestrain, regardless of how long they are viewed. A method was also proposed to provide a floating image display system with a wide angle of view. Implementation of this design proved problematic, producing various image distortions. In this paper the author discloses new methods to produce aerial images with a wide angle of view and improved image quality.

Total quality in the management of information technology (TQMIT): the case of tele-radiology and imaging technologies

Abstract: Addresses the management of health care information technology (HCIT) from a total quality perspective with a focus on associated technologies in radiology and imaging. The aim is to chart a course for the application of these advancing technologies within the context of an integrated delivery system (IDS) to prepare radiologists and other medical technologists facing a rapidly changing health service delivery system. In this context, a critical step is the task of strategic HCIT planning, design and implementation to realize an efficient, appropriate and effective HCIT infrastructure for developing seamless, integrated radiological services. The key factors underlying this challenge in face of rapid advances in radiological and imaging technology are often poorly understood. The concept of a total quality management information technology (TQMIT) model is explored and illustrated. The central theme is to demonstrate how this sort of thinking can be applied philosophically, logically and physically to guide management and radiologists in strategy formulation and in taking critical steps to plan, design and develop high-quality services that will facilitate distributed image processing, information exchange and sharing among multiple health care providers within an IDS.

Knowledge Discovery through the Navigation Inside the Human Body

Abstract: One of remarkable progress in medical image processing is the rapid extension of three-dimensional (3D) images of human body. Imaging technology such as CT and MRI has made it possible to acquire 3D images of patients in fine spatial resolution. Novel usage of such 3D images in both diagnosis and treatment is now being studied actively. Interesting examples include virtualized endoscope system, preoperative surgical simulation, intraoperative surgical aid, and the mass screening of lung cancer. In spite of very active development of new applications, research of these applications from the viewpoint of knowledge processing has not been reported. Although comprehensive surveys were published in [1][2], studies of these kinds of image processing as knowledge processing are not referred