Showing papers on "Imaging technology published in 2001"

MR Imaging of the Breast for the Detection, Diagnosis, and Staging of Breast Cancer

Abstract: With the introduction of contrast agents, advances in surface coil technology, and development of new imaging protocols, contrast agent-enhanced magnetic resonance (MR) imaging has emerged as a promising modality for detection, diagnosis, and staging of breast cancer. The reported sensitivity of MR imaging for the visualization of invasive cancer has approached 100%. There are many examples in the literature of MR imaging--demonstrated mammographically, sonographically, and clinically occult breast cancer. Often, breast cancer detected on MR images has resulted in a change in patient care. Despite these results, there are many unresolved issues, including no defined standard technique for contrast-enhanced breast MR imaging, no standard interpretation criteria for evaluating such studies, no consensus on what constitutes clinically important enhancement, and no clearly defined clinical indications for the use of MR imaging. Furthermore, this technology remains costly, and issues of cost-effectiveness and cost competition from percutaneous biopsy have yet to be fully addressed. These factors along with the lack of commercially available MR imaging--guided localization and biopsy systems have slowed the transfer of this imaging technology from research centers to clinical breast imaging practices. Technical requirements, potential clinical applications, and potential pitfalls and limitations of contrast-enhanced MR imaging as a method to help detect, diagnose, and stage breast cancer will be described.

Optical Coherence Tomography for Optical Biopsy: Properties and Demonstration of Vascular Pathology

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 such as the width of intimal caps and the presence of fissures to be determined. The extent of lipid collections, which had a low backscattering intensity, also were well documented. Conclusions 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. It does not require direct contact with the vessel wall and can be performed with a catheter integrated with a relatively inexpensive optical fiber. The high contrast among tissue constituents, high resolution, and ability to penetrate heavily calcified tissue make OCT an attractive new imaging technology for intracoronary diagnostics.

Advanced cardiac MR imaging of ischemic heart disease.

Abstract: Important advances in rapid magnetic resonance (MR) imaging technology and its application to cardiovascular imaging have been made during the past decade. High-field-strength clinical magnets, high-performance gradient hardware, and ultrafast pulse sequence technology are rapidly making the vision of a comprehensive “one-stop shop” cardiac MR imaging examination a reality. This examination is poised to have a significant effect on the management of coronary artery disease by means of assessment of wall motion with tagging and pharmacologic stress testing, evaluation of the coronary microvasculature with perfusion imaging, and direct visualization of the coronary arteries with MR coronary angiography. This article reviews current state-of-the-art pulse sequence technology and its application to the evaluation of ischemic heart disease by means of MR tagging with dobutamine stress testing, MR perfusion imaging, and MR coronary angiography. Cutting edge areas of research in coil design and exciting new area...

Flat-panel cone-beam CT: a novel imaging technology for image-guided procedures

Abstract: The use of flat-panel imagers for cone-beam CT signals the emergence of an attractive technology for volumetric imaging. Recent investigations demonstrate volume images with high spatial resolution and soft-tissue visibility and point to a number of logistical characteristics (e.g., open geometry, volume acquisition in a single rotation about the patient, and separation of the imaging and patient support structures) that are attractive to a broad spectrum of applications. Considering application to image-guided (IG) procedures - specifically IG therapies - this paper examines the performance of flat-panel cone-beam CT in relation to numerous constraints and requirements, including time (i.e., speed of image acquisition), dose, and field-of-view. The imaging and guidance performance of a prototype flat panel cone-beam CT system is investigated through the construction of procedure-specific tasks that test the influence of image artifacts (e.g., x-ray scatter and beam-hardening) and volumetric imaging performance (e.g., 3D spatial resolution, noise, and contrast) - taking two specific examples in IG brachytherapy and IG vertebroplasty. For IG brachytherapy, a procedure-specific task is constructed which tests the performance of flat-panel cone-beam CT in measuring the volumetric distribution of Pd-103 permanent implant seeds in relation to neighboring bone and soft-tissue structures in a pelvis phantom. For IG interventional procedures, a procedure-specific task is constructed in the context of vertebroplasty performed on a cadaverized ovine spine, demonstrating the volumetric image quality in pre-, intra-, and post-therapeutic images of the region of interest and testing the performance of the system in measuring the volumetric distribution of bone cement (PMMA) relative to surrounding spinal anatomy. Each of these tasks highlights numerous promising and challenging aspects of flat-panel cone-beam CT applied to IG procedures.

Improved endoscopic imaging and treatment of anatomic structures

Abstract: The present invention discloses methods of infrared endoscopic imaging technology and the uses thereof. Specifically, devices and methods that allow visualization of sensitive structures normally invisible under visible light illumination in real-time are presented. Examples of the imaging technology are confocal imaging, pulse oximetry, laser doppler and transillumination. Also provided are various configurations of the endoscopic devices.

Optical coherence tomography

Abstract: Optical Coherence Tomography (OCT) is a new technology for performing high-resolution cross sectional imaging. OCT is analogous to ultrasound imaging, except that it uses light instead of sound. OCT can provide cross sectional images of tissue structure on the micron scale in situ and in real time. OCT functions as a type of optical biopsy and is a powerful imaging technology for medical diagnostics because unlike conventional histopathology which requires removal of a tissue specimen and processing for microscopic examination, OCT can provide images of tissue in situ and in real time. OCT can be used where standard excisional biopsy is hazardous or impossible, to reduce sampling errors associated with excisional biopsy, and to guide interventional procedures.

Imaging prostate cancer: current and future applications.

Abstract: Various treatment options are available for adenocarcinoma of the prostate--the most common malignant neoplasm among men in the United States. To select an optimum management strategy, we must be able to identify an organ-confined disease (in which local therapy such as surgery or radiation may be beneficial) vs prostate cancer beyond the confines of the gland (for which other treatment approaches may be more appropriate). At present, no standard imaging modality can by itself reliably diagnose and/or stage adenocarcinoma of the prostate. Standard transrectal ultrasound, magnetic resonance imaging (MRI), computed tomography, bone scans, and plain x-ray are not sufficiently reliable when used alone. Fortunately, advances in imaging technology have led to the development of several promising modalities. These modalities include color and power Doppler ultrasonography, ultrasound contrast agents, intermittent and harmonic ultrasound imaging, MR contrast imaging, MRI with fat suppression, MRI spectroscopy, three-dimensional MRI spectroscopy, elastography, and radioimmunoscintigraphy. These newer imaging techniques appear to improve the yield of prostate cancer detection and staging, but are limited in availability and thus require further validation. This article reviews the status of current imaging modalities for prostate cancer and identifies emerging imaging technologies that may improve the diagnosis and staging of this disease.

Four-dimensional ultrasound in prenatal diagnosis: leading edge in imaging technology

Abstract: Since the introduction of the three-dimensional imaging technique, significant improvements have been undertaken. With the development of computer technology, calculation times become shorter and the software becomes more sophisticated. In the initial years, three-dimensional ultrasound allowed the production of only still volumes. Thus, scans only represented one single moment within the total examination. Serial re-scanning is one of the newest developments in three-dimensional ultrasound. In the volume-rendering mode, still imaging now may be replaced by three-dimensional ultrasound ‘movies’. This technique may also be called four-dimensional ultrasound' or live three-dimensional ultrasound'. However, a frame rate of about 10 frames per second would be necessary to bring this technique to ‘real-time’ mode. Possible applications in prenatal diagnosis are examinations of the fetal extremities, fetal face and may be fetal behavior. Among the many advantages of four-dimensional ultrasound, improvem...

Imaging of acute stroke.

Abstract: The utility of diagnostic imaging during the critical first few hours after stroke onset has many important applications. First and foremost, imaging technologies that can reliably detect and quantify the location of acute stroke will greatly enhance the clinician's ability to accurately diagnose individual stroke patients. Secondly, if imaging technology could provide information about the likely severity of the ischemic injury, patient prognosis and management would be enhanced. The possibility of potentially distinguishing severely injured and likely irreversible ischemic brain tissue from ischemic tissue likely not yet irreversibly injured may soon be attainable. The ability of imaging technology to reliably distinguish the status of focally ischemic brain will presumably dramatically impact upon patient management. This information, along with the data about the severity and extent of blood flow and tissue perfusion abnormalities, will help acute stroke care evolve beyond rigid time windows to individualized, pathophysiologically based treatment decisions. Not only will decisions to treat or not be made based upon imaging-derived status, but also the most appropriate type of therapy to be employed, i.e. thrombolysis, neuroprotection, therapy to reduce secondary reperfusion-related injury or combinations of these modalities. In this brief and necessarily incomplete overview of acute stroke imaging, the focus will be on new developments in CT and MRI.

Developments in digital radiography: an equipment update.

Abstract: Digital X-ray imaging technology has advanced rapidly over the past few years. This review, particularly aimed at those involved in using and purchasing such technology, is an attempt to unravel some of the complexities of this potentially confusing subject. The main groups of X-ray imaging devices that are considered are digitisers of conventional radiographs, image-intensifier-based fluorography systems, photostimulable phosphor computed radiography, amorphous selenium-based technology for thorax imaging and flat-panel systems. As well as describing these different systems, we look at ways of objectively assessing their image quality. Concepts that are used and explained include spatial resolution, grey-scale bit resolution, signal-to-noise ratio and detective quantum efficiency. An understanding of these basic parameters is vital in making a scientific assessment of a system's performance. Image processing and techniques are also briefly discussed, particularly with reference to their potential effects on image quality. This review aims to provide a basic understanding of digital X-ray imaging technology and enables the reader to make an independent and educated assessment of the relative merits of each system.

Current urologic applications of digital imaging.

Abstract: One of the most significant developments in imaging technology has been the process of digitalization. By incorporating currently available digital imaging equipment into surgical practice, urologists can be assured of obtaining real-time video images with optimal clarity and detail. In addition, one can efficiently capture and store still images that are crisper and sharper than their analog counterparts. These factors greatly improve the diagnostic capabilities and organization of today's endourologist.

Imaging of acute stroke

Abstract: The utility of diagnostic imaging during the critical first few hours after stroke onset has many important applications. First and foremost, imaging technologies that can reliably detect and quantify the location of acute stroke will greatly enhance the clinician's ability to accurately diagnose individual stroke patients. Secondly, if imaging technology could provide information about the likely severity of the ischemic injury, patient prognosis and management would be enhanced. The possibility of potentially distinguishing severely injured and likely irreversible ischemic brain tissue from ischemic tissue likely not yet irreversibly injured may soon be attainable. The ability of imaging technology to reliably distinguish the status of focally ischemic brain will presumably dramatically impact upon patient management. This information, along with the data about the severity and extent of blood flow and tissue perfusion abnormalities, will help acute stroke care evolve beyond rigid time windows to individualized, pathophysiological-based treatment decisions. Not only will decisions to treat or not be made based upon imaging-derived status, but also the most appropriate type of therapy to be employed, i.e., thrombolysis, neuroprotection, therapy to reduce secondary reperfusion-related injury or combinations of these modalities. In this brief and necessarily incomplete overview of acute stroke imaging, the focus will be on new developments in CT and MRI.

Safe use of thermal imaging technology

Abstract: Regardless of the benefits of thermal imagers, these new lifesaving tools come with their share of safety concerns. Mike Richardson identifies and recommands solutions for some of the common safety issues related to using the technology.