X-ray computed tomographic (CT) phantom designed for the development of techniques for measurement of myocardial perfusion.
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Coronary Circulation↗
Biomedical subjects
R A Robb
Publications and source records attributed to R A Robb.
Brain surface cortical sulcal lengths: quantification with three-dimensional MR imaging.
The repeatability and accuracy of brain surface cortical sulcal length measurements obtained with three-dimensional (3D) reconstructions of volumetric, gradient-echo magnetic resonance (MR) images were tested. The brains of eight healthy adult volunteers and one cadaver were imaged in both the coronal and sagittal planes to yield a set of 128 1.5-2.0-mm-thick contiguous sections. 3D reconstructions of the brain cerebral cortical surfaces were obtained with computer software. Location and distance measurements of surface sulci were repeated on each reconstructed image. The same structures in the cadaver brain were independently measured with a 3D electromagnetic digitizer to validate the results of the 3D MR imaging method. All measurements from reconstructed images had high repeatability, and there were no statistically significant differences between measurement trials. The accuracy of measurements with 3D MR imaging was also good; the mean difference between digitizer and 3D MR measurements for sulcal lengths was 0.81 cm (average, 5.45-12.9 cm).
Adult↗
Multiplanar quantitative computed tomography for bone mineral analysis in dogs.
The purpose of this study was to determine the precision and accuracy of quantitative computed tomography bone mineral analysis in dogs in coronally reconstructed images. Nonhomogeneous tissues, such as bones with fractures or deformities, may be better analyzed if multiplanar reconstruction of the transaxial data could be performed without degradation of information. Our analysis demonstrated that coronal reconstruction of quantitative-computed tomography data was precise (1.2 to 4.7%) and accurate (1.3 to 7.5%) in vitro. The technique displays high-quality images, which can be analyzed at any location within the volume scanned. Quantitative computed tomography of canine osteotomy healing in vivo accurately determined bone mineral density of selected regions of interest. Bone mineral density correlated highly with calcium content of the tissue (R2 = 0.76, P less than 0.0001).
Animals↗
A software system for interactive and quantitative visualization of multidimensional biomedical images.
A comprehensive software system called ANALYZE has been developed which permits detailed investigation and evaluation of 3-D biomedical images. The software can be used with any 2-D or 3-D imaging modality, including x-ray computed tomography, radionuclide emission tomography, ultrasound tomography, magnetic resonance imaging and both light and electron microscopy. The package is unique in its synergistic integration of fully interactive modules for direct display, manipulation and measurement of multidimensional image data. Several original algorithms are included which improve image display efficiency and quality. One of the most versatile and powerful algorithms is interactive volume rendering, which is optimized to be fast without compromising image quality. An important advantage of this technique is to display 3-D images directly from the original data and to provide on-the-fly combinations of selected image transformations and/or volume set operations (union, intersection, difference, etc.). The inclusion of a variety of interactive editing and quantitative mensuration tools significantly extends the usefulness of the software. Any curvilinear path or region-of-interest can be manually specified and/or automatically segmented for numerical determination and statistical analyses of distances, areas, volumes, shapes, densities and textures. ANALYZE is written entirely in "C" and runs on several standard UNIX workstations. It is being used in a variety of applications by over 40 institutions around the world, and has been licensed by Mayo to several imaging companies. The software architecture permits systematic enhancements and upgrades which has fostered development of a readily expandable package. ANALYZE comprises a powerful "visualization workshop" for rapid prototyping of specific application packages, including applications to interactive surgery simulation and radiation treatment planning. ANALYZE offers the potential to accurately and reproducibly examine, from images, the structure and function of any cell, tissue, limb, organ or organ system of the body, much like a surgeon or pathologist might do in real life, but entirely non-invasively, without pain or destruction of tissue. These capabilities promise exciting new insights into the basic processes of life, and major advances in health care delivery through improved diagnosis and treatment of disease.
Computer Graphics↗
A computer model for the evaluation of the effect of corneal topography on optical performance.
We developed a method that models the effect of irregular corneal surface topography on corneal optical performance. A computer program mimics the function of an optical bench. The method generates a variety of objects (single point, standard Snellen letters, low contrast Snellen letters, arbitrarily complex objects) in object space. The lens is the corneal surface evaluated by a corneal topography analysis system. The objects are refracted by the cornea by using raytracing analysis to produce an image, which is displayed on a video monitor. Optically degraded images are generated by raytracing analysis of selected irregular corneal surfaces, such as those from patients with keratoconus and those from patients having undergone epikeratophakia for aphakia.
Computer Simulation↗
EEG scalp electrode projection onto three-dimensional surface rendered images of the brain.
A technique is described for generating magnetic resonance-based, surface rendered images of the brain with electroencephalographic (EEG) scalp electrode positions projected onto the cortical surface. This technique (EEG electrode projection) was used in 10 patients who subsequently underwent surgery for medically intractable frontal lobe epilepsy. In most cases of intractable epilepsy, successful surgery entails the resection of electrophysiologically abnormal cortical tissue rather than an identifiable mass lesion. EEG electrode projection is a unique and useful surgical tool because it provides images that spatially correlate the surface anatomy of the brain and the electrophysiologic abnormality recorded at the scalp. Excellent correlation was found between cortical topography delineated by the surface rendered images and cortical anatomy at surgery. Agreement between EEG electrode projection and electrocorticography as to the location of the electrophysiologic abnormality increases confidence that appropriate cortical areas have been identified for resection. The technique provides new and unique insight into important anatomic-electrophysiologic relationships and aids in formulation of surgical strategy.
Adult↗
Three-dimensional reconstruction of the temporal bone.
Study of the complex anatomy and pathology of the temporal bone has traditionally used microscopy which permits analysis in only two dimensions. Recent advances in bioimaging technology have permitted visualization and reconstruction of computed tomography images in three dimensions. We have developed a technique that applies this technology in the imaging and reconstruction of human temporal bones. Data taken from serial histologic sections of the temporal bone are entered into a computer. The sections are edited and, through the use of specially developed software, a realistic three-dimensional reconstruction is produced. The reconstructed image can be rotated along any of three axes, and structures within the temporal bone can be isolated for more detailed analysis. Applications for the study of pathologic conditions of the temporal bone will be discussed.
Adult↗
A system for interactive volume analysis (SIVA) of 4-D biomedical images.
We have developed a powerful new microcomputer-based system that permits detailed investigations and evaluation of 3-D and 4-D (dynamic 3-D) biomedical images. The system comprises a special work station to which all the information in a large 3-D image database is accessible for rapid display, manipulation, and measurement. The system provides important capabilities for simultaneously representing and analyzing both structural and functional data and their relationships in various organs of the body. This paper provides a detailed description of this sophisticated system, as well as the rationale, background, theoretical concepts, and practical considerations related to implementation of even more advanced capabilities for interactive display and analysis of 4-D biomedical images.
Computers↗
Reconstruction of a chromosome model from its projections.
As a pilot experiment towards the reconstruction of human chromosomes from their electron microscopic projections, a chromosome model was photographed and several cross-sectional planes successfully reconstructed. Some practical constraints and conditions for this type of work are defined.
Chromatin↗
Display and visualization of three-dimensional reconstructed anatomic morphology: experience with the thorax, heart, and coronary vasculature of dogs.
A new method, termed reprojection, is used to visualize anatomic morphology contained within three-dimensional reconstructions made up of images of multiple parallel cross sections. This method involves the projection, either orthographically into a plane or radially onto a cylinder, of the volume picture elements (voxels) of the reconstruction. Orthographic reprojection images, formed by mathematically summing the magnitudes of the voxels along selected parallel paths through the reconstructed volume, are analagous to conventional radiographs formed by the passage of an X-ray beam through the volume. The reprojection image is a two-dimensional array of picture elements that is displayed on a television monitor using a digital-to-video scan converter. Also described are the techniques of noninvasive selective tissue dissolution and numerical dissection, whereby obscuring portions of the reconstructed volume are either partially "dissolved" or totally eliminated before reprojection. Utilizing these methods, anatomic information present in a three-dimensional reconstruction but not clearly seen in a reprojection image is rendered visible after removal of superposed structures. The usefulness of these methods is demonstrated utilizing three-dimensional reconstructions of the thorax, heart, and coronary arteries of dogs.
Animals↗
High speed synchronous volume computed tomography of the heart.
A new generation, fully electronic high-speed whole-body computed tomography system is being developed to provide accurate dynamic visualization and measurement of the vital functions of the heart based on rapid changes in its shape, dimensions, and perfusion. This Dynamic Spatial Reconstruction System (DSR) will provide stop-action (1/100 sec.), rapidly sequential (60/sec.) synchronous volume (240 simultaneous, 1mm-thick cross sections) reconstructions and display of the full anatomic extent of the internal and external structures of the heart throughout successive cardiac cycles, and will permit visualization of the three-dimensional vascular anatomy and circulation throughout the myocardium.
Animals↗
Non-invasive visualization and quantitation of cardiovascular structure and function.
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Animals↗
Quantitative measurement of fractional bone volume using digital scanning videodensitometry.
A method is described for reproducible and rapid quantitative measurements of fractional bone volume in sections of a bone biopsy. The presence or absence of bone is determined at several thousand points over the entire surface area of each specimen by high-speed digitization and computer analysis of video scans of enlarged microradiographic images of bone sections. An operator interactive light-pen assembly permits selective delineation of desired areas of the video image to facilitate computation of regional bone mass within each specimen. Tests of the reproducibility of the method of performed and are described. The results obtained from application of the method to determine the amount of bone in various age groups and in two groups of patients before and after therapy are also presented. These data indicate the potential of this technique for high volume, high resolution measurements of the fractional bone volume in both investigative and clinical diagnostic studies of age dependent and disease dependent processes.
Absorptiometry, Photon↗
Osteocyte lacunar area in normal bone, hyperparathyroidism, renal disease, and osteoporosis.
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Bone and Bones↗
Quantitative imaging of the structure and function of the heart, lungs, and circulation.
A 28-x-ray-source, cylindrical-scanning, transaxial tomographic x-ray-imaging system is in the process of being fabricated. This system will scan synchronously up to 250 parallel transverse cross sections of the human body over an axial range of 25 cm within 0.01 second at a maximum rate of 60 scans per second. The system will provide numerous variations of scanning configurations to permit quantitative assessment of the relative importance of transverse section thickness, image contrast, spatial and temporal resolution, and related computerized algorithms and display techniques. Synchronous imaging at high temporal resolution of a three-dimensional volume--for example, the heart--eliminates the need for successive periods of breath-holding and gated imaging techniques and is essential for quantitation of cardiovascular and pulmonary function and structure in intact animals or humans. Initial clinical applications are expected to be in the early detection of lung cancer and the diagnosis of the nature and degree of congenital and acquired cardiovascular disabilities.
Animals↗
Finite element analysis of myocardial diastolic stress and strain relationships in the intact heart.
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Animals↗
Quantitation of left ventricular myocardial fiber hypertrophy and interstitial tissue in human hearts with chronically increased volume and pressure overload.
Using new techniques, we quantitated left ventricular myocardial fiber hypertrophy and interstitial tissue in four groups of autopsied hearts free of coronary disease: 1) 22 normal hearts, 2) 20 hearts from patients with mitral incompetence (NYHA Class II-III) who died early after mitral valve replacement from causes other than cardiac failure, 3) 22 hearts from patients with mitral incompetence (NYHA Class III-IV) who died early after mitral valve replacement from cardiac failure with low cardiac output syndrome, and 4) 22 hearts from patients with hypertensive heart disease (NYHA Class II-III). Myocardial fiber hypertrophy was quantitated by measuring cross-sectional myocardial fiber diameter; the proportion of interstitial tissue was quantitated by using a computerized, high-resolution video image-digitizing system. Myocardial fiber average diameter in groups 2, 3 and 4 was significantly higher than group 1. The proportion of interstitial tissue was significantly increased in group 3. In chronic mitral incompetence an increase in left ventricular interstitial tissue may play a role in the development of severe cardiac failure.
Cardiomegaly↗
A computer-based videodensitometric system for studying banded human chromosomes illustrated by the analysis of the normal morphology of chromosome 18.
A computer-based, high-resolution, high-speed system is described for the digitization of television images of human G-banded chromosomes, on-line directly from a microscope. The digitized data are processed by a computer to determine the total length and centromere index of individual chromosomes and to obtain an integrated density profile representing the band pattern. The density profile is reduced by the computer to a series of dark and light bands, each with a defined position, width, and density. The results are displayed by the computer on a television monitor in a form that simulates routine laboratory preparations and that allows cytogenetic inspection. The system is easy to operate, and it includes a wide range of options for operator interaction to ensure reliability. The results of the computer analysis of the no. 18 chromosomes from five cells from each of 10 different persons demonstrated the usefulness of the system for detecting, measuring, and analyzing individual bands in human populations and its application to establishing band patterns of chromosomes in different states of contraction.
Azure Stains↗