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PubMed1989

Quantitative SPECT of uptake of monoclonal antibodies.

Absolute quantitation of the distribution of radiolabeled antibodies is important to the efficient conduct of research with these agents and their ultimate use for imaging and treatment, but is formidable because of the unrestricted nature of their distribution within the patient. Planar imaging methods have been developed and provide an adequate approximation of the distribution of radionuclide for many purposes, particularly when there is considerable specificity of targeting. This is not currently the case for antibodies and is unlikely in the future. Single photon emission computed tomography (SPECT) provides potential for greater accuracy because it reduces problems caused by superimposition of tissues and non-target contributions to target counts. SPECT measurement of radionuclide content requires: (1) accurate determination of camera sensitivity; (2) accurate determination of the number of counts in a defined region of interest; (3) correction for attenuation; (4) correction for scatter and septal penetration; (5) accurate measurement of the administered dose; (6) adequate statistics; and (7) accurate definition of tissue mass or volume. The major impediment to each of these requirements is scatter of many types. The magnitude of this problem can be diminished by improvements in tomographic camera design, computer algorithms, and methodological approaches.

Antibodies, Monoclonal↗
PubMed2005

Prospective bone density changes after periacetabular osteotomy: a methodological study.

We used computed tomography (CT) and 3D design-based sampling principles (stereology) to estimate changes in acetabular bone density after periacetabular osteotomy. We included six consecutive patients with hip dysplasia in the study. Baseline density was measured within the first 7 days following periacetabular osteotomy and compared with bone density 2 years later. Double measurements were performed on three patients, and the coefficient of error of the mean was estimated to 0.05. Bone density in zone 1 increased significantly in the anteromedial quadrant as well as in the posteromedial quadrant of the acetabulum. In the anterolateral and the posterolateral quadrant, bone density was unchanged. In zone 2 and 3, bone density was unchanged 2 years postoperatively. We suggest that the observed increase in bone density medially represents a remodelling response to an altered load distribution after osteotomy. The method used is a precise tool to estimate changes in acetabular bone density.

Acetabulum↗
PubMed2001

A methodology for web-enabling a computer-based patient record with contributions from cognitive science.

Cognitive science is a rich source of insight for creative use of new Web technologies by medical informatics workers. I outline a project to Web-enable an existing computer-based patient record (CPR) in the context of ideas from philosophy, linguistics, artificial intelligence, and cognitive psychology. Web prototypes play an important role (a) because Web technology lends itself to rapid prototype development, and (b) because prototypes help team members bridge among disparate medical, computing, and business ontologies. Six Web-enabled CPR prototypes were created and ranked. User scenarios were generated using a user communication matrix. Resulting prototypes were compared according to the degree to which they satisfied medical, computing, and business constraints. In a different organization, or at different time, candidate prototypes and their ranking might have been different. However, prototype generation and comparison are fundamentally influenced by factors usefully understood in a cognitive science framework.

Cognitive Science↗
PubMedDate not supplied

Staging rectal cancer with CT: methodology, signs and parameters.

Computed Tomography plays a major role in the staging of rectal carcinoma even if discordant results are reported in literature. The use of more sophisticated procedures has markedly improved its accuracy which is still high in advanced tumors and is irreplaceable, though with considerable limitations, in the assessment of distant lymphadenopathy. The methods, the indications and limitations of computed tomography are reported. Attention is focused on the pathological findings for the definition of TNM, which is mandatory to plan a correct therapeutic approach.

Humans↗
PubMed2005

The humanID gait challenge problem: data sets, performance, and analysis.

Identification of people by analysis of gait patterns extracted from video has recently become a popular research problem. However, the conditions under which the problem is "solvable" are not understood or characterized. To provide a means for measuring progress and characterizing the properties of gait recognition, we introduce the HumanID Gait Challenge Problem. The challenge problem consists of a baseline algorithm, a set of 12 experiments, and a large data set. The baseline algorithm estimates silhouettes by background subtraction and performs recognition by temporal correlation of silhouettes. The 12 experiments are of increasing difficulty, as measured by the baseline algorithm, and examine the effects of five covariates on performance. The covariates are: change in viewing angle, change in shoe type, change in walking surface, carrying or not carrying a briefcase, and elapsed time between sequences being compared. Identification rates for the 12 experiments range from 78 percent on the easiest experiment to 3 percent on the hardest. All five covariates had statistically significant effects on performance, with walking surface and time difference having the greatest impact. The data set consists of 1,870 sequences from 122 subjects spanning five covariates (1.2 Gigabytes of data). The gait data, the source code of the baseline algorithm, and scripts to run, score, and analyze the challenge experiments are available at http://www.GaitChallenge.org. This infrastructure supports further development of gait recognition algorithms and additional experiments to understand the strengths and weaknesses of new algorithms. The more detailed the experimental results presented, the more detailed is the possible meta-analysis and greater is the understanding. It is this potential from the adoption of this challenge problem that represents a radical departure from traditional computer vision research methodology.

Adult↗
PubMed2004

Computer assisted telephone interviewing (CATI) for health surveys in public health surveillance: methodological issues and challenges ahead.

This article describes methodological issues, challenges, and a vision for using computer assisted telephone interviewing (CATI) in a comprehensive public health surveillance system in the 21st century. Methodological issues include funding of surveys, survey frequency, sample size considerations, response rates, and types of bias to be considered in questionnaire design. Challenges include the recognition of the merits and limitations of CATI, and the potential for greater use in surveillance of public health issues in health regions requiring rapid and regular data. The vision of a CATI survey-based, rapid, flexible, cost-effective public health surveillance system is described. It is concluded that further discussion and views on improvements with regard to CATI methodological and practical issues will help build a better CATI survey-based public health surveillance system for the future.

Canada↗
PubMed1999

Theoretical considerations of monitor unit calculations for intensity modulated beam treatment planning.

A treatment planning system to compute intensity modulated radiotherapy (IMRT) treatments using inverse planning was investigated. The system was designed to optimize the intensity patterns required to treat a specified target volume with specified normal structure constraints. A beam model that uses the convolution of pencil beams was used to compute the dose distributions. A multileaf collimator leaf-setting sequence intended to produce the intensity pattern was computed along with the monitor units required to deliver each of a number of fixed-gantry modulated fields. Computer calculations are commonly verified using an independent manual procedure. It is difficult to calculate treatment delivery monitor units for this variant of IMRT using manual methods. Since manual calculations are not feasible, it is important both to understand and to verify the calculation of treatment monitor units by the planning system algorithm. A formal analysis was made of the dose calculation model and the monitor unit calculation embedded in the algorithm. Experimental verification of the dose delivered by plans computed with the methodology demonstrated an agreement of better than 4% between the dose model and measurements.

Algorithms↗
PubMed2004

Volumetric analysis of maxillary sinuses of Zulu and European crania by helical, multislice computed tomography.

INTRODUCTION: The volumes of the maxillary sinuses are of interest to surgeons operating endoscopically as variation in maxillary sinus volume may mean variation in anatomical landmarks. Other surgical disciplines, such as dentistry, maxillo-facial surgery and plastic surgery, may benefit from this information. OBJECTIVES: To compare the maxillary sinus volumes of dried crania from cadavers of European and Zulu descent, with respect to ethnic group and gender. METHODOLOGY: Helical, multislice computed tomography (CT) was performed using 1-mm coronal slices. The area for each slice was obtained by tracing the outline of each slice. The CT machine calculated a volume by totalling the slices for each sinus. RESULTS: Ethnic and gender variations were found in the different groups. It was found that European crania had significantly larger antral volumes than Zulu crania and men had larger volumes than women. Race and gender interaction was also assessed, as was maxillary sinus side. CONCLUSION: A variation in maxillary sinus volume between different ethnic groups and genders exists, and surgeons operating in this region should be aware of this.

Adult↗
PubMed1990

Stereotactic craniotomy.

Computed tomography-based stereotactic biopsy procedures for diagnosing intracranial tumors are common today. In addition, point stereotaxis is used to center a craniotomy over a superficial lesion or to find a deep one. Technical innovations have improved performance of these operations. The author describes the instrumentation and current methodology for computer-assisted stereotactic laser microsurgical extirpation of intra-axial lesions and discusses the results.

Brain Neoplasms↗
PubMed2004

Three-dimensional computer visualization of forensic pathology data.

Despite a decade of use in US courtrooms, it is only recently that forensic computer animations have become an increasingly important form of communication in legal spheres within the United Kingdom. Aims Research at the University of Nottingham has been influential in the critical investigation of forensic computer graphics reconstruction methodologies and techniques and in raising the profile of this novel form of data visualization within the United Kingdom. The case study presented demonstrates research undertaken by Aims Research and the Department of Forensic Pathology at the University of Sheffield, which aims to apply, evaluate, and develop novel 3-dimensional computer graphics (CG) visualization and virtual reality (VR) techniques in the presentation and investigation of forensic information concerning the human body. The inclusion of such visualizations within other CG or VR environments may ultimately provide the potential for alternative exploratory directions, processes, and results within forensic pathology investigations.

Adult↗
PubMedDate not supplied

Neural networks in astronomy.

In the last decade, the use of neural networks (NN) and of other soft computing methods has begun to spread also in the astronomical community which, due to the required accuracy of the measurements, is usually reluctant to use automatic tools to perform even the most common tasks of data reduction and data mining. The federation of heterogeneous large astronomical databases which is foreseen in the framework of the astrophysical virtual observatory and national virtual observatory projects, is, however, posing unprecedented data mining and visualization problems which will find a rather natural and user friendly answer in artificial intelligence tools based on NNs, fuzzy sets or genetic algorithms. This review is aimed to both astronomers (who often have little knowledge of the methodological background) and computer scientists (who often know little about potentially interesting applications), and therefore will be structured as follows: after giving a short introduction to the subject, we shall summarize the methodological background and focus our attention on some of the most interesting fields of application, namely: object extraction and classification, time series analysis, noise identification, and data mining. Most of the original work described in the paper has been performed in the framework of the AstroNeural collaboration (Napoli-Salerno).

Astronomy↗
PubMed2002

Computer simulations of a two-dimensional system with competing interactions.

The results and methodology of large scale computer simulations of the two-dimensional dipolar Ising model with long-range interactions are reported. Systems as large as 117,649 particles were studied to elucidate the elementary excitations and phase diagram of two-dimensional systems, such as Langmuir monolayers, thin garnet films, and adsorbed films on solid surfaces, which spontaneously form patterns of stripes, bubbles, and intermediately shaped domains. The challenging numerical investigations of large scale systems with long-range interactions at low temperatures were made possible by combining the fast multipole method and a non-Metropolis Monte Carlo sampling technique. Our simulations provide evidence that, at sufficiently high ratios of the repulsive to the attractive coupling constant for the model, twofold stripe order in the systems of interest is lost through a defect-mediated mechanism. Heat capacity data and the excitations observed in our simulations as the system disorders indicate that it is most likely an instance of a Kosterlitz-Thouless phase transition. The results from simulations with and without external field are in excellent agreement with the predictions of an analytic scaling theory [A. D. Stoycheva and S. J. Singer, Phys. Rev. E 64, 016118 (2001)], confirming the phase diagram furnished by the analytic model. The scaling theory suggests that, under certain conditions, defect-mediated stripe melting may be supplanted by Ising like disordering within stripes for small repulsion strength. A qualitative discussion of a model that supports both disordering mechanisms is presented.

Journal Article↗
PubMed2005

Porphyrin distortion from resonance Raman intensities of out-of-plane modes: Computation and modeling of N-methylmesoporphyrin, a ferrochelatase transition state analog.

Resonance Raman spectra of porphyrins are computed with DFT/CIS methodology to monitor out-of-plane distortions. A framework is established for assessing protein-induced distortion of porphyrin bound to a ferrochealatase antibody. Tests on undistorted porphyrins give good agreement with the experimental intensity pattern of in-plane modes for free-base porphine (FBP) and mesorporphyrin IX free base (MP). The computed spectrum of N-methylmesoporphyrin (NMP), in which the methyl-substituted pyrrole ring is tilted 32 degrees from the mean porpyrin plane, also gives reasonable agreement with experiment and reveals activation of out-of-plane (oop) vibrational modes. To model oop distortions systematically, an artificial molecule, FBP-X8, was constructed, in which the H atoms attached to the FBP pyrrole Cb atoms are replaced by heavy substituents, as in physiological porphyrins. Oop mode enhancements are computed for FBP-X8 by displacing it along the canonical distortion coordinates: doming, saddling, ruffling and waving. When FBP-X8 is constrained to the NMP porphyrin geometry, normal coordinate decomposition reveals significant contributions also from modes higher in frequency than the canonical modes, and they contribute importantly to the computed RR intensities. NMP-constrained FBP-X8 gives a reasonable facsimile of the NMP RR spectrum, but better results are obtained with a full computation of MP, constrained in the same way; thus the physiological substituents have significant influence on the RR spectra, over and above their effective masses. Attention focuses on a mode analogous to gamma 15 in 4-fold symmetric porphyrins, which is a kind of saddling mode. This mode is selectively enhanced in NMP-constrained MP; a corresponding RR band is induced upon binding MP to a ferrochelatase antibody.

Computer Simulation↗
PubMed2001

Computer-assisted diagnostics: application to prostate cancer.

Artificial neural networks (ANNs) have only recently been applied to solve problems in the diagnosis, staging, and prediction of treatment outcome in prostate cancer. A literature search provided information on 10 published journal articles that were selected for review and analysis. In all but one of the studies that compared the ANN output with logistic regression modeling, the ANN performed better. Specific training issues for neural networks are discussed and examples provided. We conclude that the continued development and refinement of computer-assisted diagnostic methodology are warranted to enhance conventional statistical approaches to the classification and pattern recognition found in data sets from men either suspected of having or known to have prostate cancer.

Diagnosis, Computer-Assisted↗