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Biomedical subjects

C E Kahn

Publications and source records attributed to C E Kahn.

14 recordsLinked to original sources
PubMed1992

Magnetization transfer contrast imaging of the human leg at 0.1 T: a preliminary study.

Magnetization transfer contrast imaging is an MR technique that capitalizes on interactions between the protons of mobile and macromolecularly bound water molecules. Studies to date, conducted primarily on 4.7 T and 1.5 T MR systems, have yielded results unique from conventional T1- and T2-weighted imaging studies. In this study, performed on a 0.1 T device, a section of lower leg was imaged in 20 normal human subjects and one patient with muscular dystrophy, using both a standard 500/22 gradient-echo sequence and a 500/22 gradient-echo sequence combined with off-resonance radio frequency irradiation designed to elicit magnetization transfer contrast. Results of the two techniques were compared. Our findings suggest that magnetization transfer contrast imaging is feasible at 0.1 T, and that this technique allows reproducible tissue characterization and improves contrast between certain tissues.

Adipose Tissue↗
PubMed1992

Computer-aided detection of diffuse liver disease in ultrasound images.

The authors are developing an automated method of determining measures of texture in liver ultrasound images to improve the accuracy of diagnosis of diffuse liver abnormalities. In each digitized image, the background trend of pixel values is estimated to isolate the underlying pattern of liver texture. After correcting for background trend, the root mean square (RMS) variation and the first moment of the power spectrum are calculated; these measures have been applied successfully to texture analysis of digital chest radiographs. Background trend-corrected measurements detected statistically significant differences in digitized ultrasound images of 11 normal and 11 abnormal livers. Without correction for background trend, the measures are unable to distinguish normal from abnormal liver texture. The authors also investigated the effect on the texture measures of varying several ultrasound imaging parameters in normal patients and in an ultrasound phantom.

Adult↗
PubMed1991

A radiology hypertext system for education and clinical decision making.

Hypertext is a computer-based means of organizing information that allows one to explore the connections among related subjects. FACT/FILE is a hypertext computer system that provides access to a wide variety of information of interest to radiologists and radiology residents. Information is presented as notecards, or frames, which can contain textual information about relevant anatomy, physiology and pathology, as well as differential diagnosis "gamut" listings. More than 800 frames are available. Users can choose frames from an alphabetical index produced automatically from key words in each frame's title, or from a hierarchically organized subject index. Links between frames allow users to explore related frames and then return to the original frame. Physicians can add new frames to the system, so that specialized knowledge can be shared. This system has been implemented as a module of the radiology information system at the University of Chicago Medical Center.

Computer-Assisted Instruction↗
PubMed1991

Vena Tech vena cava filter: experience and early follow-up.

Vena caval filters, such as the Vena Tech filter, that employ low-profile introducer systems have provided physicians with a variety of options for percutaneous placement. From April 1989 to April 1990, 81 patients underwent percutaneous placement of the Vena Tech filter at the authors' institution. Follow-up has been obtained to evaluate the filter with regard to the prevention of pulmonary embolism, the maintenance of caval patency, and mechanical stability. Two cases of pulmonary embolism have been seen following filter placement. Three cases of caval thrombosis have occurred, with recanalization of the cava seen in two of these cases. There have been one broken filter and one case of incomplete filter opening. Limited filter tilting and migration have occurred, though in no case has filter tilt or migration been clinically significant. This experience with the Vena Tech filter suggests that it is safe and effective for the prevention of pulmonary embolism.

Adolescent↗
PubMed1991

Validation, clinical trial, and evaluation of a radiology expert system.

The PHOENIX Radiology Consultant is a rule-based expert system which assists physicians in planning radiological work-up strategies. This article describes the methods used to create and validate the system's knowledge base. The feasibility and acceptability of PHOENIX were tested for two years in a clinical trial. During this period, the system was used 1,421 times, an average of 13.7 times per week, primarily by medical students and nonradiologist physicians. Much of the system's use occurred at night and on weekends, when the radiology department was not fully staffed. Several physicians were enlisted to further evaluate the utility of the system. The results of their evaluation indicate that an expert system that helps physicians select diagnostic-imaging studies can serve as a useful and informative component of a radiology information system, and is particularly useful for medical students and physicians in training.

Algorithms↗
PubMed1990

Family structure: a general program for displaying complex pedigree data.

A general method for automated presentation of complex pedigree data is described. This method, called 'family structure,' allows presentation of genetic relationships for an unlimited number of individuals, and is well suited for description of both human and non-human animal populations. The method is especially useful for populations in which families are interrelated or individuals produce offspring by several mates. This method has been incorporated into a computer system for animal pedigree storage and analysis.

Animals↗
PubMed1988

Combined bone marrow and gallium imaging. Differentiation of osteomyelitis and infarction in sickle hemoglobinopathy.

The clinical records and scintigrams of patients with sickle hemoglobinopathy who underwent combined Tc-99m bone marrow imaging and Ga-67 imaging to differentiate osteomyelitis from bony infarction were reviewed. Of 18 paired examinations in 15 patients, osteomyelitis was diagnosed correctly in six cases; in all six, gallium uptake at the symptomatic site was incongruently increased relative to the bone marrow activity. Of the 12 episodes of infarction, 11 showed congruent activity on both Tc-99m and Ga-67 images. The remaining study was interpreted incorrectly as osteomyelitis due to incongruent Tc-99m and Ga-67 uptake. The use of sequential Tc-99m bone marrow and Ga-67 imaging is an effective means of distinguishing osteomyelitis from bony infarction in patients with sickle hemoglobinopathy.

Adolescent↗
PubMed1987

PHOENIX. An expert system for selecting diagnostic imaging procedures.

The authors developed a computer system that assists physicians in planning the use of diagnostic imaging procedures. This system, the PHOENIX Radiology Consultant, guides the user through a rational, sequential work-up for a variety of common clinical problems. PHOENIX provides explanations of its reasoning, descriptions of the imaging procedures, and citations of relevant literature.

Diagnostic Imaging↗
PubMed1980

A new algorithm for clustering lymphocyte typing sera.

An algorithm is presented for clustering antisera by computer. It has two novel features: the leading serum to which all other sera in the cluster are compared is chosen as the most centrally located serum in the cluster; the similarity between two sera is defined from the 2 X 2 table of serum reactions as s = 2a/(2a + b + c). This similarity index is a better measure of the similarity between two sera than conventional measures of similarity such as the correlation coefficient. Finally, the identification of cluster and serum subsets provides a more complete analysis of cross-reactivity and multispecificity, and suggests which absorptions might yield monospecific typing sera. A computer program which performs this serum cluster analysis is available upon request.

Blood Grouping and Crossmatching↗
PubMedDate not supplied

Brachial plexopathy as a complication of intraarterial cisplatin chemotherapy.

Intraarterial administration of chemotherapeutic agents provides greater local concentration at the tumor site without increased systemic toxicity. Although intravenous infusion of cisplatin is known to cause peripheral neuropathy and intraarterial administration has been reported to cause lumbosacral plexopathy, brachial plexopathy has not been described. We present a case in which infusion of cisplatin into the axillary artery resulted in permanent neurological damage to the posterior cord of the brachial plexus. Proper positioning of the infusion catheter is necessary to minimize potential neural damage.

Adult↗
PubMedDate not supplied

Efficient storage and analysis of immunogenetic phenotypes: the phenotype-element technique.

An efficient means of representing genetic phenotype data is presented. This method employs 'phenotype elements', which are trinary indicators of observed traits. Each phenotype element describes phenotypic information such as an individual's reaction to an antiserum, and assumes a value of positive, negative or unknown. A genotype-phenotype table allows calculation of possible genotypes which correspond to a given phenotype. Applications of the technique are discussed.

Genotype↗