PubMed Health⌕ Search

Biomedical subjects

R F Wagner

Publications and source records attributed to R F Wagner.

At least 109 records · Page 6Linked to original sources
PubMed1990

Complete spontaneous regression of multiple basal cell carcinomas in the basal cell nevus syndrome: the possible role of transepithelial elimination.

A 36-year-old Latin American man with the basal cell nevus syndrome had multiple, soft, hairless, depressed scars of the face, scalp, neck, and back, ranging in size from 0.3 x 0.5 cm to 3.5 x 3.9 cm. These areas had never been treated and previously were sites of basal cell carcinomas that underwent complete spontaneous regression 4-5 years from the date of onset. Pathology of these spontaneously regressed sites was consistent with the criteria established by Curson and Weedon (1979). Type III transepithelial elimination was demonstrated for a basal cell carcinoma. Type III transepithelial elimination may play a role in the spontaneous regression of basal cell carcinomas.

Adult↗
PubMed1990

New primary basal cell carcinomas arising in skin flaps following Mohs micrographic surgery for primary and recurrent basal cell carcinoma.

Two patients developed new primary basal cell carcinomas (BCCs) in skin flaps used to reconstruct wounds that followed an earlier primary BCC and a recurrent BCC treated by Mohs micrographic surgery. Criteria for distinguishing a new primary BCC arising in a skin flap or full-thickness skin graft at a previous treatment site for BCC from a truly recurrent BCC are presented. The distinction between a new primary BCC and true tumor recurrence is important for accurate clinical assessment and may have a dramatic impact on the type of subsequent treatment. In addition, there may be less medicolegal liability in the case of a new primary BCC arising at the site of a previously treated BCC than for a BCC that is determined to be recurrent.

Adult↗
PubMed1990

Describing small-scale structure in random media using pulse-echo ultrasound.

A method for estimating structural properties of random media is described. The size, number density, and scattering strength of particles are estimated from an analysis of the radio frequency (rf) echo signal power spectrum. Simple correlation functions and the accurate scattering theory of Faran [J.J. Faran, J. Acoust. Soc. Am. 23, 405-418 (1951)], which includes the effects of shear waves, were used separately to model backscatter from spherical particles and thereby describe the structures of the medium. These methods were tested using both glass sphere-in-agar and polystyrene sphere-in-agar scattering media. With the appropriate correlation function, it was possible to measure glass sphere diameters with an accuracy of 20%. It was not possible to accurately estimate the size of polystyrene spheres with the simple spherical and Gaussian correlation models examined because of a significant shear wave contribution. Using the Faran scattering theory for spheres, however, the accuracy for estimating diameters was improved to 10% for both glass and polystyrene scattering media. It was possible to estimate the product of the average scattering particle number density and the average scattering strength per particle, but with lower accuracy than the size estimates. The dependence of the measurement accuracy on the inclusion of shear waves, the wavelength of sound, and medium attenuation are considered, and the implications for describing the structure of biological soft tissues are discussed.

Models, Theoretical↗
PubMed1990

Aperture optimization for emission imaging: effect of a spatially varying background.

A method for optimizing the aperture size in emission imaging is presented that takes into account limitations due to the Poisson nature of the detected radiation stream as well as the conspicuity limitation imposed by a spatially varying background. System assessment is based on the calculated performance of two model observers: the best linear observer, also called the Hotelling observer, and the nonprewhitening matched-filter observer. The tasks are the detection of a Gaussian signal and the discrimination of a single from a double Gaussian signal. When the background is specified, detection is optimized by enlarging the aperture; an inhomogeneous background results in an optimum aperture size matched naturally to the signal. The discrimination task has a finite optimum aperture for a flat background; a nonuniform background drives the optimum toward still-finer resolution.

Image Processing, Computer-Assisted↗
PubMed1990

Iatrogenic contamination of multidose vials in simulated use. A reassessment of current patient injection technique.

An investigation of the potential spread of iatrogenic infections through contaminated multidose vials was performed. Contamination of a multidose vial was hypothesized to occur after a single syringe is used to inject an infected patient with medication, and the same syringe subsequently is used to withdraw additional medication from the multidose vial. If the contaminated multidose vial is used for another patient, an iatrogenic infection may be spread. Laboratory study of this injection technique found that viral plaque-forming units could be transmitted to a multidose vial in this manner. A survey of 100 fellows of the American Academy of Dermatology from the United States found that 24% of the respondents used this potentially unsafe procedure. The potential for iatrogenic spread of the human immunodeficiency virus and hepatitis B virus is described. Recommendations to avoid patient infection are made.

Cross Infection↗
PubMed1990

Modern treatment approaches to vitiligo.

Vitiligo is a common disorder for which treatment is frequently difficult and disappointing. The current medical and surgical treatment options are reviewed and fully discussed. Several recently developed therapeutic modalities that may be useful options in the future are described.

Humans↗
PubMed1990

The necessity for treatment of childhood port-wine stains.

The pulsed tunable dye laser has recently become available for the treatment of children with port-wine stains. Parental reactions and psychosocial implications of untreated port-wine stains in children are reviewed. It is recommended that children with port-wine stains be treated as early as possible to prevent adverse sequelae to their psychological development.

Child↗
PubMed1990

Physical methods for the management of hirsutism.

Physical methods for the management of unwanted hair are critically reviewed. Electrolysis and thermolysis are popular and medically proven electrochemical and electrosurgical techniques for permanent hair removal. Many patients seek consultation with their physician prior to having this elective procedure performed. Clinical guidelines are presented for a successful consultation with such patients. Many years ago the unregulated practice of x-ray therapy by unlicensed and poorly trained personnel resulted in tragic morbidity and mortality. Some historical parallels exist between this disturbing period and present day electrolysis and thermolysis practice: only twenty-seven states currently require licensing for permanent hair removal, which is a procedure with rare but potentially serious complications.

Electrolysis↗
PubMed1990

Patient personal injury litigation against dermatology residency programs in the United States, 1964-1988. Implications for future risk-management programs in dermatology and dermatologic surgery.

A national survey reviewing patient injury litigation against US dermatology residency programs revealed that 50% of the respondents had experienced at least one lawsuit between 1964 and 1988. The northeast region reported the most legal activity. Fifty percent of the lawsuits related to therapeutic or surgical complications. Plaintiffs were successful in 37.9% of the lawsuits. The mean award was $26,505, and the largest reported award of $200,000 was for failing to diagnose herpes simplex in an immunocompromised patient. In view of several recent trends in dermatology, the amount of litigation against dermatologists may increase.

Dermatology↗
PubMed1989

Physics and statistics of medical imaging.

Extraordinary progress has been made over the last two decades in the development and dissemination of new medical imaging technologies. The development of computed tomography, positron emission tomography, and magnetic resonance imaging, as well as major innovations to the conventional imaging modalities, have revolutionized medical diagnostic imaging. Despite their many differences, all of these modalities can be viewed from a common perspective: being described in terms of the underlying physical properties imaged, the type of radiation/detection system used to produce the images, and the imaging performance that the modality achieves, both in absolute terms and relative to that of a conceptual ideal observer. This is a US government work. There are no restrictions on its use.

Diagnostic Imaging↗
PubMed1989

Quantitative ultrasonic detection and classification of diffuse liver disease. Comparison with human observer performance.

A multiparameter ultrasonic tissue characterization system has been developed and tested on several types of diffuse liver disease. The four tissue characterization parameters used are based on the first and second order statistics of the B-scan image. Performance of the system was evaluated using receiver operating characteristic (ROC) analysis and was compared with the performance of experienced human observers viewing B-scan images. The machine-based multiparameter system achieved an area under the ROC curve (Az) of 0.88 for detection of chronic hepatitis in more than 100 proven cases of the disease. This was dramatically better than the performance of human observers (Az = .64, P less than .05) and compares favorably to the performance of other accepted diagnostic tests such as head CT and the PAP smear. For detection of Gaucher's disease, the Az for the system was .92, whereas for separating hepatitis from Gaucher's disease Az was .84. Human observers also did well at these tasks (P greater than .8) using organomegaly as their major criterion for diagnosing Gaucher's disease. For primary biliary cirrhosis the system Az was .80, for glycogen storage disease Az was .94. These results suggest that use of multiparameter tissue characterization can significantly increase the usefulness of ultrasound for evaluation of diffuse liver disease.

Gaucher Disease↗