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Biomedical subjects

J A Hanson

Publications and source records attributed to J A Hanson.

At least 73 records · Page 4Linked to original sources
PubMed1988

Facial affect recognition in children: a comparison of the performance of children with right and left hemisphere lesions.

This study tests the hypothesis that the right hemisphere is specialized for the processing of emotional information in children, as it is in adults. We compared the performance of eight children with right-hemisphere lesions and eight with left-hemisphere lesions on a test of facial affect recognition. The mean score of the right-hemisphere group fell significantly below that of the left-hemisphere group and normal controls, suggesting that the specialization of the right hemisphere occurs early in development. This finding is consistent with clinical observations that children with right-hemisphere dysfunction manifest a high incidence of difficulty in social interactions.

Brain Diseases↗
PubMed1985

Thoracolumbar burst fractures: CT dimensions of the spinal canal relative to postsurgical improvement.

Cross-sectional spinal canal area was measured before and after surgery in 12 patients with thoracolumbar burst fractures and canal narrowing caused by retropulsed fragments. Patients were classified into Denis type A or type B. Denis type A fractures have comminution of both end-plates of the vertebral body creating multiple smaller fractures; Denis type B fractures have comminution of the superior end-plate only with a single vertical fracture line into the inferior end-plate creating larger fragments. The degree of neurologic impairment was assessed before and after surgery using the Frankel system. There was no correlation between degree of canal narrowing and degree of neurologic impairment. The degree of spinal canal narrowing reflects the final resting position of the vertebral body fragments after trauma; during trauma, greater degrees of canal impingement may have occurred. Also, significant canal narrowing may be present without pinching of the cord or cauda equina. All patients with Denis type A fractures had near-anatomic reduction of fragments out of the spinal canal by surgery; less than half of the patients with Denis type B had good reduction. There was no correlation between reduction of retropulsed fragments and subsequent neurologic improvement. However, this should not preclude surgery as a therapeutic option: Eight of 10 patients with neurologic impairment experienced some improvement in symptoms after surgery; the other two were unchanged.

Adult↗
PubMed1984

Investigating the efficacy of current quality assurance performance tests in diagnostic ultrasound.

The efficacy of four current quality assurance performance tests in diagnostic ultrasound was investigated. This was done by comparing the ability of the performance tests to detect fluctuations in gray scale, depth of penetration, axial resolution and lateral resolution on a real-time scanner with the ability of sonologists and sonographers to detect the same fluctuations. The performance tests for gray scale, depth of penetration, and axial resolution were found to be efficacious. The lateral resolution test was judged nonefficacious . This suggested a need to revise the protocol for the lateral resolution test with regard to real-time scanners.

Evaluation Studies as Topic↗
PubMed1984

Estimating fetal weights less than 2000 g: an accurate and simple method.

An accurate estimated fetal weight in the low-birth-weight infant can provide valuable information for the obstetrician faced with a decision concerning mode and time of delivery. Four existing equations for calculating fetal weight were analyzed and compared with data consisting entirely of infants with birth weights of 500-2000 g. A new formula, birth weight-grams = 10.1 (abdominal circumference-cm X biparietal diameter-cm) - 481, is proposed as a simple yet accurate alternative. This equation has a standard deviation of 99 g/kg.

Birth Weight↗
PubMed1982

CT and radiation therapy planning: impact of LOCATE ScoutView images.

LOCATE, a new computer software program, was used to outline tumor margins on scanned projection radiographs (ScoutView). This information was transferred to simulator radiographs and the results compared with tumor margins determined by all other methods. Twenty-two patients with various types of tumors in different parts of the body were studied with computed tomography and then therapy planned without the benefit of images from this program. When program information was made available, it stimulated a change in the radiation therapy plan in 18 cases (82%). Phantom studies demonstrated that magnification inherent in the program images was not significantly different from that in simulator radiographs. Program-generated tumor margins on ScoutView images were shown to accurately reflect tumor margins outlined on cross-sectional computed tomographic images as long as no patient motion occurred on the table during the study. LOCATE provides a useful means of tumor localization for therapy planning in many cases.

Humans↗
PubMed1976

An outbreak of duck virus enteritis (duck plague) in Alberta.

Duck plague (Duck virus enteritis) was disgnosed in a resident population of Muscovy ducks (Cairina moschata) on a small game farm in Alberta. This disease has not been reported previously in Canada. Clinical signs consisted of cyanosis, depression and acute death. Necropsy of two Muscovy ducks revealed lesions typical of the disease. There were ulcerations with pseudomembranes in the small intestine, ulcerations with caseous plaques in the esophagus and eosinophilic intranuclear inclusion bodies in the spleen. Clinical disease with mortality was reproduced in young ducklings injected with tissue homogenates from field cases. All surviving inoculated ducklings seroconverted to highly significant titres of neutralizing antibodies to duck virus enteritis (DVE) virus. All attempts to isolate the agent in embryonating duck eggs or primary tissues cultures of duck and chicken kidney were negative. Identification of the DVE virus was accomplished by serum neutralization with ducklings as the host system.

Alberta↗
PubMedDate not supplied

Ultrasonographic appearance of splenic disease in 101 cats.

The sonographic findings in 101 cats with splenic abnormalities are presented. Diagnosis was made by ultrasound-guided fine needle aspirate or fine-needle biopsy (n = 91), ultrasound-guided core biopsy (n = 1), surgical core biopsy (n = 1), or necropsy (n = 10). Two cats had more than one diagnostic procedure (fine needle aspirate and necropsy or core biopsy and necropsy). The splenic abnormalities included lymphosarcoma (n = 30), mast cell tumor (n = 27), extramedullary hematopoiesis and/or lymphoid hyperplasia (n = 27), epithelial tumors (n = 6), mesenchymal tumors (n = 4), malignant histiocytosis (n = 2), myeloproliferative disease (n = 2), pyogranulomatous inflammation (n = 2), erythroleukemia (n = 1), eosinophilic syndrome (n = 1), hematoma (n = 1), and granulomatous splenitis (n = 1). Three cats had more than one splenic abnormality (mast cell tumor and metastatic carcinoma, pyogranulomatous inflammation and lymphoid hyperplasia, histiocytic lymphosarcoma, and lymphoid hyperplasia). Pathognomonic changes were not seen for any of the diseases.

Animals↗
PubMedDate not supplied

Compton scatter densitometry with polychromatic sources.

The use of x-ray tubes as radiation sources for Compton scatter densitometry (CSD) is evaluated theoretically. Bias correction factors (bcf's) which correct for differential attenuation due to Compton shift and polychromaticity, and differential scattering cross section due to polychromaticity, are defined to facilitate comparison of monochromatic and x-ray tube CSD devices. Computer modeling indicates that a 100-kVp x-ray tube spectrum hardened with 0.64 mm of Pb filtration yields bcf's 0.008 to 0.34% higher than a 70-keV monochromatic source for various samples of nylon, and human muscle and bone. This difference is insignificant because multiple scatter errors are typically 1000% higher than errors corrected by bcf's. The high equivalent activities of x-ray tubes (10 to 80 TBq) and their small focal spots (1.0 to 2.0 mm) allow the long-standing CSD problems of marginal statistical precision, long counting times, and low spatial resolution to be overcome.

Absorptiometry, Photon↗
PubMedDate not supplied

Compton scatter with polychromatic sources for lung densitometry.

A mobile lung densitometer using conventional x-ray tubes, NaI detectors, and principles of two-source, two-detector Compton scattered densitometry, is described. The device is capable of one to two per second density measurements from a 45-cm3 volume with a precision of 5%. The expected in vivo accuracy (2%-3%) is determined by using an anthropomorphic phantom with replaceable lung inserts. The unintentional detection of multiple-scattered x rays results in a small density-dependent error. This error is predictable and relatively insensitive to differences in surrounding absorbers such as the chest wall. With this device, dynamic in vivo densitometry of the lung in the clinical laboratory and intensive care unit will be possible.

Absorptiometry, Photon↗