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Biomedical subjects

J T Payne

Publications and source records attributed to J T Payne.

16 recordsLinked to original sources
PubMed1991

Escherichia coli bacteremia associated with hypertrophic osteodystrophy in a dog.

Escherichia coli bacteremia was detected in a dog that had hypertrophic osteodystrophy. The dog improved after treatment with cephalothin sodium, iv fluid therapy, and cage rest. The cause of hypertrophic dystrophy has not been determined, although an infectious cause has been suggested. Dogs that are suspected of having hypertrophic osteodystrophy should be monitored closely for evidence of septicemia, and the administration of prophylactic antibiotics may be advisable.

Animals↗
PubMed1991

Thoracolumbar vertebral osteochondroma in a young dog.

Osteosarcoma was diagnosed in a 7-month-old female German Shepherd Dog with hind limb paresis. Radiography revealed a circumscribed calcified mass in the dorsal vertebral lamina at T13-L1 resulting in extradural compression of the spinal cord. Surgical excision of the mass resulted in gradual return to normal neurologic function. Four weeks after surgery, the dog became severely atactic after rolling onto its back. A chip fracture of T13 was identified, and the dog was euthanatized at the owners' request.

Animals↗
PubMed1991

Effect of left hepatic vein ligation on hepatic circulation, function, and microanatomy in dogs.

Eighteen healthy dogs were allotted to 3 groups (n = 6 dogs each). All dogs were evaluated at the beginning of the study by complete physical examination; total and differential WBC counts; serum biochemical analysis (alanine transaminase and alkaline phosphatase activities and bilirubin and albumin concentrations); sulfobromophthalein excretion, ammonia tolerance, and glucagon response testing; portal and intraparenchymal pressure determinations; operative mesenteric portography; and histologic assessment of hepatic biopsy specimens. The left hepatic vein was ligated completely in dogs of groups 1 and 2. Group-3 (control) dogs had a ligature placed loosely around the left hepatic vein. Dogs of groups 1 and 3 were reevaluated 24 hours after surgery by use of the aforementioned hematologic and biochemical tests. Group-1 dogs were reevaluated by use of portal and intraparenchymal pressure determinations, jejunal vein portography, and complete necropsy at 48 hours after surgery. At 4 weeks after surgery, dogs of groups 2 and 3 were reevaluated by use of all aforementioned tests. Results indicated transient hepatic congestion, which resolved by the fourth postoperative week. Longstanding effect on hepatic structure, circulation, or function was not found. We concluded that left hepatic vein ligation in clinically normal dogs does not cause severe or permanent liver damage.

Alanine Transaminase↗
PubMed1991

Axial pattern flap based on the caudal auricular artery in dogs.

An axial pattern flap that was based on the sternocleidomastoideus branches of the caudal auricular artery and vein was developed. Control flaps, which included ligation and division of the caudal auricular artery and vein, were similarly developed on the contralateral aspect of the neck. Mean survival of caudal auricular artery axial pattern flaps (85.2%), compared with control flaps (63.9%), was significantly different (P less than 0.05). On the basis of results of this study, an axial pattern flap based on the sternocleidomastoideus branches of the caudal auricular artery and vein may be a source of skin for reconstructive procedures of the head and neck.

Animals↗
PubMed1989

Bone healing.

Bone is a tissue composed of organic (cells and matrix) and inorganic (mineral) components. When the mechanical strength of bone is exceeded, fracture occurs. Healing progresses through inflammatory, reparative, and remodeling phases similar to other tissues, but, unlike other tissues, bone possesses the unique capability to completely regenerate and return to pre-injury strength. The bone healing process is influenced by many factors, including mechanical stress, biochemical mediators, bioelectric and piezoelectric properties, and neural and endocrine influences. In short, any factor capable of altering the metabolism of osteogenic cells can influence bone healing.

Animals↗
PubMed1978

Protocol for a computed tomography scanner performance repository.

An argument is presented for organization of a Computed Tomography Scanner Performance Repository. Performance data on CT scanners would be distributed in statistical form to the radiological community. A Protocol is presented for the uniform collection of data. Results of exposure, resolution and visibility measurements made by the authors are presented for the EMI 5005/U, Pfizer 0200 FS and General Electric CT/T scanners.

Humans↗
PubMed1978

Effective atomic number and electron density as measured with a computed tomography scanner: computation and correlation with brain tumor histology.

The mathematical basis and methodology for determining the effective atomic number and electron density of a tissue are presented. Cranial computed tomography (CT) scanning is performed at two different energy levels, both with and without contrast enhancement. The histology of 15 brain tumors has been correlated with the effective atomic number and electron density of the tumor, with parameters of the linear attenuation coefficient, and with statistical values of the CT numbers. The most useful value in separating gliomas from meningiomas from metastases appears to be the percentage change of effective atomic number following contrast enhancement.

Absorptiometry, Photon↗
PubMed1978

CT determination of parameters for inhomogeneity corrections in radiation therapy of the esophagus.

Accurate dose prediction for megavoltage photon therapy of carcinoma of the esophagus requires information on tumor depth, lung thickness, and lung density. The authors found that CT localization of internal and external contours is accurate within +/- 1 mm. Lung density can be measured with an error of less than 0.02 g/cm3 in the range 0.25-1.00 g/cm3. Variance between predicted and measured dosage was less than 3% in all patients and in most RANDO phantom measurements. Accurate radiation therapy planning is possible with CT information from a commercial scanner.

Computers↗
PubMed1978

Patient dosage in computed tomography.

The maximum surface dosage in most clinical CT scans seems to range from 2-10 rads/study but much larger dose per study values seem possible with both rotate-translate and rotary geometry designs. The CT scanner type in itself does not significantly reduce doses. Secondary radiation dose values were measured for critical organs and indicate that dosage from secondary radiations may be reduced significantly by external shielding. Dose values in the vicinity of most CT scanners are typically 1-2 mrad/scan at 1 meter at the parameters of a typical clinical scan.

Female↗
PubMed1977

The nonspecificity of absorption coefficients in the differentiation of solid tumors and cystic lesions.

Eleven lesions of the brain were analyzed and compared; they had absorption coefficients uniformly at the cerebrospinal fluid (CSF) level following contrast enhancement, and ranged from benign to malignant and solid to cystic. Grossly solid tumors may have absorption coefficients on the CT scan equal to CSF even after contrast enhancement. Absorption coefficients are misleading as histological indicators and in diagnosis; it is impossible to separate cystic from non-cystic, benign from malignant, and neoplastic from non-neoplastic lesions by absorption coefficients alone.

Absorption↗
PubMed1976

Performance evaluation and quality assurance of computed tomography scanners, with illustrations from the EMI, ACTA, and Delta scanners.

Performance evaluation of equipment for computed tomography (CT) involves the integration of: (a) establishing performance criteria; (b) designing and implementing test procedures; and (c) reconciling test results in terms of desired performance. Precision (noise), contrast scale, linearity, accuracy, spatial independence, spatial resolution, artifacts, reproducible performance, and patient exposure are several parameters discussed, as are problems of measurement with regard to non-water bath scanners. Performance and quality control tests for the ACTA, Delta, and EMI scanners are outlined. Guidance for the prospective purchaser of CT equipment is presented as a summary of the ideas discussed.

Computers↗
PubMed1975

A survey of the benefits and risks in the practice of radiology.

The findings from both animal and human studies on the radiation risk at low doses and low dose rates are far from conclusive, primarily due to statistical limitations. However, to arrive at some estimate of radiation risk, a conservative approach has been taken, and a linear extrapolation of radiation effects from high doses to low doses has been made. Thus, it is assumed that any exposure to radiation carries some risk of somatic or genetic damage and that there is no threshold or safe dose. In medical practice, diagnostic radiological procedures should be performed only if useful clinical information will be derived. In addition, this information should be obtained at the least possible risk to the patient. For mass chest X-rays, mammography, and lung scans, a quantitative determination of benefit to risk is developed. This approach, though possible desirable, is exceedingly difficult to establish for most diagnostic radiological procedures. Thus, good clinical judgement should be employed in radiological practice, just as it should be employed in all aspects of medical practice.

Background Radiation↗
PubMedDate not supplied

X-ray-transmission computed tomography.

The immediate goal of clinically based x-ray-transmission computed tomography (CT) is to provide a measurement of the x-ray linear attenuation coefficient in cross section with the ultimate goal of impacting on patient management and care. To do this with the accuracy needed for clinical goals requires the careful integration of x-ray physics, detector technology, and mathematical reconstruction theory. Performance evaluation and quality assurance are necessary adjuncts to a CT scanning program. A number of investigative studies are underway.

Fourier Analysis↗