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Biomedical subjects

G D Frey

Publications and source records attributed to G D Frey.

7 recordsLinked to original sources
PubMed1995

Quantitative mammography contrast threshold test tool.

Mammographic contrast is commonly evaluated by visualizing small objects of varying size or mass divided by projected area. These qualitative contrast determinations are commonly performed by imaging a phantom like the American College of Radiology accreditation phantom at clinical mammographic settings. However, this contrast assessment does not take into account the kVp of the machine. This work describes a quantitative mammography contrast threshold test tool which examines light object contrast on a uniform background for a contrast range of 0.32% to 1.38% at 25 kVp. For this mammography contrast threshold test tool, contrast is defined by delta I/I = loge (psi O/ psi b), where psi O is the target energy flux, and psi b is the background energy flux. Contrast threshold is defined as the lowest contrast value for which the objects are visible. Unlike traditional assessments of mammographic contrast, this measurement of contrast threshold is kVp corrected. The mammography contrast threshold test tool is constructed out of common plastics and provides a quantitative means of assessing contrast threshold for individual mammographic units and total mammographic systems.

Accreditation↗
PubMed1986

Quantitative analysis of the cervical spinal canal by computed tomography.

Computed tomography measurements of the AP diameter, width, and cross-sectional area of the bony cervical canal were derived from cervical spine examinations of fifty-two normal adults. These quantitative parameters were then used to evaluate 80 patients with various cervical abnormalities to determine the clinical usefulness of the measurements. With the exception of spinal stenosis, quantitative cervical canal analysis was found to be of limited usefulness since normal measurements frequently occurred in the presence of significant cervical pathology.

Adolescent↗
PubMed1986

Diagnosis of adult respiratory distress syndrome with Tc-99m human serum albumin and portable probe.

A gamma-camera and computer were used to measure pulmonary accumulation of technetium-99m human serum albumin in 15 patients who met the criteria for adult respiratory distress syndrome (ARDS), and in ten asymptomatic patients. The ratio of lung to blood-pool activity increased in ARDS patients, but did not change in nonARDS patients. Lung to heart measurements by a portable probe with scaler correlated well with those obtained simultaneously with the gamma-camera and computer: probe measurements over 60 min increased significantly (p less than .0001) more in ten ARDS patients than in the nonARDS patients or in five postARDS patients, three with pneumonia and two with congestive heart failure. We conclude that the probe with scaler is sensitive enough to detect abnormal pulmonary accumulation of albumin in ARDS patients.

Adult↗
PubMed1985

Computed tomography evaluation of pheochromocytoma in pregnancy.

Two cases representative of the spectrum of the problem of pheochromocytoma in pregnancy are presented. One patient was typical of many cases of pheochromocytoma not diagnosed until delivery, with resultant maternal and fetal death. Computed tomography accurately preoperatively localized a pheochromocytoma involving the organ of Zuckerkandl in the second patient, with subsequent uncomplicated removal of the tumor during a cesarean delivery. A discussion of pheochromocytomas in pregnancy and the relative risk and benefits of preoperative localization with computed tomography are presented.

Adrenal Gland Neoplasms↗
PubMed1985

Liposomes as carriers of iodolipid radiocontrast agents for CT scanning of the liver.

We studied the potential of liposomes to deliver oil soluble radiocontrast agents to the liver and have developed a new preparation for CT liver scanning. The preparation consists of Ethiodol with a large amount of phospholipids. Nuclear magnetic resonance (NMR) spectroscopy was done for this lipid preparation, and the spectra show that the lipids are in the bilayer liposome configuration. Electron microscopy provides direct visualization of the liposomes. X-ray fluorescence measurements suggest that the Ethiodol is incorporated in the liposomes, and since no other particulate configurations are observed, we conclude that the Ethiodol is contained within the hydrophobic region of the liposomes. We used a GE CTT-8800 scanner and a rabbit model to study the liver uptake of the iodine from the Ethiodol. The iodine uptake in the liver was rapid and significant, and an increase in HU number of more than 40 was observed within 20 minutes after i.v. injection of 50 mg I/kg of body weight. Significant image enhancement was obtained. The iodine from the Ethiodol remained in the liver for several hours. Studies in rabbits with hepatic implants of the VX2-carcinoma show that while normal liver concentrates, areas of tumor do not concentrate the Ethiodol liposomes. Tumors not visible on ordinary scans become visible after administration of this combination. The advantages of this liposomal mode of radiocontrast agent administration are small particle size, rapid uptake in the liver, long retention times, a large increase in HU number and low iodine dose.

Animals↗