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Biomedical subjects

G L Wolf

Publications and source records attributed to G L Wolf.

At least 19 recordsLinked to original sources
PubMed1992

Diagnostic role of gadolinium-DTPA in pediatric neuroradiology. A retrospective review of 655 cases.

We retrospectively reviewed the findings in 655 consecutive young patients who underwent contrast-enhanced MR examinations (1.5T) of the head or spine. Their ages ranged from 4 months to 20 years (mean 10 years). There was a 1.7% incidence of minor adverse reactions to gadolinium (Gd)-DTPA, none of which required treatment; no serious adverse reactions were encountered. Based on the radiologic diagnosis the patients were divided into three groups: (1) normal, (2) CNS neoplasm, (3) abnormal but not neoplasm. There were 178 patients thought to have CNS neoplasms and of these 156 (88%) enhanced. Of 124 histologically confirmed neoplasms 115 (93%) showed enhancement after Gd-DTPA. Eight children had histologically confirmed spinal neoplasms; 5 of 6 neurofibromas and 2 ependymomas enhanced. In the 216 patients with abnormalities thought not to be neoplastic, the enhancement rate was 11%; most of the enhancing lesions were vascular malformations. There were very few examples of inflammatory disease, acute trauma or stroke among our patients.

Adolescent↗
PubMed1992

Experimental otitis media evaluated by magnetic resonance imaging: an in vivo model.

The use of magnetic resonance imaging in otitis media research is being explored in our laboratory. In this study, we present a new method for studying changes in the middle ear cleft due to an episode of induced otitis media in the chinchilla model. It uses gadolinium-diethylenetriamine pentaacetic acid, a magnetic resonance imaging contrast agent, to examine the uptake and washout characteristics of middle ear mucosa during an inflammatory episode. Parameters such as the time to maximum intensity of the mucosa and the washout rate of the contrast agent from the mucosa were significantly correlated to the duration of the infection.

Animals↗
PubMed1991

The oxygen and nitrous oxide indices of flammability of endotracheal tubes determined by laser ignition.

This study determines the flammability of polyvinylchloride (PVC), red rubber (RR), and silicone (Si) endotracheal tubes in oxygen- and nitrous-oxide-enriched atmospheres. Flammability is measured by using the oxygen and nitrous oxide indices of flammability with laser ignition. The laser-ignited oxygen (O2) index of flammability of the endotracheal tubes is: PVC, 0.25; RR, 0.19; Si, 0.20. The laser-ignited nitrous oxide (N2O) index of flammability of the endotracheal tubes is: PVC, 0.45; RR, 0.37; and Si, 0.41. These results are similar to the previously reported O2 and N2O indices of flammability with propane-torch ignition. This study validates the concept that the indices of flammability are useful measures of endotracheal tube flammability and are independent of the ignition source.

Fires↗
PubMed1979

Inability to show clot: one limitation of ultrasonography of the abdominal aorta.

Ultrasonography is accurate for diagnosis of abdominal aneurysms and clots within them. However, due to technical factors, occlusive clots within the aorta can be missed even at high gain. The authors report three cases in which total occlusion of the abdominal aorta was misdiagnosed as a free lumen occupied by a small clot. An explanation for the shortcomings of ultrasound is offered.

Adult↗
PubMed1978

Distinguishing ischemic from fibrotic myocardium during ventriculograpy by means of physiological potentiation.

Physiological potentiation during ventriculography is more helpful than the routine ventriculogram in predicting postoperative ventricular function. The authors describe a control device which allows the operator to flexibly program a pacing stimulus, thus making it possible to obtain both a resting beat and an optimum potentiated beat during a single ventriculographic study.

Angiocardiography↗
PubMed1978

Contrast agents lower ventricular fibrillation threshold.

Ventricular fibrillation thresholds were measured in anesthetized, closed-chest dogs during the injection of Renografin 76 or Conray 400 into the left coronary artery. Both agents significantly lowered fibrillation threshold--Renografin to 58 +/- 7%; Conray to 20 +/- 5% of control, respectively. The experimental method estimates fibrillatory potential of contrast media more precisely than previous methods. The initial results parallel relative toxicities observed in clinical usage.

Animals↗
PubMed1977

Regional distribution of coronary blood flow during left ventriculography in anesthetized dogs.

Changes in total and regional left coronary blood flow in response to ventriculography were studied using electromagnetic and microsphere techniques. Correlation of coronary flows by these methods showed excellent agreement (r = 0.947). Ventriculography produced a characteristic triphasic response in total flow and in endocardial/epicardial perfusion ratios. Changes in coronary flow can be explained as a result of hypotension and vasodilatation.

Angiocardiography↗
PubMed1977

Accuracy of estimates of contrast media concentration.

An animal model was used to prepare 18 experimental roentgenograms with differing dilutions of Conray 400 in each renal pelvis. Fifty radiologists were asked to estimate the iodine concentrations after they had been shown examples with known iodine concentrations. It was found there was a great deal of variation in the ability of individual subjects to accurately estimate the iodine concentration present. When the urinary iodine was less than 25 mg/ml, contrast estimations became grossly unreliable. At higher concentrations, the average performance of the sixty subjects was fairly clos to observed densotimetric readings. This study demonstrates that the ability to estimate iodine concentration is similar to other perceptive abilities in demonstrating both thereshold sensitivity and a near normal distribution among observes of the ability to judge perceptable differences in contrast media density.

Absorptiometry, Photon↗
PubMed1977

The radiology corner. Is an air-fluid level within a gastric ulcer a reliable roentgen sign of benignancy?

A review of 108 cases of benign gastric ulcers and 33 ulcerated malignant gastric neoplasms showed that air-fluid levels were present within 25 benign ulcers and in only one malignant ulcer. These differences are statistically significant. Since, however, in unusual circumstances, a malignant ulcer may contain an air-fluid level, use of this roentgen sign alone to determine benignancy is not recommended. If used in conjunction with other accepted roentgen criteria, the presence of an air-fluid level within a gastric ulcer substantiates the diagnosis of benignancy in the majority of cases.

Adenocarcinoma↗
PubMed1976

Glucagon and barium enema examinations: a controlled clinical trial.

In a double-blind crossover clinical trial, 10 healthy volunteers received placebo and 2 mg glucagon intramuscularly preceding barium enema examination on separate days. In addition, 50 patients were given either placebo or 2 mg glucagon prior to barium enema examination in a double-blind study. The results of 38 variables determined on each study population were similar. When glucagon was given, both the patients and examiners noted significantly less discomfort and more bowel relaxation. There were no significant changes in pulse, blood pressure, or electrocardiogram. Adverse reactions did not occur frequently enough to allow confident comparison of placebo and glucagon. It is concluded that the use of glucagon can provide a more comfortable barium examination with acceptable safety.

Adult↗
PubMed1975

The effect of angiotensin-II during ventriculography in dogs with normal coronary arteries.

Left ventriculography was performed with and without angiotensin-II in dogs with normal coronary arteries. Concomitant administration of angiotensin significantly attenuated the myocardial depression associated with ventriculography. The beneficial effect of angiotensin may be due to its ability to maintain aortic diastolic pressure and thus flush the contrast material from the myocardium more rapidly, at least in animals without imposed coronary stenosis.

Angiocardiography↗