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Biomedical subjects

R B Shafer

Publications and source records attributed to R B Shafer.

At least 19 recordsLinked to original sources
PubMed1979

Assessment of left ventricular function in aortic insufficiency using echocardiography, gated scintigraphy and contrast angiography.

Echocardiography, gated scintigraphy and contrast angiography were used to measure left ventricular ejection fractions in 20 patients with varying degrees of aortic insufficiency. There was good correlation between the radionuclide and the angiographic ejection fractions. Echocardiographic ejection fraction correlated less well with the angiographic ejection fraction. The radionuclide left ventricular ejection fraction may prove valuable in the noninvasive serial evaluation of left ventricular function in patients with chronic aortic insufficiency.

Adult↗
PubMed1979

Abnormal images of right heart disorders.

Increasing attention is being given to radioisotopic studies of the right heart. Measurement of right ventricular ejection fraction has become more common. We present examples of cardiac images which were obtained during the scintigraphic assessment of right sided cardiac disorders. Images of the first pass, of the gated cardiac study, and of the nongated cardiac blood pools offer complementary information to the overall radionuclide evaluation of right heart disease.

Blood Pressure↗
PubMed1979

Radionuclide left ventricular dV/dt for the assessment of cardiac function in patients with coronary disease.

To investigate potential uses of left-ventricular (LV) systolic ejection rate (LV dV/dt) in the evaluation of LV function, we examined the effect of exercise, angiotensin, and leg raising on LV ejection fraction and LV dV/dt in patients with coronary-artery disease. The following observations were made: a) LV ejection fraction and dV/dt changed proportionately, but in opposite directions, during supine exercise; b) LV ejection fraction and dV/dt decreased to a similar extent during angiotensin infusions; and c) LV ejection fraction and dV/dt were unchanged by leg raising. The changes in peak and mean LV dV/dt were similar. Regardless of the physiologic state, peak LV dV/dt occurred during the first third of systole. These data imply that in this population there were no specific advantages of LV dV/dt over LV ejection fraction in the evaluation of LV performance.

Angiotensin II↗
PubMed1978

Comparison of two radioimmunoassays and a microbiologic assay for bleomycin.

Recently two radioimmunoassays have been independently developed for determination of bleomycin levels. In this study these assays are compared with each other and with a standard microbiologic assay for bleomycin. Bleomycin levels were determined in serum and urine samples obtained at varying intervals following intramuscular bleomycin injection. There were systematic differences between the assays. One radioimmunoassay indicated bleomycin levels lower than the levels indicated by the microbiologic assay with serum samples. With urine samples, both radioimmunoassays indicated bleomycin levels greater than the microbiologic assay.

Antibody Specificity↗
PubMed1978

A review of carotid cavernous fistula including diagnosis and evaluation by nuclear medicine angiography.

The various causes and differential diagnosis of carotid cavernous fistula are discussed as well as the description of the use of radionuclide angiography in the diagnosis and evaluation of patients with carotid cavernous fistulas. Radionuclide angiography has proven extremely useful in the diagnosis and follow-up of patients with carotid cavernous fistulas. The procedure is of maximum benefit in situations where repeat studies are required at frequent intervals. Five cases are described in which the nuclear medicine technique was instrumental in primary diagnosis and follow-up.

Adult↗
PubMed1978

Implications of liver activity associated with 133Xe ventilation lung scans.

A series of 35 xenon-133 (133Xe) ventilation studies yielded nine cases demonstrating accumulation of activity in the liver. Maximum intrahepatic deposition of radioxenon occurred during the washout phase of the study. In addition to those clinical instances which make this phenomenon possible, i.e., obesity, alcoholic-induced liver steatosis and diabetes mellitus, we found that hyperlipidemia and coronary artery disease also favor xenon-133 localization into the hepatic parenchyma. It is concluded that the lipid avidity of 133Xe facilitates its liver accumulation hyperlipidemic patients and in patients with coronary artery disease, and that this action may be explored to further understand deranged metabolic pathways in the liver of these patients. Hepatic accumulation of 133Xe during ventilation studies must be considered when assessing regional ventilation/perfusion relationships.

Adult↗
PubMed1978

Fenestrated sagittal sinus mimicking posterior cerebral infarction.

Two patients who presented with abnormal neurological findings and focal abnormalities on static brain imaging, were felt to have infarction in the distribution of the posterior cerebral artery. However, the posterior flow study delineated the cause of the abnormality as being a fenestrated anomaly of the sagittal sinus. The incidence of occlusive disease of the posterior cerebral artery, its clinical and scintigraphic presentation and the potential pitfalls for misinterpretation are reviewed.

Brain↗
PubMed1977

Pancreatic scanning using retrograde injection of technetium-99m-labeled compounds.

With increased clinical availability of endoscopic retrograde pancreatography, a method for retrograde injection of radionuclides into the pancreas became available. A dog model was developed to evaluate resolution and toxicity of retrograde imaging prior to human use. Two groups of technetium-99m-labeled compounds were used. The first included ionic carriers--pertechnetate and pyrophosphate--and the second included particulate carriers--sulfur colloid and albumin microspheres. Parenchymal visualization, absorption patterns, and toxicity in dogs were studied. The results suggest that pyrophosphate, sulfur colloid, and albumin microspheres would all be feasible technetium carriers for use in humans.

Animals↗
PubMed1977

A radioimmunoassay for bleomycin.

A radioimmunoassay for bleomycin, suitable for monitoring serum and urine drug levels, has been developed. Antisera were obtained from rabbits immunized with a conjugate of bleomycin and human serum albumin.Bleomycin labeled with 57Co was used as the tracer. Antibody-bound and free bleomycin were separated by precipitation with polyethylene glycol. The assay could determine bleomycin levels down to 0.025 mug/ml. The assay was precise, with a coefficient of variation of 2.8% Other drugs likely to be administered in combination with bleomycin did not interfere with the radioimmunoassay.

Animals↗
PubMed1976

Evaluation of the posterior flow study in brain scintigraphy.

To evaluate the usefulness of the posterior cerebral flow study, a prospective study was instituted. Of 32 adult patients examined for presumed posterior disease, 17 were found to have a positive posterior flow study that yielded information not available from the anterior study. Indications for posterior flow studies include posterior parietal, occipital, and posterior fossa tumors, posteriorly located arteriovenous malformations, Paget's disease involving occipital bone, posterior cerebral infarcts, and sagittal sinus occlusions. Our experience indicates that the posterior flow study is a valuable adjunct in those patients carefully screened for suspected posterior cerebral disease.

Adult↗
PubMed1976

Quality assurance for 99mTc-Sn-pyrophosphate.

Because skeletal images obtained with a commercial lyophilized preparation of 99mTc-Sn-pyrophosphate were occasionally degraded by liver and spleen uptake, a method for preparing 99mTc-Sn-pyrophosphate and a system for in-house quality assurance were developed. Control of the age of the stannous chloride solution and the final pH of the 99mTc-Sn-pyrophosphate eliminated the undesirable uptake. The quality and body distribution of the in-house preparation were compared to those of the radiopharmaceutical from a commercial kit.

Animals↗