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Biomedical subjects

F Vieras

Publications and source records attributed to F Vieras.

At least 19 recordsLinked to original sources
PubMed1991

Quantitation of differential renal function with Tc-99m MDP.

This study was designed to evaluate the usefulness of the bone tracer Tc-99m MDP for quantitative assessment of relative renal function as compared with renal imaging radiotracers used for that purpose. Differential renal function, i.e., the percent contribution each kidney makes to global renal function, was determined prospectively in 15 consecutive patients using Tc-99m MDP and a renal radionuclide tracer, either Tc-99m DTPA or Tc-99m GHA. Differential function was computed in all cases from the early (1-3 minutes) renal uptake of the tracers by region-of-interest analysis of the computer-acquired data. There was a high correlation between values of differential function obtained with Tc-99m MDP and those obtained with Tc-99m DTPA or Tc-99m GHA (r = 0.98, P less than 0.0001). Qualitative assessment of the images revealed equivalent scintigraphic patterns in all patients. It is concluded that the early characteristics of renal handling of Tc-MDP are sufficiently similar to those of Tc-DTPA and Tc-GHA so that accurate estimates of differential renal function are possible with this agent, and that Tc-MDP-determined renal differential most likely reflects differential glomerular filtration rate.

Aged↗
PubMed1988

Gallium-67 localization in herpetic skin lesion.

Previous cases of gallium localization in various cutaneous lesions have been reported, including sporotrichosis, acne vulgaris, sarcoid, lymphoma, and exfoliative erythroderma. This is a report of a case of gallium localization in cutaneous lesions of herpes zoster.

Abdomen↗
PubMed1987

Extrapulmonary localization of gallium in sarcoidosis.

This paper describes the spectrum of extrapulmonary localization of gallium in patients with sarcoidosis. The usefulness of Ga-67 scintiscans in detecting clinically occult lesions, in directing clinicians to accessible sites for biopsy, and in following the course of extrapulmonary sites of involvement with therapy is emphasized.

Bone Diseases↗
PubMed1985

The effect of electrical current on the healing of mandibular freeze-dried bone allografts in dogs.

Low levels of electrical current have been shown to affect the process of osseous repair. This study experimentally evaluated the effect of electrical stimulation on the healing of freeze-dried mandibular allogeneic bone grafts in dogs. Healing of the grafts was monitored by sequential submento-occlusal radiographs and radionuclide bone imaging at two, four, six, and eight weeks after grafting. Results indicated no significant difference in the osseous repair of stimulated and nonstimulated freeze-dried allogeneic bone grafts.

Animals↗
PubMed1985

Preoperative scintigraphic detection of cervical metastases from thyroid carcinoma with technetium-99m pertechnetate.

A young man with papillary-follicular thyroid carcinoma demonstrated clear visualization of cervical metastases from thyroid cancer on Tc-99m pertechnetate scintigraphy while exhibiting a palpably and scintigraphically normal thyroid gland. This is a very rare occurrence which demonstrates that Tc-99m pertechnetate scintigraphy is capable of detecting cervical metastases from thyroid carcinoma before the appearance of palpable thyroid nodules or defects on scintigraphy.

Adenocarcinoma↗
PubMed1980

In vivo receptor binding of iodinated beta-adrenoceptor blockers.

Six radiolabeled beta-adrenoceptor blocking agents with a range of affinity constants were evaluated as radioindicators for adrenoceptors in guinea-pig heart and lung. All concentrated in the heart and lung at levels in excess of 0.1% dose/g tissue. On the basis of displacement studies using propranolol, two of the six compounds showed beta-adrenoceptor binding in the lung, and one, H-3 carazolol, showed receptor binding in the heart. These results agree qualitatively with a bi-molecular reversible equilibrium model, and suggest that the beta-adrenoceptor blockers as a group will not be useful in vivo probes of receptor concentration in the heart because of the low affinity constants and high levels of nonreceptor binding associated with the present-day clinical beta blockers. Beta-adrenoceptor blocking agents with affinity constants in excess of 10(9) will be needed to give heart-to-blood ratios of 10.

Adrenergic beta-Antagonists↗
PubMed1979

Radionuclide evaluation of pulmonary function following hemithorax irradiation of normal dogs with 60Co or fast neutrons.

To assess the effects of therapeutic doses of radiation on regional pulmonary function, 28 dogs had serial chest radiographs and quantitative ventilation, perfusion, and aerosol studies at three-, six-, nine-, and twelve-month intervals after hemithorax irradiation with 60-Co-gamma photons or 15-MeV fast neutrons. Findings showed marked reductions in perfusion and aerosol deposition in the irradiated lungs of dogs in the high-dose photon and neutron groups and in the medium-dose neutron group. The effects of large photon and small neutron doses were similar (neutron RBE = 4.5). Radionuclide studies were found to be useful for detecting these alterations.

Animals↗
PubMed1979

Diffuse pulmonary uptake of Indium-111 chloride in idiopathic myelofibrosis.

Unusual indium-111 accumulation and extramedullary hematopoiesis in the lungs of a patient with idiopathic myelofibrosis are described. The bone marrow scan taken 24 hours after intravenous injection of 111InCl3 faithfully depicted the abnormal distribution of marrow elements as assessed histologically at autopsy, thereby supporting the usefulness of 111InCl3 for marrow imaging.

Aged↗
PubMed1979

Preliminary observations on the potential of 99mTc-sulfur colloid as a radiopharmaceutical for detection of deep vein thrombosis.

The potential usefulness of 99mTc-sulfur colloid (Tc-SC) as a radiopharmaceutical for thrombus detection was evaluated in an animal model of deep vein thrombosis. One hour after injection of Tc-SC and 24 hours after induction of thrombus formation, a mean thrombus-to-blood uptake ratio of 11.38 was obtained in 12 beagles. This ratio is high enough to allow external detection.

Animals↗
PubMed1979

Quantitative radionuclide imaging for early determination of fate of mandibular bone grafts.

Clinical assessment of bone-graft healing in the maxillofacial region is generally limited to clinical evaluation, radiographs, and biopsy. A noninvasive quantitative radionuclide method has been developed in an animal model, and it seems to allow earlier prediction of graft failure or success than conventional methods. Using a localization technique to identify preselected regions of interest reproducibly in the graft and adjacent host bone, an activity ration was developed between the graft region and a contralateral control. Two mandibular grafting systems were evaluated with this technique. When the activity ratio for the graft region over the period of study approached, or was greater than, the activity ratio for the host bone, the graft subsequently proved successful by clinical observation and gross dissection. When the activity ratio for the host bone remained greater than that of the graft, healing did not occur and the grafts were unsuccessful. This method allowed prediction of graft fate by 6 wk after grafting, and preceded radiographic confirmation of repair or failure by 2-3 wk.

Animals↗
PubMed1979

Gated and cinematic perfusion lung imaging in dogs with experimental pulmonary embolism.

To determine how pulmonary respiratory motion affects detection of pulmonary emboli, 11 dogs had routine lung scans and gated or cinematic perfusion images after undergoing autologous experimental pulmonary embolism. Six dogs had routine six-view perfusion studies, plus end-inspiratory and end-expiratory gated perfusion studies performed with a physiologic synchronizer set to 80% threshold. Five other dogs had three-view ungated and cinematic (post., LPO, RPO) perfusion images. Cinematic studies were acquired by synchronizing a camera-computer system to the Harvard respirator that ventilated the dog. Before death, all animals received i.v. India ink to outline pulmonary perfusion defects, and postmortem lung dissection verified sites of emboli. An ROC curve analysis of randomized perfusion studies showed that end-inspiratory gated images yielded true-positive rates 5--10% higher than ungated images at any given false-positive rate. Lesion detection by cinematic studies was comparable to detection by ungated images, but detection by end-expiratory images was worse. End-inspiratory gated imaging may be useful as an occasional adjunct to routine perfusion lung imaging.

Animals↗
PubMed1979

The distribution of the muscarinic acetylcholine receptor antagonists, quinuclidinyl benzilate and quinuclidinyl benzilate methiodide (both tritiated), in rat, guinea pig, and rabbit.

The distribution of [3H]quinuclidinyl benzilate and its methiodide salt was determined in rat, guinea pig, and rabbit. Accumulation in the myocardium of up to 2% of the injected dose per gram of tissue was obtained with both compounds, providing heart-to-blood ratios of approximately 30 and heart-to-lung ratios of approximately 4. The accumulation in the heart was blocked (89%) by preinjection of atropine. The distribution of tritium in rabbit heart corresponds to the muscarinic receptor densities determined in vitro. Calculation of the theoretical maximum for the bound-to-free ratio, based on in-vitro equilibrium binding isotherms, resulted in ratios in reasonable agreement with the experimental results. Because of the high accumulation in the heart with low serum concentration, we conclude that the methiodide salt of quinuclidinyl benzilate represents an ideal parent structure for the design of a receptor-binding gamma-emitting radiopharmaceutical for imaging of the myocardium.

Acetylcholine↗