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Biomedical subjects

F Vieras

Publications and source records attributed to F Vieras.

34 records · Page 2Linked to original sources
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↗
PubMed1977

Radionuclide lymphangiography in the evaluation of pediatric patients with lower-extremity edema: concis communication.

The results of 99mTc-sulfur colloid lymphangiography in seven pediatric patients with lower-extremity edema were reviewed. Three scintigraphic patterns were identified: (A) normal uptake in the ilioinguinal nodes bilaterally, found in edema as a result of extrinsic venous obstruction; (B) diffusely increased activity over the involved extremity, with decreased visualization of the ipsilateral ilioinguinal nodes, found in secondary lymphedema; and (c) markedly decreased uptake by the ilioinguinal nodes on the affected side, found in primary (idiopathic) lymphedema. These preliminary results suggest that radionuclide lymphangiography is a useful procedure in the evaluation of pediatric patients with limb swelling.

Adolescent↗
PubMed1976

Focal decreased skeletal uptake secondary to metastatic disease.

Two cases are reported in which bone imaging with 99mTc-labeled phosphate compounds revealed localized areas of decreased uptake corresponding to osteolytic metastases on bone radiographs. These "cold" bone lesions, although infrequent, should be considered to avoid false negative interpretations.

Adult↗
PubMed1975

Diagnostic value of renal imaging incidental to bone scintigraphy with 99mTc-phosphate compounds.

An assessment of the sensitivity and reliability of renal images obtained incidentally to bone scintigraphy with 99mTc-phosphate compounds is reported, and certain patterns of abnormalities associated with those renal images are described. Renal images in 119 bone scintigrams were reviewed and correlated retrospectively with radiographic procedures done within 2 weeks of the bone images. The detection rate for renal abnormalities was 97.4%; the "false-positive" rate was 8.6% and the "false-negative" rate was 2.6%. Abnormal renal images were categorized as (A) nonvisualization of one kidney (13 cases), (B) asymmetric uptake (11 cases), (C) focal decreased uptake (4 cases), (D) bilateral decreased uptake (6 cases), (E) focal increased uptake (4 cases), And (F) miscellaneous (6 cases). The first three categories were always associated with renal abnormalities. Bilaterally decreased uptake and focal increased uptake were not reliable in detecting disease. Extensive metastatic carcinoma of the prostate was noted in three of four patients with bilateral decreased uptake and normal intravenous pyelography. We conclude that renal imaging incidental to bone scintigraphy with phosphate compounds is a valuable diagnostic test. An understanding of the different patterns of abnormalities described should improve the overall reliability of the test.

Adult↗