Search PubMed⌕ Search

Biomedical subjects

U Buell

Publications and source records attributed to U Buell.

117 records · Page 7Linked to original sources
PubMed1978

Computerized transaxial tomography and cerebral serial scintigraphy in intracranial tumors--rates of detection and tumor-type identification: concise communication.

In 215 cases of intracranial tumors with subsequent histological identification, computerized transaxial tomography (CTT), and cerebral serial scintigraphy (CSS) with [99mTc] pertechnetate were carried out to compare the efficiency of each method in detecting and classifying such tumors. With a tumor detection rate of 99%, CTT turned out to be superior to CSS (91%). On the other hand, CSS findings enhanced the CTT rate of correctly identified tumor types in meningiomas from 85 to 92% and in high-grade gliomas from 82 to 89%. In metastases, low-grade gliomas, and various other tumors, CSS supported CTT by confirming a number of these tumor types. Therefore, the most important use of CSS in intracranial tumors today is its role as a supplement to CTT in order to establish and confirm type-specific diagnoses.

Brain Neoplasms↗
PubMedDate not supplied

Cardiac stress-rest single-photon emission computed tomography with technetium 99m-labeled tetrofosmin: influence of washout kinetics on regional myocardial uptake values of the rest study with a 1-day protocol.

BACKGROUND: The purpose of this study was to evaluate (1) the washout kinetics of 99mTc-labeled tetrofosmin, separately for myocardium with normal and reduced perfusion, and (2) its influence on quantitative analysis in a 1-day stress-rest protocol. METHODS AND RESULTS: Twenty-five patients with angiographically proved coronary artery disease underwent bicycle exercise stress testing with injection of 200 MBq 99mTc-labeled tetrofosmin and first single-photon emission computed tomographic (SPECT) imaging 40 minutes after injection. A second SPECT was acquired 2.3 +/- 0.4 hours after the first one immediately before rest injection of 800 MBq 99mTc-labeled tetrofosmin. The rest (third) SPECT was acquired 15 minutes thereafter. The relative washout fraction per time (WOFt) was calculated assuming linear washout kinetics. Thirty-three regional uptake values per study were calculated, normalized to the perfusion maximum (100%) in either the postexercise SPECT and the rest SPECT, for the latter with and without correction of remaining counts from stress injection. In regions with normal perfusion, WOFt was 11.5% +/- 3.5% per hour. In regions with markedly reduced perfusion (relative uptake < 50%, WOFt was 8.3% +/- 9.9% per hour. The highest variation of the relative uptake values between rest SPECT with and without correction of remaining counts from stress injection was 5.4% +/- 3.5% in regions with stress-induced ischemia. CONCLUSION: To use a 1-day protocol with a stress-rest radioactivity ratio of 1:4 and an interval of more than 2 hours between the examinations, a correction for remaining counts from stress injection seems not to be necessary for the quantitative analysis of rest SPECT.

Adult↗
PubMedDate not supplied

Dosimetry of a 188rhenium-labeled self-expanding stent for endovascular brachytherapy in peripheral arteries.

PURPOSE: Radioactive stents have been proposed as endovascular irradiation device to prevent in-stent restenosis by inhibiting neointimal proliferation. 32P-stents have been used in several studies so far, but require large-scale labeling procedures and endovascular barotrauma for stent expansion supporting the development of edge restenosis. Purpose of this study was to establish dosimetry of a self-expanding nitinol stent for peripheral vascular disease, which was radiolabeled with 188rhenium (188Re) by a dip coating technique. METHODS AND MATERIALS: The surface of nitinol Memotherm FLEXX stents was polymer-coated providing functional NH(2) groups for diethylenetriaminepentaacetic acid (DTPA) binding, providing the ligand for the complexation of 188Re onto the stent surface. Stability of radiolabeling was tested over 48 h using an in vitro blood circulation (Chandler Loop). Radial and longitudinal dose distributions of a radiolabeled stent were obtained with a plastic scintillator dosimetry system. RESULTS: Stents with a length of 30 mm and a diameter of 8 mm were labeled with up to 33 MBq 188Re. A total of 69+/-4% of the labeled 188Re remained stable on the stent surface after 48 h. Ninety-five percent of the infinitely accumulated dose was supplied to the target tissue within 72 h. Including correction for radioactivity washout from the stent, the infinitely accumulated dose at 1 mm radial distance from the stent surface was 1.85+/-0.19 Gy/MBq 188Re/cm stent length. CONCLUSIONS: We developed a technique for radiolabeling of self-expanding nitinol stents with 188Re by dip coating and formation of 188Re chelate complexes. We provide dosimetry data useful for application of this beta-emitting stent for endovascular brachytherapy in peripheral vascular occlusive disease.

Brachytherapy↗
PubMedDate not supplied

Radionuclide angiography and Doppler sonography to detect patients with cerebrovascular disease. A correlation with radiographic angiography.

Cerebral radionuclide angiography with 99mTc pertechnetate (RNA) and directional Doppler sonography (DS) were employed to study patients with cerebrovascular disease (CBVD). The 86 patients investigated were divided following radiographic angiography (RGA) into normals (n = 26) and into patients with intracranial (n = 22) and extracranial (n = 38) vascular lesions. Of the patients with angiographically demonstrated CBVD, RNA detected 90%, DS 53.3%. The combined evaluation had a sensitivity of 93.3%. If intracranial arterial disease was excluded, the sensitivity of the studies was 92.1% for RNA and 84.2% for DS and combined evaluation had a sensitivity of 97.4%. The diagnostic accuracy by combined evaluation was 93.8% for the extracranial arterial lesions if the clinical findings were also used in patients with normal RGA pattern. RNA and DS complement each other as RNA contributes to the detection of intracranial blood flow alterations indicating vascular changes in either the extra- or intra-cranial vessels and helps confirm and complete DS findings.

Arterial Occlusive Diseases↗
PubMedDate not supplied

Sensitivity of computer assisted radionuclide angiography in transient ischemic attack and prolonged reversible ischemic neurological deficit. Comparison with findings in radiographic angiography and transmission computerized axial tomography.

Computer assisted radionuclide angiography (CARNA) with 99mTc-DTPA was employed to study 143 patients with transient ischemic attacks (TIA) and 79 patients with prolonged reversible ischemic neurologic deficit (PRIND). The results of CARNA were compared with findings from radiographic angiography (RGA) in 173 patients and with findings in transmission computerized axial tomography (T-CAT) in 154 patients. In patients with TIA, CARNA showed a hemispherical perfusion deficit in 74.8%, and with PRIND 87.3%. This deficit, determined as the relative difference between the involved and the non-involved hemisphere, was significantly (p less than 0.0025) greater in PRIND (minus 23%) than in TIA (minus 17%). Sensitivity of CARNA was independent of the interval from ictus to examination for more than 4 months. RGA in TIA revealed true positives in 82.0%, in PRIND it was 89.5%. T-CAT was positive in TIA in only 16.8% but in PRIND it was 64.4%. Combined sensitivities in TIA (92.4%) and in PRIND (94.0%) were highest with the combination of CARNA and RGA. However, in PRIND the combination of non-invasive methods (CARNA and T-CAT) revealed 93.2% positive findings. Combinations of these evaluation methods may be used to detect cerebrovascular disease in patients with such dysfunction.

Brain Ischemia↗