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U Buell

Publications and source records attributed to U Buell.

At least 19 recordsLinked to original sources
PubMed1992

Fluorine-18 deoxyglucose PET for assessment of viable myocardium in perfusion defects in 99mTc-MIBI SPET: a comparative study in patients with coronary artery disease.

Extent and frequency of viable tissue in myocardial segments yielding a perfusion defect on technetium-99m methoxyisobutylisonitrile (99mTc-MIBI), single photon emission tomography (SPET) at rest was prospectively investigated with 2-18F-2-deoxyglucose (18FDG) positron emission tomography (PET) in 46 patients with chronic coronary artery disease (CAD). Of these, 43 had a history of old myocardial infarction. For comparative visual and quantitative evaluation of identical anatomical slices, PET image files were converted into the SPET file structure and into the same matrix size. SPET and PET images were documented and visually (9 segments/patient) or semiquantitatively evaluated by a target-like polar map. Relative perfusion was expressed in percentage of peak 99mTc-MIBI uptake. Sample 18FDG uptake was related to the 18FDG uptake in the area of such maximal perfusion (18FDG uptake was 100% at the 100% 99mTc-MIBI uptake area). Of 414 segments, 167 (40%) revealed a resting perfusion defect. 18FDG uptake was present in 38 (23%) of the defects, while another 40 (24%) segments yielded 18FDG uptake in the periphery of the defect. When grouped according to the degree of 99mTc-MIBI uptake-reduction (in percentage of peak activity), 80% of severe defects (less than or equal to 30% of peak uptake), 48% of moderate (31%-50% of peak uptake) and 31% of mild (greater than 50% of peak uptake) defects were considered as non-viable on the basis of 18FDG uptake. Complete viability was found in none of the severe defects in contrast to 29% of moderate and 35% of mild perfusion defects.(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary Disease↗
PubMed1992

The radiation dose to surgical personnel during intraoperative radioimmunoscintimetry.

To estimate the radiation exposure to surgical personnel caused by intraoperative radioimmunoscintimetry, we measured dose rates at different distances from patients who had been injected with 950 MBq technetium-99m-labelled intact carcinoembryonic antigen (CEA)-specific antibodies (Szintimun CEA, Behring AG Marburg, FRG) for immunoscintigraphy 24 h earlier. At 0.05 m (corresponding to working positions during surgery) we found 2.0-16.0 microSv h-1 (average 6.4), which is similar to results for nuclear medicine staff. Thus, if radioimmunoscintimetry is to become a routine procedure, according to national regulations in some countries of the European Communities surgical personnel might be regarded as professionally exposed to radiation.

Colorectal Neoplasms↗
PubMed1992

Basics and recommendations for brain SPECT. Task Group "Neurology" of the European Association of Nuclear Medicine.

In this article guidelines for single-photon emission computerized tomography (SPECT) of the brain are presented by the Task Group "Neurology" of the European Association of Nuclear Medicine (EANM). Under separate headings are discussed: the pathophysiologic principles of various brain diseases, pharmacokinetics and pharmacodynamics of various radiopharmaceuticals, physical principles of SPECT imaging, computerized data processing, clinical protocols and the evaluation of SPECT results.

Brain↗
PubMed1992

Uptake kinetics of technetium-99m-methoxyisobutylisonitrile and thallium-201 in adult rat heart endothelial and fibroblast-like cells in comparison to myocytes.

Endothelial and fibroblast-like cells comprise 5%-10% of total cardiac cell volume and are more resistant to hypoxia than cardiomyocytes. However, their role in the uptake of radiotracers used for myocardial perfusion imaging has largely been ignored. Net uptake of 201TI and 99mTc-hexakis-2-methoxyisobutylisonitrile (99mTc-sestamibi) by cultured rat heart endothelial and fibroblast-like cells and quiescent myocytes was examined. Over a 30-min period, endothelial cells continuously accumulated 99mTc-sestamibi. Initial 201TI accumulation paralleled that of 99mTc-sestamibi; however, after 7 min 201TI accumulation plateaued whereas there was continued slow accumulation of 99mTc-sestamibi. Net uptake of the two radiotracers by fibroblast-like cells was similar to that of 201TI by endothelial cells. In the quiescent myocytes, there was an initial accumulation of both tracers with 201TI net uptake quickly reaching a plateau, whereas 99mTc-sestamibi accumulation continued throughout the 30-min period reaching a level 15-fold greater than that for 201TI. Myocyte uptake of 99mTc-sestamibi was approximately eight times greater than by the endothelial cells when expressed either as activity per mg protein or activity per cell volume. Although significant uptake differences exist among the three cell types, the fact that there is uptake by endothelial and fibroblast-like cells should be considered during image interpretation, particularly in situations in which the hypoxia resistant endothelial and fibroblast-like cells might be the remaining healthiest cell types.

Animals↗
PubMed1991

PET reflections.

Explore the source record for details and available documents.

Humans↗
PubMed1991

Patterns of brain infarctions in internal carotid artery dissections.

In 15 patients with internal carotid artery (ICA) dissections, patterns of brain infarctions visible on CT were categorized according to a pathogenetically oriented classification system. This differentiated ischemic brain damage due to low flow from thromboembolic infarctions. Simultaneously, cerebral hemodynamic reserve was evaluated by means of both CO2-dependent vasomotor reactivity and HMPAO- and 99mTc-RBC-SPECT. Six out of 11 patients with ischemic infarctions had the territorial type of brain lesion, suggesting distal embolism. Five patients revealed the pattern of hemodynamically induced low-flow infarctions. Cerebral hemodynamic reserve was significantly decreased only in these latter patients. In ICA dissections the frequencies of hemodynamically and thromboembolically induced brain infarctions is approximately equal. This finding suggests that only half of the patients with symptoms of symptomatic dissections had brain emboli, whereas in the other half the dissections lead to a low-flow effect in terminal supply areas which is so severe that non-embolic brain infarctions occur. This differentiation can help decide whether antithrombotic or hemodynamic treatment should be given.

Adult↗
PubMed1991

Clinical and hemodynamic aspects of low-flow infarcts.

We used single-photon emission computed tomography to measure cerebral blood flow, cerebral blood volume, and cerebral perfusion reserve and transcranial Doppler sonography with CO2 stimulation to assess hemispheric vasomotor reactivity in 37 patients and in normal controls. Computed tomography and magnetic resonance imaging were performed to differentiate morphologically low-flow infarcts (n = 17) from territorial infarcts (n = 20). In patients with either type of infarct, blood flow was decreased and blood volume was increased in the infarcted areas compared with the same areas in the controls. Perfusion reserve and vasomotor reactivity were significantly reduced in patients with territorial infarcts and carotid artery occlusions (n = 12) and even more reduced in patients with low-flow infarcts (p less than 0.001). Both parameters were normal in patients with cardiac embolic territorial infarcts (n = 8). In patients with territorial infarcts, blood flow and perfusion reserve changes were restricted to the infarcted areas, whereas in patients with low-flow infarcts, regions of decreased perfusion reserve considerably exceeded the area of the infarct. Low-flow infarcts are related to the hemodynamic effects of severe extracranial carotid artery disease.

Adult↗
PubMed1991

MRI measurements of left ventricular systolic wall thickening compared to regional myocardial perfusion as determined by 201Tl SPECT in patients with coronary artery disease.

Magnetic resonance imaging (MRI) of the left ventricle (LV) is an excellent method of measuring systolic wall thickening (SWT). The aim of the present study was (a) to describe a new approach for measurement of SWT and (b) to define the relationship between SWT and regional myocardial perfusion as determined by 201Tl SPECT. 79 patients -51 with and 28 without history of earlier myocardial infarction - underwent SPECT and, within the next two weeks. MRI. End-diastolic and end-systolic spin echo images were obtained by a reduced permutation technique. For MRI measurements, only long-axis sections through the LV in the equatorial plane were used. Slice orientation was selected according to the findings of SPECT, imaging the infarcted wall segment by single or double angulation. At 7 equidistant points around the LV wall SWT was measured and compared with the corresponding regional myocardial uptake values from SPECT in percent of maximal perfusion. Wall thickness of the anterior wall was normal. Because the majority of myocardial infarctions were posterior-inferior (55%), thickness of the posterior wall was markedly decreased. A close relationship of perfusion to SWT was found. Higher perfusion areas (greater than 50% of maximal TI uptake) corresponded with normal SWT (greater than 3.0 mm), a marked decrease of SWT (less than 1 mm) was found in areas with perfusion deficits (less than 40%). Thus, a 201TI uptake value at rest of 41-50% of the respective myocardial maximum acts as a threshold by discriminating normal from severely reduced SWT.

Adult↗
PubMed1990

The large striatocapsular infarct. A clinical and pathophysiological entity.

We examined 29 patients with strictly subcortical large striatocapsular infarctions. Eight of them had aphasia or neglect. All patients underwent transcranial Doppler ultrasonography or selective carotid angiography, magnetic resonance imaging, and single photon emission tomography for assessment of cerebral blood flow, blood volume, and cerebral perfusion reserve. The signs were compatible with cortical territorial infarctions rather than lacunes. On both magnetic resonance imaging and computed tomographic scans, the lesions corresponded to the territories of the medial and lateral group of the lenticulostriate arteries, Heubner's artery, or the anterior choroidal artery. The infarctions were either due to cerebral embolization into the M1 segment of the middle cerebral artery or due to stenosis at the same site, ie, lesions that acutely and simultaneously occluded the orifices of the lenticulostriate or neighboring arteries. Persistent occlusion of the middle cerebral arteries and a decrease of cortical regional cerebral blood flow were only found in patients with aphasia or neglect. All patients without aphasia or neglect showed a rapid recanalization of the middle cerebral artery occlusion or a stenosis of the M1 segment and no cortical regional cerebral blood flow decrease. Large striatocapsular infarctions occur due to occlusive disease of the middle cerebral artery (large-vessel disease) and not due to a disseminated in situ occlusion of the long penetrating arteries (small-vessel disease), as in lacunes. Neuropsychological deficits can be explained by decreased cortical blood flow due to a persistent occlusive lesion of the middle cerebral artery.

Adult↗
PubMed1990

Reduced technetium 99m labelled NCA-95/CEA-antibody uptake in liver due to gentle antibody reconstitution. Technical note.

The influence of reconstituting a murine monoclonal IgG1 antibody kit with pertechnetate technetium 99m on antibody distribution in the liver, spleen and sternal bone marrow of patients was examined. The 99mTc-labelled antibody used is directed against non-specific cross-reacting antigen (NCA-95) and carcinoembryonic antigen (CEA) and has been successfully applied for imaging tissue inflammation and bone marrow scanning. Radioactivity uptake was determined in the liver, spleen, bone marrow and a precordial background region in a consecutive series of 25 patients, examined with an antibody preparation, routinely radiolabelled according to the manufacturer's recommendations and in 14 patients, in whom the antibody was reconstituted with special care, avoiding bubble formation and dropping of buffer into the antibody-containing vial. Gentle compared with routine antibody reconstitution caused a highly significant reduction of the antibody uptake in the liver, as determined by count densities, normalized to injected dose and acquisition time (13.2 +/- 5.5 vs 20.1 +/- 6.0 cpm per pixel, means +/- SD, P = 0.008). The liver to background ratio was reduced from 3.4 +/- 1.4 to 1.9 +/- 0.5 (P less than 0.001). Spleen, sternal bone marrow and precordial background count rates were not significantly affected. These results clearly demonstrate that gentle antibody reconstitution can decrease non-specific antibody uptake in the liver by 34% +/- 6.4% (means +/- SEM). Thus, scan quality is improved, and the potential deleterious camouflage of underlying structures is avoided.

Antibodies, Monoclonal↗
PubMed1990

Methoxyisobutylisonitrile (MIBI) Tc 99m SPECT to establish a correlate to coronary flow reserve, the perfusion reserve, from global and regional myocardial uptake after exercise and rest.

With 99mTc-MIBI SPECT and a 4 h exercise (E: 150 MBq iv) and rest (R; 800 MBq iv) protocol, global and regional left ventricular (LV) myocardial uptake was determined in 70 patients with angiographically confirmed coronary heart disease (CHD) and in 10 controls. The aim was to establish an E/R ratio as a correlate to coronary vascular reserve, representing perfusion reserve (PR). E/R ratios, obtained from total LV myocardium or from normal or impaired regions, were greater than 1.19 under all conditions, indicating the presence of higher flow during exercise than at rest (even in areas of low flow). Global PR separated (P less than 0.01) controls (1.63 +/- 0.21; mean +/- SD) from severely diseased patients (1.29 +/- 0.14 in 2- or 3-vessel disease) only. Improved differential diagnosis was gained from calibrating the regional E/R ratio to regional differences (E minus R) of uptake. For the left ventricle regional PRs (RPR) for 25 ROIs of the target, framing the myocardium, were determined. RPR at the regional maximum of 99mTc-MIBI uptake was similar in both controls (1.66) and patients (1.63), indicating a high probability of meeting some areas with functionally normal perfusion in patients with CHD. RPR allowed sufficient separation (P less than 0.025) concerning the degree of coronary artery stenosis (RPR in occlusion, 0.26; stenosis greater than 75%, 0.39; less than 75%, 0.56). In controls, the overall value for RPR was 1.14 +/- 0.28 (P less than 0.001). LV global PR and RPR were useful in separating patients with CHD vs controls and in classifying the severity of vascular stenosis.

Adult↗
PubMed1990

99Tcm-methoxy-isobutyl-isonitrile SPECT to evaluate a perfusion index from regional myocardial uptake after exercise and at rest. Results of a four hour protocol in patients with coronary heart disease and in controls.

In 70 patients with angiographically confirmed coronary heart disease and in 10 controls, a 4 h exercise (E) (injection of 150 MBq 99Tcm-MIBI) rest (R) (800 MBq) protocol was employed. Of these, 10 patients with 21 myocardial defects after E received a third injection 24 h after. SPECT was used to image myocardial distribution, and visual findings separated three patterns of perfusion defects after E v. R (reversible [REV], partial reversible (PREV), irreversible (IRR)). Relative regional uptake was obtained from a target-like (33 ROIs) evaluation of short-axis cuts, establishing a perfusion index (PI) by relating the defect uptake to individual maximum uptake (100%) after exercise (PIE), at rest (PIR) and the respective differences Delta PI (PIR-PIE, i.e. filling in by the second 99Tcm-MIBI injection). Visually, the sensitivity was 86% in patients or 69% in involved vessels (stenoses of greater than 33%). Vascular supply areas revealed minimal PIE values of 74.7 +/- 10.6% (control), 62.4 +/- 9.2% (REV), 46.1 +/- 7.7% (PREV) and 33.5 +/- 9.9% (IRR) (p less than 0.01). Delta PI was +13.2% or +10.1% in REV or PREV (n.s.) and +2.1% in IRR (p less than 0.01) or -0.2% in controls. PIE values did not correlate to the degree of stenosis. In areas with old myocardial infarction, the same sequence of significant decrease of PIE with reversibility occurred, independent of the patency of the supplying vessel. 33 of 35 IRR defects (94.3%) revealed PIE of less than 45%, thus predicting IRR already after the E examination. PIR values from the 4 h protocol correlated to PIR values 24 h thereafter with r = 0.94 (n = 21). 99Tcm-MIBI may be employed in a short one day E-R protocol in clinical routine. Evaluation of PI seems to be a promising tool to quantify visual defects aimed at describing the perfusional state of the terminal vascular supply area.

Adult↗
PubMed1989

Radioimmunoimaging for diagnosis of bone marrow involvement in breast cancer and malignant lymphoma.

Granulopoietic bone-marrow was scintigraphically imaged in 15 patients with carcinoma of the breast and known skeletal metastases, 10 patients with malignant lymphomas, and 15 controls without suspected malignant disease, with a technetium-99m labelled murine monoclonal IgG1 antibody directed against nonspecific cross-reacting antigen (NCA-95) and carcinoembryonic antigen. Immunoscintigraphy revealed more lesions than did bone scanning in both patient groups. This method offers a sensitive, cost-effective, and easy-to-perform whole body technique for evaluating metastatic spread.

Antibodies, Monoclonal↗
PubMed1989

Radioimmunoscintigraphy with 111In labelled monoclonal antibody fragments (F(ab')2 BW 431/31) against CEA: radiolabelling, antibody kinetics and distribution, findings in tumour and non-tumour patients.

Forty seven patients with suspected malignant disease (mainly colorectal cancer) were studied with 111In labelled F(ab')2 fragments of an anti-CEA monoclonal antibody (BW 431/31). The kinetic data revealed a long whole body retention of the label (62% after 4 days) and a rapid blood clearance (77% within 24 h, 89% within 48 h) leading to an early positive tumour contrast 24 h p.i. and optimal scintigrams 48 h p.i. Diagnostic results were promising in local recurrences of colorectal cancer (8/10 positive = 80%) though false positive findings in patients with inflammatory bowel disease occurred probably due to cross-reaction with a human granulocyte antigen. Liver metastases and tumours neighbouring liver and spleen were often missed (10/27 = 37%) because of high nonspecific uptake in these organs. Thus BW 431/31 proved to be a suitable compound for radioimmunodetection, however, further improvements to optimize tumour affinity and specificity of the antibody are mandatory.

Aged↗