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Biomedical subjects

U Buell

Publications and source records attributed to U Buell.

At least 109 records · Page 6Linked to original sources
PubMed1988

Combined SPECT imaging of regional cerebral blood flow (99mTc-hexamethyl-propyleneamine oxime, HMPAO) and blood volume (99mTc-RBC) to assess regional cerebral perfusion reserve in patients with cerebrovascular disease.

In 53 patients with cerebrovascular disease (CVD), regional cerebral blood flow (CBF) and blood volume (CBV) were imaged by SPECT within one session. Slice division (CBF: CBV) yielded distribution of regional cerebral perfusion reserve (CPR). Semiquantitative evaluation was obtained from manually set ROIs by interhemispherical ratios (for CBF, CBV and CPR), using 2 SD from a normal group (n = 10) as a threshold. Sensitivities were 59% for CBF, 94% for CBV and 83% for CPR. Combined sensitivity was 98%. Establishing three constellations for CBF, CBV and CPR, regionally normal CBFs but quantitatively increased CBVs (+69%) and decreased CPRs (-31%) were found in relatively early stages of CVD. Very advanced cases showed decreased CBFs (-65%), CBVs (-40%), CPRs (-49%) and a surrounding penumbra. In 87% (46/53 patients), such rheologically postulated constellations could be demonstrated. We conclude that combined CBF and CBV SPECT, assisted by CPR images, is a promising tool to detect CVD and to assess its individual regional severity.

Aged↗
PubMed1987

Quantitative evaluation of myocardial stress/rest 201TL SPECT: results of a ROI-based method in 108 patients with CHD.

ROI-based polar maps (33 ROIs) were employed to evaluate quantitatively stress/rest myocardial 201Tl SPECT in 108 patients with angiographically proven coronary heart disease (CHD) in comparison with 30 controls. Sensitivity in detecting a CHD with stenoses of greater than 50% of luminal diameter was determined versus normal regional values (+/- 2.5 SD) employing vitality (VI) and wash-out corrected redistribution (RD). The method was evaluated referring to the severity of the disease, to the number of ROIs displaying changes [(a) 1 ROI, (b) greater than 2 ROIs], to validity of VI, RD or a combination thereof, and for specificity. Wash-out values were found to depend on degree of stress individually achieved and thus were not used as a threshold criterion. Sensitivity in supply areas with old myocardial infarctions was 95% (a) and 86% (b), resp. With no infarction, it was 96% (a) and 79% (b), resp. VI in stenosis greater than 75% was more sensitive than RD. However, combined evaluation of VI and RD yielded sensitivities from 91-100% (a) and 77-94% (b), resp. for different main supply areas. In stenosis less than 50% with normal VI, RD was positive in 18-31%. Specificity turned out to be 91% (a) and 97% (b), resp. We conclude that the method presented is reliable to quantify numerically 201Tl kinetics in myocardial SPECT, aimed at detecting and describing CHD.

Adult↗
PubMed1986

Combined evaluation of first-pass radionuclide angiography and equilibrium radionuclide ventriculography in the diagnosis of coronary artery disease. I. Results at rest.

The results of 203 patients who underwent first-pass radionuclide angiography (FP), as well as quantitative equilibrium radionuclide ventriculography (qERNV), were stored in a data base system and evaluated statistically. In patients with coronary artery disease (CAD) without previous myocardial infarction (MI), evaluation of global and regional ejection fraction (gEF, rEF) at rest revealed a poor sensitivity of 64% (Rest-qERNV) and 69% (Rest-FP), respectively. In patients with a history of one previous MI, the sensitivity of both methods was equivalent: FP 87% and qERNV 84%. In patients with several MIs, sensitivity was higher than 90%. Concerning localization of MI, remarkable differences between FP and qERNV were found. In posterior wall infarction, the FP sensitivity was 87% and qERNV only 67%, whereas in anterior wall infarction, the results were similar for both methods: 93% (FP) and 96% (qERNV), respectively. Since 30 degrees RAO camera position achieves the best visualization of the anterior and posterior wall, FP is superior to qERNV in the evaluation of posterior wall asynergies. In addition, qERNV often fails to discriminate anterior and posterior wall motion abnormalities.

Coronary Disease↗
PubMed1986

Pathological cerebral blood flow during motor function in schizophrenic and endogenous depressed patients.

In this investigation we examined eight Type I (positive symptoms without marked negative symptomatology), eight Type II (marked negative symptoms) schizophrenic patients of the disordered and paranoid diagnostic subgroups (DSM-III 295.1 and 295.3), eight severely (HAMD above 35) and eight less severely (HAMD below 20) endogenous depressed patients, and eight control persons using the 133Xe inhalation method in resting condition and during motor activity of the dominant right hand. In all patient groups we found flow activation patterns that were different from those observed in normal control persons. During motor activation in Type I schizophrenics and in less severely endogenous depressed patients, we found a bilateral hyperflow and a diffuse cortical flow increase, also involving deeper cerebral structures. In Type II schizophrenics and severely endogenous depressed patients, however, we found a widespread nonreactivity of the regional cerebral blood flow (rCBF) to motor activation, with no flow increase in the contralateral primary motor area. In normal control individuals, we reproduced a 25% flow increase that was strictly limited to the contralateral primary motor area, as already reported by other authors. As only the schizophrenic patients were not under antipsychotic medication (4 with a washout of at least 1 week prior to the investigation, 12 never treated with drugs before), contaminating effects of the medication cannot be ruled out for the endogenous depressed patient groups. However, in schizophrenic patients, these results suggest a diffuse disorganization and lack of laterality of motor functional systems. In addition, the change from hyperactivity to hyporeactivity might indicate cerebral functional correlates of the change from Type I to Type II symptomatology in schizophrenic patients, which could possible prove to be of clinical importance.

Adolescent↗
PubMed1984

Time course of thyroglobulin autoantibodies in patients with differentiated thyroid carcinoma after radioiodine therapy.

The time course of thyroglobulin (Tg) was monitored in patients with differentiated thyroid carcinoma after ablative therapy (thyroidectomy + 131I-treatment) with particular respect to endogeneous antibodies (Tg-ABs). In 232 patients (196 without Tg-ABs, 36 with Tg-ABs at the time of treatment) a sensitivity of 88% (accuracy, 93%) was found at the first follow up examination. Twelve months later, 11 of the 36 patients did not present Tg-ABs, therefore, the sensitivity increased to 91% (accuracy, 94%) at that time. It is expected that the determination of Tg can also be employed in patients presenting ABs initially.

Autoantibodies↗
PubMed1984

Dynamic SPECT with Xe-133: regional cerebral blood flow in patients with unilateral cerebrovascular disease: concise communication.

To validate xenon-133 dynamic single photon emission tomography (SPECT) clinically, 74 patients were examined. Strictly unilateral cerebrovascular disease was confirmed in 47 patients by clinical history and by transmission computerized tomography (TCT) and contrast angiography. Twenty-seven were excluded, considered normal. SPECT flow maps were evaluated visually (against TCT) or by automated region of interest (ROI) techniques (12 areas per slice) to measure area flow (AF) (ml/100 g-min) and interhemispherical area flow ratios (AR). These were compared with normal values. Minimum AF in affected hemisphere decreased, and AR-to-normal difference increased, with the severity of the disease. Visually, low-flow areas were detected twice as frequently in SPECT as areas of low density of TCT. In reversible episodes, sensitivity of AF alone ws significantly below the sensitivity of combined evaluation of flow and ratio.

Adult↗
PubMed1983

Influence of background and absorption correction on nuclear quantification of left ventricular end-diastolic volume.

Left ventricular (LV) end-diastolic volume (EDV) was determined in millilitres by equilibrium radionuclide ventriculography (MUGA) in 38 patients and in 15 normal individuals by applying corrections for background (BC), LV blood self-absorption and for absorption by the thoracic and LV walls. Volume calibration was performed by measuring a syringe containing the patient's venous blood with the gamma camera. Single plane cineventriculography (CVG) served as the reference method. Without absorption correction, LV volume values were underestimated by a factor of 3.6 on the average. Several background models (uniform, parabolic, no background) were investigated. Without BC, EDV was overestimated, and with uniform BC, EDV was underestimated. EDV calculated using a parabolic BC with a correction for absorption yielded the best correlation (r = 0.96) with volumes (VOL) obtained by CVG (VOLMUGA [ml] = -6.83 + 1.060 X VOLCVG).

Background Radiation↗
PubMed1983

Detection of severe cornary heart disease with TI-201: comparison of resting single photon emission tomography with invasive arteriography.

To investigate the application of TI-201 single photon emission computed tomography (SPECT) at rest in the confirmation of coronary heart disease (CHD), we studied 95 patients who had all undergone coronary angiography and cineventriculography. We separated three groups, patients with (a) prior myocardial infarction (MI) (n = 45), (b) no history of MI (n = 40), and (c) no abnormality of coronary angiogram (n = 23). The results of planar imaging with computer-assisted evaluation (scintimetry, SCM) and of SPECT with a three-plane reconstruction (transverse, sagittal, frontal) were compared with the invasive, arteriographic findings. SPECT yielded a higher sensitivity (93%) than SCM (68%) in the detection of defects in both infarcted and noninfarcted groups. The specificity was found to be almost equal in the two imaging modalities. A significant (p less than or equal to 0.01) increase in accuracy was found in SPECT in the assessment of the posterior wall (54% compared with 88%) as well as in the general detection of defects (68% compared with 88%). Applying the SPECT imaging technique increases both the diagnostic accuracy of TI-201 myocardial imaging and the anatomical association of CHD.

Adult↗
PubMed1982

A comparison of bone imaging with Tc-99m DPD and Tc-99m MDP: concise communication.

Bone to soft tissue (ST) ratios for both high-uptake bone (sacrum) and low-uptake bone (femoral diaphysis) were obtained with a derivative of phosphonic acid, TC-99m 2,3-dicarboxypropane-1, 1-diphosphonate (DPD), in 26 normal subjects and 177 patients with malignant disease but without metastases. Tests were run 2 hr after tracer injection. Similar ratios were obtained with Tc-99m methylene diphosphonate (MDP) in 220 normal subjects and 451 patients. With MDP, the influence of incubation time (5-10 min in 416 cases, 45 min in 185 cases) on these ratios was determined. DPD was superior to MDP for both ratios. With MDP, prolonged incubation time yielded significantly enhanced ratios; however, the ratios for the DPD were still higher. With either agent and preparation, sacrum-to-ST ratios decreased with increasing subject age, and in patients with malignant disease the ratios tended to be higher than those obtained from normals.

Adult↗
PubMed1979

Sensitivity of computed tomography and serial scintigraphy in cerebrovascular disease.

Computed tomography and serial scintigraphy with 99mTc-pertechnetate (radionuclide angiography and early and late static imaging) were compared in 214 patients with cerebrovascular disease. CT correctly identified 151 (95.0%) of 159 patients with completed ischemic stroke but was positive in only 11 (25%) of 44 patients with asymptomatic stenosis, transient ischemic attacks (TIA), or prolonged reversible ischemic neurological deficit (PRIND). Scintigraphy was positive in 93.1% of patients with completed stroke. CT detected 175 territories of vascular supply involved, scintigraphy 164. In patients with asymptomatic stenosis, TIA, or PRIND, scintigraphy was correct in 77.3% of cases. The combined evaluation offered a sensitivity of 97.5% in patients with completed stroke and 86.4% in those with asymptomatic stenosis, TIA, or PRIND. The rate of true-positive scintigraphic findings in patients with completed stroke did not change as the interval between ictus and study increased. In patients with intracerebral hematoma, CT was far more specific than scintigraphy. If cerebrovascular disease is suspected, radionuclide angiography should be performed first.

Adult↗