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At least 73 records · Page 4Linked to original sources
PubMed2001

Comparison of glucose-insulin-thallium-201 infusion single photon emission computed tomography (SPECT), stress-redistribution-reinjection thallium-201 SPECT and low dose dobutamine echocardiography for prediction of reversible dysfunction.

The usefulness of glucose-insulin-thallium-201 (GI-Tl) infusion single photon emission computed tomography (SPECT) in predicting reversible dysfunction has not been evaluated, so the present study recruited 20 patients with regional ischemic dysfunction for investigation. All patients underwent GI-Tl SPECT, post-stress Tl reinjection imaging and low dose dobutamine echocardiography. The diagnostic accuracy of these 3 techniques in predicting functional recovery was evaluated by receiver operating characteristic (ROC) analysis. In segments with functional recovery, regional Tl activities of GI-Tl SPECT were significantly higher than those of reinjection imaging (p<0.05), although there were no significant differences in segments without recovery. The area under the ROC curve for GI-Tl SPECT (0.75+/-0.06) was greater than that for reinjection imaging (0.68+/-0.07). The optimal cutoff values to identify viable myocardium were considered to be 55% of peak activity for GI-Tl SPECT and 50% for reinjection imaging. At this cutoff point, the sensitivity and specificity for detection of functional recovery were, respectively, 85% and 61% for GI-Tl SPECT, and 73% and 61% for reinjection imaging. Dobutamine echocardiography had the same sensitivity (85%), but lower specificity (48%) than GI-Tl SPECT. Continuous infusion of GI-Tl solution enhances regional Tl uptake compared with conventional post-stress reinjection imaging. This study suggests that GI-Tl SPECT is superior to reinjection imaging and dobutamine echocardiography in predicting functional recovery after ischemic left ventricular dysfunction.

Aged↗
PubMed1996

Early and delayed thallium-201 scintigraphy in thyroid nodules: the relationship between early thallium-201 uptake and perfusion.

Seventy-six patients with thyroid nodules were studied. Initially, 74 MBq of thallium-201 was injected. The thyroid gland was imaged 15 min (early) and 3 h (delayed) after the injection. Thereafter, 185 MBq technetium-99m pertechnetate was injected. Immediately after the injection, a 1-min perfusion image was acquired, followed by an image at 20 min. Increased early and delayed 201Tl uptake compared with the contralateral thyroid tissue was adopted as the criterion for malignancy. Sensitivity, specificity and negative predictive values were found to be 85%, 64% and 78%, respectively, in operated patients, but these values were 86%, 87% and 95%, respectively, in the whole group, including patients followed with fine-needle aspiration biopsy. With the purpose of investigating the relationship between perfusion and early 201Tl uptake, both perfusion and early images were graded comparing nodular activity with contralateral thyroid activity. There was a poor correlation between perfusion and 201Tl uptake. The correlation was even worse in hyperactive nodules. It is concluded that early and delayed 201Tl imaging should not be used in the differential diagnosis of cold nodules and that early 201Tl uptake seems to be more closely related to factors other than perfusion.

Adolescent↗
PubMed1996

Clearance of thallium-201 from the peripheral blood: comparison of immediate and standard thallium-201 reinjection.

As several reinjection procedures have shown encouraging results in terms of imaging, we investigated whether the kinetics of thallium-201 would differ between the standard stress-redistribution-reinjection approach and the stress-immediate reinjection approach. In 53 consecutive patients with undiagnosed chest pain, 75 MBq (2 mCi) 201Tl was injected at maximal exercise. In 26 of these patients (group I), 37 MBq (1 mCi) 201Tl was reinjected immediately after completing the exercise images (the immediate reinjection procedure) and in 27 patients (group II), 37 MBq (1 mCi) 201Tl was reinjected after completing 3-h redistribution images (the standard reinjection procedure). Mean peak 201Tl blood activity after exercise was 17.7+/-12.5 kBq/ml (4.8+/-3.4 mCi/ml) for group I versus 16.4+/-9.2 kBq/ml (4.4+/-2.5 mCi/ml) for group II (NS). The relative increase in 201Tl blood activity after reinjection of half the initial dose [37 MBq (1 mCi)] exceeded 50% of the initial peak in both groups. The relative amount of 201Tl delivered to the myocardium was assessed by the area under the curve after both exercise and reinjection, and was 117%+/-72% for group I and 112%+/-73% for group II (NS). Blood clearance of 201Tl was at least biexponential. Mean early decay constants (lambda 1) after exercise and reinjection were 0.30+/-0.18 min-1 and 0.22+/-0.046 min-1 respectively for group I (T 1/2 2.3 min and 3.2 min respectively, NS), and 0.30+/-0.12 min-1 and 0.24+/-0.07 min-1 respectively for group II (T1/2 2.3 min and 2.9 min respectively, NS). For both procedures no significant differences were found between lambda 1 after exercise and lambda 1 after injection. The mean late clearance (lambda 2) from the blood was 0.032+/-0.056 min-1 and 0.012+/-0.012 min-1 respectively for group I (T1/2 21.6 min and 57.7 min respectively, NS), and 0.036+/-0.030 min-1 and 0.014+/-0.014 min-1 respectively for group II (T1/2 19.3 min and 49.5 min respectively, NS). Also, no significant differences were found between lambda 2 after exercise for both groups and between lambda 2 after reinjection for both groups. We conclude that reinjection of 37 MBq (1 mCi) 201Tl (half the initial dose) results in a relative increase in the initial peak and a relative increase in the amount of 201Tl delivered to the myocardium of more than 50% for both the standard and the immediate reinjection procedure. The clearance of 201Tl from the blood was not influenced by exercise or by the time of reinjection. Based on 201Tl kinetics as measured in the peripheral blood, there is no reason to postpone reinjection until 3-4 h following exercise.

Angina Pectoris↗
PubMed1994

Combined study with I-123 fatty acid and thallium-201 to assess ischemic myocardium: comparison with thallium redistribution and glucose metabolism.

To assess the clinical value of combined SPECT imaging with I-123-15-(p-iodophenyl)-3-methyl pentadecanoic acid (BMIPP) and thallium-201 (Tl), the findings were compared with those obtained in a stress Tl study and positron emission tomography (PET) with fluorine-18-fluorodeoxyglucose (FDG) in 22 patients with myocardial infarction. In 20 patients who underwent a stress Tl study, among 75 hypoperfused segments, 27 segments exhibited less BMIPP uptake than Tl (discordant segments), and the remaining 48 segments showed a similar decrease in BMIPP uptake (concordant segments). Twenty-two of 27 discordant segments (81%) exhibited redistribution on stress Tl study. On the other hand, only one of the 48 concordant segments had redistribution (p < 0.001). In 10 patients who underwent a FDG PET study, among 33 hypoperfused segments, seven segments were discordant segments, and the remaining 25 segments were concordant segments. Seven of the eight discordant segments (88%) demonstrated an increase in FDG uptake. In contrast, only five of 25 concordant segments (20%) showed increase in FDG uptake (p < 0.01). Thus, the segments showing discordant BMIPP uptake are considered to be ischemic but viable myocardium. We conclude that combined imaging with BMIPP and Tl is a useful mean for evaluating tissue viability in patients with coronary artery disease, but it may underestimate the extent of tissue viability, compared with FDG PET imaging.

Adult↗
PubMed2003

Effects of thallium(I) and thallium(III) on liposome membrane physical properties.

The hypothesis that thallium (Tl) interaction with membrane phospholipids could result in the alteration of membrane physical properties was investigated. Working with liposomes composed of brain phosphatidylcholine and phosphatidylserine, we found that Tl(+), Tl(3+), and Tl(OH)(3) (0.5-25 microM): (a) increased membrane surface potential, (b) decreased the fluidity of the anionic regions of the membrane, in association with an increased fluidity in the cationic regions, and (c) promoted the rearrangement of lipids through lateral phase separation. The magnitude of these effects followed the order Tl(3+), Tl(OH)(3)>Tl(+). In addition, Tl(3+) also decreased the hydration of phospholipid polar headgroups and induced membrane permeabilization. The present results show that Tl interacts with membranes inducing major alterations in the rheology of the bilayer, which could be partially responsible for the neurotoxic effects of this metal.

Brain Chemistry↗
PubMed1982

Thallium-205 nuclear magnetic resonance study of the thallium(I)-gramicidin A association in trifluoroethanol.

Association of the thallous ion with gramicidin in 2,2,2-trifluoroethanol has been investigated by thallium-205 NMR spectroscopy. The data obtained suggest that the gramicidin dimer has two strong binding sites and one or more weak binding sites. Association constants for the strong binding sites were found to have the same value. From the temperature dependence of the strong binding site association constants, values for the association enthalpy and entropy of -2.13 +/- 0.12 kcal/mol and +5.45 +/- 0.04 eu, respectively, were obtained.

Binding Sites↗
PubMed1990

Pectoralis muscle uptake of thallium-201 after arm exercise ergometry. Possible confusion with lung thallium-201 activity.

Pectoralis muscle uptake of thallium-201 was noted in 8 (73%) out of 11 patients after exercise arm ergometry. Uptake varied from mild to marked and potentially could be confused with pulmonary Tl-201 activity with a resulting false-positive diagnosis of exercise-induced left ventricular dysfunction. The three patients exhibiting negative or trace Tl-201 uptake had suboptimal exercise efforts. The characteristics of pectoralis muscle Tl-201 uptake are illustrated, and differentiation from true lung Tl-201 activity is discussed.

Arm↗
PubMed2004

Detecting viable myocardium and predicting functional improvement: comparisons of positron emission tomography, rest-redistribution thallium-201 single-photon emission computed tomography (SPECT), exercise thallium-201 reinjection SPECT, I-123 BMIPP SPECT and dobutamine stress echocardiography.

BACKGROUND: Low-dose dobutamine stress echocardiography (LDDE) has become a useful and safe method for identifying hibernating or stunned myocardium and for predicting improvement in wall motion after coronary revascularization. METHODS AND RESULTS: In the present study, fluorine-18 fluorodeoxyglucose positron emission tomography (FDG-PET), rest-redistribution thallium-201 ((201)Tl) single-photon emission computed tomography (RR-Tl SPECT), (123)I-15-(p-iodophenyl)-3-(R,S)-methyl pentadecanoic acid (BMIPP) and LDDE were performed in 30 patients with acute myocardial infarction (AMI) at 10+/-3 days after the onset of AMI. Also, exercise (201)Tl reinjection SPECT (RI-Tl SPECT) was performed at 14+/-2 days. Follow-up echocardiography was performed 5+/-3 months later in all patients after interventional therapy for the assessment of functional recovery. Of the 390 segments analyzed by echocardiography, 110 (28%) had abnormal wall motion. There were no significant differences between RR-Tl SPECT and LDDE in sensitivity, specificity, positive predictive value and negative predictive value using the chi(2)-test; however, in akinetic segments, there was a significant difference in sensitivity. Among FDG-PET, RI-Tl SPECT, BMIPP and LDDE, there were significant differences in 3 variables. In akinetic segments, LDDE is superior to RR-Tl SPECT in sensitivity and to FDG-PET in specificity. In hypokinetic segments, LDDE is superior to RI-Tl SPECT and BMIPP in sensitivity, and to FDG-PET and BMIPP in specificity. CONCLUSIONS: LDDE could detect functional recovery of viable myocardium in the early period of AMI and can be performed easily and safely.

Aged↗
PubMed1991

The significance of resting thallium-201 delayed SPECT for assessing viability of infarcted regions--comparison with exercise thallium-201 SPECT.

To clarify the clinical significance of resting thallium-201 (Tl) delayed SPECT for assessing the viability of infarcted regions, we studied resting Tl initial and delayed Tl SPECT one week after exercise (Ex) Tl SPECT in 38 patients (40 regions) with old myocardial infarction (OMI) and 35 patients (37 regions) with effort angina pectoris (EAP). Analysis of resting Tl and Ex Tl SPECT divided the patients with OMI into 3 groups. Twenty-three patients whose perfusion defect (PD) on resting delayed image was same as that of Ex delayed image were divided into 12 patients with Ex Tl redistribution (RD) (G1) and 11 patients without Ex Tl RD (G3). Fifteen patients showed a decrease of PD on resting delayed image compared with Ex delayed image (G2). Thirty-five patients with EAP were divided into 18 patients who had no PD on Ex delayed image (G1) and 17 patients whose PD did not disappear on Ex delayed image but disappeared on resting delayed image (G2). The increase of pulmonary artery wedge pressure on Ex was higher in G2 than in G1 of both OMI and EAP (OMI; G1 15 +/- 16 mmHg vs G2 27 +/- 7 mmHg; p less than 0.01, EAP; G1 12 +/- 7 mmHg vs G2 22 +/- 6 mmHg; p less than 0.05). The percent Tl uptake of the PD on Ex Tl initial images was lower in G2 than in G1 of both OMI and EAP (OMI: G1 63 +/- 7% vs G2 55 +/- 9%; p less than 0.05, EAP: G1 72 +/- 7% vs G2 65 +/- 9%; p less than 0.05). That of the PD on resting Tl delayed images was higher in G1 and G2 than in G3 of OMI (G1 78 +/- 7%, G2 74 +/- 8%, G3 41 +/- 10%; G1 vs G3, G2 vs G3 p less than 0.001). The prevalence of akinetic or dyskinetic wall motion on left ventriculography was higher in G2 than G1, and in G3 than G2 (G1 24.3%, G2 52.2%, G3 85.7%; p less than 0.001). Thus, in patients with OMI the decrease of Tl PD on resting Tl delayed images compared with Ex delayed images may indicate severe ischemia induced by stress as well as in patients with EAP, and furthermore the presence of viable muscle. On the other hand, the infarcted region without decrease of Tl PD on resting delayed images may lack viable muscle.

Aged↗
PubMed1991

Inadequate exercise leads to suboptimal imaging. Thallium-201 myocardial perfusion imaging after dipyridamole combined with low-level exercise unmasks ischemia in symptomatic patients with non-diagnostic thallium-201 scans who exercise submaximally.

This study was undertaken to establish the additional value of 201TI imaging after dipyridamole in combination with low-level exercise in 15 symptomatic patients with non-diagnostic 201TI scans, who exercised submaximally. Most patients had angina, ST-segment depression and even exertional hypotension and were referred for stress 201TI testing for determining the functional significance of known coronary artery disease. Six patients with a normal exercise 201TI test and one patient with an apical defect only were found to have 37 segments (of 105 segments) with reversible perfusion defects after dipyridamole infusion. One patient showing two reversible defects after exercise had five reversible segments after dipyridamole. Seven patients with fixed defects in 28 segments after exercise and two with small areas of border zone ischemia in seven additional (sub)segments, demonstrated fixed in defects in only nine segments but reversible defects in 40 segments after dipyridamole. Quantitative analysis resulted in 24.8 +/- 28.5 (mean value) sample points below -2 s.d. of the mean normal uptake after exercise, which increased to 72 +/- 26.5 after dipyridamole infusion (p less than 0.005). The washout analysis resulted in a mean value of 5.5 +/- 8.1 sample points below -2 s.d. after exercise, increasing to 33.3 +/- 22.1 after dipyridamole (p less than 0.005). Thallium-201 myocardial perfusion imaging after dipyridamole combined with low-level upright bicycle exercise may unmask scintigraphic evidence for ischemia in symptomatic patients who would otherwise have non-diagnostic imaging studies during submaximal exercise.

Coronary Disease↗
PubMedDate not supplied

Polar presentation of coronary angiography and thallium-201 single photon emission computed tomography. A method for comparing anatomic and pathologic findings in coronary angiography with isotope distribution in thallium-201 myocardial SPECT.

Individual results of coronary angiography were compared with tomographic myocardial scintigraphy (SPECT) in 99 patients. Coronary angiography findings were transferred to polar maps. Borders between arteries were assigned angles in a coordinate system constructed as a compass-rose. Areas perfused by different arteries were described by sectors. Findings were visually compared with the perfusion defects in a polar presentation of thallium-201 SPECT also described by angles. The mean values and SD for the angles representing arterial borders and perfusion defects were presented. The left ventricular myocardium was perfused by 3 coronary arteries in 92/99 patients. Dominant left artery was present in 7/99 patients; 79 perfusion defects were related to 118 arterial sectors 84 per cent had totally or partially matched stenotic arteries. Inter-individual differences in distribution of coronary arteries influence the localization of perfusion defects in myocardial SPECT and can be estimated with this polar presentation method.

Adolescent↗
PubMed1997

Thallium in French agrosystems--I. Thallium contents in arable soils.

The thallium (Tl) content of the upper horizons of 244 French soils was determined as the first step towards the creation of a reference data bank for total Tl content of arable soils. Forty soil samples were collected in the vicinity of potential anthropogenic sources of Tl, but the remainder came from rural areas. The distribution of Tl concentrations in soils was characterized by a median value of 0.29 mg Tl kg(-1) and a 90th percentile value of 1.54 mg Tl kg(-1). Very high pedogeochemical contents were found (up to 55 mg Tl kg(-1)) but none could be attributed to obvious anthropogenic pollution. Areas of very high Tl concentration belong to an epihercynian transgression zone with a contact between a sedimentary basin and a crystalline massif. This contact is associated with stratified mineralizations (Zn, Pb, F, Sb, Ba, Tl and pyrites). High Tl concentrations were common in limestone, marl or granite derived soils, and the Tl in limestones or marls is probably concentrated in the sulfides contained in these rocks because Tl has a high affinity to S. In granites, Tl may be in the micas and feldspars because Tl+ can replace K+ in these minerals. Silty or clay-silty soils showed the highest concentrations. These granulometric fractions contain the majority of the minerals, which are supposed to be the major hosts of Tl in soils, i.e. clay minerals, oxides and micas. Tl in the soils was positively correlated with Ba, V, Pb, Fe, Ni, Cd, Zn, Co, As and especially Mn. A significant proportion of Tl may be in the Mn oxides: in oxidizing conditions, Tl(III) could enter the Mn oxides by sorption, or Tl(I) could replace K(I) in the oxide.

Journal Article↗
PubMed1997

Thallium in French agrosystems-II. Concentration of thallium in field-grown rape and some other plant species.

The aim of this study was to assess thallium (Tl) uptake into the aerial parts of selected crop species grown on French soils with high Tl content of pedogeochemical origin (0.3-40 mg Tl kg(-1) on a dry wt (DW) basis). Husked wheat and maize grains contained less than 4 microg Tl kg(-1) DW, but rape shoots accumulated Tl with a shoot-soil partition coefficient (PC) > 1, and rape seeds had PC > 3. Tl content of rape seed reached 33 mg Tl kg(-1) DW and higher concentrations in soil corresponded to increased concentrations in rape seeds. It is argued that parent material of the soil and pedogenesis have a considerable effect on Tl accumulation in rape seeds. These results show enhanced phytoavailability of Tl of pedogeochemical origin and prompt questions on the potential for food chain contamination by Tl in rape cattle cakes.

Journal Article↗