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PubMedDate not supplied

Quantitative investigations on the diaplacental transfer of thallium by field desorption mass spectrometry.

The placental transfer of thallium cations in pregnant mice was investigated by determining the thallium concentrations in fetal and maternal tissue 0.5 to 24 h after application of thallium. The maternal dose of thallium was 8 mg/kg body weight throughout. Uterus and fetus were found not to differ from other organs like heart and liver in time course and magnitude of thallium uptake with an initial surge during the first few hours of exposure to thallium and a rapid decrease to steady 12 and 24 h values somewhat lower than those found in the kidney. Diaplacental transfer is therefore assumed comparatively rapid and a specific placental barrier for thallium does not seem to exist. For the determination of thallium concentrations Field Desorption Mass Spectrometry was utilized as a reliable, fast and sensitive method for the analysis of metal cations in biological material. This method does not require extensive pretreatment of the tissue and total sample amounts in the range of milligrams and less are sufficient for quantitative analysis.

Animals↗
PubMed1994

Exercise tomographic thallium-201 imaging in patients with severe coronary artery disease and normal electrocardiograms.

OBJECTIVE: To assess the incremental value and cost-effectiveness of exercise tomographic thallium-201 imaging compared with clinical and exercise electrocardiographic variables for detecting three-vessel or left main coronary artery disease in patients with normal at-rest electrocardiograms. DESIGN: Prospective cohort study. PARTICIPANTS: 411 patients (77 [19%] had three-vessel or left main disease) with normal at-rest electrocardiograms who underwent exercise tomographic thallium-201 studies and subsequently had coronary angiography. MEASUREMENTS: Clinical, exercise, and thallium-201 variables; univariate followed by multivariate logistic regression analysis to determine predictors of three-vessel or left main disease (clinical variables; clinical and exercise electrocardiographic variables; and clinical, exercise, and thallium-201 variables). Patients were classified by each of these models into low-, intermediate-, and high-risk groups. SETTING: A tertiary referral center. RESULTS: Among the clinical variables, diabetes mellitus, sex, age, and typical angina were independently associated with severe coronary disease (46% of patients were correctly classified into low- or high-risk groups). The peak exercise heart rate-blood pressure product and the magnitude of the exercise-induced ST depression added independent information to clinical variables. Among the thallium variables, the change in the global thallium-201 score (a measure of redistribution) added independent information to clinical and exercise variables, resulting in only 3% of the patients being reclassified regarding their predicted risk for severe coronary disease. The cost per additional reclassification was estimated to be $20,550. Twenty-one cardiac events occurred (7 cardiac deaths and 14 myocardial infarctions) after thallium study (follow-up, 2.8 +/- 1.0 years). Event-free survival was 94% to 97% regardless of the predicted probability of developing three-vessel or left main coronary artery disease by any model. CONCLUSIONS: When the at-rest electrocardiogram is normal, thallium-201 scintigraphy adds little information to clinical and exercise variables in identifying patients with severe coronary artery disease. The high cost of this information may not justify the routine use of sophisticated imaging for this purpose.

Coronary Angiography↗
PubMed1999

Thallium-201 single-photon emission CT versus CT for the detection of recurrent squamous cell carcinoma of the head and neck.

BACKGROUND AND PURPOSE: Thallium-201 single-photon emission computed tomography (SPECT) can be used to detect primary squamous cell carcinoma (SCCA) of the head and neck. Nevertheless, there have very few studies performed to evaluate the ability of thallium-201 to depict recurrent SCCA. The purpose of this study was to compare the ability of thallium-201 SPECT with CT to enable detection of recurrent SCCA of the upper aerodigestive tract. METHODS: Thirty-three patients with a history of previously treated SCCA of the extracranial head and neck underwent thallium-201 SPECT imaging and contrast-enhanced CT. A neuroradiologist and nuclear medicine physician with knowledge of the primary site evaluated all thallium-201 studies for abnormal radiotracer uptake at the primary site. These results were correlated with histologic findings and clinical follow-up in all patients. All patients were followed up for a minimum of 2 years after completion of treatment. The McNemar test was used to determine statistical significance. RESULTS: The diagnostic accuracy of thallium-201 SPECT was as follows: sensitivity, 88%; specificity, 94%; positive predictive value, 93%; and negative predictive value, 89%. The diagnostic accuracy of CT was as follows: sensitivity, 100%; specificity, 24%; positive predictive value, 55%; and negative predictive value, 100%. The diagnostic accuracy of thallium was superior to CT (P = .01). CONCLUSION: Thallium-201 SPECT is superior to CT for differentiating recurrent tumor from post-treatment changes and may complement CT in the evaluation of previously treated SCCA of the extracranial head and neck.

Adult↗
PubMed1990

[A study of the variations in myocardial perfusion induced by systemic thrombolysis in acute myocardial infarct using sequential scintigraphy with 201-thallium].

To assess scintigraphic changes induced by intravenous streptokinase therapy, serial rest redistribution thallium-201 perfusion imaging was performed in 62 patients with acute myocardial infarction lasting less than 6 hours. Twenty-seven patients randomized to treatment with intravenous streptokinase (group A) and 35 to conventional therapy (group B) underwent thallium-201 scintigraphy as soon as possible after admission to the coronary care unit (early study). Regional myocardial perfusion was assessed using thallium-201 scintigraphy 7-9 days later in each patient (late study). The size of the perfusion defect was evaluated using a semi-quantitative score. The size of the perfusion defect decreased in serial scans in both group A (preintervention score: 12.1 +/- 6.8; redistribution score: 11.4 +/- 6.8; late study: 8.8 +/- 7.0) and group B (12.8 +/- 6.5; 12.3 +/- 6.7; 10.6 +/- 7.5, respectively). No statistical difference in myocardial perfusion was found between the two groups, on late study. Peak serum creatine kinase MB (CKMB) was earlier in group A than in group B (1030.8 +/- 326.6 vs 1361.0 +/- 271.1: p less than 0.001). The fast CKMB release group (onset of symptoms-peak of CKBM less than or equal to 900 minutes) exhibited higher thallium-201 uptake when compared to the slow CKMB release group, at the time of late study (perfusion defect score: 6.1 +/- 5.7 vs 10.7 +/- 7.3: p = 0.03). Reversibility was observed in 21/62 patients (34%). Reversibility corresponded to unchanged or improved perfusion defect score on late study in 18/21 patients (86%). Nevertheless 20/41 (49%) patients not showing redistribution of thallium-201 within pre-treatment defect had an improvement in regional perfusion on late study. Reversibility was observed in 9/14 (64%) patients with fast CKMB release and in 12/47 (26%) patients with slow CKMB release. We conclude that the early peak of CKMB is associated with a higher uptake of thallium-201 on late study. Furthermore, the reversibility of perfusion defect on redistribution imaging forecasts evolution of scintigraphic perfusion, but, when this is not present, it doesn't rule out late improvement of thallium-201 myocardial uptake. The low sensitivity and specificity of redistribution imaging and the procedure related delay in instituting therapy make thallium-201 scintigraphy unreliable in the evaluation of myocardial reperfusion following thrombolysis.

Adult↗
PubMed1990

ECG-gated and static technetium-99m-SESTAMIBI planar myocardial perfusion imaging: a comparison with thallium-201 and study of observer variabilities.

To assess the diagnostic accuracy of planar diastolic and static Technetium-99m-SESTAMIBI, myocardial perfusion imaging at rest and during exercise, was performed in 60 consecutive patients. The results were compared with coronary angiographic findings, obtained within 3 months of the exercise test and Thallium-201 images, obtained on the same day and to the same exercise level as Technetium-99m-SESTAMIBI exercise. Exact segmental concordance between static Technetium-99m-SESTAMIBI and Thallium-201 was 77% and between the diastolic images and Thallium-201 76%. Concordance between static and diastolic images was 92%. Nineteen percent of all 900 segments demonstrated ischemia with both static and diastolic Technetium-99m-SESTAMIBI and 20% with Thallium-201. Overall sensitivity to detect hemodynamically significant coronary artery disease with static Technetium-99m-SESTAMIBI was 86%, specificity 78%, with diastolic images 89% and 70% and with Thallium-201 89% and 78% (differences not significant). Vessel-specific comparative detection rates revealed no statistical significant differences between both radiopharmaceuticals as well. Intra-observer variability for the static images was 12%, for the diastolic images 21% and Thallium-201 14%. Inter-observer variability for the static images was 14%, diastolic images 24%, and Thallium-201 17%. Although the physical characteristics of Tc-SESTAMIBI enable to perform high-count density imaging and electrocardiographic gating, no significant differences are found when planar diastolic and static Technetium-99m-SESTAMIBI images are compared with Thallium-201 and are well within observer variabilities.

Coronary Disease↗
PubMed1989

[Comparison of thallium-201 images in dilated cardiomyopathy and ischemic cardiomyopathy].

Comparison of thallium-201 image between 21 patients with dilated cardiomyopathy (DCM) and 12 patients with ischemic cardiomyopathy (ICM) was made in this study. All cases had abnormal thallium images. Multiple myocardial segments presenting with patchy pattern were seen in all 21 patients with DCM. 75.0% of patients with ICM also had patchy pattern on the thallium image, but the number of patchy pattern segments on image was significantly less in ICM than in DCM (P less than 0.001); complete defects on thallium image were noted in 75.0% of patients with ICM, however, only one case with DCM had complete defect on thallium scan (P less than 0.001). When the thallium image characterized by multiple patchy pattern segments without complete defects was used as a diagnostic criterion for DCM. 95.2% of patients with DCM coincide with the criterion. When the thallium image showing complete defect was used as a diagnostic criterion for ICM, 75.0% of patients with ICM coincide with the criterion. The characteristics of thallium-201 image are useful either for diagnosis of DCM and ICM or in differentiating DCM from ICM.

Adult↗
PubMed1995

[Prediction of left ventricular functional recovery in patients with acute myocardial infarction using single photon emission computed tomography with thallium-201 and iodine-123-beta-methyl-p-iodophenyl-pentadecanoic acid].

The relationships between myocardial perfusion, fatty acid metabolism, and cardiac function were investigated using dual single photon emission computed tomography (SPECT) with thallium and iodine-123-beta-methyl-p-iodophenyl-pentadecanoic acid (123I-BMIPP) during the acute (10 +/- 1 days) and recovery (60 +/- 14 days) phases in 29 patients with acute myocardial infarction. There were 18 patients who underwent successful primary coronary angioplasty (PTCA group) and 11 patients who received conservative therapy (non PTCA group). Thallium and BMIPP uptakes were scored visually by a 4-point system and left ventricular ejection fraction (LVEF) was calculated by radionuclide ventriculography. Although significant positive correlations between thallium and 123I-BMIPP scores were observed during both phases, BMIPP scores were significantly lower than thallium scores in both acute and recovery phases in the PTCA group. No significant difference in thallium and 123I-BMIPP scores was observed at the recovery phase in the non PTCA group. LVEF significantly correlated with thallium and 123I-BMIPP scores in both phases in the PTCA group. Furthermore, the difference between thallium and 123I-BMIPP scores during the acute phase significantly correlated with the improvement of LVEF during the follow-up period in the PTCA group (y = 0.92x-0.77, r = 0.65, p < 0.005). These findings suggest that mismatch of perfusion and metabolism in infarcted myocardium assessed by thallium and 123I-BMIPP SPECT is increased by reperfusion therapy and persists at least until the recovery phase of myocardial infarction. The recovery of left ventricular function depends on the extent of the mismatched uptake, indicating a predictor for functional recovery following acute myocardial infarction.

Adult↗
PubMedDate not supplied

Dobutamine thallium 201 perfusion imaging in candidates for lung transplantation.

BACKGROUND: Thallium-201 stress imaging is the most often used noninvasive test for detection of coronary artery disease. Its utility in patients with end-stage lung disease has not been defined. METHODS: Feasibility, safety, and reliability of thallium 201 perfusion imaging was evaluated in 23 consecutive candidates for lung transplantation. All underwent graded dobutamine thallium 201 single photon emission computed tomography imaging. The perfusion imaging results were correlated with results of coronary angiography, radionuclide angiography, and right heart catheterization. RESULTS: The testing was completed without complications in all patients. No perfusion abnormality was detected in five patients, and none had evidence of coronary artery disease on coronary angiography. In 18 patients with abnormal thallium 201 imaging, coronary artery disease was detected in four patients only, and no angiographic data was available in three patients. Thus, in at least 11 of 23 patients, thallium 201 imaging was falsely positive. There was a trend toward lower left ventricular ejection fraction in patients with abnormal thallium 201 imaging. No correlation was found between thallium 201 results, pulmonary artery and right atrial pressures at rest. Possible noncoronary origin of the perfusion defects include the following (1) presence of sarcoid in the myocardium, (2) left ventricular attenuation by hypertrophied right ventricle, and (3) altered left ventricular anatomy, function, and coronary perfusion as a result of right ventricular pressure overload. CONCLUSIONS: Dobutamine thallium 201 stress test can be safely performed in lung transplant candidates. However, its specificity for detection of coronary artery disease is low. Selective use of coronary angiography in patients with multiple risk factors is likely a more cost-effective approach.

Cardiac Catheterization↗
PubMedDate not supplied

Clinical symptomatology of coronary artery disease and results of exercise thallium scintigraphy: gender-related differences.

Exercise thallium stress test is the mainstay of the noninvasive assessment of patients with symptomatology suggestive of coronary artery disease. The diagnostic accuracy of thallium scintigraphy as a screening test for coronary artery disease in women as compared to men, however, remains controversial. In order to determine whether gender-related differences in the detection of coronary artery disease using exercise thallium scintigraphy are demonstrable in all age groups, we analyzed the exercise thallium results in 335 outpatients (189 male, 146 female), who were referred by their primary physicians to our institution for evaluation of clinically suspected coronary artery disease. Overall, 50.3 percent of men had a positive for ischemia thallium stress test vs 29.5 percent of women (p < 0.0002). In the subgroup of patients 65 years of age or above, 67.4 percent of men had a positive for ischemia thallium stress test vs 27.6 percent of women (p < 0.003). In the subgroup of patients upto 40 years of age, 37.9 percent of men had a positive for ischemia thallium stress test vs 25.0 percent of women (p = NS). We conclude that symptoms suggestive of coronary artery disease are less predictive of positive exercise thallium stress tests in women as compared to men even above age 65 when the prevalence of coronary artery disease is known to be similar. This suggests that women may have lower threshold for perception of symptoms or that physicians have lower threshold for referring women for screening of coronary artery disease.

Adult↗
PubMed1996

A Prussian blue-based reactive electrode (reactrode) for the determination of thallium ions.

A reactive electrode (reactrode) made of Prussian blue (PB), graphite and paraffin can be used for a selective determination of thallium ions down to a concentration of 2. 10(-8) mol 1(-1). The working principle of the reactrode is that thallium ions can be pumped into Prussian blue during alternating oxidation-reduction cycles. After a preconcentration of thallium ions in PB, the voltammetric determination follows as usually in anodic stripping voltammetry, i.e. the thallium ions are reduced to thallium metal which is subsequently oxidized to give the anodic stripping signal. The peculiarity of the Prussian blue-thallium system is that the thallium ions are situated in the holes of the PB matrix. When reduced to metallic thallium, they are substituted by potassium ions. Cd(2+), Fe(3+), Zn(2+), Cu(2+) and Ni(2+) do not interfere up to a hundredfold excess, NH(4)(+) does not interfere up to a thousandfold - and Bi(3+) up to tenfold excess. The interference by Pb(2+) can be suppressed with EDTA.

Journal Article↗
PubMed1999

Imaging assessment of the responses of osteosarcoma patients to preoperative chemotherapy: angiography compared with thallium-201 scintigraphy.

BACKGROUND: Assessment of the responses of osteosarcoma patients to preoperative chemotherapy is of clinical importance. The purpose of this study was to estimate the accuracy of angiography and thallium-201 scintigraphy, compared with histology, in assessing the responses of patients with osteosarcoma to preoperative chemotherapy. METHODS: Nineteen patients with osteosarcoma who were diagnosed between 1992 and 1997 were studied. The findings of angiography and thallium-201 scintigraphy before and after preoperative chemotherapy were compared with the percentage of necrosis of tumor cells and the response grade as determined histologically. Quantitative analysis of the isotopic uptake by thallium-201 scintigraphy before and after chemotherapy, defined as the alteration ratio, was correlated with the percentage of tumor necrosis. RESULTS: Angiography yielded a sensitivity of 88%, a specificity of 73%, and a predictive accuracy of positive test of 70%, whereas thallium-201 scintigraphy achieved 88%, 100%, and 100%, respectively. Both angiographic and scintigraphic assessment showed a significant correlation with response grade as determined histologically (P < 0.05 and P < 0.0003, respectively). The alteration ratio of thallium-201 scintigraphy showed a strong, highly significant correlation with the percentage of tumor necrosis (P < 0.0001). CONCLUSIONS: A change in the tumor uptake of thallium-201 scintigraphy after preoperative chemotherapy can predict the tumor necrosis in osteosarcoma precisely. Thallium scintigraphy is a noninvasive technique and seems to be more useful than angiography in assessing the response of osteosarcoma to preoperative chemotherapy.

Adolescent↗
PubMed1997

Quantitative evaluation of blood flow distribution to exercising and resting skeletal muscles in patients with cardiac dysfunction using whole-body thallium-201 scintigraphy.

BACKGROUND AND HYPOTHESIS: Decreased blood flow to working muscles makes an important contribution to exercise intolerance in patients with chronic heart failure. This study was undertaken to examine whether maldistribution of skeletal muscle blood flow is closely related to exercise intolerance in patients with cardiac dysfunction. METHODS: Whole-body thallium scintigraphy was performed during one-leg exercise in 11 patients with left ventricular (LV) dysfunction (LV ejection fraction < 45%). Blood flow distribution to the exercising and resting legs was quantified by expressing regional thallium counts as a percentage of the whole-body counts at rest, at the level of anaerobic threshold, and at peak exercise. RESULTS: At anaerobic threshold, the thallium activity of exercising muscle increased from 4.2 +/- 0.7 to 14.0 +/- 2.5% (p < 0.05) in the thigh and from 1.7 +/- 0.3 to 4.1 +/- 0.9% (p < 0.05) in the calf, compared with the resting value. Consequently, the ratio of thallium activity between exercising and resting legs increased to 2.7 +/- 0.7 (p < 0.05) in the thigh and to 2.3 +/- 0.7 (p < 0.05) in the calf. When plotted as a function of anaerobic threshold, thallium activity of the exercising thigh (r = 0.78, p < 0.05) and the thallium ratio between exercising and resting thigh (r = 0.69, p < 0.05) declined with the reduction of exercise tolerance. These correlations were not observed in calves. CONCLUSION: Whole-body thallium scintigraphy demonstrated a maldistribution of leg blood flow in patients with reduced aerobic exercise capacity, suggesting that this abnormality could play an important role in exercising intolerance in these patients.

Adult↗
PubMed1988

Prenatal and postnatal thallium exposure in rats: effect on development of vasomotor reactivity in pups.

Vasomotor reactivity has been evaluated in rats exposed perinatally and postnatally to thallium sulphate (1 mg/dl in their drinking water ad libitum). Prenatal and postnatal exposure to thallium did not modify the values of the systolic arterial blood pressure on the 30th and 60th day in pups of normotensive and DOCA-hypertensive rats. The hypertensive responses induced by endosinusal carotid hypotension and by 1-noradrenaline in pups of normotensive and DOCA-hypertensive rats, exposed or not exposed to thallium sulphate, were more intensive on the 60th than on the 30th day. Similar effects were observed for the hypotensive responses induced by 1-isoprenaline and acetylcholine. Prenatal exposure to thallium did not modify hypertensive responses induced by endosinusal carotid hypotension on the 30th and 60th days, but it caused a decrease of hypertensive responses induced by 1-noradrenaline on the 30th and 60th days and hypotensive responses induced by 1-isoprenaline and acetylcholine exclusively on the 60th day. Postnatal exposure to thallium did not modify hypertensive responses induced by endosinusal carotid hypotension and hypotensive responses induced by acetylcholine, but it caused a decrease of hypertensive responses induced by 1-noradrenaline on the 30th and 60th days in pups of normotensive rats and exclusively on the 60th day in pups of DOCA-hypertensive rats. Moreover, postnatal exposure to thallium caused a decrease of the hypotensive response induced by 1-isoprenaline exclusively on the 60th day. Our findings show that prenatal and postnatal exposure to thallium sulphate modifies the rat's developing vascular autonomic nervous system with a reduction of the alpha, beta-adrenergic and muscarinic vasomotor reactivity.

Animals↗
PubMed1993

A comparison of dobutamine and maximal exercise as stress for thallium scintigraphy.

In the assessment and evaluation of patients with suspected coronary artery disease there is a need for pharmacological stress combined with thallium scintigraphy. Thallium images were obtained following stress both with dobutamine infusion (5-20 micrograms kg-1 min-1) and with symptom-limited bicycle ergometry in 20 patients (age 39-70 years) with chest pain who had been admitted for coronary angiography. Percentage thallium uptake was calculated using a region of interest technique. Detailed comparison was performed of the presence, size and distribution of left ventricular thallium perfusion defects; the percentage thallium uptake in ventricles, lung and liver; and the haemodynamic response to stress. Each stress produced a similar number of abnormal segments in each of three views (total EX 166/300; DOB 167/295), but exercise produced larger defects in the anterior view (P < 0.025). Thallium uptake in left and right ventricles and relative uptake to lungs were similar, but dobutamine produced higher relative liver uptake [EX 1.55 (0.67); DOB 2.97 (1.23) P < 0.0001]. Fourteen patients were able to tolerate dobutamine 20 micrograms kg-1 min-1. The ratio of peak stress to rest double product was smaller with dobutamine in both patients with (DOB 1.3; EX 2.0; P < 0.0047) and patients without beta-blockade (DOB 1.5; EX 2.4; P < 0.008). Dobutamine produced fewer conventional stress endpoints of chest pain and ST depression. In conclusion, dobutamine produces a well-tolerated incremental pharmacological stress with thallium images similar to maximal exercise, and provides a useful alternative stress in patients unable to perform adequate dynamic exercise.

Coronary Angiography↗
PubMed1992

Safety and diagnostic accuracy of adenosine thallium-201 scintigraphy in patients unable to exercise and those with left bundle branch block.

Three hundred forty consecutive patients (mean age 69 +/- 9 years) were evaluated with adenosine tomographic thallium-201 scintigraphy for suspected coronary artery disease. Minor side effects occurred in 91% of patients. Out of 28 patients (8%) with potentially serious side effects, 28 had significant atrioventricular (AV) block (second-degree, 24 patients; third-degree, four patients; syncope occurred in two patients). Acute bronchospasm and severe refractory angina pectoris occurred in one patient each. All side effects were transient and without sequelae. One hundred twenty-one patients underwent coronary angiography within 9 days of adenosine thallium imaging. The predictive accuracies of adenosine thallium imaging for identifying and localizing ischemia to a specific coronary distribution were: left anterior descending = 88%, left circumflex = 84%, right coronary = 88%. The predictive accuracy of adenosine thallium imaging in patients with left bundle branch block was 91%, and was higher than the 71% predictive accuracy noted in 39 patients who underwent exercise thallium testing (p = 0.04). It is concluded that adenosine thallium-201 myocardial scintigraphy was (1) highly accurate for the detection and localization of significant coronary artery disease; (2) it was more accurate at detecting ischemia in patients with left bundle branch block than exercise thallium testing, and (3) subjective side effects were common and were of no diagnostic importance; transient AV block occurred occasionally.

Adenosine↗
PubMed1993

Myocardial hibernation in the infarcted region cannot be assessed from the presence of stress-induced ischemia: usefulness of delayed image of exercise thallium-201 scintigraphy.

To examine the relationship between the improvement of wall motion in infarcted regions after percutaneous transluminal coronary angioplasty (PTCA) and thallium-201 uptake in the delayed image of exercise thallium-201 scintigraphy before PTCA, 14 patients with anterior old myocardial infarction were studied. Exercise thallium-201 scintigraphy was performed before PTCA of left anterior descending artery, and mean percent thallium-201 uptake of abnormal segments was calculated in the initial and 4-hour delayed images. Left ventricular angiography was performed during catheterization, before, and 4 to 13 months after PTCA; and regional ejection fraction of anterior wall was calculated. Atrial pacing stress test with the measurement of lactate concentration of aorta and great cardiac vein was performed during catheterization before PTCA. In five patients with mean percent thallium-201 uptake in the delayed image < or = 50% (group I), regional ejection fraction did not increase after PTCA (23% +/- 9% to 24% +/- 12%). In the other nine patients with mean percent thallium-201 uptake > 50% (group II), regional ejection fraction increased significantly after PTCA (39% +/- 18% to 47% +/- 14%; p < 0.05). There was no significant difference in regional ejection fraction, lactate extraction ratio during maximal pacing, and the redistribution of exercise thallium-201 scintigraphy between the two groups before PTCA. Thus the delayed image before PTCA is useful to detect reversible nonfunctioning viable myocardium (hibernating myocardium) in the infarcted region. However, the wall-motion abnormality and the degree of stress-induced ischemia in the infarcted region before PTCA may not be necessarily useful for the detection of hibernating myocardium.

Aged↗
PubMed1993

Identification of high-risk patients with left main and three-vessel coronary artery disease using stepwise discriminant analysis of clinical, exercise, and tomographic thallium data.

This large-scale study examined the ability of stepwise discriminant analysis of clinical, exercise, and thallium tomographic data to detect high-risk patients with three-vessel or left main disease. There were 834 patients, 229 with three-vessel or left main disease (group 1) and 605 (group 2) with either two-vessel disease (n = 236), one-vessel disease (n = 195), or no coronary artery disease (n = 174). The two groups were different in age, exercise heart rate, ST segment depression during exercise, exercise systolic blood pressure, abnormal thallium scans, reversible perfusion defects, extent of thallium abnormality, number of vascular territories with perfusion abnormalities, left ventricular cavity dilatation, and increased lung thallium uptake. On multivariate stepwise discriminant analysis, only three variables were independent predictors of high risk. These included multivessel thallium abnormality (F = 107, p < 0.001), exercise heart rate (F = 27, p < 0.001), and ST segment depression (F = 8, p < 0.01). Based on these three variables, patients could be stratified into three categories with different prevalences of left main or three-vessel disease; the prevalence was 53% in 239 patients, 24% in 271 patients, and 12% in 324 patients. Thus high-risk patients with left main or three-vessel disease can be identified by exercise thallium tomographic imaging that uses a model based on stepwise discriminant analysis. The thallium data are far more powerful than the clinical or treadmill exercise data.

Aged↗
PubMed1993

Identification of high-risk patients with left main and three-vessel coronary artery disease by adenosine-single photon emission computed tomographic thallium imaging.

The purpose of this study was to examine the ability of SPECT imaging with thallium-201 during adenosine-induced coronary hyperemia to detect high-risk patients with left main or three-vessel CAD. There were 339 patients: 102 with either left main or three-vessel CAD (group 1) and 237 with no CAD, one-, or two-vessel disease (group 2). By means of univariate analysis, several variables were found to differ between groups 1 and 2: Q wave myocardial infarction (35% vs 25%, p < 0.05), ST segment depression (35% vs 19%, p < 0.001), age (67 +/- 9 vs 62 +/- 10 years, p < 0.001), resting systolic blood pressure (142 +/- 22 vs 135 +/- 20 mm Hg, p < 0.01), abnormal thallium images (95% vs 74%, p < 0.0001), multivessel thallium abnormality (76% vs 39%, p < 0.0001), extent of thallium abnormality (24 +/- 11% vs 19 +/- 13%, p < 0.0001), and increased lung thallium uptake (39% vs 15%, p < 0.01). According to stepwise discriminant analysis, only three variables were predictors of high risk: multivessel thallium abnormality (chi 2 = 27), increased lung thallium uptake (chi 2 = 10), and ST depression (chi 2 = 5). On the basis of these variables, patients were divided into three groups with different prevalence rates for left main and three-vessel CAD: 63% in 68 patients, 30% in 137 patients, and 13% in 137 patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine↗