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PubMed1998

Comparative value of thallium and glucose SPECT imaging in childhood brain tumors.

Thallium-201 chloride (201Tl) single-photon emission computed tomography (SPECT) detects a high percentage of histologically and anatomically diverse pediatric brain tumors. Thallium-201 chloride SPECT and F-18 fluoro-deoxy-glucose (18F-FDG) positron emission tomography (PET) are the most commonly used radionuclide techniques in neuro-oncology. Having developed a methodology to image 18F-FDG with SPECT, the authors performed SPECT scans coupled with magnetic resonance imaging to assess the comparative sensitivity of 201Tl and 18F-FDG in 19 children with brain tumors. Tumors were detected using 201Tl SPECT in 14 of 19 patients. Five of five postoperative residual tumors were detected by 201Tl SPECT, and six of seven after irradiation recurrences were detected. F-18 fluoro-deoxy-glucose SPECT detected tumors in only three of 19 patients, all of whom had abnormal 201Tl studies (all three after therapy recurrences). Thallium-201 chloride SPECT could be interpreted in 18 of 19 patients without magnetic resonance imaging confirmation, but none of the 19 18F-FDG SPECT studies could be interpreted without magnetic resonance imaging. Thallium-201 chloride SPECT is more sensitive than 18F-FDG SPECT in the detection of primary or recurrent childhood brain tumors. The failure of 18F-FDG SPECT in follow-up after therapy is primarily a problem of limited fluoro-deoxy-glucose uptake, not spatial resolution. Thallium-201 chloride SPECT is a promising imaging modality in neuro-oncology.

Brain Neoplasms↗
PubMed1999

Two-year assessment by exercise thallium scintigraphy of myocardial revascularization using bilateral internal mammary and gastroepiploic arteries.

OBJECTIVE: To assess the blood flow supply offered to the myocardium by surgical revascularization using bilateral internal mammary (IMAs) and gastroepiploic (GEA) arteries. METHODS: Two-year assessment by exercise thallium myocardial scintigraphy without medical treatment was performed in 122 patients (mean age 61 +/- 9 years) who underwent coronary artery bypass grafting (CABG) with exclusive use of IMAs and GEA. Usually, the right IMA was used to bypass the left anterior descending coronary artery, and the left IMA to bypass the diagonal and the marginal arteries as a sequential graft if required. The GEA was used to bypass the right coronary artery (RCA) in 50 patients and its posterior branches in 72 patients. RESULTS: During maximal or submaximal exercise stress testing, 119 patients (98%) were asymptomatic and 26 patients (21%) exhibited moderate ischemic ECG modifications which were correlated (P < 0.01) with incomplete revascularization and with the use of GEA to bypass the RCA. A third of patients had moderate ischemic thallium defects on exercise reversible after redistribution (anterior, 10; lateral, 2; inferior, 28). Silent residual myocardial ischemia detected by thallium scintigraphy was correlated (P < 0.001) with ECG modifications and incomplete revascularization; and inferior thallium defects were more frequent when GEA bypassed the RCA (P < 0.05). However, 26% of patients had residual ischemia despite a complete revascularization, and in at least 18% of cases for GEA and 8% for right IMA, arterial graft blood flow was insufficient at maximum exercise level and caused silent residual myocardial ischemia detected by thallium scintigraphy. CONCLUSIONS: Myocardial revascularization using bilateral IMAs and GEA offers a satisfactory myocardial perfusion in the majority of cases; however silent residual myocardial ischemia was detected in a third of patients and was related to incomplete revascularization and to insufficient blood flow supply probably due to small diameter of the arterial grafts.

Adult↗
PubMedDate not supplied

An incremental evaluation of the diagnostic value of thallium single-photon emission computed tomographic imaging and lung/heart ratio concerning both the presence and extent of coronary artery disease.

BACKGROUND: The goal was to assess the incremental diagnostic value of thallium single-photon emission computed tomographic (SPECT) imaging and lung/heart ratio (LHR) over other clinical and exercise electrocardiographic (ECG) variables concerning the presence and extent (three vessel/left main) of coronary artery disease. METHODS AND RESULTS: Multivariable logistic regression analysis that used an incremental study design was applied to clinical, exercise test, SPECT, LHR, and catheterization data from 323 patients with suspected coronary disease. The following variables were evaluated as predictors of presence and extent of disease: clinical (age, sex, symptoms, diabetes, and smoking), exercise ECG (millimeters of ST segment depression, slope of ST segment depression, peak heart rate, change in systolic blood pressure, and metabolic equivalents of the task), and thallium (defect reversibility and intensity of hypoperfusion and LHR). Discrimination and incremental value were assessed by receiver operating characteristic (ROC) curve analysis. SPECT imaging (segment hypoperfusion score) was an independent predictor of both presence and extent of disease (p < 0.0001) irrespective of the percent stenosis criterion used. However, it added significant incremental diagnostic information over clinical and exercise ECG data only concerning presence (e.g., ROC curve areas: presence of disease-clinical plus exercise ECG = 83 +/- 2 vs clinical, exercise ECG, plus SPECT = 87 +/- 2, p < 0.001; extent of disease-clinical plus exercise ECG = 83 + 4 vs clinical, exercise ECG, plus SPECT = 85 +/- 3, p = 0.11). Thallium LHR was an independent predictor of both presence and extent of disease (p < 0.05), but the incremental information added to SPECT data did not reach statistical significance (e.g., ROC curve areas: presence of disease--SPECT = 87 +/- 2 vs SPECT plus LHR = 88 +/- 2, p = 0.24; disease extent--SPECT = 85 +/- 2 vs SPECT plus LHR = 86 +/- 2, p = 0.24). However, when combined, LHR and SPECT data had significant incremental value over clinical and exercise ECG data alone concerning extent of disease (e.g., ROC curve areas: clinical plus exercise ECG = 83 +/- 4 vs clinical, exercise ECG, SPECT and LHR = 86 +/- 3, p = 0.04). CONCLUSION: SPECT thallium imaging variables are independent predictors of both presence and extent of coronary disease. However, they have significant incremental value over clinical and exercise ECG data concerning only presence of disease. Thallium LHR is an independent predictor of both presence and extent of disease but adds only a small insignificant amount of incremental diagnostic information over SPECT data. However, there was significant incremental value to the addition of LHR to SPECT data concerning extent of disease.

Adult↗
PubMedDate not supplied

Independent and incremental prognostic value of exercise thallium single-photon emission computed tomographic imaging in women.

BACKGROUND: This study examined the independent and incremental prognostic value of exercise thallium single-photon emission computed tomographic imaging in 212 women who also underwent coronary angiography. METHODS AND RESULTS: The left ventricular ejection fraction was normal (65% +/- 15%). During a mean follow-up of 40 months, 27 women had events (cardiac death or nonfatal myocardial infarction). Univariate Cox survival analysis showed several variables to be different between patients with events and those without events: age, exercise heart rate, the extent of coronary artery disease, reversible thallium defects, number of segments with reversible abnormality, and size of perfusion abnormality. Multivariate survival analysis showed that a large perfusion abnormality and age were the independent predictors of events. Actuarial life-table analysis showed that women with a large thallium abnormality (> or = 15% of the myocardium) had significantly worse event-free survival rates than had women with no or small abnormalities (Mantel-Cox statistic = 16; p = 0.0001). CONCLUSIONS: Thus exercise thallium-201 single-photon emission computed tomographic imaging provides independent and incremental prognostic information to clinical, exercise, and coronary angiographic results in women. The presence of a larger thallium abnormality identifies women at high risk of cardiac events.

Adult↗
PubMedDate not supplied

Prognostic value of tomographic rest-redistribution thallium 201 imaging in medically treated patients with coronary artery disease and left ventricular dysfunction.

BACKGROUND: Previous studies show that rest-redistribution thallium imaging is useful in the assessment of myocardial viability. The impact of such studies on patient outcome is not well defined. This study examined the prognostic value of tomographic rest-redistribution 201T1 imaging in 81 medically treated patients with coronary artery disease and left ventricular dysfunction. METHODS AND RESULTS: Rest-redistribution single-photon emission computed tomographic images were obtained and analyzed quantitatively. The segmental thallium uptake (20 segments per patient) was interpreted as normal, reversible defect, mild to moderate fixed defect, or severe fixed defect. The thallium images were abnormal in 80 patients, with no redistribution (no ischemia) in 43 patients and redistribution (ischemia) in 38 patients. The left ventricular ejection fraction was 27% +/- 8% in patients with no redistribution and 26% +/- 7% in patients with redistribution (difference not significant). In patients with no ischemia, there were 7 +/- 5 severe fixed defects and 5 +/- 4 mild to moderate fixed defects per patient. In patients with ischemia there were 7 +/- 4 reversible defects, 3 +/- 3 mild to moderate fixed defects, and 5 +/- 4 severe fixed defects per patient. The number of any abnormal segments was 11 +/- 5 in patients with no ischemia and 14 +/- 4 in patients with ischemia (p = 0.03). During a mean follow-up of 31 +/- 24 months, there were 11 cardiac deaths in patients with no ischemia (26%) and 22 in patients with ischemia (58%); the survival rate was worse in patients with than without ischemia (p < 0.05). Multivariate Cox survival analysis on important clinical, angiographic, and thallium variables showed that the presence of redistribution was an independent predictor of death (x2 = 5; p = 0.03). CONCLUSIONS: Patients with left ventricular dysfunction and redistribution on rest thallium imaging, a marker of hibernating myocardium, have a higher mortality rate with medical therapy than do patients with a comparable degree of left ventricular dysfunction but with fixed defects only. Thus observations similar to those made with positron emission tomography can be made in a much more straightforward, simple, and probably cost-effective manner with single-photon emission computed tomography.

Aged↗
PubMedDate not supplied

Prognostic value of coronary angiography in patients with chronic ischemic left ventricular dysfunction and evidence of viable myocardium on thallium reinjection imaging.

BACKGROUND: We evaluated the independent and incremental prognostic value of cardiac catheterization and coronary angiographic data over thallium reinjection after stress redistribution imaging in patients with myocardial infarction and left ventricular dysfunction. METHODS AND RESULTS: Sixty-nine patients with a first myocardial infarction (> 8 weeks) and left ventricular ejection fraction < or = 40% underwent thallium-201 reinjection after stress redistribution tomographic imaging and cardiac catheterization. During follow-up (mean 26 months) 11 cardiac events (8 cardiac deaths and 3 nonfatal myocardial infarctions) occurred. On Cox regression analysis independent predictors of cardiac events were the sum of reversible and moderately irreversible defects at thallium reinjection (chi 2, 16.4, p < 0.005) and the number of reversible defects at stress redistribution (chi 2, 5.1, p < 0.05). Moreover, thallium reinjection imaging improved the prognostic power of clinical, exercise, and stress redistribution data (p < 0.01). The inclusion of left ventricular ejection fraction produced a borderline improvement (p = 0.06), whereas the number of vessels with coronary disease did not. In contrast, in patients at high risk such as those with at least 25% of viable myocardium at reinjection, the number of diseased vessels provided additional prognostic information (p < 0.05). CONCLUSIONS: In patients with chronic ischemic left ventricular dysfunction, left ventricular ejection fraction, but not the number of diseased vessels, provides additional prognostic information to thallium imaging. Therefore coronary angiography seems unnecessary in these patients, unless a significative amount of viable myocardium is detectable.

Chronic Disease↗
PubMedDate not supplied

Prognosis in patients with left bundle branch block and normal dipyridamole thallium-201 scintigraphy.

BACKGROUND: The presence of complete left bundle branch block (LBBB) is commonly associated with a poorer prognosis, especially in patients with coronary artery disease (CAD). In the general population with suspected CAD and normal intraventricular conduction, a normal dipyridamole-thallium scintigraphy is a strong marker of a favorable outcome. OBJECTIVE: Our objective was to assess the prognosis in patients with LBBB and a normal dipyridamole thallium-201 scintigram. POPULATION AND METHODS: Patients with complete LBBB and normal myocardial perfusion on dipyridamole SPECT thallium-201 scintigraphy performed in our center for suspected CAD between 1988 and 1995 were monitored for clinical events. RESULTS: Sixty-nine patients (36 women and 33 men) with a mean age of 59 years (range 56 to 61) were monitored for a mean period of 33 months (range 25 to 35). During this period, 4 patients had unstable angina, 2 of whom underwent myocardial revascularization. There were no deaths or myocardial infarction. All events occurred at least 2 years after the thallium-201 scintigraphy. CONCLUSION: The presence of a normal myocardial perfusion with dipyridamole thallium-201 scintigraphy in this group of patients with suspected CAD and LBBB was associated with a very good prognosis, a low rate of clinical events occurring only 2 years after the myocardial scintigraphy, and no hard events.

Bundle-Branch Block↗
PubMed2006

Luminescent amidate-bridged one-dimensional platinum(II)-thallium(I) coordination polymers assembled via metallophilic attraction.

The neutral square-planar complexes [Pt(RNH2)2(NHCO(t)Bu)2] (R = H, 1; Et, 2) and [Pt(DACH)(NHCO(t)Bu)2] (DACH = 1,2-diaminocyclohexane, 3) act as metalloligands and make bonds to closed-shell Tl(I) ions to afford one- and two-dimensional platinum-thallium oligomers or polymers based on heterobimetallic backbones. A series of heteronuclear platinum(II)-thallium(I) complexes have been synthesized and structurally characterized. The structures of the Pt-Tl compounds resulted from [Pt(RNH2)2(NHCO(t)Bu)2] and TlX [X = NO3(-), ClO4(-), PF6(-), and Cp2Fe(CO2)2(2-)] are dependent on both counteranions and the amine substituents. The compounds [Pt(NH3)2(NHCO(t)Bu)2Tl]X (X = NO3(-), 8; ClO4(-), 9) adopt one-dimensional zigzag chain structures consisting of repeatedly stacked [Pt(NH3)2(NHCO(t)Bu)2Tl]+ units, whereas [{Pt(NH3)2(NHCO(t)Bu)2}2Tl2]X2 (X = PF6(-), 10) consists of a helical chain. Compound 3 reacts with Tl+ to give [{Pt(DACH)(NHCO(t)Bu)2}2Tl](NO3) x [Pt(DACH)(NHCO(t)Bu)2] x 3 H2O (14) and one-dimensional polymeric [{Pt(DACH)(NHCO(t)Bu)2}2Tl2]X2 (X = ClO4(-), 15; PF6(-), 16). Reactions of [Pt(DACH)(NHCOCH3)2] with Tl+ ions afford one-dimensional coordination polymers [{Pt(DACH)(NHCOCH3)2}2Tl2]X2 (X = NO3(-), 17; ClO4(-), 18; PF6(-), 19). The polymeric [{Pt(DACH)(NHCOR')2}2Tl2]2+ (R = CH3, (t)Bu) complexes adopt helical structures, which are generated around the crystallographic 2(1) screw axis. The distance between the coils corresponds to the unit cell length, which ranges from 22.58 to 22.68 A. The platinum-thallium bond distances fall in a narrow range around 3.0 A. The complexes derived from [Pt(NH3)2(NHCO(t)Bu)2] are luminescent at 77 K. The trinuclear complexes [{Pt(RNH2)(NHCO(t)Bu)2}2Tl]+ do not emit at room temperature but are emissive at 77 K, whereas the polymeric platinum-thallium complexes containing 1,2-diaminocyclohexane are intensively luminescent at both room temperature and 77 K. The color variations are interesting; 15 exhibits intense yellow-green, 16 exhibits green, and 17-19 exhibit blue luminescence. The presence of bonding between platinum and thallium is supported by the short metal-metal separations and the strong low-energy luminescence of these compounds in their solid states.

Crystallography, X-Ray↗
PubMed2005

Uptake of thallium from artificially and naturally contaminated soils into rape (Brassica napus L.).

An inductively coupled plasma mass spectrometry (ICP/MS) method was used for the evaluation of thallium transfer from naturally (pedogeochemically) and artificially contaminated soils into rape. Two sets of three different types of top soils (heavy, medium, and light) were used for pot experiments. The first set was collected from areas with high levels of pedogeochemical thallium (0.3, 1.5, and 3.3 mg kg(-1) DM). The second set of three soils with naturally low content of thallium was artificially contaminated with thallium sulfate to achieve five levels of contamination (0, 0.4, 2, 4, and 6 mg kg(-1) DM Tl). The soil samples and the samples of winter and spring rape (straw, seeds) from both sets were collected and analyzed. Plant and soil samples from fields were collected at 42 selected sites situated in South Bohemia and in Czech-Moravian Highlands where higher pedogeochemical content of thallium was expected. More intensive transport (better availability) of Tl was observed in the case of artificially contaminated soils. The physicochemical form and the total content of Tl in soil were found to be the main factors influencing its uptake by plants. The concentration of Tl in rapeseeds in the field samplings was mostly 45% of its content in the particular soil. Nevertheless the uptake of Tl from soils with naturally high pedogeochemical content can be high enough to seriously endanger food chains. These findings are very important because of the high toxicity of Tl and the absence of threshold limits for Tl in soils, agricultural products, feedstuffs, and foodstuffs in most countries including the Czech Republic.

Brassica napus↗
PubMed2002

Thallium in terrestrial environments--occurrence and effects.

In this investigation thallium contents in soil and plants in the EuroRegion Neisse were analysed and the distribution determined. The median top-soil content is 0.5 mg/kg in the area investigated. In this low-contaminated area the moss Pleurozium schreberi contains 0.04-0.13 microg/g and the moss Polytrichumformosum between 0.01 and 0.05 microg/g Tl. The effects of thallium on man and the terrestrial environment were examined. In an epidemiological study a significant positive correlation was found between the thallium content of the two mosses and the incidence of diseases of the circulatory system. The LOEC for thallium in bioassays with terrestrial invertebrates and plants in artificial soil ranged from 1 to 500 mg/kg, which indicates an toxicity of thallium up to 100 times higher than that of Cadmium.

Animals↗
PubMed1990

The effect of captopril on thallium 201 myocardial perfusion in systemic sclerosis.

In systemic sclerosis, abnormalities of myocardial perfusion are common and may be caused by a disturbance of the coronary microcirculation. We evaluated the long-term effect of captopril (75 to 150 mg per day) on thallium 201 myocardial perfusion in 12 normotensive patients with systemic sclerosis. Captopril significantly decreased the mean (+/- SD) number of segments with thallium 201 myocardial perfusion defects (6.5 +/- 1.9 at baseline and 4.4 +/- 2.7 after 1 year of treatment with captopril; p less than 0.02) and increased the mean global thallium score (9.6 +/- 1.7 at baseline and 11.4 +/- 2.1 after captopril; p less than 0.05). In a control group of eight normotensive patients with systemic sclerosis who did not receive captopril, no significant modification in thallium results occurred. Side effects with captopril included hypotension (six patients), taste disturbances (one patient), and skin rash (one patient). These side effects subsided when the dosage was reduced. These findings demonstrate that captopril improves thallium 201 myocardial perfusion in patients with systemic sclerosis and may therefore have a beneficial effect on scleroderma myocardial disease.

Adult↗
PubMed1994

Thallium-201 SPECT and positron emission tomography equal predictors of glioma grade and recurrence.

Quantitative indexes based on regions of interest ratios from preoperative thallium-201 SPECT and F-fluorodeoxyglucose (FDG)-positron emission tomography (PET) scans were compared for their ability to predict the histological grade of cerebral gliomas. Of the five different ratios used to determine the index for each PET scan, the ratio of tumour versus ipsilateral hemisphere in the same plane as the tumour showed the most significant correlation with glioma grade (p < 0.001). A large study of 62 thallium-201 SPECT scans showed equally good correlation with glioma grade (p < 0.0005). The use of thallium-201 SPECT for detection of tumour recurrence had 100% sensitivity in this series, while PET scans had 90.9% sensitivity. Patients with a rate of change in serial thallium indexes of 0.475 +/- 0.278 per month survived 5.93 +/- 2.25 months from onset of index increase, while those with little change in the index (0.069 +/- 0.063 per month) survived 17.93 +/- 5.25 months from onset of index increase. Results indicate thallium-201 SPECT correlates well with tumour grade and is equally efficient as PET in screening for glioma recurrence.

Brain Neoplasms↗
PubMed1989

An automated analysis technique for thallium images.

The use of stress thallium-201 scans in the non-invasive assessment of myocardial perfusion is well established, despite several reports of considerable inter-observer variability in the assessment of perfusion defects. By applying a simple statistical algorithm to a set of normal thallium images and using a well defined criterion of abnormality, the threshold of normality in these 'statistical images' was obtained for each of four projections. Subsequently a test set of images from both normal volunteers and patients with arteriographically documented coronary artery disease were reported using statistical images at four levels (70, 75, 80 and 85% of the mean of the hottest pixels) and standard thallium images viewed on the computer monitor in both colour and black and white. Significant reductions in the inter-observer disagreement and enhanced predictive accuracy in the detection of significant coronary artery disease were obtained using the statistical images. The technique described and assessed would permit the reporting of thallium scans at a preselected value of sensitivity and specificity depending on the requirements of the particular study. It could be readily implemented, after local validation, in any department performing thallium scans where the gamma camera is interfaced to a computer.

Adult↗
PubMed1993

Dipyridamole thallium-201 scintigraphy for improved detection of left anterior descending coronary artery stenosis in patients with left bundle branch block.

In patients with left bundle branch block (LBBB) undergoing thallium-201 exercise scintigraphy septal perfusion defects are frequently observed irrespective of the presence or absence of coronary artery disease. Consequently, in these patients the specificity for detecting stenoses in the left anterior descending coronary artery (LAD) by thallium-201 scintigraphy is relatively low. It has been hypothesized that pharmacological vasodilation would result in higher specificity than conventional exercise thallium-201 scintigraphy because of a more uniform exploitation of coronary flow reserve. Twenty-five consecutive patients with LBBB underwent dipyridamole thallium-201 imaging and coronary arteriography within 3 months. The prevalence of coronary artery disease was estimated at 48 +/- 19%. Sensitivity for detection of LAD lesions was 100% and specificity was 88%. The positive predictive accuracy and the negative predictive accuracy were 80% and 100% respectively. The 'false positive' septal defects were of the non-reversible type. The appearance of septal perfusion defects was not dependent on changes in heart rate during dipyridamole infusion. This study indicates the value of dipyridamole thallium-201 imaging for non-invasive detection of LAD stenosis in patients with LBBB.

Aged↗
PubMed1993

Diagnostic value of 123I-phenylpentadecanoic acid (IPPA) metabolic and thallium 201 perfusion imaging in stable coronary artery disease.

The diagnostic value of 123I-phenylpentadecanoic acid (IPPA) metabolic cardiac imaging was studied in a group (n = 29) of patients with angiographically confirmed CAD using single photon emission computed tomography (SPECT). A symptom-limited exercise test was first done with IPPA, and 2 days later with thallium. Medications were not withheld during testing. Fourteen healthy control subjects participated in parallel IPPA and 15 in thallium tests. Data acquisition and output were comparable in the two imaging modalities. By testing various relatively simple criteria for abnormality we found that the semiquantitative interpretation was more accurate than the visual readings. The best compromise of accuracy with the scored criteria consisted of a sensitivity of 86% and a specificity of 86%, obtained with IPPA polar tomograms (mild exercise defect) and a sensitivity of 86% and a specificity of 80% obtained with thallium (regionally decreased washout). With visual interpretation alone, a sensitivity of 83% and a specificity of 71% was detected with IPPA (mild exercise defect) and 72% and 73%, respectively, with thallium (partial reversibility). The sensitivity of the exercise ECG alone was 62%. The results of this study imply that IPPA imaging could be a rational, uncomplicated clinical method for non-invasive diagnosis of CAD. The diagnostic ability of IPPA is at least as good as that of thallium, and it is possible to use them in succession.

Adult↗
PubMed1990

Physiological inverse relationship between heart rate and thallium-201 lung uptake, clearance and lung/myocardial uptake ratio.

Increased lung uptake of thallium-201 during exercise has been suggested to indicate left ventricular dysfunction. The normal lung thallium-201 uptake, clearance and lung/myocardial uptake ratio were studied prospectively in 7 healthy men. Initial and delayed (3 h) images were quantitated by computer from regions of interest over the heart and lungs, after three bicycle exercise tests: to maximal, 80% and 60% of predicted maximal heart rate. The initial lung uptake was lowest at peak heart rate, and increased linearly to 121% and 140% of this at 80% and 60% of predicted maximal heart rate. The three delayed lung images were identical. The myocardial activity was highest at maximal exercise, and decreased linearly with heart rate, resulting in a net fall in the sum of initial lung and myocardial activity to 93% and 86% at the two lowest exercise levels. The mean initial lung/myocardial uptake ratio was 0.44, 0.67, and 1.00 from highest to lowest heart rate, and the lung thallium-201 clearance 9%, 21% and 33%. These results suggest that the initial lung thallium-201 uptake, clearance and lung/myocardial uptake ratio are normally inversely related to cardiac output. When used as indicators of left ventricular dysfunction, interpretation should be cautious in patients performing submaximal exercise tests. The lung thallium prognostic indicators seem less specific than previously indicated.

Adult↗
PubMed1992

Assessment of myocardial perfusion with thallium-201 scintigraphy in exercise-induced left bundle branch block: diagnostic value and clinical significance.

Myocardial perfusion scintigraphy with thallium-201 was performed in 33 subjects (mean age 45 years, range 28-61) with exercise-induced, rate-dependent left bundle branch block (LBBB) in order to assess both the value of Thallium-201 myocardial imaging for the diagnosis of coronary artery disease (CAD) and the pathogenesis (ischaemic or not) of the conduction defect. Of the 33 patients evaluated, 16 had chest pain suggestive of CAD and 17 were asymptomatic. None had a history of prior myocardial infarction or clinical and echocardiographic signs of heart disease. LBBB appeared at a heart rate ranging from 70 to 160 b.min-1. Eighteen patients showed repolarization abnormalities (ST segment depression with deep inverted T waves) compatible with ischaemia, after QRS normalization. Thallium-201 myocardial uptake was normal in 12 subjects; in the remaining 21, reversible Thallium-201 defects were demonstrated in the septum (18 patients), septum and apex (2), and septum and infero-apical wall (1). No patient had irreversible defects and all had normal coronary angiography, with negative ergonovine tests for coronary artery spasm. The patients were followed up for a mean of 43 months (range 16-80). One patient died from sudden death, but no cardiac event occurred in the other patients. In conclusion, exercise Thallium-201 myocardial scintigraphy showed a high prevalence (64%) of reversible perfusion defects in a group of patients with exercise-induced LBBB without any evidence of CAD at angiography or coronary spasm at ergonovine test. Moreover, follow-up showed a relatively low rate of major cardiac events.

Adult↗
PubMed1987

Value of tomographic thallium-201 imagining in patients with chest pain following coronary artery bypass grafting.

To determine whether thallium-201 washout profile analysis can detect regional myocardial ischemia caused by coronary artery bypass graft occlusion or progression of disease in nonbypassed coronary arteries, 19 consecutive patients with chest pain following bypass grafting were evaluated with coronary arteriography and thallium-201 scintigraphy. Twenty of the 55 coronary artery regions were perfused by an occluded bypass graft or a significantly stenosed (greater than or equal to 70% diameter narrowing) nonbypassed coronary artery, while 35 coronary regions were perfused by patent bypass grafts or insignificantly diseased coronary arteries. The tomographic thallium-201 washout profile results correlated with the bypass graft and coronary arteriographic findings (k = 0.67, P less than 0.001). The sensitivity of tomographic thallium-201 washout profile abnormalities for arteriographic abnormalities was 75%, while the specificity was 86%. The authors conclude that tomographic thallium-201 washout profile analysis may be very useful in the evaluation of patients with chest pain following coronary artery bypass grafting by detecting regional myocardial ischemia caused by occlusion of specific bypass grafts or progression of disease in nonbypassed coronary arteries.

Adult↗