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PubMed2003

Thallium poisoning: emphasis on early diagnosis and response to haemodialysis.

Thallium poisoning is known for its diverse manifestations and these can delay the diagnosis if a clear history of poisoning is not forthcoming. A 42 year old man presented on the third day of illness with flaccid quadriparesis and paresthesia, which were confused with Guillain-Barré syndrome. Because of associated loose motions, skin lesions, and liver and kidney dysfunction arsenic poisoning was considered. In the second week he developed ophthalmoplegia, nystagmus, and neck tremor and later developed alopecia, and thallium poisoning was suspected. His serum thallium level on the 18th day of illness was 40 980 micro g/ml. He was subjected to haemodialysis, potassium supplementation, laxatives, and B complex supplementation. He showed significant improvement after haemodialysis and at three months he was able to walk with support. At six months of follow up he was independent for activities of daily living. Severe paresthesia, ophthalmoplegia, cerebellar and extrapyramidal signs, and alopecia are highly suggestive of thallium poisoning. Haemodialysis may be effective even in the third week of poisoning.

Adult↗

PubMed1978

Thallium-201 distribution in the thyroid: relationship to thyroidal trapping function.

Experiments were undertaken to determine the behavior of thallium-201 in the thyroid in relation to the iodide-trapping mechanism in rats. Iodide trapping was compared to thyroidal thallium-201 trapping 30 minutes after intravenous injection. Thallium-201 uptake followed iodide uptake in control rats. TSH- and T3-treated rats but did not decrease in the same manner as iodide concentration in perchlorate-treated rats. These studies suggest that thallium-201 distribution in the thyroid may reflect the cationic side of the iodide pump or possible thyroidal blood flow.

Animals↗

PubMed1985

Supine thallium 201 cardiac testing compared with treadmill testing.

Although thallium 201 stress testing is usually performed on a treadmill (Tl-TM), supine bicycle-ergometer-exercise thallium 201 testing (Tl-SB) has been reported. We performed a study to evaluate the accuracy of Tl-SB in evaluation of coronary artery disease and to correlate its results with those of Tl-TM. Fifty patients underwent both Tl-SB and Tl-TM testing in random sequence an average of 1 week apart. Tl-TM produced significantly higher maximal pulse rates and pulse-pressure products. Cardiac thallium kinetics differed significantly between Tl-SB and Tl-TM with Tl-TM producing greater initial myocardial uptake and greater thallium 201 washout between immediate and delayed images. Compared with results of catheterization, Tl-TM was significantly more accurate than Tl-SB for evaluation of coronary artery disease, with higher sensitivity and specificity.

Coronary Disease↗

PubMed1984

Thallium-201 myocardial imaging in patients on chronic hemodialysis.

10 long-term hemodialysis patients had immediate and redistribution thallium-201 myocardial imaging performed after a course of hemodialysis. Subjects had EKGs done on the same day before and after dialysis. 3 of the 10 subjects had resting thallium-201 myocardial imaging obtained on non-dialysis days. 60% of the electrocardiograms showed changes with dialysis. All 13 thallium studies were abnormal, showing multiple transient filling defects at rest. Most subjects had permanent filling defects as well. It is concluded that hemodialysis patients have a high frequency of abnormal thallium-201 myocardial images at rest. The cause of these abnormal studies is uncertain.

Adult↗

PubMed1980

Thallium-201 myocardial perfusion imaging in infants and children. Value in distinguishing anomalous left coronary artery from congestive cardiomyopathy.

In infants and children, anomalous origin of the left coronary artery (ALCA) from the pulmonary artery may be difficult to distinguish from congestive cardiomyopathy (CCM) of other causes. We performed thallium-201 myocardial perfusion imaging in seven children with ALCA and in nine with CCM to study the usefulness of this technique in distinguishing between these lesions. Localized abnormalities of thallium uptake were present in each of the seven patients with ALCA, including two asymptomatic 4-year-old children. Thallium distribution was normal in five patients with CCM, diffusely irregular in three, and was absent in the lateral and posterobasal portions of the left ventricle in one patient. We conclude that thallium-201 imaging is a sensitive noninvasive method of detecting ALCA. However, perfusion abnormalities are not limited to patients with coronary artery abnormalities, and may be present in patients with myocardial ischemia or infarction of other causes.

Child, Preschool↗

PubMed1982

Thrombolysis in acute myocardial infarction using intracoronary streptokinase: assessment by thallium-201 scintigraphy.

Twenty-one patients with acute myocardial infarction, admitted to the hospital within 4 hours after the onset of symptoms, were studied by seven-pinhole thallium-201 scintigraphy before and 1 hour and 24 hours after intracoronary fibrinolysis using streptokinase. The size of the thallium-201 perfusion defect was assessed from myocardial cross sections reconstructed from the original seven-pinhole data and expressed as a fraction of left ventricular circumference. Recanalization was achieved in 16 patients within 3.9 +/- 1.6 hours after onset of symptoms (group A). In these patients, the size of the perfusion defect had decreased from 36 +/- 17% to 19% +/- 15% (p less than 0.001) at 24 hours. No significant change was detected by redistribution at 1 hour after the intervention. In five patients, intracoronary fibrinolysis was unsuccessful, and the vessel remained occluded (group B). The thallium-201 perfusion defect affected 40 +/- 15% of the left ventricular circumference before the intervention; it remained virtually unchanged at 1 hour (37 +/- 16%) and at 24 hours (41 +/- 15%) after fibrinolysis. The perfusion defect was most reduced in patients with extensive collaterals supplying the ischemic area or with subtotal occlusion of the affected coronary artery. We conclude that successful intracoronary fibrinolysis may reduce the size of the thallium-201 perfusion defect in many patients with acute myocardial infarction. One important factor in the final result may be the presence of residual coronary flow supplied by extensive collaterals or by subtotal occlusion of the affected coronary artery when reperfusion is achieved around 4 hours after the onset of symptoms.

Adult↗

PubMed1982

Comparison of thallium-201 scanning in idiopathic dilated cardiomyopathy and severe coronary artery disease.

To determine whether cardiomyopathy could be distinguished from coronary artery disease, we used thallium scanning to study 25 patients with severe left ventricular dysfunction and chronic heart failure. Ten patients had normal coronary arteries and idiopathic cardiomyopathy (ejection fraction 20 +/- 5%), and 15 patients had multivessel coronary disease and left ventricular dysfunction (ejection fraction 25 +/- 6%). The exercise time and maximal heart rate were similar in the two groups. Two patients with cardiomyopathy and 11 with coronary artery disease had a positive exercise ECG (p less than 0.05). Thallium scans showed perfusion defects in all 25 patients. The perfusion defects were complete in nine coronary artery disease patients (60%) and in one patient (10%) with cardiomyopathy (p less than 0.05). Extensive defects involving more than 40% of the left ventricular circumference, the number of segments involved, redistribution on the 4-hour scan, lung uptake and ventricular size were similar in the two groups. Perfusion defects on thallium scanning can occur in patients with idiopathic dilated cardiomyopathy and chronic heart failure. Thallium scanning cannot be reliably used in patients with chronic heart failure to distinguish coronary artery disease from cardiomyopathy unless complete defects are present.

Adult↗

PubMed1982

Thallium-201 uptake in variant angina: probable demonstration of myocardial reactive hyperemia in man.

Myocardial thallium scintigraphy was performed in four subjects with variant angina and in one subject with isolated, fixed coronary obstruction. Three subjects with variant angina had short episodes of ischemic ST-segment elevation that lasted 20--100 seconds. Thallium scintigrams demonstrated excess uptake in regions judged to be ischemic by angiographic and electrocardiographic criteria. Two subjects, one with variant angina and the other with a fixed coronary lesion, had prolonged episodes of ischemia that lasted 390--900 seconds. Both had reduced thallium uptake in the ischemic regions. We conclude that myocardial reactive hyperemia is the cause of excess thallium uptake in patients with variant angina who have short episodes of myocardial ischemia.

Adult↗

PubMed1987

Measurement of infarct size and percentage myocardium infarcted in a dog preparation with single photon-emission computed tomography, thallium-201, and indium 111-monoclonal antimyosin Fab.

Single photon-emission tomography (SPECT) and indium 111-labeled monoclonal antimyosin Fab fragments were used to measure myocardial infarct size in 12 dogs, six subjected to balloon catheter-induced coronary artery occlusion for 6 hr (late reperfusion) and six subjected to occlusion with reperfusion at 2 hr (early reperfusion). Tomographic imaging was performed 24 hr after the intravenous injection of labeled Fab fragments with the use of a dual-head SPECT camera with medium-energy collimators. Immediately after the first tomographic scan, thallium-201 was injected into nine of 12 dogs and imaging was repeated. Estimated infarct size in grams was calculated from transaxially reconstructed, normalized, and background-corrected indium SPECT images with the use of a threshold technique for edge detection. Estimated noninfarcted myocardium in grams was calculated from obliquely reconstructed thallium SPECT images by a similar method. The animals were killed and infarct size in grams and true infarct size as a percentage of total left ventricular myocardial volume were measured by triphenyl tetrazolium chloride staining. Estimated infarct size from indium SPECT images showed an excellent correlation with true infarct size (r = .95, SEE = 4.1 g). Estimated percentage myocardium infarcted was calculated by dividing estimated infarct size from indium images by the sum of estimated infarct size plus estimated noninfarcted myocardium obtained from thallium images. Correlation between the estimated percentage of myocardium infarcted and true percentage of myocardium infarcted was excellent (r = .93, SEE = 4.4%). We conclude that dual-isotope SPECT with indium 111-monoclonal antimyosin antibodies and thallium-201 can accurately estimate infarct size and percentage myocardium infarcted.

Animals↗

PubMed1998

Effects of moderate exercise training on thallium uptake and contractile response to low-dose dobutamine of dysfunctional myocardium in patients with ischemic cardiomyopathy.

BACKGROUND: There is evidence that exercise training can induce myocardial and coronary adaptations in both animals and humans. However, the significance of these potentially important changes remains to be determined in patients with ischemic heart disease and left ventricular (LV) systolic dysfunction. METHODS AND RESULTS: To investigate whether exercise training can improve thallium uptake and the contractile response to low-dose dobutamine of dysfunctional myocardium, 46 patients (42 men, 4 women; mean age, 57+/-9 years) with chronic coronary artery disease and impaired LV systolic function (ejection fraction < 40%) were randomly assigned to two groups. The exercise group (n = 26) underwent exercise training at 60% of peak oxygen uptake for 8 weeks. The control group (n = 20) was not exercised. At baseline and after 8 weeks all patients underwent an exercise test with gas exchange analysis and stress echocardiography using low-dose dobutamine (5 to 10 microg/kg per minute) followed by thallium myocardial scintigraphy. Coronary angiography was performed in 23 patients at baseline and after 8 weeks. After 8 weeks, peak oxygen uptake increased significantly only in trained patients (24%). Significant improvements in the contractile response to dobutamine and thallium activity were observed in trained patients (28% and 31%, respectively; trained versus control: P<.001 for both). In a subgroup of trained patients, both improvements were correlated with an increase in the coronary collateral score (P<.005 and P<.001, respectively). CONCLUSIONS: Moderate exercise training improves both thallium activity and the contractile response of dysfunctional myocardium to low doses of dobutamine in patients with ischemic cardiomyopathy. The implication of this study is that even a short-term exercise training may improve quality of life by improvement of LV systolic function during mild-to-moderate physical activity in patients with ischemic cardiomyopathy.

Adaptation, Physiological↗

PubMed1998

Prognostic value of dipyridamole-thallium myocardial scintigraphy in patients with Kawasaki disease.

BACKGROUND: Although coronary artery lesions are critical complications of Kawasaki disease, their long-term outcome is still unclear. It is sometimes difficult to monitor progressive changes from aneurysms to stenotic lesions because coronary angiography (CAG) cannot be repeated very often, especially in infants. Our prospective study was designed to evaluate the prognostic value of dipyridamole-thallium single-photon-emission CT (SPECT) in the long-term follow-up of patients with Kawasaki disease. METHODS AND RESULTS: Of 459 consecutive patients with Kawasaki disease, coronary aneurysms were detected in 90 cases by echocardiography during the acute stage. After paired studies of selective CAG and SPECT were conducted, all patients were followed up and monitored for the occurrence of any cardiac events for > or =8 years. During the follow-up interval, there were 15 cardiac events (1 death, 5 infarctions, 2 coronary artery bypass graft operations, and 7 occurrences of unstable angina). Of patients who had some event, thallium redistribution was found on SPECT in 14 (93%, P<0.001). Of the various clinical and scintigraphic image variables, the presence of thallium redistribution was the best multivariate independent predictor of a late cardiac event (chi2=57.8, P<0.0001). The number of aneurysms detected on CAG added minimal statistical improvement to the model (chi2=1.9, P=0.0009). CONCLUSIONS: Dipyridamole-thallium SPECT is safely performed and is useful and important for risk stratification in the long-term follow-up of patients with Kawasaki disease.

Age of Onset↗

PubMed1988

The resting cardiointegram: correlation with stress thallium perfusion studies.

The cardiointegram is a noninvasive technique for the analysis of the electrical signals of the heart obtained by a transformation of the voltage versus time format by a series of integrations. The stress thallium perfusion study is a widely used test for the detection of coronary artery disease. In order to evaluate the correlation between the resting cardiointegram and the stress thallium 201 perfusion study, 20 patients with normal resting electrocardiograms underwent stress thallium tests and resting cardiointegrams. The cardiointegram was determined on two resting complexes of leads I, II, V4, V5, and V6 and called abnormal if five of ten complexes deviated outside a normalized template. There was concordance of the cardiointegram and the thallium study in 16 of 20 patients (80%). The sensitivity for the detection of coronary artery disease was 71%, and the specificity was 80%. The overall accuracy was 74%. Thus in patients with normal electrocardiograms, the cardiointegram is a useful noninvasive test for the detection of coronary artery disease.

Coronary Disease↗

PubMed1981

The usefulness of thallium-201 myocardial perfusion scintigraphy in the diagnosis of chronic cor pulmonale.

To open up the possibility of exact clinical diagnoses of chronic cor pulmonale, we performed thallium-201 myocardial perfusion scintigraphy on patients with chronic pulmonary disease. From the thallium activity in the left ventricle (plus ventricular septum) and right ventricle counted scintigraphically, we determined the thallium activity ratio of left to right ventricle (TAR). The intra- and inter-observer variations of this ratio were negligible. We compared TAR with pulmonary hemodynamic findings and with left to right ventricular mass ratio measured at autopsy, and obtained the following results. 1) Left to right ventricular mass ratio determined in 11 autopsied patients by the method of Fulton et al. was closely correlated with TAR values (r = 0.90, p less than 0.001). 2) In patients with chronic pulmonary disease, there were highly significant exponential inverse correlations between TAR and pulmonary arterial mean pressure, total pulmonary vascular resistance and right ventricular systolic pressure the the coefficients of -0.75, 0.72 or -0.77, respectively (p less than 0.001). These results suggested the possibility that the severity of pulmonary circulatory disturbance may be ascertained non-invasively by TAR measurement. Thus, thallium-201 myocardial perfusion scintigraphy is able to reveal non-invasively right ventricular hypertrophy in patients with chronic pulmonary disease, and it might be a useful means of clinically diagnosing chronic cor pulmonale. If TAR obtained from scintigrams is smaller than 2, the patient concerned may possibly have right ventricular hypertrophy and he or she may be diagnosed as having chronic cor pulmonale.

Adult↗

PubMed1981

Evaluation of myocardial infarction by radioisotope myocardial imaging with special reference on thallium-201 myocardial perfusion imaging.

One hundred and three patients with myocardial infarctions were studied with 201-thallium chloride and/or 99m-technetium pyrophosphate myocardial imaging and were followed-up for an average of 23 months. There were 24 false negative cases with 201-thallium chloride, but no deaths or serious complications occurred during the follow-up period in these false negative cases. There were six patients with widened QRS complexes (more than 0.12 seconds) without bundle branch blocks and in three of them myocardial infarction was not identified by electrocardiography. However, there were large myocardial perfusion defects in the anterior-inferior wall of the left ventricle. All of this group of patients died suddenly during the follow-up period. The incidence of complications and mortality rose sharply in patients whose myocardial perfusion defects detected by thallium-201 were larger than 40% of the entire left ventricle. The myocardial infarction areas measured by 99m-technetium pyrophosphate were 28.5 +/- 9.8 cm2 in non-survivors and 16.5 +/- 1.7 cm2 in survivors. In addition, ten patients with acute myocardial infarction were studied by double scan methods with thallium-201; myocardial perfusion defect areas were reduced from 29 +/- 3% of the entire left ventricle to 19 +/- 4% by nitrate administration, indicating that there were reversibly ischemic areas in acute myocardial infarction which could be transiently reduced by nitrate. Thus, the study suggests the possibility of decreasing myocardial perfusion defects in the early phase of acute myocardial infarction, leading to a better long term prognosis for the patients.

Adult↗

PubMed1988

Relationship between the relative regional thallium-201 uptake and the regional systolic or diastolic filling function.

Both the resting thallium-201 imaging and resting gated radionuclide ventriculography were conducted in the left anterior oblique view in 35 patients with isolated disease of the left anterior descending coronary artery (LAD), and the corresponding involved region was compared from two differing perspectives, one measuring regional ventricular function and the other regional myocardial perfusion. In the thallium-201 imaging, the thallium activity in the septal or apical region supplied by the LAD was calculated as an activity ratio between the mean value of the normally perfused lateral region and that of the septal or apical region, and was called relative thallium uptake (%T1 uptake). In the gated radionuclide ventriculographic study, a computer program subdivided the image of the left ventricle into 4 regions. The time-activity and first-derivative curves were computed in the septal and apical regions. Significant positive correlations were present between the %T1 uptake and the ejection fraction or peak ejection rate both in the septal and apical regions, indicating that the regional systolic function diminishes progressively as the perfusion abnormality increases. However, positive but poor and scattering correlations were found between the %T1 uptake and the peak filling rate, and there were no significant correlations between the %T1 uptake and the filling period in these affected regions. Thus, we could suppose that the regional systolic function is closely related to the regional %T1 uptake which probably reflects the amount of the residual viable myocardium, but there is the possibility that the regional diastolic filling function may be not so much related to the amount of the viable myocardium as is systolic function or may be modulated by some factors other than the amount of the regional viable myocardium.

Adult↗

PubMed1989

Effects of coronary artery bypass surgery on regions showing persistent defects in thallium myocardial images.

The indications for revascularization surgery and its effects on myocardial regions showing persistent defects in thallium myocardial images are controversial. The effects of aortocoronary bypass surgery on myocardial perfusion and wall motion in the regions with persistent defects were evaluated in 47 patients with thallium-201 single photon emission computed tomography and left ventriculography. In areas showing persistent thallium defects preoperatively the rate of improvement of perfusion was only 24% by postoperative thallium imaging, and 57% by wall motion analysis. These results were significantly inferior to those of regions with transient defects, which were 84% and 82%, respectively. A persistent defect may not be a definitive marker of a non-viable scar, but the results of surgery on such regions were unsatisfactory. It is concluded, therefore, that revascuralization surgery in regions with persistent defects is not always recommended and that the indications for surgery should be individually determined with operative risk balanced against benefits.

Adult↗

PubMed1993

Usefulness of thallium-201 re-injection method for the evaluation of myocardial viability.

Areas of the heart which are supposedly absent of myocardial viability due to persistent thallium defect in exercise thallium myocardial scintigraphy sometimes recover ventricular wall motion through coronary revascularization. To avoid such underestimation of myocardial viability, a "re-injection method" was developed. At the peak of supine ergometer exercise in 51 patients with coronary artery disease, 111 MBq thallium was injected. Conventional exercise and 3 h-delay images were then obtained using single photon emission computed tomography. Subsequently, 55 MBq thallium was injected and a re-injection image was obtained 1 h later. Each image was divided into 12 segments and compared by left ventriculography and coronary angiography. Redistribution was found in 36 patients (71%) on the delayed images and in 44 patients (86%) on either the delayed or the re-injection images (p < 0.05). There were 127 redistribution segments (38%) on the delayed images and 163 (49%) on the re-injection images out of 336 defects on the exercise images (p < 0.001). In normokinetic segments with significant coronary stenosis and in hypokinetic segments, redistribution was found in 42% and 45% of the defects, respectively, on the delayed images, and in 65% and 62% of the defects, respectively, on the re-injection images (p < 0.01). However, no significant differences were observed between the delayed and either the delayed or re-injection images in the akinetic segments. These results suggest that the re-injection method is useful for avoiding underestimation of myocardial viability.

Aged↗

PubMed1998

Comparison of filled-in myocardial segments after early and late reinjection of thallium-201--influence of the timing of reinjection on fill-in.

Thallium-201 (201Tl) late reinjection after stress-redistribution imaging improves the detection of viable myocardium. Recently, early reinjection of 201Tl immediately after stress imaging was proposed as a new method for distinguishing ischemic myocardium, hibernating myocardium, and myocardial scar. However, there are no data on the influence of the timing of reinjection on "fill-in." This study was designed to assess whether the reinjection time influences "fill-in" in chronic coronary artery disease. Thirty-three patients with chronic coronary artery disease were studied. All patients underwent exercise 201Tl tomography. Immediately after stress imaging, 37 MBq of thallium was reinjected earlier than usual and early reinjection delayed image (ERDI) was acquired 3 h later. With the same protocol, all patients also underwent a second study involving late reinjection of 201Tl within 1 week. An additional 37 MBq of thallium was reinjected 3 h after stress imaging, and late reinjection delayed image (LRDI) was obtained 10 min later. All images were analyzed qualitatively using a 4-point grading uptake score. Of the 72 hypoperfused segments on stress images, 66 segments showed fill-in and 6 showed persistent defects on ERDI, and of the same 72 segments 55 segments displayed fill-in and the remaining 17 showed persistent defects on LRDI (p<0.05). The delta uptake score (the uptake score of the delayed image minus that of stress image) in early reinjection was 1.60+/-0.80, which was significantly higher than that in late reinjection (1.24+/-0.94, p<0.01). A small dose of thallium reinjected immediately after stress imaging with delayed images obtained 3 h later is convenient and might provide another technique for determining myocardial viability.

Aged↗