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PubMed1992

[Three-dimensional display and its quantification of exercise stress myocardial tomography using thallium-201].

For accurate and stereoscopic delineation of the location and extent of perfusion abnormality by exercise stress myocardial emission tomography using thallium-201, three-dimensional myocardial images (3D image) were reconstructed from ordinary tomograms. We also quantitated perfusion abnormality, with myocardial thickness taken into consideration. We evaluated the usefulness of these 2 methods in patients with coronary artery disease (CAD). Sixty-one patients with 75% or more narrowing of at least one of their major coronary arteries were studied. Myocardial imaging was performed with thallium-201 immediately after exercise stress, and 3 hours thereafter (redistribution) using a rotating gamma camera. We reconstructed 3 routine oblique images and bull's eye maps which included myocardial thallium-201 washout rate maps. In addition to visual interpretation, washout rate abnormality (< 30%) was used as a criterion for exercise-induced myocardial ischemia. For reconstruction of 3D image, we used short-axis images. To identify the cardiac surface, an appropriate count threshold level was determined and image elements exceeding the threshold level were considered the cardiac surface. The heart was observed from 16 points around it and the brightness of the cardiac surface was adjusted in accordance with the distance between the observation point and the cardiac surface. Gradient shading was added and a stereoscopic 3D image was obtained. For the quantitative analysis of the perfusion abnormality, we selected short-axis images. By approximating each short-axis image using 2 circles which contacted the epicardial and endocardial surfaces, we readily calculated the total left ventricular myocardial voxel numbers and the perfusion abnormality voxel numbers. The ratio between these 2 parameters was expressed as % defect. The sensitivity of the 3D image for detecting CAD was 84%, which was similar to that of routine oblique images and the bull's eye method. We also detected the location and extent of perfusion abnormalities and their changes between exercise stress and redistribution in real size and stereoscopically. In patients who had initial myocardial infarction and one-vessel disease but no exercise-induced additional perfusion abnormalities, % defect correlated linearly with the left ventricular ejection fraction (r = -0.85, p < 0.005) and the peak level of the serum cardiac myosin light chain I in the acute phase of myocardial infarction (r = 0.81, p < 0.01). In addition, the relationship between % defect and the number and/or location of coronary artery stenosis in 22 patients with CAD, in whom exercise-induced perfusion defects had completely resolved at redistribution, showed that % defect is a useful indicator for quantitating perfusion abnormalities. In conclusion, the extent of perfusion abnormalities can be expressed in the unit of gram with this method.

Adult↗
PubMed1992

[Value of thallium-201 in the non-invasive evaluation of coronary cardiopathy].

Normal myocardial cells actively uptake the radioisotope Thallium-201 and its myocardial distribution is a reflection of the existent regional coronary artery blood flow at the moment of the examination. Thallium-201 reaches quickly a high intracellular concentration and then leaves myocardial cells in a mean time of 4 to 8 h. In the presence of significant coronary artery disease, uptake and elimination rates of Thallium-201 are delayed in ischemic tissue, compared to normal tissue. This leads to regional differences in relative concentrations which allow to identify viable areas with insufficient coronary flow in conditions of vasodilatation induced by exercise or pharmacologic means. This phenomenon does not occur in the irreversibly damaged myocardium, and affected areas fail to uptake the radioisotope. Clinical applications of this test are: 1.--Search for coronary artery disease. 2.--Assessment of patients with known coronary artery disease. 3.--Evaluation of patients after revascularization procedures. 4.--Assessment of coronary risk before peripheral vascular surgery. 5.--Detection of viable myocardium. 6.--Assessment of coronary reserve in patients with angor and normal coronary vessels.

Coronary Disease↗
PubMed1992

Correlation between left ventricular systolic function and dipyridamole thallium SPECT redistribution patterns in coronary artery disease.

The dipyridamole thallium-201 single photon emission computed tomography (SPECT) and resting gated blood pool ventriculography were sequentially conducted in 31 consecutive patients with angiographically proven coronary artery disease. The functional significance of various thallium redistribution patterns was assessed. The patients with an entirely complete (CR) or partial (PR) redistribution pattern had a higher global left ventricular ejection fraction than those with combined PR and no redistribution (NR), while patients with an entirely CR pattern did not have a statistically better ejection fraction than those with PR. Furthermore, myocardial segments with normal perfusion (N) and those with CR or PR had a higher regional ejection fraction than those with NR in the infero-apical area and the septal area. The regional ejection fraction was statistically higher in patients with CR than in those with PR in the septal area and higher, though not statistically significant, in the infero-apical area. The functional difference between groups with N and CR was not significant. Thus, we conclude that the redistribution patterns of dipyridamole thallium SPECT are closely correlated with systole function. Myocardium, in the presence of redistribution, will have a better functional performance in coronary artery disease.

Adult↗
PubMed1992

Exercise thallium-201 tomographic scintigraphy in the diagnosis of coronary artery disease: emphasis on the effect of exercise level.

Exercise thallium-201 imaging using single-photon emission computed tomography (SPECT) was evaluated in 154 patients with angiographically documented coronary artery disease (CAD) and in 25 normal subjects. Of the 154 patients with CAD, 134 (87%) had abnormal thallium images. By contrast, only 77 (50%) patients had ischemic ST-segment depression (p < 0.001). Among 25 normal subjects, 20 had normal exercise SPECT images. The specificity of exercise SPECT imaging (80% or 20/25) in excluding patients with CAD was not significantly higher than that of exercise electrocardiography (76% or 19/25). For the detection of individual vessel involvement by analysis of territories of perfusion abnormalities, the sensitivity and specificity of exercise SPECT were 72% and 96% for the left anterior descending, 78% and 85% for the right coronary, and 47% and 98% for the left circumflex artery. Ninety (group 1) of the 154 patients with CAD achieved adequate exercise end points (ischemic ST-segment depression or > 85% of maximal predicted heart rate) and 64 (group 2) did not. Exercise SPECT showed significantly more perfusion abnormalities in group 1 than in group 2 (96% vs 75%, p < 0.001). We conclude that: (1) exercise SPECT thallium imaging is more sensitive than exercise electrocardiography for detecting patients with CAD; (2) the sensitivity of the test is affected by the level of exercise; and (3) it is valuable in the identification of individual vessel involvement.

Coronary Disease↗
PubMedDate not supplied

Semi-quantitative planar scintigraphy using thallium 201 for detection and localization of coronary artery disease: correlation with coronary angiography.

Thallium 201 exercise redistribution planar myocardial perfusion scan using semiquantitative technique was performed in 80 symptomatic patients undergoing coronary angiography. Out of the 240 vessels studied by angiography, more than 70% luminal narrowing was detected in 87 vessels, borderline stenosis was found in 49 arteries and the remaining 104 vessels were normal. Thallium scan correctly identified the significant stenosis in 76 vessels and the absence of stenosis in 102 vessels. In addition, perfusion abnormality was found in relation with 21 vessels of borderline stenosis. The sensitivity and specificity of Thallium scan were estimated as 92% and 95% for left anterior descending artery (LAD), 79% and 98% for left circumflex artery (LCX), 88% and 100% for right coronary artery (RCA) and 87% and 98% for all coronary arteries combined together (ACA).

Adult↗
PubMed1992

Acute thallium toxicosis in a dog.

A Doberman Pinscher was evaluated for acute onset of gastroenteritis, characterized by anorexia, hematemesis, and hematochezia. The dog had ingested mole bait containing thallium 2 days prior to admission. Thallium toxicosis was confirmed by detection of thallium in the urine, using colorimetric analysis. The dog responded well to administration of antibiotics, fluids administered IV, warm-water enemas, and oral administration of activated charcoal slurries.

Ampicillin↗
PubMed1992

Predictive value of dipyridamole thallium imaging in a patient with myocardial bridging but without fixed obstructive coronary artery disease.

Both dipyridamole and exercise-201Tl imaging are sensitive, specific and of prognostic value in patients with suspected coronary artery disease, following myocardial infarction, and undergoing major noncardiac surgery. Though reported sensitivities and specificities vary widely from 60% to 100%, the consensus is that both are between 80% and 90% for both dipyridamole and exercise studies (23). Moreover, when compared directly in the same study populations, the two have equal sensitivities and specificities (9,11,13,23). Transient thallium perfusion abnormalities are the most consistent predictors of adverse cardiac events and have more predictive power than clinical and angiographic parameters. Thallium reversibility may be a better predictor of adverse cardiac events than angiography since it represents more of a physiologic rather than a purely anatomic evaluation of the heart. It is difficult to make an exact comparison of some of the studies in the literature because they use different patient populations, sometimes define coronary stenosis in different ways, may have different cardiac endpoints and may not differentiate between reversible and fixed thallium perfusion defects. Exercise has the advantage of a graded examination and more experience historically and is of importance in a detailed study of cardiopulmonary hemodynamics, as in cardiac transplantation. Dipyridamole is more useful in patients who cannot achieve symptom-limited, submaximal exercise. It may also be more useful for patients who are bedridden or have peripheral vascular disease. Angina occurs less frequently with dipyridamole.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Patients with symptomatic ischemia have larger thallium perfusion abnormalities and more adverse prognosis than patients with silent ischemia.

OBJECTIVE: To evaluate the mechanism for silent ischemia and the effect on prognosis. DESIGN: To test the hypothesis that patients with silent (compared with symptomatic) ischemia have less severe ischemia and a more favorable prognosis, the authors prospectively evaluated 152 consecutive patients with a positive exercise electrocardiogram with exercise thallium scintigraphy and followed them for two years. SETTING: Tertiary care university-based hospital. RESULTS: Asymptomatic patients during the exercise test had a greater exercise duration (9.4 +/- 3.1 versus 6.3 +/- 2.5 mins, P < 0.01), maximal heart rate (155 +/- 20 versus 136 +/- 20 beats/min, P < 0.01), systolic blood pressure (184 +/- 21 versus 176 +/- 23 mmHg, P < 0.05) and double product than patients who were symptomatic with chest pain. Although there was no difference in the magnitude of ST depression, time to ST depression was greater in the asymptomatic (5.6 +/- 2.7 mins), compared with symptomatic (4.6 +/- 2.6 mins), group (P < 0.01). Thallium ischemic score was smaller during asymptomatic ischemia (2.1 +/- 2.7) compared with symptomatic ischemia (3.9 +/- 3.1, P < 0.01). These findings were also demonstrated in a subgroup of 107 patients with both a positive exercise electrocardiogram and positive thallium scan. The patients with asymptomatic ischemia had a two-year cardiac event rate of 5.1% compared with 13.8% in the symptomatic patients (P = 0.065). CONCLUSIONS: Patients with asymptomatic ischemia have less severe myocardial ischemia and a better prognosis than patients with symptomatic myocardial ischemia during exercise testing.

Angina Pectoris↗
PubMed1977

Visualization of atrial myocardium with thallium-201: case report.

An adult patient evaluated for cyanotic congenital heart disease was found to have pulmonary atresia with intact ventricular septum, hypoplastic right ventricle, and right atrial enlargement. Thallium-201 myocardial imaging before surgical correction showed thallium activity in the right atrium. Following the establishment of a conduit from the right atrium to pulmonary artery, the right-atrial thallium uptake was even more prominent.

Adult↗
PubMedDate not supplied

[Obtaining bioluminescent bacterial strains for detection of thallium ions].

The possibility of Alcaligenes eutrophus T1 luxphenotype creation by temperature induced mutagenesis has been shown. These mutants are able to emit light after induction by thallium ions. This biological method of thallium detection possesses high specificity and sensitivity (0.5 microM of metal). Such microbial cells can be used to quantify bioavailability of thallium part in the environment.

Biological Availability↗
PubMed1992

Early thallium imaging after percutaneous transluminal coronary angioplasty: tomographic evaluation during adenosine-induced coronary hyperemia.

This study examined the immediate results of 201Tl imaging during adenosine-induced coronary hyperemia in 25 patients with one-vessel coronary artery disease, 4 +/- 3 days after percutaneous transluminal coronary angioplasty (PTCA). There were special features in our study: use of quantitative angiography and single-photon emission computed tomography (SPECT); a homogeneous group of patients (one-vessel disease) and a uniform stress (adenosine infusion). As a group, quantitative coronary angiography showed a decrease in percent diameter stenosis from 72% +/- 12% to 23% +/- 14%, p < 0.001. The thallium images were normal in 17 patients and abnormal in eight patients. However, of the eight patients, four had residual stenosis either in a secondary branch or downstream; one patient had local dissection (the residual stenosis could not be assessed reliably), two patients had > 50% residual diameter stenosis, and one patient had previous Q-wave myocardial infarction with a corresponding fixed thallium defect. In each of the eight patients with an abnormal image, a logical explanation could be identified. Thus, our results suggest that maximum reactive coronary hyperemia returns to normal immediately after PTCA, and that abnormal thallium results are due to inadequate dilatation or associated lesions.

Adenosine↗
PubMed1992

[Dipyridamole-thallium myocardial imaging in patients unable to exercise adequately: comparison with arm and bicycle ergometer].

We assessed the usefulness of dipyridamole-thallium myocardial imaging in patients unable to exercise adequately, compared with arm-ergometer and standard (bicycle) ergometer. Fifty-six patients with arteriosclerosis obliterans, aortic aneurysm, aortic dissection and so on, who were revealed normal imaging, were studied. Only one of 13 cases with arm-ergometer and two of 14 with bicycle ergometer reached target heart rate. Lung thallium uptake in the cases with arm-ergometer (37 +/- 9%) is higher than that with dipyridamole (29 +/- 5%). This elevation may be confused with pectoralis muscle uptake. Washout rate is 45 +/- 9% with dipyridamole and 46 +/- 12% with bicycle ergometer, respectively, though there was no significant differences. Myocardial/background counts ratio with dipyridamole (4.6 +/- 0.8%) is significantly higher than that with arm and bicycle ergometer (arm-ergometer; 3.5 +/- 0.7, bicycle ergometer; 4.2 +/- 0.9). Then, myocardial image with dipyridamole have superior quality. We concluded that dipyridamole-thallium myocardial imaging is very useful in the patients who have suboptimal exercise efforts.

Aged↗
PubMed2003

Thallium-199 myocardial perfusion scintigraphy in the diagnosis of restenoses after balloon dilatation and stenting of the coronary arteries.

AIM: To evaluate the diagnostic importance of thallium-199 myocardial perfusion single-photon emission computed tomography (SPECT) in the recognition of coronary restenoses and stenoses de novo of varying sites after endovascular treatment of coronary artery disease (CAD). MATERIAL AND METHODS: Myocardial perfusion scintigraphy was used to examine forty-six patients presenting with CAD before, 2-3 weeks, 3-6 months and 1-2 years after balloon dilatation and/or stenting of the coronary arteries (CA). The presence, character and magnitude of perfusion defects were estimated. RESULTS: The coronary angioplasty resulted in a 76% decrease of the mean size of transient ischemic zones. The reversible defects of thallium accumulation coexisted after operation with incomplete myocardial revasculization in patients with hemodynamically significant multivessel lesions. In the long-term follow up (3-6 months and 1-2 years after endovascular treatment), aggravation of coronary insufficiency in patients with incomplete revascularization proceeded mainly due to an increase in the size of the areas marked by persistent disturbance of coronary microcirculation determined not only by acute necrotic myocardial infarction but also by transformation of transient ischemic zones to the new stable perfusion defects. As compared to the early times, the patients with verified restenoses and stenoses de novo showed in the later period (3-6 months after coronary angioplasty) a significant increase in the mean size of the transient ischemic zones, exceeding the preoperative level. In six of the eleven patients, the appearance of the new stable defects was marked after 1-2 years in the area of blood supply to the recanalized CA. Meanwhile the condition of myocardial perfusion in the group of patients without restenoses did not undergo any noticeable changes. CONCLUSION: Myocardial perfusion scintigraphy using thallium-199 chloride allows to objectively evaluate over time the results of endovascular treatment of CAD. Also, there is every probability of success of predicting restenoses and stenoses de novo.

Angina, Unstable↗
PubMed2004

Thallium-201 myocardial perfusion imaging in patients with systemic lupus erythematosus.

The cardiovascular system is frequently affected in systemic lupus erythematosus (SLE). The observation of clinical manifestations related to the presence of coronary artery disease has not been frequently documented in young SLE patients. In these patients, the presence of inflammatory or thrombotic vascular lesions is often documented by anatomo-histological studies in the absence of previous clinical manifestations. The purpose of this study was to evaluate the presence of myocardial perfusion defects in SLE patients. The study was carried out in 15 patients without clinical signs of myocardial ischemia, 1 male and 14 females, 24 to 64 years old, with a mean SLE duration of 10.2 +/- 7.5 years. All the patients had normal blood pressure; electrocardiogram and Doppler-echocardiographic analysis showed values in the normal range. All the patients underwent thallium-201 exercise stress imaging repeated 3 hours later at rest, with tomographic SPECT analysis. Exercise test was carried out until submaximal load, without induction of ST segment alterations or symptoms. Scintigraphic scan showed normal thallium-201 SPECT imaging in 11/15 patients, while the other 4 patients had a slight perfusion defect, 3 of them in the inferior segment, in 2 non reversible and in 1 reversible; 1 patient had a non reversible defect in the septal segment. These slight perfusion defects, prevalently non reversible, may sometimes be a false positive imaging. Our results are in contrast with the literature observations concerning the frequent incidence of thallium-201 perfusion defects in SLE patients. In young asymptomatic SLE patients, our study does not report very important data indicating myocardial ischemia and suggesting the presence of significant coronary obstruction or vasculitis.

Adult↗
PubMed1992

[Clinical usefulness of the quantitative assessment of exercise thallium-201 myocardial imaging in patients with ischemic heart disease].

To clarify the significance of the quantitative analysis of the area of decreased activity in exercise thallium-201 myocardial imaging, 42 patients with one vessel disease (20 patients with angina pectoris without myocardial infarction, 22 patients with old myocardial infarction: MI) were evaluated by exercise thallium scan and compared with clinical findings and wall motion assessed by left ventriculography (LVG). Patients with MI were divided into two groups by LVG (Mild MI: MI with only hypokinesis on LVG, Severe MI: MI with akinesis or dyskinesis on LVG). The degree of defected area was expressed by the ratio of the counts of defected area to the normal area (Relative Activity: RA). RA of the area of decreased activity in patients with angina was higher than that of patients with MI (77.5 +/- 4.59% vs. 65.7 +/- 7.85%, p < 0.05). RA of the area of decreased activity in patients with mild MI was higher than that of patients with severe MI (69.5 +/- 4.78% vs. 61.3 +/- 8.45%, p < 0.01). The above results suggest that the regional thallium-201 uptake ratio in the scintigram may help to differentiate viable zones from necrotic ones and detect the degree of MI.

Evaluation Studies as Topic↗
PubMedDate not supplied

Determination of thallium in brain tissue by stable isotope dilution and field desorption mass spectrometry.

The utility of field desorption mass spectrometry for quantitative metal cation analysis in forensic sciences is demonstrated by the determination of a lethal thallium level in the brain tissue of an experimental animal. Stable isotope dilution and accumulation of the electrically recorded field desorption ion currents with a multi-channel analyzer allowed a direct estimation of thallium in homogenized tissue samples without further pretreatment. Experiments with standard solutions revealed the limit of detection for thallium to be about 10 pg of the metal cation.

Animals↗
PubMedDate not supplied

Detecting coronary artery disease using SPECT imaging: a comparison of thallium-201 and teboroxime.

Thirty subjects underwent single photon emission computed tomography (SPECT) imaging with technetium-99m teboroxime (TEBO). Of these, 26 underwent thallium SPECT imaging and 25 underwent quantitative coronary arteriography (QCA). Twenty-one of the subjects underwent all three studies. SPECT images were reviewed by two independent observers blinded to the clinical data. Stenoses were considered significant if there was a greater than or equal to 50% diameter narrowing as defined by QCA analysis of the coronary arteriograms. The overall sensitivity and specificity was 78% and 78%, respectively, for thallium-201. The overall sensitivity and specificity for teboroxime was 72% and 80%, respectively. The results obtained for these two tracers were not statistically different. Some of the false-positive results obtained from teboroxime imaging appear to have been due to the 10-min acquisition protocol and can be reduced with the use of new software programs using a continuous 3-min acquisition and dipyridamole. Teboroxime's rapid biologic half-life allows completion of SPECT imaging within 60-90 min, compared with the minimum of 4 h required for thallium SPECT imaging.

Coronary Angiography↗
PubMed2004

[Nervous system involvement in three children poisoned with thallium].

Three children, aged 5, 10 and 16 years, poisoned with thallium were hospitalized. Two of them suffered from sensory-motor and third from sensory polyneuropathy and additionally in the youngest child severe encephalopathy was observed. The correlations between serum and urine thallium levels and the severity of the symptoms in the course of the disease were positive. The most severe symptoms and the highest thallium level were observed in the youngest child.

Adolescent↗