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PubMed1986

Simultaneous measurement of left ventricular function and myocardial perfusion during a single exercise test: dual isotope imaging with gold-195 m and thallium-201.

The state of left ventricular function and myocardial perfusion are important determinants of prognosis in patients with coronary artery disease and information on both can be valuable for planning individual patient management. We have studied the feasibility of simultaneous measurement of left ventricular ejection fraction with ultra short-lived gold-195 m (half life 30.5 seconds) and myocardial perfusion with thallium-201, at rest and after exercise with a single-crystal gamma camera. The results with first-pass radionuclide angiocardiography (RNA) using gold-195 m at rest were reproducible and agreed closely with the results obtained using technetium-99 m equilibrium radionuclide angiocardiography (r = 0.93). Ejection fraction by first-pass gold-195 m RNA during semi-supine ergometric exercise decreased by greater than 5% in 13 out of 18 patients with coronary artery disease and stable angina. Simultaneous myocardial imaging with thallium-201 was abnormal in all patients. The change in regional wall motion abnormality score during exercise correlated with the change in myocardial perfusion (r = 0.71, P less than 0.01) and with the change in global left ventricular ejection fraction (r = 0.77, P less than 0.001). The widely differing energy levels and half-lives of gold-195 m and thallium-201 made it possible to separate clearly the images due to each radionuclide. This study has demonstrated the feasibility of simultaneous or sequential assessment of left ventricular function and myocardial perfusion during a single exercise test, a technique which can offer advantages in clinical evaluation of patients with coronary artery disease.

Adult↗
PubMed1987

The role of ambulatory ST-segment monitoring in the diagnosis of coronary artery disease: comparison with exercise testing and thallium scintigraphy.

The value of ambulatory ST-segment monitoring in the detection of underlying coronary artery disease was investigated in one hundred consecutive patients who underwent exercise testing and coronary arteriography for chest pain. Forty-seven also had thallium-201 radioisotope imaging performed. Six of the 26 patients with normal coronary arteries and 52 of the 74 patients with significant coronary artery disease had ST-segment changes during 48 h of ambulatory monitoring (sensitivity 77%). In comparison, the sensitivity of conventional exercise testing was 73% and specificity was 81%. Previous myocardial infarction did not influence the results, but patients with poor left ventricular function more often had absence of ambulatory ST-segment changes. Three-vessel coronary artery disease was detected more efficiently (sensitivity 80%), compared with single vessel disease (sensitivity 50%). Thallium scintigraphy demonstrated defects of uptake in nine patients without ambulatory ST-segment changes (sensitivity 82%, specificity 71%). The majority of these patients had small inferior or posterior defects in thallium uptake. Only one patient with ambulatory ST-segment changes had normal coronary arteries and demonstrable spasm. Thus, ambulatory ST-segment monitoring is as valuable as stress testing in the detection of coronary artery disease and in addition helps detect patients with coronary spasm and normal coronary arteries.

Ambulatory Care↗
PubMed1988

Dipyridamole-thallium 201 scintigraphy in the early post-infarction period. (Safety and accuracy in predicting the extent of coronary disease and future recurrence of angina in patients suffering from their first myocardial infarction).

To evaluate the safety and usefulness of myocardial thallium-201 scintigraphy after intravenous dipyridamole during the early post-infarction period, 35 patients under 60 years of age and with recent first transmural uncomplicated myocardial infarction (27 inferior, 8 anterior) were examined between the 5th and 13th day of hospitalization. Although four patients experienced angina and transient ischemic ST depression during the test, there were no serious complications. Patients were followed for a mean period of 11.4 +/- 6.3 months after hospital discharge. None of the patients experienced recurrent infarction and there were no cardiac deaths. In 11 patients there were reversible perfusion defects in areas different from those of myocardial infarction. Of these patients, seven (one with infarct vessel stenosis only and six with multivessel coronary disease) developed angina during the follow-up: five underwent coronary surgery because of severe angina refractory to full medical therapy. Out of the 24 patients without reversible perfusion defects, only two (with multivessel coronary disease) showed typical angina symptoms. The presence of redistribution on thallium scans was significantly more frequent in patients who developed a recurrence of angina over a period of 11.4 +/- 6.3 months of follow-up (P less than 0.0005). Thus dipyridamole-thallium 201 scintigraphy is a safe, non-invasive stress test which may be used early following uncomplicated myocardial infarction in order to identify patients at risk for the recurrence of angina.

Adult↗
PubMed1995

Preoperative dipyridamole thallium imaging and ambulatory electrocardiographic monitoring as a predictor of perioperative cardiac events and long-term outcome.

BACKGROUND: Dipyridamole thallium imaging (DTI) and ambulatory electrocardiography (AEGC) have been advocated as means to stratify risk before vascular surgery. The purpose of this study was to compare the predictive value of both tests in noncardiac surgery patients for perioperative cardiac morbidity and long-term mortality. METHODS: One hundred eighty patients were referred to the nuclear cardiology laboratory for DTI before noncardiac surgery. In patients with normal electrocardiograms and who consented, an ambulatory electrocardiogram was recorded for 24 h. DTI results were classified as negative, positive, or strongly positive (included in positive). Patients were assessed for a minimum of 12 months, and Kaplan-Meier cardiovascular survival curves were constructed with a log-rank statistic of equality with P < 0.05 significant. RESULTS: One hundred nine patients had both tests and then underwent surgery, sustaining 10 perioperative cardiac events (cardiac death, myocardial infarction, or symptomatic ischemia). The positive predictive values for DTI (18%) and AECG (25%) were similar, as were the likelihood ratios for positive tests (DTI = 2.1, AECG = 3.3). The likelihood ratios of a negative test were also similar (DTI = 0.45, AECG = 0.48). A strongly positive thallium defect had a somewhat greater likelihood ratio (3.5) for in-hospital events and was the only test result associated with a significantly worse long-term cardiac survival. CONCLUSIONS: AECG and DTI demonstrated a similar, although lower than initially reported, ability to stratify risk and predict short-term outcome. Only quantitative dipyridamole thallium also had predictive value for long-term prognosis.

Aged↗
PubMed1990

Postoperative myocardial infarction and cardiac death. Predictive value of dipyridamole-thallium imaging and five clinical scoring systems based on multifactorial analysis.

Sixty-six patients unable to complete a standard preoperative exercise test because of physical limitations were studied to determine the predictive value of individual clinical parameters, of clinical scoring systems based on multifactorial analysis, and of dipyridamole-thallium imaging before major general and vascular surgery. Study endpoints were limited to postoperative myocardial infarction or cardiac death before hospital discharge. There were nine postoperative cardiac events (seven deaths and two nonfatal infarctions). There was no statistical correlation between cardiac events and preoperative clinical descriptors, including individual clinical parameters, the Dripps-American Surgical Association score, the Goldman Cardiac Risk Index score, the Detsky Modified Cardiac Risk Index score, Eagle's clinical markers of low surgical risk, and the probability of postoperative events as determined by Cooperman's equation. There were no cardiac events in 30 patients with normal dipyridamole-thallium scans or in nine patients with fixed myocardial perfusion defects. Of 21 patients with reversible perfusion defects who underwent surgery, nine had a postoperative cardiac event (sensitivity, 100%; specificity, 43%). In the six other patients with reversible defects, preoperative angiography showed severe coronary disease or cardiomyopathy. Thus in patients unable to complete a standard exercise stress test, postoperative outcome cannot be predicted clinically before major general and vascular surgery, whereas dipyridamole-thallium imaging successfully identified all patients who sustained a postoperative cardiac event.

Aged↗
PubMed1984

Detection of sclerosing adenosis of the breast on a thallium scan.

Uptake of thallium in a patient with sclerosing adenosis of the breast was detected. Although thallium has been reported to accumulate in primary carcinoma of the thyroid, lung, and liver, detection of a breast lesion on a thallium scan has not been previously reported.

Coronary Disease↗
PubMed1992

The relationship between thallium uptake, blood flow, and blood pool activity in bone and soft tissue tumors.

Twenty patients with known primary untreated and recurrent bone and soft tissue tumors underwent thallium imaging and three-phase bone imaging in the same session. The ratio of thallium uptake in the tumor tissue to the contralateral normal tissue areas was compared with the same ratio for phase 1 (blood flow or arterial phase), phase 2 (blood pool), and phase 3 (delayed medroxy-diphosphonate, MDP, uptake). There was poor correlation between Tl uptake and phases 1 and 3 of the bone scan ratios; r = 0.37 and 0.46; P = 0.097 and 0.047, respectively. The thallium uptake ratios correlated well with blood pool ratios (phase 2) (r = 0.84 and P less than 0.01). In contrast to uptake into normal muscle, Tl-201 uptake into tumor is not highly dependent on blood flow alone and other factors predominate in determining its magnitude.

Bone Neoplasms↗
PubMedDate not supplied

Adenosine thallium imaging: pharmacodynamics and patient monitoring.

Because many critical care patients have cardiac, trauma, or other complications that rule out usual exercise cardiac stress testing, the new use of adenosine for thallium imaging may be used for these patients. Because of its vasodilating properties, adenosine can be combined with thallium imaging to determine the presence of coronary artery disease in persons unable to exercise. This author describes the pharmacodynamics of adenosine, the process of thallium imaging, and the interpretation of the images which help the nurse prepare the patient and prevent complications.

Adenosine↗
PubMedDate not supplied

Intracoronary thallium-201 assessment of thrombolysis in acute myocardial infarction. Validation of the method of imaging before and after therapy.

In order to study acute changes in perfusion with intracoronary thrombolytic therapy, we have used ten times the pretherapy intracoronary thallium-201 dose for the posttherapy study. Because of the larger posttherapy dose, the posttherapy images had ten times as many counts as the pretherapy images. Since the change in image quality between the pretherapy and posttherapy studies might affect interpretation, we studied the effect of image statistics on interpretation of perfusion scintigraphy. The pretherapy and posttherapy images were scored on a four-point scale in five segments on each of three views. In 31 patients, Poisson-distributed pseudorandom noise was added to the posttherapy study in order to match the statistical accuracy of the pretherapy study. A blinded interpretation of the pretherapy and posttherapy noise-added images was performed in the same way as the initial unblinded interpretation. The mean difference between the unblinded pretherapy and posttherapy scores (the improvement in thallium distribution with therapy) was 2.5+/-0.8 (standard error) compared with the difference between the blinded pretherapy and posttherapy noise-added scores which was 2.6+/-1.0. The correlation between readings of similar pairs of data was higher than the correlation between pretherapy and posttherapy studies. Thus, the difference in statistic quality of the pretherapy and posttherapy studies did not affect the interpretation of these studies. Therefore, our evaluation of pretherapy and posttherapy studies using a ten-fold increase in thallium-201 dosage is valid.

Coronary Vessels↗
PubMed1993

Thallium myocardial perfusion tomography using intravenous dipyridamole combined with maximal dynamic exercise.

Exercise thallium imaging is effective and provides information on exercise tolerance and symptoms, but is less sensitive if exercise is submaximal. When dipyridamole alone is used for such patients, the exercise parameters are lost and high background uptake results. This study examines dipyridamole combined with maximal exercise, to capitalize on the strengths of both techniques. Thallium tomography was performed in 122 patients with dipyridamole (group 1), exercise (group 2), or dipyridamole with maximum exercise (group 3). In patients with coronary artery disease, thallium tomography was abnormal in 92, 93 and 95% (P = ns), with reversible ischaemia in 82, 81 and 84% (P = ns) in the three groups, respectively. Among patients in groups 2 and 3 who exercised submaximally, detection of individual arterial stenoses was improved in group 3 (P < 0.05) and larger defects were found (2.4 versus 4.2 segments, P < 0.01). In group 3, no serious complications occurred and fewer vasodilatory side effects were seen than in group 1 (P < 0.01). The heart to splanchnic count ratio in groups 2 and 3 (1.61 versus 1.65, P = ns) was significantly greater than in group 1 (1.28, P < 0.0001). Compared with exercise alone, additional dipyridamole improved diagnostic accuracy in patients with limited exercise potential. Compared with dipyridamole alone, additional exercise provided useful exercise information, reduced vasodilatory side effects and improved scan quality. Combined dipyridamole and exercise stress is safe, and could be used routinely, but a larger study is required to establish if there is an overall diagnostic improvement.

Adult↗
PubMed1998

The safety of dipyridamole-thallium imaging in patients with critical aortic valve stenosis and angina.

Angina pectoris occurs in many patients with critical aortic valve stenosis, but in less than 50% of cases is it due to atherosclerotic coronary disease. Pre-operative coronary angiography is used to determine whether coronary revascularization is required in addition to aortic valve replacement. The aim of this study was to determine the safety and image quality of dipyridamole-thallium imaging (DPT) in excluding coronary artery disease requiring a coronary artery bypass graft in patients with aortic valve stenosis requiring aortic valve replacement. Dipyridamole-thallium imaging and coronary angiography were performed less than one month apart in patients with clinical and echo-Doppler evidence of aortic valve stenosis requiring aortic valve replacement. Coronary angiography and DPT were each interpreted by experienced observers blind to the other result. The safety of DPT was judged by symptoms, ECG changes, haemodynamic effects and the need for stress reversal. Image quality was determined from the myocardial-to-background thallium uptake ratio in a normal segment. Twelve patients with aortic valve stenosis (gradient 95 +/- 24 mmHg) were studied, all of whom had left ventricular hypertrophy. The dominant symptom was angina pectoris in eight patients, syncope in three and dyspnoea in one. None had previous myocardial infarction, but two were smokers, six were hyperlipidaemic and one was hypertensive. The patients tolerated DPT well and only one required stress reversal. The quality of the DPT images was good. The DPT image was entirely normal in eight (66%) patients, none of whom had coronary artery disease. Reversible defects were seen in four patients, all of whom had significant coronary artery disease. We conclude that DPT is safe in patients with aortic valve stenosis and angina pectoris. The image quality is good despite left ventricular hypertrophy. In patients with angina pectoris and aortic valve stenosis, coronary angiography can safely be restricted to those with abnormal myocardial perfusion results.

Aged↗
PubMed1991

What have we learnt from Graham Frederick Young? Reflections on the mechanism of thallium neurotoxicity.

The recent death of the psychopathic poisoner, Graham Frederick Young, prompts the question: has our knowledge of the toxic effects of thallium been increased as a result of his activities? The answer is 'yes' but very little. However, the poisonings led to a re-examination of the topography and pathogenesis of thallium intoxication and the suggestion that there are close similarities with chronic thiamine deficiency neuropathy and arsenical neuropathy. They might be termed chronic energy deprivation neuropathies and are associated with damage to other organs with high energy requirements, namely skin and its appendages, testis and heart. While the exact metabolic 'lesion' in thallium intoxication is not yet known, circumstantial evidence continues to suggest that it may be related to the known interaction of this ion with riboflavin, with consequent effects upon energy generation mechanisms associated with tissue flavoproteins.

Crime↗
PubMed1982

Clinical indications for thallium-201 myocardial perfusion scanning.

Thallium -201 myocardial perfusion scanning can assess regional myocardial perfusion noninvasively. As it is both time-consuming and expensive its use should be restricted to specific diagnostic problems. The clinical indications in known or suspected coronary artery disease are reviewed. In suspected coronary artery disease thallium scanning is most useful in patients with chest pain when the exercise ECG is uninterpretable, in men with probable angina but a negative exercise ECG, or conversely a positive exercise ECG without typical angina, and in women with probable angina and either a positive or a negative exercise ECG. In known coronary artery disease, thallium scanning may help determine the functional significance of a coronary obstruction found at angiography and may determine the site of myocardial ischaemia when multiple obstructions are present.

Angina Pectoris↗
PubMed1996

Comparison of optimised planar scintigraphy with SPECT thallium, exercise ECG and angiography in the detection of coronary artery disease.

BACKGROUND: Thallium SPECT has been shown to be more sensitive than planar imaging in the detection of coronary heart disease (CAD) in a number of reported series. Early (< 10 minutes) redistribution on planar imaging has been demonstrated in clinical studies and this may partly contribute to its lower sensitivity. AIM: To determine whether thallium SPECT is superior to planar scintigraphy (with the timing of imaging performed optimally so that it was commenced within five minutes of injection) in the detection of CAD. METHODS: Planar and SPECT studies were performed in 44 patients with significant (> 70% stenosis) CAD, seven patients with borderline stenoses (50-69%) and in 18 patients with no significant CAD. RESULTS: The sensitivity of planar imaging was 66% which was higher than exercise ECG 54% (ns) but significantly lower than SPECT 86% (p < 0.005). The specificity of planar thallium scintigraphy was 100% which was higher than SPECT (83%) and significantly higher than exercise ECG 72% (p < 0.05). SPECT had a significantly higher sensitivity for LAD and single vessel disease than planar imaging and this was unrelated to a history of prior myocardial infarction. CONCLUSION: Even when planar imaging is timed optimally to minimise the impact of early redistribution, SPECT is more sensitive than either planar imaging or exercise ECG in the detection of CAD, but its specificity is lower.

Adult↗
PubMed1979

Thallium-201 myocardial imaging in evaluation of asymptomatic individuals with ischaemic ST segment depression on exercise electrocardiogram.

Asymptomatic adults with normal physical examination, normal resting electrocardiogram, and normal routine laboratory evaluation who have a positive exercise electrocardiogram and abnormal exercise thallium-201 myocardial image have a very high probability of angiographically significant coronary artery disease. If, on the other hand, the exercise electrocardiogram is positive for "ischaemic" ST segment changes, but the exercise thallium image is normal, the probability for coronary disease is low. The exercise electrocardiogram combined with thallium-201 myocardial image are safe non-invasive methods which can be performed on an out-patient basis.

Adult↗
PubMed1984

Improved detection of myocardial infarction by emission computed tomography with thallium-201. Relation to infarct size.

Emission computed tomography with thallium-201 was compared with planar imaging in its ability to detect myocardial infarctions of various sizes four weeks after the onset. Tomography was performed after planar imaging at rest in 160 patients with a first myocardial infarction, in whom infarct size was prospectively estimated by the peak value of creatine kinase activity at the time of the acute episode and in 39 patients without infarction. The planar images and the transaxial, short axial, and long axial tomograms were interpreted qualitatively. Tomography was significantly more sensitive than planar imaging in detecting anterior (87% v 96%), inferior (73% v 97%), and non-transmural (47% v 87%) infarcts. The increased sensitivity was confined to detecting small infarcts as assessed by the peak creatine kinase value (44% v 89% when peak creatine kinase activity was less than or equal to 1000 IU/l). The overall sensitivity was 96% for tomography and 78% for planar imaging. The specificity was similar (92%) with the two techniques. Thus emission computed tomography can improve the detection rate of small infarcts that cannot be identified on planar images, by showing the three dimensional distribution of thallium-201, and increases the diagnostic value of thallium-201 scintigraphy.

Adult↗
PubMed1986

Dipyridamole combined with exercise for thallium-201 myocardial imaging.

A new stress test for thallium-201 myocardial imaging in which pharmacological coronary vasodilatation with dipyridamole is combined with dynamic exercise is described. In 38 patients with coronary artery disease the sensitivity, total number of defects, degree of redistribution, and visual quality of thallium-201 imaging were greater after dipyridamole with exercise testing than after exercise alone. When the data from these 38 patients were combined with the results of dipyridamole-exercise imaging in 49 patients in whom exercise electrocardiography had been inconclusive then the technique gave a sensitivity for coronary disease of 87% and a specificity of 92%. Dipyridamole also increased the sensitivity of the exercise electrocardiogram, so that no patient with coronary disease had a strictly negative dipyridamole-exercise stress test. Only five of 214 patients who have now undergone this test have had complications requiring reversal of vasodilatation with aminophylline. The combined use of dipyridamole and exercise in this simple technique is a reliable and safe improvement on standard thallium-201 imaging tests.

Adult↗
PubMed1988

Prognosis and thallium-201 scintigraphy in patients admitted with chest pain without confirmed acute myocardial infarction.

Exercise and rest thallium scintigraphy and exercise electrocardiography were performed after discharge in 158 patients aged less than 76 years admitted with chest pain in whom a suspected diagnosis of acute myocardial infarction had not been confirmed. During a follow up of 12-24 months (median 14 months) there were 10 cardiac events--that is, non-fatal acute myocardial infarction or cardiac deaths. Transient thallium defects and abnormal ST response (that is ST segment deviation or uninterpretable ST segment) during exercise were correlated significantly with an unfavourable prognosis. One hundred and four patients with neither of these characteristics were at lower risk of a cardiac event than the 19 patients with both of these characteristics. The percentages of patients in these two groups without a cardiac event after one year were 98.1 and 78.8 respectively. Thallium scintigraphy, alone or in combination with exercise electrocardiography, can be used to identify groups at high and low risk of future cardiac events, in patients with chest pain in whom acute myocardial infarction is suspected but not found.

Chest Pain↗