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PubMedDate not supplied

Comparison of dobutamine stress echocardiography and stress thallium-201 single-photon emission computed tomography for detecting coronary artery disease.

Dobutamine stress echocardiography and stress thallium-201 single-photon emission computed tomography (SPECT) were compared for detecting coronary artery disease in 120 consecutive patients who underwent concomitant quantitative coronary angiography. The left ventricle was divided into anterior, inferior, and lateral regions. Wall motion or perfusion abnormalities observed within each region were classified as ischemia or fixed abnormality. Both tests showed 81% agreement in all 120 patients. Complete agreement was observed in 77% of the 360 regions analyzed. The overall sensitivity of dobutamine stress echocardiography and thallium-201 SPECT for the detection of coronary artery disease was 85% and 89%, and the specificity was 93% and 85%, respectively. A good correlation was found between the wall motion score index and perfusion defect size at peak stress and at rest (r = 0.70). Dobutamine stress echocardiography and thallium-201 SPECT exhibit a comparable accuracy for diagnosing coronary artery disease, localizing coronary artery stenosis, and detecting regional myocardial abnormalities. The wall motion score index may be useful for evaluating the myocardial area at risk.

Adult↗
PubMed1999

Cardiac assessment with thallium scanning prior to aortic aneurysm repair.

Coronary artery disease occurs commonly in patients with aortic aneurysms and is a major cause of morbidity and mortality. The role of screening and intervention for cardiac disease prior to aneurysm repair is controversial. The outcome after cardiac screening with thallium scanning and/or angiography in 102 consecutive patients undergoing aortic aneurysm repair was documented. Significant coronary artery disease was found in 34 (33%) patients and two patients had either coronary artery bypass or angioplasty prior to aneurysm repair. There was no cardiac mortality after aneurysm repair and the overall mortality on an intention-to-treat basis was 2%. There was good correlation between prior history of cardiac events, electrocardiography (ECG) and the results of screening with thallium scanning and angiography. There was no correlation between cardiac history, ECG and the incidence of cardiac events in the postoperative period. Significant coronary artery disease was found in 33% of patients without a cardiac history or abnormal ECG. Cardiac screening with thallium scanning confirmed a high incidence of significant coronary disease in patients with aortic aneurysm. In this study, cardiac intervention followed by expedient aneurysm repair in 20 patients was associated with zero mortality. The short-term benefit of such a policy is difficult to prove and its main advantage may be better long-term survival.

Aged↗
PubMedDate not supplied

Assessment of myocardial viability by dynamic tomographic iodine 123 iodophenylpentadecanoic acid imaging: comparison with rest-redistribution thallium 201 imaging.

BACKGROUND: This study examined the ability of dynamic 123I-labeled iodophenylpentadecanoic acid (IPPA) imaging to detect myocardial viability in patients with left ventricular (LV) dysfunction caused by coronary artery disease. METHODS AND RESULTS: Serial 180-degree single-photon emission computed tomographic (SPECT) images (five sets, 8 minutes each) were obtained starting 4 minutes after injection of 2 to 6 mCi 123I at rest in 21 patients with LV dysfunction (ejection fraction [EF] 34% +/- 11%). The segmental uptake was compared with that of rest-redistribution 201Tl images (20 segments/study). The number of perfusion defects (reversible and fixed) was similar by IPPA and thallium (11 +/- 5 vs 10 +/- 5 segments/patient; difference not significant). There was agreement between IPPA and thallium for presence or absence (kappa = 0.78 +/- 0.03) and nature (reversible, mild fixed, or severe fixed) of perfusion defects (kappa = 0.54 +/- 0.04). However, there were more reversible IPPA defects than reversible thallium defects (7 +/- 4 vs 3 +/- 4 segments/patient; p = 0.001). In 14 patients the EF (by gated pool imaging) improved after coronary revascularization from 33% +/- 11% to 39% +/- 12% (p = 0.002). The number of reversible IPPA defects was greater in the seven patients who had improvement in EF than in the patients without such improvement (10 +/- 4 vs 5 +/- 4 segments/patient; p = 0.075). CONCLUSIONS: 123I-labeled IPPA SPECT imaging is a promising new technique for assessment of viability. Reversible defects predict recovery of LV dysfunction after coronary revascularization.

Adult↗
PubMedDate not supplied

Prognostic utility of increased pulmonary thallium uptake in patients without ischemia.

BACKGROUND: Although the combination of increased pulmonary thallium uptake and ischemia has demonstrated prognostic utility, the value of pulmonary uptake independent of ischemia has not been evaluated critically. Accordingly, our purpose was to evaluate the prognostic utility of thallium lung uptake in patients who do not have stress-induced defects. METHODS AND RESULTS: We studied 184 patients who were divided into three groups. Patients with increased pulmonary uptake were grouped into either the normal perfusion (n = 48) or fixed defect (n = 44) scan group and were compared with a third group (n = 92) of control patients who had normal scans and no lung uptake. During a mean follow-up of 23 +/- 13 months, there were 13 cardiac events (death or myocardial infarction) and the incidence per year was 0.6%, 2%, and 12% in the control, normal, and fixed defect groups, respectively (p < 0.00001). Life table analysis demonstrated greater event-free survival rates in the control and normal groups compared with the group with fixed defects. A Cox regression analysis showed that the number of fixed defects (infarct segments) was the most important independent prognostic factor (p < 0.00001) for future cardiac events. CONCLUSION: In patients with increased pulmonary thallium uptake and no stress perfusion defects, the prognosis is similar to that of control patients. However, patients with infarct segments and lung uptake have a significantly worse prognosis.

Coronary Circulation↗
PubMed1999

Rest-redistribution thallium-201 myocardial scintigraphic study in cardiac amyloidosis.

BACKGROUND: Histopathological study in amyloid heart demonstrates that myocyte destructed by the extracellular deposition of amyloid protein together with viable myocyte is present. We hypothesized that rapid thallium washout may be found in amyloid heart as in regions which have a mixture of viable myocyte and scar tissue in patients with myocardial infarction. Thus, the purpose of this study was to evaluate the extent and severity of myocardial damage due to amyloid deposits using the washout rate of the tracer on rest-redistribution thallium-201 (201Tl) myocardial scans in cardiac amyloidosis patients. METHODS: Rest-redistribution 201Tl myocardial scintigraphy was performed in 5 patients with biopsy-proved systemic amyloidosis with cardiac involvement (amyloidosis group). The initial and delayed images were obtained 15 min and 4 h, respectively, after intravenous injection of the tracer of 111 MBq. Washout rate of the tracer was calculated. Twelve patients with no apparent heart disease served as controls (control group). RESULTS: Mean washout rate of the whole heart was higher in the amyloidosis group than in the control group (56 +/- 9% vs 36 +/- 6%, p < 0.001). Particularly, 4 of the 5 patients in the amyloidosis group presented a very high rate of thallium clearance which ranged from 57 to 61%, and died in less than a year. In the remaining 1 patient who had a normal washout rate of the tracer in the first study, it changed from 40 to 53% during the 5-year follow-up period. CONCLUSIONS: Washout rate in the setting of rest and delayed 201Tl images may represent the severity of amyloid depositions in the myocardium and may provide prognostic information.

Aged↗
PubMed2000

Diagnosis of coronary artery disease in patients with permanent cardiac pacemaker by dobutamine stress echocardiography or exercise thallium-201 myocardial tomography.

This study evaluated the use of dobutamine stress echocardiography and exercise thallium-201 myocardial computed tomography (CT) in the diagnosis of coronary artery disease (CAD) in patients with permanent transvenous pacemaker with the electrode implanted in the right ventricle (RV). Twenty-nine consecutive patients with pacemaker underwent dobutamine stress echocardiography, exercise thallium-201 myocardial CT, and coronary arteriography over a period of 8 +/- 1 days. None of these patients had suffered a myocardial infarction (MI). The cardiac rhythm of every patient was electrically paced during echocardiography and tomography. Sixteen (55%) patients showed CAD on angiography (stenosis > or = 50% of the luminal diameter of a major epicardial vessel). The detection sensitivity for CAD was 94% for the tomography and 88% for the echocardiography (P = NS). The difference between the sensitivities of the two techniques in detecting CAD based on the affected coronary artery was not statistically significant. Of the 13 patients without CAD, tomography showed a positive result in nine cases, i.e., a specificity of 31%, whereas echocardiography showed a positive result in only one case, i.e., a specificity of 92% (P < 0. 01). Exercise thallium-201 myocardial computed tomography produces an increased rate of false-positive results in patients with permanent transvenous cardiac pacemaker (PCP) implanted in the right ventricle (RV). Dobutamine stress echocardiography can thus be used to reduce considerably the level of false-positive results in these patients and still retain a detection sensitivity for CAD equal to that of myocardial tomography.

Aged↗
PubMed1986

Nifedipine and thallium-201 myocardial perfusion in progressive systemic sclerosis.

Heart disease in patients with progressive systemic sclerosis may be due in part to myocardial ischemia caused by a disturbance of the coronary microcirculation. To determine whether abnormalities of myocardial perfusion in this disorder are potentially reversible, we evaluated the effect of the coronary vasodilator nifedipine on myocardial perfusion assessed by thallium-201 scanning in 20 patients. Thallium-201 single-photon-emission computerized tomography was performed under control conditions and 90 minutes after 20 mg of oral nifedipine. The mean (+/- SD) number of left ventricular segments with perfusion defects decreased from 5.3 +/- 2.0 to 3.3 +/- 2.2 after nifedipine (P = 0.0003). Perfusion abnormalities were quantified by a perfusion score (0 to 2.0) assigned to each left ventricular segment and by a global perfusion score (0 to 18) for the entire left ventricle. The mean perfusion score in segments with resting defects increased from 0.97 +/- 0.24 to 1.26 +/- 0.44 after nifedipine (P less than 0.00001). The mean global perfusion score increased from 11.2 +/- 1.7 to 12.8 +/- 2.4 after nifedipine (P = 0.003). The global perfusion score increased by at least 2.0 in 10 patients and decreased by at least 2.0 in only 1. These observations reveal short-term improvement in thallium-201 myocardial perfusion with nifedipine in patients with progressive systemic sclerosis. The results are consistent with a potentially reversible abnormality of coronary vasomotion in this disorder, but the long-term therapeutic effects of nifedipine remain to be determined.

Adult↗
PubMed1994

Dipyridamole-thallium scintigraphy and gated radionuclide angiography to assess cardiac risk before abdominal aortic surgery.

BACKGROUND: Because many patients with atherosclerotic disease of the abdominal aorta also have coronary artery disease, assessment of cardiac risk before abdominal aortic surgery has received much attention. Our prospective study was designed to identify predictors of cardiac risk in consecutive patients evaluated preoperatively with dipyridamole-thallium single-photon-emission computed tomography (SPECT) to assess myocardial perfusion and radionuclide angiography to measure left ventricular ejection fraction. METHODS: Clinical and scintigraphic data were collected prospectively during hospitalization in 457 consecutive patients undergoing elective abdominal aortic surgery. Adverse cardiac outcomes were predicted with multivariate analyses. RESULTS: Eighty-six patients (19 percent) had one or more of the following postoperative complications: prolonged myocardial ischemia (61 patients), myocardial infarction (22), congestive heart failure (20), and severe ventricular tachyarrhythmia (2). Twenty patients died postoperatively (4.4 percent), half of them from cardiac causes. Information about myocardial perfusion obtained from dipyridamole-thallium SPECT did not accurately predict adverse cardiac outcomes. The best correlates of cardiac complications were definite clinical evidence of coronary artery disease (odds ratio, 2.6; 95 percent confidence interval, 1.6 to 4.3) and age greater than 65 years (odds ratio, 2.3; 95 percent confidence interval, 1.4 to 3.6). Measurement of the ejection fraction was useful only in the prediction of left ventricular failure. Age greater than 65 years was the only predictor of death (odds ratio, 26.4; 95 percent confidence interval, 3.5 to 200.0). CONCLUSIONS: The presence of definite clinical evidence of coronary artery disease and older age were the most important preoperative predictors of an adverse cardiac outcome after abdominal aortic surgery. These results suggest that the routine use of dipyridamole-thallium SPECT and radionuclide angiography for screening before abdominal aortic surgery may not be justified.

Aged↗
PubMedDate not supplied

Nicorandil affords cardioprotection in patients with acute myocardial infarction treated with primary percutaneous transluminal coronary angioplasty: assessment with thallium-201/iodine-123 BMIPP dual SPECT.

BACKGROUND: It has been reported that nicorandil restores blood flow to reperfused myocardium in patients with acute myocardial infarction. However, whether nicorandil might decrease infarct size remains unclear. The aim of this study was to assess the effect of nicorandil on infarct size with thallium-201/beta-methyl-p-iodophenyl pentadecanoic acid (BMIPP) dual-isotope single photon emission computed tomography. METHODS: A total of 62 patients were randomly assigned to receive intravenous nicorandil (4 mg in 5 minutes at admission, immediately followed by 6 mg/hr over a 24-hour period) or placebo. All patients were divided into 4 groups: Group N-a, 16 patients with preexisting angina treated with nicorandil; N-b, 15 patients without preexisting angina treated with nicorandil; C-a, 14 patients with preexisting angina given placebo; C-b, 17 patients without preexisting angina given placebo. Tl-201/BMIPP imaging was performed in the 62 patients within 7 days after admission. Dual-isotope single photon emission computed tomographic images were quantified by severity index with a polar map. RESULTS: The BMIPP severity index was similar among the 4 groups. Only the thallium severity index in the N-a group was significantly less (P<.05). The ratio of the thallium severity index to that of BMIPP in the N-a group was significantly decreased compared with those of the other groups. CONCLUSION: Nicorandil has a protective effect in patients with acute myocardial infarction and preexisting angina treated with primary balloon angioplasty.

Angina, Unstable↗
PubMed1985

Selection of patients for preoperative coronary angiography: use of dipyridamole-stress--thallium myocardial imaging.

To identify patients likely to benefit from preoperative coronary angiography, a method utilizing pharmacologically induced coronary vasodilatation in conjunction with serial thallium 201 myocardial perfusion imaging was investigated. Fifty-four patients admitted for elective aortic or femoropopliteal procedures were studied. There were no cardiac ischemic complications in 32 patients with normal scans or persistent defects (scar). In contrast, 7 of 15 patients with thallium redistribution (ischemia) on pre-operative scanning had perioperative ischemic events, including one death and two acute infarcts. An additional seven patients with positive scans (redistribution) underwent coronary angiography prior to vascular surgery; surgically important two- or three-vessel disease was confirmed in all. Dipyridamole-thallium imaging facilitates selection of the subset of truly high-risk patients in whom preoperative coronary angiography may be warranted.

Aged↗
PubMed1983

Thallium poisoning in group assassination attempt.

The use of thallium in an attempted assassination of four members of a political organization is described. The intended victims first complained of abdominal pain within two days of eating a snack prepared by their host; painful peripheral neuropathy occurred within one week and loss of hair within three weeks. Swelling of the optic disk was observed in one patient. The diagnosis was made on clinical grounds and confirmed by the detection of high levels of thallium in serum, urine, and hair and/or nail samples. All patients recovered completely. The possibility of thallium poisoning should be considered in patients who present with acute onset of gastrointestinal symptoms, pain and paresthesias in the legs, and hair loss, so that appropriate treatment can be initiated at an early stage.

Adult↗
PubMed2003

Usefulness of thallium-201 SPECT scintimammography to differentiate benign from malignant breast masses in mammographically dense breasts.

The purpose of this study was to assess the usefulness of thallium-201 (Tl-201) single-photon emission-computed tomography (SPECT) scintimammography to differentiate benign from malignant breast masses in 32 female Taiwanese patients with indeterminate mammographic probability of malignancy because of mammographically dense breasts. All breast masses were removed, and final histopathological diagnoses were obtained in all cases. The results showed that thallium-201 SPECT scintimammography findings were true-positive in 22 cases, false-positive in 1 case, true-negative in 7 cases, and false-negative in 2 cases. The diagnostic sensitivity, specificity, and accuracy were 91.7%, 87.5%, and 90.6%, respectively, for detecting breast cancer in mammographically dense breasts. In conclusion, thallium-201 SPECT scintimammography is a useful tool for differentiating benign from malignant breast masses in patients with indeterminate mammograms because of mammographically dense breasts.

Adult↗
PubMed1973

Effects of thallium salts on neuronal mitochondria in organotypic cord-ganglia-muscle combination cultures.

A functionally coupled organotypic complex of cultured dorsal root ganglia, spinal cord peripheral nerve, and muscle has been employed in an experimental approach to the investigation of the neurotoxic effects of thallium. Selected cultures, grown for up to 12 wk in vitro, were exposed to thallous salts for periods ranging up to 4 days. Cytopathic effects were first detected after 2 h of exposure with the appearance of considerably enlarged mitochondria in axons of peripheral nerve fibers. With time, the matrix space of these mitochondria became progressively swollen, transforming the organelle into an axonal vacuole bounded by the original outer mitochondrial membrane. Coalescence of adjacent axonal vacuoles produced massive internal axon compartments, the membranes of which were shown by electron microprobe mass spectrometry to have an affinity for thallium. Other axoplasmic components were displaced within a distended but intact axolemma. The resultant fiber swelling caused myelin retraction from nodes of Ranvier but no degeneration. Impulses could still propagate along the nerve fibers throughout the time course of the experiment. Comparable, but less severe changes were seen in dorsal root ganglion neurons and in central nerve fibers. Other cell types showed no mitochondrial change. It is uncertain how these findings relate to the neurotoxic effects of thallium in vivo, but a sensitivity of the nerve cell and especially its axon to thallous salts is indicated.

Animals↗
PubMed1998

Lung uptake of thallium-201: a marker of defect reversibility?

High lung uptake of thallium-201 at stress is reported to be associated with a large number of perfusion defects and poor prognosis. This study was performed to assess whether the reversibility of stress perfusion defects was related to lung uptake. Gated planar thallium scans at stress and at redistribution from 102 consecutive patients with essentially normal left ventricular ejection fraction (using 99mTc gated blood pool ventriculography) were graded in terms of defect size. Lung and myocardial uptake of thallium were quantitated by region of interest methods relative to the given activity in a previously validated method. There was no significant correlation (non-parametric) between lung uptake and degree of redistribution (p = ns, rs = 0.140). There was a weak but positive correlation between lung uptake and defect size (p < 0.05, rs = 0.188). Both exercise time and double product showed a negative correlation with lung uptake (e.g. for double product, p < 0.0005, rs = -0.541). In conclusion, contrary to our expectation, lung uptake is not related to the degree of redistribution. High lung uptake seems to reflect poor cardiovascular reserve.

Biophysical Phenomena↗
PubMed1992

Diagnostic accuracy of exercise thallium-201 scintigraphy in men with asymptomatic essential hypertension.

Coronary artery disease is responsible for much of the morbidity and mortality in patients with essential hypertension, and these complications have proven to be relatively resistant to antihypertensive therapy. However, the diagnosis of coronary disease in the hypertensive population has been considered problematic. In the present study, 30 asymptomatic patients with mild to moderate hypertension with positive exercise electrocardiograms (ECG) or stress thallium-201 scintigrams underwent coronary angiography to determine the accuracy of these tests for coronary artery disease. The exercise ECG was positive in 25 subjects, of whom 15 had significant coronary lesions and 10 did not. Thallium-201 scintigraphy proved more accurate: 17 of 18 patients with reversible abnormalities had significant obstructive coronary disease anatomically corresponding to the defect, one patient with a fixed defect had normal coronary arteries and was found to have an idiopathic cardiomyopathy, and 9 of 11 without defects had no significant lesions. The results were similar in populations with and without echocardiographic criteria for left ventricular hypertrophy. These findings indicate that despite previous suggestions to the contrary, thallium-201 scintigraphy can accurately diagnose coronary artery disease in most patients with asymptomatic essential hypertension, and that most asymptomatic hypertensive patients with physiologic evidence of myocardial ischemia have associated coronary artery disease.

Adult↗
PubMed1993

Prognostic value of thallium-201 myocardial scintigraphy after atrial transoesophageal pacing in patients with suspected coronary artery disease.

Fifty-five patients with suspected coronary artery disease underwent planar thallium-201 myocardial scintigraphy after atrial transoesophageal pacing. Coronary angiography was carried out in all patients. Eighteen patients had no myocardial infarction, but a greater than 50% narrowing of at least one main vessel: initial hypoperfusion with redistribution at 4 h occurred in 16 patients (sensitivity 89%). Twenty-one patients had had a previous myocardial infarction: a reversible thallium defect was observed in 12 patients and an irreversible defect in the nine remaining patients. Sixteen patients had normal coronary arteries: a reversible thallium defect was observed in three patients (specificity 81%). After a mean follow-up of 22 +/- 13 months (range 6 to 40), 23 cardiac events occurred: cardiac death in one patient, unstable angina in three, and revascularization procedures for recurrent angina despite medical therapy in 19 (coronary artery bypass surgery in 7 and coronary angioplasty in 12). By univariate analysis, the predictors of future cardiac events were a history of previous myocardial infarction (odds ratio 5.5, P < 0.02), multivessel coronary artery disease (odds ratio 9.6, P < 0.0002), angina during atrial pacing (odds ratio 5.1, P < 0.05), abnormal scintigraphy (odds ratio 17.1, P < 0.001) and reversible perfusion defect after pacing (odds ratio 7.9, P < 0.002). By multivariate analysis, multivessel disease (P < 0.004) and reversible perfusion defect after pacing (P < 0.02) were the only independent predictors of future cardiac events.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Thallium-201 scintigraphy after dipyridamole infusion with low-level exercise. III. Clinical significance and additional diagnostic value of ST segment depression and angina pectoris during the test.

Intravenous dipyridamole thallium testing is a useful alternative procedure for assessing coronary artery disease (CAD) in patients who are unable to perform maximal exercise tests. Ischaemic ST segment depression and angina pectoris are frequently observed during the test, in particular when exercise is added to dipyridamole infusion. To establish the clinical significance and additional diagnostic value of these markers of ischaemia during dipyridamole low-level exercise testing (DXT) 57 patients with CAD (group A), 21 patients with normal or near-normal coronary arteries at coronary arteriography (group B), and 20 healthy subjects with low likelihood of CAD (group C) were studied. During DXT ischaemic ST segment depression was observed in 28 patients (47%) of group A and in two patients (10%) of group B. Angina pectoris was experienced by 35 patients (61%) of group A and by five patients (24%) of group B. The positive predictive value of both ST depression and angina pectoris was high (88 and 93%, respectively), but the negative predictive values were low (42 and 40%, respectively). Combining ST segment analysis with the findings of thallium imaging significantly increased the diagnostic accuracy of the test. ST segment depression, angina pectoris, and thallium abnormalities were highly specific findings if the study population consisted of asymptomatic subjects with a low likelihood of CAD (group C). Sensitivity for the detection of the presence of CAD increased with the extent of CAD for all parameters studied. Thus, ST depression and angina pectoris, alone or in combination, during DXT have little diagnostic significance, although sensitivity is increased in patients with triple-vessel CAD.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

Thallium-201 exercise testing in patients 6-8 weeks after myocardial infarction: limited value for the detection of multivessel disease.

In a clinical study, the value of exercise electrocardiography and thallium-201 scintigraphy was determined for the detection of multivessel disease in 176 patients 6-8 weeks after a first myocardial infarction. In all patients coronary arteriography was performed within 3 days after the non-invasive procedure. Of the 176 patients, 77 patients had multivessel disease (prevalence 44%). The exercise electrocardiogram was positive in 49 of these 77 patients (sensitivity 64%), while the thallium scintigram was positive in only 24 patients (sensitivity 31%). When the results of both procedures were added, a moderate sensitivity of 66% and a similar specificity of 62% was found; the positive and negative predictive values were 57% and 70%, respectively, and were considered too low for the adequate clinical diagnosis of multivessel disease after myocardial infarction. Based on our results, it is concluded that qualitative assessment of thallium exercise scintigraphy, alone or combined with electrocardiography, should not be used to predict the absence or presence of multivessel disease in patients after previous myocardial infarction.

Aged↗