The significance of the abnormal rest thallium-201 myocardial image in coronary artery disease.

Rest Thallium-201 myocardial images were abnormal in 20 out of 40 patients with arteriographically proven coronary artery disease. The myocardial image appearances did not accurately reflect the extent of coronary artery disease present. However, in 35 of the 40 patients (88%) the presence or absence of abnormalities on the rest myocardial image correleted respectively with the presence or absence of abnormal wall motion at left ventriculography. Most rest image abnormalities could be attributed to previous myocardial infarction, but in six patients myocardial ischaemia was possibly the cause. These results suggest that though myocardial fibrosis is usually the cause of rest myocardial image abnormalities in coronary artery disease, this is not invariably so. The possible therapeutic implications are discussed.     

Thallium-201 myocardial SPECT findings at rest in sarcoidosis

In 41 patients with sarcoidosis (diagnosed according to criteria recommended by the Committee on Diffuse Pulmonary Disease, Ministry of Health and Welfare, Japan 1988), thallium-201 (²⁰¹Tl) myocardial SPECT was performed to investigate: (1) the ability of²⁰¹Tl SPECT to detect cardiac involvement of sarcoidosis with images recorded at rest and 2 hours later, and (2) the relationships between²⁰¹Tl myocardial SPECT findings and the activity of sarcoidosis or endomyocardial biopsy findings. As to the abnormal findings in²⁰¹Tl myocardial SPECT, (1) a low density area was seen in 13 of 41 cases (31.7%) and non-uniform uptake was found in 17 cases (41.5%), (2) the mean washout ratio (n=39) was 16.5±7.4%, which is significantly (p < 0.05) lower than that found in normal subjects, 23.9±7.5 % (n=10). Of the 19 patients judged visually to be normal, 5 patients had a reduced mean washout ratio less than 12%. Thus, the incidence of abnormal findings including all types of abnormality, on²⁰¹Tl myocardial SPECT in sarcoidosis was 63.4% (26/41 cases). In studying the relationship between²⁰¹Tl myocardial SPECT findings and the activity of sarcoidosis (as measured by the serum ACE (angiotensin converting enzyme) or lysozyme level, or the presence of more than 30% symphocyte fraction in BALF (broncho-alveolar lavage fluid)), 20 (80%) of 25 cases with²⁰¹Tl abnormality were judged to be active sarcoidosis, while only 6 (37.5%) of 16 cases with normal findings on²⁰¹Tl SPECT were judged to be active. This suggests that there is a significant (p < 0.01) relationship between the presence or absence of an abnormal finding on²⁰¹Tl myocardial SPECT and the activity of sarcoidosis. Among 13 patients examined by endomyocardial biopsy, 10 patients had abnormal findings on²⁰¹Tl myocardial SPECT and 7 of these 10 patients had no histological evidence of cardiac sarcoidosis. In all of these 7 patients, however, sarcoidosis was judged to be active. This suggest that endomyocardial biopsy is of limited value in the diagnosis of cardiac sarcoidosis.     

Thallium-201 myocardial scintigraphy: Fractional uptake by the myocardium at rest and during exercise in patients with coronary artery disease and hypertrophic cardiomyopathy

Fractional myocardial uptake of thallium-201 was estimated by routine scintigraphic evaluation at rest and during exercise in 10 control subjects, 15 patients with coronary artery disease (CAD) and 12 patients with hypertrophic cardiomyopathy (HCM). Fractional myocardial uptake of the total dose administered at rest was 3.59±0.98% in the controls, 4.43±1.17% in patients with CAD and 5.68±1.29% in patients with HCM, and uptake during exercise was 5.07±1.23% in the controls, 4.67±1.04% in the CAD group and 7.50±1.68% in the HCM group. The value in the HCM group was significantly higher than in the controls (P<0.001 at rest) or in the CAD group (P<0.02 at rest). A percentage increment of fractional uptake during exercise was significantly smaller in the CAD group than in the controls or the HCM group (P<0.01). Thus, assessment of the fractional uptake appears to be a valuable adjunct to myocardial imaging when attempting a clinical assessment of CAD or HCM.Supported in part by Grant from the Mitsui Life Social Welfare Foundation and the Japan Tobacco and Salt Public Corporation     

Thallium-201 washout in coronary artery disease using SPECT--a comparison with coronary angiography

In this study, tomographic 201Tl washout analysis and coronary angiography were compared in 100 subjects. Seventeen subjects with healthy coronary arteries were used as reference material, on the basis of which the reference ranges for both the total washout of the heart muscle and the regional washout were determined. With angiography as the standard, this material yielded the following sensitivity values for total myocardial washout: 80% for three vessel proximal disease (n = 30), 64% for peripheral three vessel disease (n = 14), 66% for two vessel disease (n = 29) and 71% for single vessel disease (n = 17). Specificity in the reference group was 94%. Sensitivity values for regional washout were 83%, 93%, 59% and 71%, respectively. Stress ECG gave about 10% lower sensitivities. As far as sensitivity is concerned, however, visual assessment of tomographic images proved to be the best single method. In three patients, washout analysis was necessary to reveal evenly distributed ischemia and in seven cases it was essential in order to confirm an uncertain diagnosis; in other words, washout analysis had diagnostic value in 10 of the 100 patients.     

Thallium-201 washout in coronary artery disease using SPECT — a comparison with coronary angiography

In this study, tomographic ²⁰¹Tl washout analysis and coronary angiography were compared in 100 subjects. Seventeen subjects with healthy coronary arteries were used as reference material, on the basis of which the reference ranges for both the total washout of the heart muscle and the regional washout were determined. With angiography as the standard, this material yielded the following sensitivity values for total myocardial washout: 80% for three vessel proximal disease (n=30), 64% for peripheral three vessel disease (n=14), 66% for two vessel disease (n=29) and 71% for single vessel disease (n=17). Specificity in the reference group was 94%. Sensitivity values for regional washout were 83%, 93%, 59% and 71%, respectively. Stress ECG gave about 10% lower sensitivities. As far as sensitivity is concerned, however, visual assesment of tomographic images proved to be the best single method. In three patients, washout analysis was necessary to reveal evenly distributed ischemia and in seven cases it was essential in order to confirm an uncertain diagnosis; in other words, washout analysis had diagnostic value in 10 of the 100 patients.     

Thallium-201 SPECT in coronary artery disease patients with left bundle branch block

Fourteen patients with left bundle branch block (LBBB) underwent immediate postexercise and 3-hr delayed 201Tl single photon emission computed tomography (SPECT) with quantitative analysis using bullseye polar maps. Test performance in detecting individual coronary artery stenosis greater than or equal to 50% demonstrated 100% sensitivity. Specificity was 100% for circumflex stenosis, 78% for right coronary stenosis, but only 10% for left anterior descending coronary stenosis. This very low specificity was due to the fact that 3/4 (75%) patients with left anterior descending stenosis and also 9/10 (90%) patients with normal left anterior descending coronary arteries had immediate septal perfusion defects with redistribution in all cases at 3 hr. Septal abnormalities were most marked in patients who achieved high peak heart rates (greater than 170 bpm). Thus, with LBBB, 201Tl SPECT is indeterminate for left anterior descending coronary disease.     

Thallium-201 myocardial imaging: a comparison of the redistribution and rest images

Forty-one patients with chest pain and suspected coronary artery disease underwent thallium-201 myocardial imaging, performed immediately following maximal treadmill exercise, also at "redistribution" 4--5 hr after exercise, and at rest 1 wk later. All had coronary angiography. All images in seven patients without coronary artery disease were normal. Twenty-seven of the 34 (79%) patients with coronary artery disease had new, exercise-induced image defects. The redistribution and rest images were identical in 15/27 (56%) patients (complete redistribution). In 10/27 (37%) patients with exercise-induced defects, some redistribution occurred but defect size on the redistribution image was larger than that on the rest images (incomplete redistribution). In 2/27 (7%) of patients with exercise-induced defects, redistribution was absent. The presence of prior myocardial infarction, regional abnormalities of left-ventricular contraction or the severity of coronary stenoses did not correlate with the presence or absence of redistribution. Overall image quality between the two studies was similar, although image collection times for the redistribution study were prolonged. We conclude that some redistribution (complete or incomplete) occurs in most patients with exercise-induced image defects. When both fixed and reversible perfusion defects are present, defect size was often larger in the redistribution image and may thus overestimate the extent of prior myocardial infarction.     

Thallium-201 right lung/heart ratio during exercise in patients with coronary artery disease: relation to thallium-201 myocardial single-photon emission tomography, rest and exercise left ventricular function and coronary angiography

The aim of this study was to correlate lung thallium-201 uptake on exercise with ²⁰¹Tl single-photon emission tomography (SPET) myocardial perfusion imaging, rest and exercise equilibrium radionuclide angiographic and coronary angiographic findings in patients with coronary artery disease (CAD) using a simple, reproducible lung/heart (L/H) ratio that would be easy to use in clinical practice. L/H ratio was defined on the anterior planar image obtained during exercise ²⁰¹Tl SPET acquisition as the mean counts per pixel in an entire right lung field region of interest divided by the mean counts per pixel in the hottest myocardial wall region of interest. We studied 103 patients. Fifty-nine patients (group I) with <5% likelihood of CAD were used as a reference group. In 44 CAD patients (group II), L/H ratio was compared with ²⁰¹Tl SPET, radionuclide angiographic and coronary angiographic variables. The group I L/H ratio of 0.35±0.05 (mean ±1 SD) was significantly lower (P<0.001) than the group II L/H ratio of 0.45±0.10. An L/H ratio >0.45 (mean + 2 SD in group I) was considered abnormal. In group II, L/H ratio showed a significant correlation with stress and rest ²⁰¹Tl perfusion defect size (r = 0.39 and r = 0.42, P<0.01, respectively), but not with extent of ischaemic myocardium. The mean L/H ratio was 0.41±0.10 in patients with one-vessel disease (n = 15), 0.46±0.08 in those with two-vessel disease (n = 17) and 0.47±0.12 in those with three-vessel disease (n = 12), but no significant difference was found between the three subgroups. L/H ratio showed a significant inverse relation with rest and exercise left ventricular ejection fraction (r = –0.37 and r = –0.50, P<0.05 and P<0.001, respectively). Using stepwise multiple regression analysis, exercise left ventricular ejection fraction and previous history of hypertension were the sole two variables independently predictive of the L/H ratio. In conclusion, although lung thallium uptake is usually found to correlate with extent and severity of CAD, increased L/H ratio should primarily be considered as a marker of exercise-induced left ventricular systolic and perhaps diastolic dysfunction, probably independent of the underlying cardiac disease. Received 14 January and in revised form 22 February 1999     

Thallium-201 myocardial SPET in patients with collagen disease

We analysed stress 201Tl myocardial single photon emission tomography (SPET) in collagen disease patients to evaluate abnormal uptake patterns and their clinical significance in the assessment of the cardiac status of these patients. The main purpose of the study was to evaluate the clinical significance of reverse redistribution. Twenty-two collagen disease patients (13 with progressive systemic sclerosis (PSS) and nine with systemic lupus erythematosus (SLE)) were examined by 201Tl myocardial SPET with exercise (n = 9) or dipyridamole stress (n = 13). For quantitative analysis, each 201Tl SPET polar map was divided into 17 segments, and the 201Tl uptake pattern of each segment was classified into four types. Eighteen (82%) of the patients showed abnormal findings on 201Tl SPET. Of the 374 segments analysed, 295 (79%) were classified as normal, 16 (4%) as reverse redistribution, 49 (13%) as reversible defect and 14 (4%) as fixed defect. Patients were divided into two groups: those with cardiac abnormalities on conventional testing (Group A, n = 10) and those without (Group B, n = 12). The incidences of fixed defect, reversible defect and reverse redistribution were significantly higher (P <0.01, P <0.0005, P <0.05, respectively) in Group A than in Group B. Nine (90%) of the patients in Group A and nine (75%) in Group B showed abnormal findings. No significant difference was found between the PSS and SLE patients in the incidence of the individual uptake patterns. Stress 201Tl myocardial SPET appears to be an effective method of evaluating a wide spectrum of myocardial involvement in collagen disease patients and in assessing their clinical cardiac status. Reverse redistribution is found to be a significant finding in collagen disease patients.     

Thallium-201 right lung/heart ratio during exercise in patients with coronary artery disease: relation to thallium-201 myocardial single-photon emission tomography, rest and exercise left ventricular function and coronary angiography.

The aim of this study was to correlate lung thallium-201 uptake on exercise with 201Tl single-photon emission tomography (SPET) myocardial perfusion imaging, rest and exercise equilibrium radionuclide angiographic and coronary angiographic findings in patients with coronary artery disease (CAD) using a simple, reproducible lung/heart (L/H) ratio that would be easy to use in clinical practice. L/H ratio was defined on the anterior planar image obtained during exercise 201Tl SPET acquisition as the mean counts per pixel in an entire right lung field region of interest divided by the mean counts per pixel in the hottest myocardial wall region of interest. We studied 103 patients. Fifty-nine patients (group I) with <5% likelihood of CAD were used as a reference group. In 44 CAD patients (group II), L/H ratio was compared with 201Tl SPET, radionuclide angiographic and coronary angiographic variables. The group I L/H ratio of 0.35+/-0.05 (mean +/-1 SD) was significantly lower (P<0.001) than the group II L/H ratio of 0. 45+/-0.10. An L/H ratio >0.45 (mean + 2 SD in group I) was considered abnormal. In group II, L/H ratio showed a significant correlation with stress and rest 201Tl perfusion defect size (r = 0. 39 and r = 0.42, P<0.01, respectively), but not with extent of ischaemic myocardium. The mean L/H ratio was 0.41+/-0.10 in patients with one-vessel disease (n = 15), 0.46+/-0.08 in those with two-vessel disease (n = 17) and 0.47+/-0.12 in those with three-vessel disease (n = 12), but no significant difference was found between the three subgroups. L/H ratio showed a significant inverse relation with rest and exercise left ventricular ejection fraction (r = -0.37 and r = -0.50, P<0.05 and P<0.001, respectively). Using stepwise multiple regression analysis, exercise left ventricular ejection fraction and previous history of hypertension were the sole two variables independently predictive of the L/H ratio. In conclusion, although lung thallium uptake is usually found to correlate with extent and severity of CAD, increased L/H ratio should primarily be considered as a marker of exercise-induced left ventricular systolic and perhaps diastolic dysfunction, probably independent of the underlying cardiac disease.     

Correlation of an abnormal rest 201Tl myocardial image: Pathological findings in cardiac transplant recipients

Rest myocardial ²⁰¹Tl scintigraphy was undertaken in 15 males mean age 39 years (22–54) who had been accepted for cardiac transplantation. Complete pathological correlation was obtained in 14 after transplantation and in 1 who died before a suitable donor heart became available. The average time from scintigraphy to pathological evaluation was 42 days (9–103). All the ²⁰¹Tl images were grossly abnormal and on the basis of these studies it was not possible to differentiate ischemic from idiopathic cardiomyopathy. Each of the three views of the ²⁰¹Tl study was divided into three segments, therefore 135 areas were available for comparison (3×3×15). Eighty-eight of these were abnormal on scan and 78 of these were abnormal pathologically. The right ventricle was seen on all rest images but the degree of uptake bore no relationship to the measured thickness of the right ventricular wall. Structures such as the atrial wall and the enlarged papillary muscle were visualized in some patients. In two patients there was an improvement of the rest ²⁰¹Tl image in delayed views and histologically these areas showed a mixture of muscle and fibrous tissue. The sensitivity of ²⁰¹Tl imaging in this study was 89% and there was close correlation of the images with gross and microscopic pathological findings.J.H. McKillop is a Harkness Fellow of the Commonwealth Fund     

A quantitative approach to the analysis of the normal Thallium-201 myocardial image

The visual interpretation of Thallium-201 myocardial images is made more difficult by nonhomogeneity of myocardial tracer uptake in normal studies. To increase the objectivity of the study, the variation in count density in different myocardial areas has been calculated using a computer regions of interest technique in 14 healthy, young subjects following intravenous injection of the radionuclide at rest and in 10 after injection during maximal exercise. The normal ranges for regional Thallium-201 uptake so obtained are presented and discussed.     

Thallium-201 myocardial scintigraphy after intravenous infusion of adenosine triphosphate disodium: a preliminary study in the diagnosis of coronary artery disease]

The feasibility and safety of thallium-201 myocardial scintigraphy after the intravenous infusion of adenosine triphosphate disodium (ATP) (Adetphos, Kowa) were studied in eight patients with angina pectoris and/or old myocardial infarction. Coronary arteriography (CAG) was performed by the conventional method in all patients. ATP was infused for 5 min and thallium was injected at 3 min after the start of ATP infusion. ATP was given at 0.12 mg/min/kg in two patients (group A), 0.16 mg/min/kg in three patients (group B), 0.20 mg/min/kg in one patient (group C) and 0.28 mg/min/kg in two patients (group D). SPECT images were obtained at 10 min and 180 min after thallium injection. No significant hemodynamic changes were observed in group A and B. Severe hypotension was observed in group C and one member of group D. Chest pain was experienced by one patient in group A, two in group B, one in group C, and both of the two in group D. ST depression on the electrocardiogram (ECG) was documented in one patient each of groups B and C. In one group D patient, the study was discontinued because of complete atrioventricular block persistent for 5 beats. The correlation between thallium imaging and CAG was unclear in group A, reasonable in groups B and C, and obscure in group D because of side effects. None of the patients who developed side effects of ATP were administered sublingual nitroglycerin or intravenous aminophylline. Their symptoms or ECG changes improved spontaneously within 2 min and disappeared within 5 min after termination of infusion. In conclusion, the optimal ATP regimen for this purpose was considered to be a 5 min infusion at 0.16 mg/kg/min and this method was found to be feasible and safe.     

Thallium-201 myocardial perfusion imaging during adenosine-induced coronary vasodilation in patients with ischemic heart disease]

201Tl myocardial perfusion imaging during adenosine infusion was performed in consecutive 55 patients with suspected coronary artery disease. Adenosine was infused intravenously at a rate of 0.14 mg/kg/min for 6 minutes and a dose of 111 MBq of 201Tl was administered in a separate vein at the end of third minute of infusion. Myocardial SPECT imaging was begun 5 minutes and 3 hours after the end of adenosine infusion. For evaluating the presence of perfusion defects, 2 short axis images at the basal and apical levels and a vertical long axis image at the mid left ventricle were used. The regions with decreased 201Tl uptake were assessed semi-quantitatively. Adenosine infusion caused a slight reduction in systolic blood pressure and an increase in heart rate. The rate pressure products increased slightly (9314 +/- 2377 vs. 10360 +/- 2148, p < 0.001). Chest pain (24%) and headache (13%) were the frequent side effects. The second-degree atrioventricular block was developed in 11 of 55 (20%) patients. All symptoms and hemodynamic changes were well tolerated and disappeared within 1 or 2 minutes after discontinuing adenosine infusion. The sensitivity and specificity for the detection of patients with coronary artery disease were 100% (31/31) and 88% (7/8), respectively. 201Tl myocardial imaging during adenosine infusion was considered to be safe and useful for evaluating the patients with ischemic heart disease.     

Thallium-201 myocardial imaging during coronary vasodilation induced by oral dipyridamole

Myocardial perfusion imaging of 201TI injected during maximum exercise has been an important diagnostic tool for coronary artery disease. Pharmacologic coronary vasodilation by i.v. infusion of dipyridamole may be used in lieu of exercise stress for purposes of diagnostic perfusion imaging. However, i.v. dipyridamole is not currently available from commercial sources for widespread routine use. Accordingly, this study was carried out in order to determine whether high dose, oral dipyridamole would be useful as a coronary vasodilator for purposes of diagnostic perfusion imaging. Fifty-eight patients undergoing diagnostic coronary arteriography also had myocardial perfusion imaging with 201TI under conditions of rest, maximum exercise stress, and high dose oral dipyridamole. Of those patients who had a defect on exercise thallium images, 75% also had a perfusion defect on thallium images after high dose oral dipyridamole. These results indicate that oral dipyridamole causes sufficient coronary arteriolar vasodilation and increase of coronary flow in nonstenotic arteries to identify perfusion defects comparable to those seen on maximum exercise stress in at least 75% of cases. In 25% of patients with exercise defects, no perfusion defect was seen after oral dipyridamole. Thus, oral dipyridamole is a potent coronary vasodilator, comparable to exercise stress in most cases, but in a minority of patients may not be comparable to exercise stress.     

Thallium-201 imaging in anomalous left coronary artery originating from pulmonary trunk

A 3-month-old infant with anomalous origin of the left main coronary artery (LMCA) from the pulmonary trunk was evaluated using resting thallium imaging. The imaging findings were consistent with myocardial scar and ischemia of the anterolateral and posterolateral walls in the distribution of the LMCA.     

I-123 labeled hexadecenoic acid in comparison with Thallium-201 for myocardial imaging in coronary heart disease

The imaging properties of ¹²³I-16-iodo-9-hexadecenoic acid (¹²³I-HA), a terminally iodinated 17-carbon atom fatty acid analogue, were compared with Thallium-201 (²⁰¹Tl). Because of its shorter half-life, favourable photon-energy and rapid myocardial turnover rate, ¹²³I-HA possesses potential advantages in the study of regional myocardial perfusion and metabolism. Twelve patients with documented coronary artery disease (CAD) were studied; eight patients sustained an acute myocardial infarction, four patients suffered from unstable angina. Visually assessed, a similar distribution pattern and comparable imaging quality was demonstrated with both radionuclides. The scintigraphic results were also correlated with coronary arteriographic findings. A good relationship was found between the perfusion defects and the location of the coronary artery lesions in the patients with acute myocardial infarction.We conclude that ¹²³I-HA is comparable to ²⁰¹Tl in detecting areas of reduced myocardial perfusion in patients with CAD with the advantage of studying myocardial metabolism.