Myocardial Uptake Of Thallium-201 Research Articles

An extensive discrepancy in myocardial uptake of thallium-201 and iodine-123 BMIPP in a patient with ST-segment elevation myocardial infarction treated using postconditioning with lactate-enriched blood

An extensive discrepancy in myocardial uptake of thallium-201 and iodine-123 BMIPP in a patient with ST-segment elevation myocardial infarction treated using postconditioning with lactate-enriched blood

Sodium bicarbonate-augmented stress thallium myocardial scintigraphy

It is well known that sodium bicarbonate in pharmacological doses induces transient alkalosis, causing intracellular transport of serum potassium. The aims of this study were (a) to investigate whether, in humans, myocardial thallium-201 uptake can be augmented by pretreatment with a single bolus of sodium bicarbonate at a pharmacological dose, (b) to verify general safety aspects of the intervention and (c) to evaluate the clinical implications of augmentation of (201)Tl uptake, if any. Routine exercise myocardial scintigraphy was performed twice in eight adult volunteers (five normal and three abnormal), once without intervention and the second time (within a week) following intravenous administration of sodium bicarbonate (88 mEq in 50 ml) as a slow bolus 1 h prior to the injection of (201)Tl. Conventional myocardial thallium study was compared with sodium bicarbonate interventional myocardial scintigraphy with respect to myocardial uptake (counts per minute per mCi injected dose), washout patterns in normal and abnormal myocardial segments, and overall clinical interpretation based on planar and single-photon emission tomographic (SPET) images. All patients remained asymptomatic after the intervention. A mean increase of 53% in myocardial uptake of thallium was noted in post-exercise acquisitions after the intervention, confirming uptake of the tracer via the potassium-hydrogen pump and its augmentation by transient alkalosis. The washout pattern remained unchanged. The visual quality of planar and SPET images improved significantly after the intervention. Out of the five abnormal myocardial segments identified in three cases, four showed significant filling-in after the intervention, causing the diagnosis to be upgraded from "partial scar" to "ischaemia", or from "ischaemia" to "normal". The overall scan impression changed in two out of three such cases. Sodium bicarbonate augmentation may have significant implications for stress-thallium scintigraphy and may be a new parameter for defining myocardial viability.

Acipimox does not augment thallium-201 redistribution in the fasting state

Background. Recently oral glucose loading and a thallium-glucose insulin infusion have been used to augment myocardial uptake of thallium-201 (Tl-201). Acipimox is a nicotinic-acid derivative that reduces serum free fatty acid (FFA) levels and enhances myocardial glucose uptake. This study was performed to assess the effects of acipimox on Tl-201 redistribution. Methods. Fourteen patients with coronary artery disease underwent 2 successive Tl-201 perfusion studies. Stress was performed by adenosine coupled with ergometer exercise. Patients received either 500 mg of acipimox or placebo immediately after stress, and images were acquired. Redistribution imaging was carried out after 4 hours. Patients returned after 7 to 14 days for a repeat stress protocol, receiving the alternate test article. Both studies were carried out under identical conditions with identical medication with the patient in the fasting state. Image analysis was conducted quantitatively with polar plots and by using segmental uptake as a percentage of maximal counts with a 9-segment model. Results. There were no significant differences between the acipimox and placebo arms of the study of hemodynamic parameters. On polar plot analysis, there were no differences between acipimox and placebo for mean values of stress defect extent (97 ± 16.1 vs 96.5 ± 18.8 pixels), defect severity (532.2 ± 120 vs 537 ± 133.9 standard deviations [SDs]), for defect reversibility (61.7 ± 18 vs 55.4 ± 15.3 SDs), and percentage reversibility (21.2% ± 5.5% vs 19.2% ± 5.8%), respectively. Similarly, on segmental uptake analysis there was no significant difference between the acipimox and placebo arms with regard to the proportion of segments classified as normal, fixed defect, reversible defect, or reverse redistribution. Conclusion. Although acipimox has been shown to augment myocardial glucose uptake and myocardial glucose uptake has been shown to improve cellular uptake of Tl-201, in the fasting state acipimox does not enhance the redistribution after stress. This may be because serum insulin levels are not increased by acipimox, and insulin is instrumental in enhancing the joint transport of glucose and Tl-201 into myocytes.

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 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 (). There was a weak but positive correlation between lung uptake and defect size (). Both exercise time and double product showed a negative correlation with lung uptake (e.g. for double product, ). 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.

Favorable Myocardial Uptake of Thallium-201 During Dobutamine Stress in the Presence of Coronary Artery Stenoses: Implications for Pharmacologic Stress Perfusion Imaging

Favorable Myocardial Uptake of Thallium-201 During Dobutamine Stress in the Presence of Coronary Artery Stenoses: Implications for Pharmacologic Stress Perfusion Imaging

Favorable myocardial uptake of thallium-201 during dobutamine stress in the presence of coronary artery stenoses: implications for pharmacologic stress perfusion imaging

Favorable myocardial uptake of thallium-201 during dobutamine stress in the presence of coronary artery stenoses: implications for pharmacologic stress perfusion imaging

Cardiac Troponin T in Serum as Marker for Myocardial Injury in Newborns

In neonates, acute perinatal asphyxia may lead to ischemic myocardial damage (1). In some cases, subendocardial infarction has been documented (2). Generally, diagnosis of the myocardial injury (MI) is based on clinical findings, suggestive electrocardiographic and echocardiographic patterns (3), decrease in myocardial uptake of thallium (4), and classical creatine kinase (CK)-MB isoenzyme measurement (5). However, CK-MB in serum cannot be regarded as a cardiac-specific marker in the neonate, and extreme caution should be used in the interpretation of increased CK-MB activity during this period (6). Cardiac troponin T (cTnT), the structural protein that binds the troponin complex to the tropomyosin molecular strand, has recently been proposed as a more specific biochemical marker for diagnosis of myocardial infarction in the adult population (7). Here we evaluated the use of cTnT measurement in serum in the diagnosis of MI in newborns, as well as that of the determination of CK-MB mass concentration by a sensitive and specific monoclonal anti-CK-MB antibody-based immunoassay. Three groups of infants were studied. Group I consisted of 27 preterm infants (gestational age ranging from 28 to 36 weeks) without major respiratory and cardiovascular dysfunctions. Group II was 27 healthy full-term newborns (15 born by vaginal delivery and 12 by cesarean section) with a mean gestational age of 39.7 weeks. Group III was composed of seven infants (four preterm and three term) who demonstrated, during the first 3 days after birth, clinical, electrocardiographic, and echocardiographic signs of MI. In particular, in electrocardiogram (ECG) evaluation, MI was considered to be present when inversion of T waves or ST-segment depression ≥1 mm in more than two precordial leads was noted. Groups I and II underwent a clinical examination, ECG, echocardiogram, and blood collection for the measurement of total CK, CK-MB, and cTnT on day 2 after birth. Group III was evaluated …

Cardiac Ischemia During Weaning From Mechanical Ventilation

In this prospective study, we measured the ST segments, heart rate-systolic BP product (RPP), respiratory rate to tidal volume ratio (RVR), and pulse oximetry saturations of patients in our medical/cardiac ICUs before and during weaning from mechanical ventilation. Ninety-three patients were enrolled with a mean age of 66.5 +/- 15.0 years (mean +/- SD), mean acute physiology and chronic health evaluation (APACHE) II score of 16.0 +/- 6.9, and mean duration of mechanical ventilation of 5.2 +/- 8.6 days. Forty-nine patients had coronary artery disease (CAD). Six of 93 patients (6.4%) experienced ECG evidence of ischemia during weaning. Five of these six had a precedent history of CAD and four failed initial weaning attempts (22% of patients with CAD who failed weaning). The RPP, for the group as a whole, increased significantly during weaning from 12.0 +/- 3.1 to 13.4 +/- 4.0 mm Hg.bpm.10(3) (p<0.01). The rate to volume ratio did not change significantly during weaning, except in the subgroup of patients who failed to wean, in whom it increased from 98.4 +/- 45.2 to 124.9 +/- 54.9 bpm/L (p<0.05). Oxygenation also decreased significantly from 0.98 +/- 0.02 to 0.96 +/- 0.03 and was significantly associated with weaning failure (risk ratio [RR]=3.9; 95% confidence interval [CI]=1.7 to 9.0). Thirty-seven patients failed the initial weaning attempt. Cardiac ischemia (RR= 1.8; 95% CI=1.0 to 3.4) and an increased RVR (RR=1.7; 95% CI=0.9 to 3.4) tended to increase the risk of weaning failure. Cardiac ischemia, although infrequent (6%) in the general population of weaning medical/cardiac ICU patients, should be considered in patients with CAD who fail to wean.

Comparison of rest thallium-201 imaging and rest technetium-99m sestamibi imaging for assessment of myocardial viability in patients with coronary artery disease and severe left ventricular dysfunction

Objectives. We prospectively compared myocardial uptake of thallium-201 (201Tl) at rest with rest technetium-99m (99mTc) sestamibi uptake in the same patients, using quantitative single-photon emission computed tomography (SPECT).Background. Because of only slightly delayed redistribution, 99mTc-sestamibi uptake at rest may be less than 201Tl uptake, thereby underestimating the extent of viability.Methods. Twenty patients (2.25 stenoses per patient) with a mean left ventricular ejection fraction of 33 ± 2% underwent early and 3-h delayed rest 201Tl SPECT, rest 99mTc-sestamibi SPECT and two-dimensional echocardiography.Results. The 280 scan segments were classified as either a normal, mild reduction in viability, defined as delayed 201Tl uptake ≤75% and ≥5%, or a severe reduction in viability, defined as delayed 201Tl uptake <50%. Mild and severe defects were further classified as fixed or having rest 201Tl redistribution. Comparisons by patients were made using repeated measures analysis of variance and Dunnett's multiple comparisons test to compare 99mTc-sestamibi with initial rest 201Tl and delayed 201Tl uptake. Twenty patients had at least one mild fixed defect (95 total segments). The average percent uptake in these defects for initial 201Tl, delayed 201Tl and 99mTc-sestamibi was 62.5 ± 2.7%, 63.1 ± 7.1% and 67.3 ± 9.7%, respectively (p = NS). Twelve patients (27 segments) had mild redistribution defects on serial rest 201Tl imaging. The average percent uptake was 61.6 ± 5.2% for initial 201Tl, 67.0 ± 9.1% for delayed 201Tl and 67.7 ± 12.4% for 99mTc-sestamibi defects. Technetium-99m sestamibi uptake was not significantly different than that for delayed 201Tl but was significantly greater than initial 201Tl uptake. Seventeen patients (52 segments) had severe fixed 201Tl defects. The average percent uptake was 38.9 ± 7.3% for initial 201Tl, 38.3 ± 12.2% for delayed 201Tl and 42.7 ± 14.2% for 99mTc-sestamibi defects in these patients (p = NS). Ten patients (19 segments) had severe redistribution defects on rest 201Tl imaging. The average percent uptake was 37.0 ± 8.5% for initial 201Tl, 42.9 ± 8.6% for delayed 201Tl and 44.5 ± 11.3% for 99mTc-sestamibi defects. As was seen for mild 201Tl redistribution defects, 99mTc-sestamibi uptake was significantly higher than initial 201Tl uptake, but not significantly different than delayed 201Tl uptake in these severe defects.Conclusions. Technetium-99m sestamibi uptake after injection at rest is comparable to 201Tl uptake after injection at rest in patients with severe coronary artery disease and left ventricular dysfunction, suggesting comparable worth for viability assessment.

Identification of hibernating myocardium by dobutamine stress echocardiography: Comparison with thallium-201 reinjection imaging

The aim of this study was to determine the diagnostic value of dobutamine stress echocardiography (DSE) in the identification of hibernating myocardium and to compare its predictive accuracy with that of thallium-201 reinjection (RI) imaging. The subjects were 26 patients with wall motion abnormalities related to stenosed coronary arteries. DSE predicted postrevascularization improvement in 31 of 33 segments that were considered to be hibernating and identified 8 of 10 nonhibernating segments. In contrast, thallium-201 scintigraphy predicted all 33 hibernating segments when a post-RI myocardial thallium uptake in ischemic areas of ≥50% of the maximum count in normal segments was used as a positive marker of myocardial viability. However, thallium studies predicted only 30 of 33 hibernating segments when thallium redistribution (RD) was used as a marker of viability in delayed or RI images. Among the 10 nonhibernating segments, an uptake of <50% was observed in 4 segments and negative thallium-201 RD was observed in 5 segments. The sensitivity, specificity, and predictive values (PV) of DSE were 94%, 80%, positive PV 94%, and negative PV 80%, respectively. In contrast, the sensitivity, specificity, and PV of thallium-201 RI imaging were 100%, 40%, 85%, and 100% with uptake ≥50% and 91%, 50%, 86%, and 63% with RD, respectively. These results suggest that DSE may be useful for identifying hibernating myocardium and could therefore be helpful in selecting candidates for coronary revascularization.

Coronary angiographic changes during 2 years after myocardial infarction largely undetected by repeated tomographic thallium-201 scintigraphy and not reflected by clinical symptoms

Repeated coronary angiographies and single photon emission computed tomographies (SPECT) were performed at 9 and 33 months after myocardial infarction (MI) in 47 young men. Coronary lesions were classified in eight grades with respect to the reduction of the luminal diameter. The progression and regression of two steps or more in lesions of grade 2 or more, the recanalization of coronary thrombosis and an increase in collaterals were recorded. Patients were divided into three groups with regard to (A) deterioration, (B) improvement and (C) no changes in the three major coronary regions, respectively. Overall, 23 patients (49%) showed changes between the first and the second investigation. A simplified method using summarized short-axis slices for evaluation of the thallium-201 SPECT showed a significant difference in change of regional myocardial uptake of thallium-201 between groups A and B (P = 0.047) but not between the groups A and C, in lateral myocardial regions. No significant differences were found between any of the groups in respect of the anterior or inferior myocardial regions. These findings were not explained by changes in clinical status, maximum heart rate or workload, or by changes in medication. Our results suggest that substantial changes in coronary morphology can take place during the 2 years following MI without consistent changes in clinical symptoms or regional myocardial perfusion.

Balanced triple-vessel disease

Maximal stress thallium scans may prove to be 'normal' in some patients with triple-vessel disease due to global reduction in flow resulting in no focal perfusion defect. The aim of this study was to attempt to identify patients with global reduction in flow by estimating total thallium delivery to the left ventricle. Myocardial thallium uptake was calculated as a percentage of injected dose as a mean of three projections in 90 patients undergoing diagnostic arteriography and in 10 normal volunteers. These volunteers and nine patients who proved to have normal coronary arteries established a normal range. Values for myocardial thallium uptake were: 1.166 +/- 0.352% in normals (n = 19); 0.671 +/- 0.184% in patients with single- or double-vessel disease (n = 26); 0.708 +/- 0.245% in patients with triple-vessel disease (n = 55). Thallium scans were normal in 11 of 55 patients with triple-vessel disease and eight of 26 with single- or double-vessel disease. However, eight of these 11 and 5 of the eight proved to have abnormal myocardial thallium uptake. Thus combining the tests improved sensitivity from 76.5% for the scan alone to 94.5% for the scan and myocardial thallium uptake, with no reduction in specificity. Measurement of myocardial thallium uptake is a readily and reliably quantified parameter from a thallium scan which leads to enhanced detection of coronary artery disease.

Lung and myocardial thallium-201 kinetics in resting patients with congestive heart failure: Correlation with pulmonary capillary wedge pressure

Increased lung thallium-201 activity occurs with exercise in patients with severe coronary artery disease as a result of increased pulmonary capillary wedge pressure. No study has shown resting lung kinetics in chronic congestive heart failure. To better understand the relationship between lung and myocardial thallium uptake and pulmonary capillary wedge pressure, this study was performed. Resting lung and myocardial thallium uptake, expressed as a ratio, were compared with simultaneous pulmonary capillary wedge pressure in 16 patients with congestive heart failure and cardiomyopathy, all New York Heart Association class IV. There no variations in pulmonary capillary wedge pressure throughout the study protocol. There was a significant reduction in the lung/myocardium thallium ratio from 10 to 60 minutes (0.83 ± 0.30 to 0.59 ± 0.17; p < 0.001). At 60 minutes after thallium injection there was a linear correlation between the lung/myocardium ratio and capillary wedge pressure with an r value of 0.62 ( p < 0.01). Thus thallium-201 washout is rapid despite persistence of pulmonary capillary wedge pressure elevation, indicating that clearance does not imply resolution of congestive heart failure. In addition, a significant but imprecise correlation was found between capillary pressure and the lung/myocardium ratio. Rapid changes in lung activity during the early postinjection period may limit the clinical use of the lung/myocardium ratio.

Negative washout rate of myocardial thallium-201--a specific marker for high grade coronary artery narrowing.

A decline is usually observed in the myocardial uptake of thallium-201 in delayed imaging compared with initial imaging. In patients with severe coronary artery disease (CAD), the uptake is sometimes higher in the delayed than in the initial imaging, which is expressed as negative washout rate. To evaluate the diagnostic implications of this negative washout rate the findings of dipyridamole thallium scintigraphy in 582 patients with coronary artery disease were evaluated. The negative washout rate was present in 201 of 582 patients (35%). It had a significant association with high grade coronary artery narrowing of > or = 90%. Sensitivity in detecting patients with this high grade narrowing by negative washout rate was 48%, its specificity was 93%, and its positive predictive value was 94%. Sensitivity to detect individual coronary artery narrowing of > or = 90% did not decrease according to the extent of CAD, with the highest detection in the left anterior descending coronary artery and the lowest in the left circumflex coronary artery. Since patients with high grade coronary narrowing often require coronary intervention, the results of this study suggest the diagnostic importance of negative washout rate in the identification of the particular subset of patients with CAD.

Echocardiographic evaluation of fibrous replacement in the myocardium of patients with Duchenne muscular dystrophy.

To study myocardial echo amplitude in Duchenne muscular dystrophy and to examine the implications of increased echo amplitude. Regional echo amplitude, wall motion, and uptake of thallium-201 were examined in the left ventricular wall and the relation between these variables was investigated. Hara National Sanatorium, Japan. Seven healthy controls aged 10-28 years and 14 patients with Duchenne muscular dystrophy aged 12 to 30 years. Echocardiography with a sector scanner (Hitachi EUB-150, Japan) and a 3.5 MHz transducer (Hitachi EUP-S21, Japan); thallium-201 myocardial single photon emission computed tomography at rest with a rotating gamma camera system (Hitachi RC-135DT, Japan). Echo amplitude of the myocardium, thickness and wall motion of the posterior wall and ventricular septum, and myocardial uptake of thallium-201. Areas of increased echo amplitude were detected along the outer half of or throughout the posterior wall of left ventricle in nine of the 14 patients. Their posterior walls showed significantly decreased maximal systolic and diastolic endocardial velocities (mean (SE) 31.4 (16.0) and 55.6 (53.5) mm/s) compared with normal subjects (57.7(19.4) and 113.0 (27.5) mm/s), and decreased uptake of thallium-201. Their ventricular septa, however, showed normal echo amplitude and wall motion and normal uptake of thallium-201. Areas of increased echo amplitude were detected in the posterior walls of left ventricles of patients with Duchenne muscular dystrophy. These areas were suspected to be the sites of myocardial fibrosis.

Scintigraphic evaluation of myocardial uptake of thallium 201 and technetium 99m pyrophosphate utilizing a rat model of chronic doxorubicin cardiotoxicity

To evaluate the usefulness of myocardial scintigraphy as a monitoring tool for chronic doxorubicin (DXR) cardiotoxicity, a rat model was used to investigate the relationship between the myocardial uptake of thallium 201 (Tl) or rechnetium 99m pyrophosphate (99mTc-PPi) and histological changes of the heart. Although there was no significant difference in myocardial Tl uptake between control and DXR-treated rats at an early phase after Tl injection, late-phase Tl uptake was significantly higher in the DXR-treated rats than in the control rats, indicating a slow wash-out of Tl from the myocardium. The wash-out rate calculated from scintigraphic examination of DXR-treated rats was significantly decreased with increasing degree of cardiomyopathy. Since the Tl wash-out rate was sharply decreased even in animals with minimal histological changes, it may be a possible monitoring tool for the early detection of chronic DXR cardiotoxicity. On the other hand, myocardial 99mTc-PPi images could be obtained only in rats with severe myocardial changes and hence would not useful for early detection.

Early assessment of tissue viability with radioiodinated heptadecanoic acid in reperfused canine myocardium: Comparison with thallium-201

Myocardial scintigraphy with heptadecanoic acid labeled with iodine-123 (123I-HDA) may allow early noninvasive delineation of viable myocardium after reperfusion. In this study myocardial uptake of 123I-HDA was compared with that of thallium-201 in six closed-chest dogs after 5 hours of occlusion followed by 1 hour of reperfusion of the left anterior descending coronary artery. Myocardial blood flow was measured with microspheres, and myocardial viability was assessed by means of triphenyltetrazolium chloride staining. In viable areas of the reperfused region, 123I-HDA uptake, thallium-201 uptake, and myocardial blood flow were similar to those measured in the control circumflex region. However, in infarcted areas they were reduced to 48 +/- 2% (mean +/- SEM; p less than 0.001), 59 +/- 3% (p less than 0.001), and 74 +/- 5% (p less than 0.001) of control values, respectively. Results of multiple regression analysis showed that thallium-201 uptake primarily reflected the level of flow during reperfusion, whereas 123I-HDA uptake was dependent on both myocardial blood flow and viability. At each level of flow, 123I-HDA uptake was significantly lower in infarcted than in viable myocardium. By means of discriminant analysis, 123I-HDA uptake was found to be the single most important predictor of viability, whereas thallium-201 was only of limited importance. Myocardial 123I-HDA uptake greater than or equal to 71% or myocardial thallium-201 uptake greater than or equal to 73% best differentiated viable from infarcted myocardium. According to these criteria, 123I-HDA predicted myocardial viability with a sensitivity of 77%, a specificity of 84% and a predictive accuracy of 81%.(ABSTRACT TRUNCATED AT 250 WORDS)

Myocardial thallium-201 uptake and long-term functional recovery after myocardial infarction with reperfusion therapy

Myocardial thallium-201 uptake and long-term functional recovery after myocardial infarction with reperfusion therapy

Improved detection of coronary artery disease by estimated myocardial thallium uptake.

Myocardial thallium uptake has been assessed at the time of thallium scanning in a group of 50 male patients undergoing coronary arteriography and 10 young healthy volunteers. The net thallium dose injected was obtained by counting the dose prior to injection using the gamma camera and counting the syringe and IV cannula after injection. Significantly higher levels of myocardial thallium uptake were obtained in both the volunteers and patients with normal coronary anatomy (1.36% +/- 0.32%, n = 10 and 0.93% +/- 0.26%, n = 9, respectively) compared to patients with single, double or triple vessel coronary artery disease (0.63% +/- 0.19%, n = 11; 0.70% +/- 0.20%, n = 15; 0.67 +/- 0.18, n = 15, respectively). Exercise tests were positive in 46% of patients with coronary artery disease with an overall predictive accuracy of 56%. Thallium scans were positive in 68% of patients at a specificity of 89%. If the range of myocardial thallium uptake from the patients with normal coronary arteries is used to define a lower limit of normal, then the sensitivity of the thallium scan with thallium uptake is 90% with a predictive accuracy of 90% in the detection of significant coronary artery disease in this group of patients. Thus, estimation of total % thallium uptake is a simple index which yields useful diagnostic clinical information.

Improved diagnostic performance of exercise thallium-201 single photon emission computed tomography over planar imaging in the diagnosis of coronary artery disease: a receiver operating characteristic analysis

Qualitative interpretation of tomography and planar scintigrams, a five point rating scale and receiver operating characteristic analysis were utilized to compare single photon emission computed tomography and conventional planar imaging of myocardial thallium-201 uptake in the accuracy of the diagnosis of coronary artery disease and individual vessel involvement. One hundred twelve patients undergoing cardiac catheterization and 23 normal volunteers performed symptom-limited treadmill exercise, followed by stress and redistribution imaging by both tomographic and planar techniques, with the order determined randomly.Paired receiver operating characteristic curves revealed that single photon emission computed tomography was more accurate than planar imaging over the entire range of decision thresholds for the overall detection and exclusion of coronary artery disease and involvement of the left anterior descending and left circumflex coronary arteries. Tomography offered relatively greater advantages in male patients and in patients with milder forms of coronary artery disease, who had no prior myocardial infarction, only single vessel involvement or no lesion ≥50 to 69%. Tomography did not appear to provide improved diagnosis in women or in detection of disease in the right coronary artery. Although overall detection of coronary artery disease was not improved in patients with prior myocardial infarction, tomography provided improved identification of normal and abnormal vascular regions, particularly of the left anterior descending and circumflex artery regions.These results indicate that single photon emission computed tomography provides improved diagnostic performance compared with planar imaging in many clinical subgroups, and suggest that it represents the diagnostic imaging procedure of choice in exercise thallium-201 perfusion studies.