Risk stratification of patients after myocardial revascularization by stress Tc-99m tetrofosmin myocardial perfusion tomography

BACKGROUND: The aim of this study was to assess the incremental prognostic value of stress technetium 99m tetrofosmin imaging after myocardial revascularization. METHODS AND RESULTS: We studied 381 patients (aged 60 +/- 10 years, 270 men), 4.5 +/- 3.2 years after myocardial revascularization (coronary artery bypass grafting in 201 patients and percutaneous coronary intervention in 180 patients), who underwent exercise or dobutamine stress tetrofosmin single photon emission computed tomography. Events during a mean follow-up period of 3.5 +/- 1.4 years were cardiac death in 22 patients, nonfatal myocardial infarction in 11 patients (33 hard cardiac events), and late revascularization in 50 patients. There was no incidence of hard cardiac events in the 100 patients with normal perfusion. Hard cardiac events occurred in 19% of patients with reversible perfusion abnormalities and in 4% of patients without them (P <.01). The incidence of hard cardiac events was similar in patients with and without angina before stress testing (17/197 [8.6%] vs 16/184 [8.7%]). In a multivariate analysis model, predictors of cardiac death were stress rate pressure product and abnormal perfusion. Reversible perfusion abnormalities were independently associated with the composite endpoints of cardiac death, nonfatal myocardial infarction, and late revascularization. In an incremental multivariate analysis model, an abnormal scan was additive to clinical data in the prediction of hard cardiac events (model chi(2) = 17 vs 11, P <.01). CONCLUSION: Stress Tc-99m tetrofosmin myocardial perfusion imaging provides independent prognostic information for the prediction of cardiac events after myocardial revascularization. Symptoms are not predictive of outcome, and therefore asymptomatic patients should not be deferred from stress testing. A normal study identifies a very low-risk population in whom no further intervention is required.     

Underestimation of regional myocardial perfusion with Tc-99m sestamibi single-day rest-stress SPECT: a "drug washout" pitfall?

Myocardial perfusion scintigraphy with a Tc-99m sestamibi single-day SPECT protocol is a widely used technique to examine patients with possible or known coronary artery disease. A 76-year-old man with a clinical history suggestive of ischemic heart disease underwent Tc-99m sestamibi myocardial SPECT imaging with a same-day rest and stress protocol after temporary discontinuation of his current therapy, which included calcium channel and beta blockers and nitrates. The scintigraphic pattern was consistent with an asymptomatic infarction of the posterolateral myocardial wall and periinfarct ischemia. One week later, the patient had a Tc-99m sestamibi myocardial SPECT study at rest without discontinuing therapy, and scintigraphic images showed normalization of the posterolateral wall perfusion defect. The angiographic study showed a 90% stenosis of the circumflex artery. This case suggests that, during a 1-day cardiac SPECT protocol, washout of therapeutic pharmaceuticals may be responsible for underestimation of myocardial rest perfusion in territory supplied by a coronary artery with a critical stenosis.     

Accuracy of stress Tc-99m tetrofosmin myocardial perfusion tomography for the diagnosis and localization of coronary artery disease in women

Background  Earlier studies have suggested a modest accuracy of stress thallium 201 myocardial perfusion imaging (MPI) for the diagnosis of coronary artery disease (CAD) in women. The accuracy of stress MPI with technetium 99m tetrofosmin has not been studied in women. The aim of this study was to assess the accuracy of stress Tc-99m tetrofosmin MPI for the diagnosis and localization of CAD in women. Methods and Results  We studied 88 women who underwent exercise or dobutamine stress Tc-99m tetrofosmin tomography and coronary angiography within 3 months. Significant CAD was defined as a stenosis 50% or greater in diameter in at least 1 major epicardial coronary artery. Myocardial perfusion abnormalities were detected in 44 of 53 patients with significant CAD and in 7 of 35 patients without significant CAD (overall sensitivity, 83% [95% confidence interval (CI), 73%-93%]; specificity, 80% [95% CI, 67%-93%]; and accuracy, 82% [95% CI, 74%-90%]). The sensitivity was 72% (18/25) in patients with single-vessel CAD and 93% (26/28) in patients with multivessel CAD. Perfusion abnormalities were detected in 2 or more vascular distributions in 20 of 28 patients with multivessel CAD and in 4 of 60 patients without multivessel CAD (sensitivity for the identification of multivessel CAD, 71% [95% CI, 55%-88%]; specificity, 93% [95% CI, 86%-98%]; and accuracy, 86% [95% CI, 79%-93%]). The sensitivity, specificity, and accuracy were 82%, 84%, and 83%, respectively, for the diagnosis of CAD in the left anterior descending artery; 77%, 84%, and 81%, respectively, for CAD in the right coronary artery; and 74%, 80%, and 78%, respectively, for CAD in the left circumflex artery. Conclusion  Stress Tc-99m tetrofosmin MPI is an accurate noninvasive technique for the diagnosis and localization of CAD in women. Supported in part by a publication grant from GE Healthcare     

Prognostic implications of stress Tc-99m tetrofosmin myocardial perfusion imaging in patients with left ventricular hypertrophy

Background  Left ventricular hypertrophy (LVH) is associated with an increased risk of cardiac death. Data on the prognostic value of myocardial perfusion imaging (MPI) in patients with LVH are limited. The aim of this study is to assess the independent value of stress technetium 99m tetrofosmin MPI in predicting the long-term mortality rate in patients with LVH. Methods and Results  We studied 177 patients (mean age, 59±12 years; 134 men) with LVH by electrocardiographic criteria who underwent dobutamine or exercise stress Tc-99m tetrofosmin MPI. Endpoints during follow-up were cardiac and all-cause death and hard cardiac events. A normal scan was detected in 42 patients (24%). Myocardial perfusion abnormalities were fixed in 59 patients (33%) and reversible in 76 (43%). Perfusion abnormalities were observed in a single-vessel distribution in 79 patients and in a multivessel distribution in 56. During a mean follow-up period of 5.5±2 years, 60 patients (34%) died. Death was considered cardiac in 42 patients (24%). Nonfatal myocardial infarction occurred in 10 patients (6%). The annual mortality rate was 1.4% in patients with normal perfusion, 3.2% in those with perfusion abnormalities in a single-vessel distribution, and 8% in those with a multivessel distribution. In a multivariate analysis independent predictors of death were age (risk ratio [RR], 1.05; 95% confidence interval [CI], 1.02–1.07), male gender (RR, 1.9; 95% CI, 1.1–3.6), hypercholesterolemia (RR, 1.7; 95% CI, 1.0–2.9), and abnormal perfusion (RR, 2.7; 95% CI, 1.5–4.8). Conclusion  In patients referred for stress MPI, LVH is associated with a high mortality rale, with approximately one third of patients dying over a period of 5 years. Stress Tc-99m tetrofosmin MPI provides independent information for predicting death in these patients. This study was supported in part by a limited publication grant from GE Healtheare.     

Comparison of exercise, dipyridamole, adenosine, and dobutamine stress with the use of Tc-99m tetrofosmin tomographic imaging

PURPOSE: The purpose of this study was to compare defect extent and severity and myocardial uptake with exercise and pharmacologic stress with technetium-99m (Tc-99m) tetrofosmin tomographic myocardial perfusion imaging. BACKGROUND: Detection of stress-induced myocardial perfusion defects depends on both a disparity in blood flow between normal and stenotic vessels and the extraction fraction and linearity of myocardial uptake of the tracer. There are limited clinical data for exercise or pharmacologic stress with Tc-99m tetrofosmin tomographic myocardial perfusion imaging. METHODS: Thirty-one patients with coronary artery disease and 7 with a < 5% likelihood of coronary artery disease underwent on separate days Tc-99m tetrofosmin single-photon emission computed tomographic imaging at rest and after exercise, dipyridamole, adenosine, and dobutamine stress. Images were interpreted by a blinded consensus of 3 experienced readers with a 17-segment model and 5-point scoring system. RESULTS: Compared with exercise, the summed stress score was smaller with dipyridamole (P < .01), and the reversibility score was smaller with both dipyridamole (P < .01) and dobutamine (P < .05), whereas the number of abnormal and reversible segments was less with both dipyridamole (P < .01 and P < .001, respectively) and dobutamine (both P < .05). No significant differences were found in the summed stress or reversibility scores and the number of abnormal or reversible segments between exercise and adenosine. CONCLUSIONS: Compared with exercise, defect extent, severity, and reversibility are less with dipyridamole and dobutamine with Tc-99m tetrofosmin single photon emission computed tomographic imaging.     

No gender bias in referral for coronary angiography after myocardial perfusion scintigraphy with technetium-99m tetrofosmin

BACKGROUND: Several studies have shown that the application of diagnostic and invasive procedures varies between men and women. The purpose of this study was to assess if referral for coronary angiography after technetium-99m tetrofosmin myocardial perfusion scintigraphy in 616 patients with undiagnosed chest pain might demonstrate gender bias. METHODS AND RESULTS: The primary end point for this study was coronary angiography within 90 days of myocardial perfusion scintigraphy. Women had more normal perfusion images than men (207 [70.9%] vs 160 [50.5%], P < .05). Of 242 patients with abnormal images (157 men, 85 women), 28 men (17.7%) and 17 women (20.0%) were referred for further invasive testing (P = not significant). Referral for coronary angiography increased relative to the number of defects. Univariate analysis showed that reversible and persistent defects were the most predictive variables for referral to coronary angiography (odds ratio [OR] 5.45, 95% confidence interval [CI] 3.10-9.58, P < .001, and OR 2.67, 95% CI 1.52-4.67, P = .001, respectively). More importantly, multivariate analysis showed that reversible perfusion defects (OR 4.77, 95% CI 2.48-9.17, P < .001) and persistent perfusion defects (OR 2.14, 95% CI 1.11-4.14, P = .02) were predictive of subsequent coronary angiography. No significant association between gender and subsequent coronary angiography was found both in univariate and multivariate logistic regression analysis (OR 0.64, 95% CI 0.37-1.12, P = .12, and OR 0.70, 95% CI 0.36-1.36, P = .28, respectively). CONCLUSIONS: Our study reveals that after correction for the presence and the severity of myocardial perfusion abnormalities, men and women were referred to coronary angiography at a similar rate. Thus, based on the results of technetium-99m tetrofosmin myocardial perfusion imaging, no substantial evidence for a gender-related bias could be found in the referral for further invasive testing.     

Dobutamine technetium-99m tetrofosmin SPECT imaging for the diagnosis of coronary artery disease in patients with limited exercise capacity

BACKGROUND: Technetium-99m tetrofosmin single photon emission computed tomography (SPECT) imaging is increasingly used in conjunction with exercise and vasodilator stress test as a means of evaluating coronary artery disease (CAD). Dobutamine stress test is an alternative in patients with limited exercise capacity. This study assessed the accuracy of dobutamine-atropine stress tetrofosmin SPECT as a means of diagnosing and localizing CAD. METHODS AND RESULTS: We studied 124 patients (mean age, 57+/-12 years; 88 men) with limited exercise capacity and suspected CAD with dobutamine (as much as 40 microg/kg/min)-atropine (as much as 1 mg) Tc-99m tetrofosmin SPECT. Resting images were acquired 24 hours after the stress test. Significant CAD was defined as 50% or greater luminal diameter stenosis in 1 or more major coronary arteries. Myocardial perfusion abnormalities (fixed and/or reversible defects) were detected in 70 of 88 patients with CAD and in 10 of the 36 patients without CAD (sensitivity = 80%, CI, 72 to 87; specificity = 72%, CI, 64 to 80; accuracy = 77%, CI, 70 to 85). Sensitivity and accuracy rates were higher by using the criterion of any defect than by using the criterion of reversible defects only (80% vs 51%, P<.0001; 77% vs 60%, P<.01, respectively). The sensitivity rate was higher in patients with multivessel CAD than in patients with single-vessel CAD (88% vs 63%, P<.05). Patients with multivessel CAD had a larger stress perfusion defect score (4.5+/-3.1 vs. 2.7+/-2.5, P<.01) than patients with single-vessel CAD. CONCLUSION: Dobutamine stress Tc-99m tetrofosmin SPECT is a useful method for the diagnosis and localization of CAD in patients with limited exercise capacity. Optimal accuracy of the technique is achieved by using both fixed and reversible perfusion abnormalities for the diagnosis of CAD in patients without an earlier myocardial infarction.     

Simultaneous measurement of ventricular function and myocardial perfusion using the technetium-99m isonitriles

To assess both ventricular function and myocardial perfusion, five normal volunteers, 19 patients with coronary artery disease, and two patients with cardiomyopathy and normal coronary arteries were injected with 20 mCi of Tc-99m isonitrile (either methoxyisobutyl isonitrile or carbomethoxyisopropyl isonitrile) at peak bicycle exercise and again at rest. A standard Tl-201 stress test was performed in all patients at the same level of exercise within one month of the isonitrile study. In all normal subjects, myocardial perfusion was normal at stress levels and the left ventricular ejection fraction increased 5% or more with exercise. In the 19 patients with coronary artery disease, the ejection fraction response to exercise was abnormal in 14 patients. Perfusion images with the Tc-99m isonitriles correlated well with Tl-201 images during exercise and at rest, with 89% concordance in areas of ischemia or infarction and 93% in normal segments. A simultaneous study of myocardial perfusion and ventricular function can be performed using a single Tc-99m labeled myocardial agent. Tc-99m isonitriles, particularly Tc-99m MIBI, result in sufficiently high photon flux that ventricular performance can be studied at peak exercise and again during rest using the first pass method.     

Diagnostic performance of low-dose rest/stress Tc-99m tetrofosmin myocardial perfusion SPECT using the 530c CZT camera: Quantitative vs visual analysis

Background

We set out to develop normal databases and prospectively validate abnormality criteria for a low-dose Tc-99m tetrofosmin myocardial perfusion SPECT protocol using the 530c CZT camera.

Methods

All patients received 6 mCi rest/20 mCi stress doses of Tc-99m tetrofosmin. Rest and stress images were obtained over 7-9 and 5-7 minutes according to the chest size. Low-dose CT of the chest was obtained on a standalone CT scanner. Forty patients with very low likelihood (LLK) of coronary artery disease (CAD) were used to define the normal count distributions. The abnormality criteria were prospectively validated in 55 patients who had coronary angiography and in 40 patients with LLK of CAD.

Results

The results for quantitative non-attenuation-corrected (AC) and AC analysis and visual analysis were as follows: sensitivity of 79%, 85%, and 92% (P = NS) and specificity of 44%, 75%, and 56% (P = NS), respectively. The normalcy rates for quantitative non-AC and AC analyses and visual analysis were 95%, 98%, and 98% (P = NS).

Conclusions

We have developed non-AC and AC normal databases for low-dose rest/stress Tc-99m tetrofosmin myocardial perfusion SPECT protocol using the 530c CZT camera. The per-patient diagnostic performance of quantitative analyses is not significantly different from visual analysis by an experienced reader.     

Assessment of transient left ventricular dilatation on rest and exercise on Tc-99m tetrofosmin myocardial SPECT.

In myocardial perfusion imaging, multiple-vessel involvement of coronary artery disease (CAD) sometimes makes diagnosis difficult. Transient left ventricular (LV) dilatation on Tl-201 myocardial SPECT is a useful finding that enables the clinician to identify patients with multiple-vessel disease. The aim of this study was to confirm the utility of measuring transient LV dilatation for the detection of multiple-vessel CAD in exercise Tc-99m tetrofosmin myocardial SPECT. The participants were 55 CAD patients and 20 controls who underwent Tc-99m tetrofosmin myocardial SPECT exercise and resting imaging. During exercise, 370 MBq (10 mCi) Tc-99m tetrofosmin was injected. Exercise images were obtained 30 minutes after injection. At 210 minutes after injection, 740 MBq (20 mCi) Tc-99m tetrofosmin was administered intravenously. The rest SPECT images were acquired 30 minutes later. Thirty-six radii at every 10 degrees were generated from the center of short-axis images. An area surrounded by 36 maximal points of the myocardial Tc-99m tetrofosmin counts on each radius was calculated for exercise and rest images. The area surrounded by the 36 maximal points in the same slice of the exercise and rest images was assigned the variables A (Ex) and A(R), respectively. The transient dilatation index (TDI) of the left ventricle was calculated using the formula mean A (Ex)/A(R) in the apical, middle, and basal myocardial short-axis images. In the controls, the TDI was 0.970 +/- 0.021. In patients with CAD, the TDIs of one-vessel disease, two-vessel disease, and three-vessel disease were 1.034 +/- 0.032, 1.093 +/- 0.046, and 1.131 +/- 0.076, respectively. The TDIs were significantly greater in patients who had more occluded coronary arteries (P < 0.01). If the mean + 2SD of the TDI (1.012) in controls were assumed to be the normal upper limit, the sensitivity, specificity, and accuracy of this method in detecting two-vessel or three-vessel disease would be 91.4%, 76.9%, and 84%, respectively. The TDI is a useful index for evaluating subendocardial ischemia non-invasively and detecting multiple-vessel disease clinically.     

Tc-99m tetrofosmin myocardial perfusion SPECT after dipyridamole combined with low-level exercise in the diagnosis of coronary artery disease

Tc-99m tetrofosmin is a lipophilic, cationic perfusion imaging agent that changes to Tl-201 in detecting coronary artery disease during exercise testing. The purpose of this study is to evaluate the usefulness of Tc-99m tetrofosmin dipyridamole stress imaging combined with low level exercise for the detection of coronary artery disease. We examined 42 patients and 10 normal volunteers who also underwent coronary angiography. A one-day protocol was used: in the stress study, 296 MBq of tetrofosmin was injected and in the rest study 888 MBq was injected. After intravenous administration of dipyridamole (0.142 mg/kg/min for 4 minutes), the patient was exercised on a bicycle ergometer for 3 min (25 Watts). Tetrofosmin was injected 2 minutes after dipyridamole infusion during the exercise. Single photon emission computed tomographic images were obtained 30 minutes after the tracer injection. Images were interpreted as abnormal in 36 of 42 patients with coronary artery disease, and normal in all of 10 normal volunteers. The overall sensitivity of detection of coronary artery disease was 83.3% and the normalcy rate was 100%. The diagnostic values for the detection of significant stenosis in the three major arteries were: LAD sensitivity 83%, specificity 92%; LCX sensitivity 47%, specificity 91%; RCA sensitivity 75%, specificity 83%. Of the 66 arteries with more than 50% stenosis, 48 arteries were correctly identified. Of the 36 with more than 70% stenosis, 31 were identified. Scintigraphic evidence of multivessel disease was found in only 9 patients (50%). A protocol of Tc-99m tetrofosmin SPECT combined with low level exercise after dipyridamole is therefore useful for the detection of the coronary artery disease.     

Gated Tc-99m sestamibi SPECT versus stress-rest SPECT in detecting coronary artery disease: correlation with coronary angiography in patients without myocardial infarction

PURPOSE: It is possible to simultaneously evaluate wall thickening and perfusion abnormalities with radionuclide techniques that use tracers such as Tc-99m MIBI. We presumed that detection of wall thickening by gated MIBI SPECT imaging in the presence of a stress-induced perfusion defect correlates with reversibility of that defect on resting images. Therefore, the aim of our study was to analyze, in patients without myocardial infarction, resting wall thickening and stress perfusion imaging as an alternative to conventional stress-rest imaging. METHODS AND RESULTS: The patients (n = 44) underwent an exercise (n = 37) or pharmacologic (n = 7) stress protocol. All patients had previous coronary angiography within 3 months. Stress-rest MIBI SPECT and gated MIBI SPECT studies were analyzed by visual scoring. The sensitivity and specificity of segmental analysis of both stress-rest MIBI SPECT perfusion and gated MIBI SPECT studies for the overall detection of coronary artery disease were, respectively, 71% and 96%. For patient evaluation for detection of coronary artery disease, stress-rest MIBI SPECT perfusion and gated MIBI SPECT studies showed a sensitivity rate of 96% for both and specificity rates of 84% and 79%, respectively. CONCLUSIONS: Our data revealed close agreement between reversible perfusion defects on stress-rest MIBI SPECT scans and significant wall thickening on gated MIBI SPECT stress images in patients without previous myocardial infarction (95%). Gated MIBI SPECT stress, without resting studies, which provide an assessment of wall motion and wall thickening, potentially allows stress defect reversibility to be evaluated in patients without previous myocardial infarction.     

The prognostic value of a normal Tc-99m sestamibi SPECT study in suspected coronary artery disease

BACKGROUND: Myocardial perfusion is widely used for risk stratification of patients with suspected or known coronary artery disease (CAD). Recent years have seen an increasing demand for screening of such patients. The value of a normal stress thallium-201 scanning is well established. The advent of technetium 99m-sestamibi single photon emission computed tomography (SPECT) has enhanced the profile of nuclear cardiology even further as a reliable test for screening. However, in spite of previous reports, there is paucity of large-scale data regarding the prognostic value of a normal Tc 99m-sestamibi scanning result. METHODS: The aim of our study was to assess the incidence of cardiac death and non-fatal myocardial infarction in patients with an intermediate probability of coronary artery disease (CAD). A total of 473 patients with normal stress Tc-99m-sestamibi SPECT were monitored for 30+/-16 (6 to 56) months to assess serious cardiac events. There were 272 men and 201 women, with a mean age of 56+/-2 years, of whom 89% had symptoms suggestive of CAD, 65% had an abnormal exercise electrocardiography, 6% had known CAD, and 5% had a high risk of CAD. The average workload was 9.14 metabolic equivalents, peak exercise heart rate was 93%+/-13% of the age predicted target. RESULTS: The annualized mortality rate was 0.2% (95%CI 0.02% to 0.7%) and no infarctions occurred in this group. CONCLUSIONS: A normal stress Tc-99m-sestamibi is highly predictive of a benign outcome, even in patients with intermediate probability of CAD.     

Combined assessment of regional perfusion and wall motion in patients with coronary artery disease with technetium 99m tetrofosmin

Background

Technetium 99m tetrofosmin is a new^99mTc-labeled myocardial perfusion agent that can be labeled easily and provides excellent myocardial perfusion images. In addition, bolus administration of the tracer allows first-pass radionuclide ventriculography.

Methods and Results

This study examined the diagnostic value of combined assessment of regional perfusion by tetrofosmin tomography and wall motion by first-pass radionuclide ventriculography both at rest and during stress in 24 patients suspected of having coronary artery disease. All patients underwent stress-rest tetrofosmin tomography, stress-delayed thallium 201 tomography, and coronary angiography. Stress tetrofosmin tomography showed abnormal perfusion in all 23 patients with angiographic evidence of coronary artery disease, whereas stress²⁰¹Tl tomography showed abnormal perfusion in 22 of the 23 patients. For detection of significant (≥50% diameter stenosis) stenotic coronary arteries, the two perfusion studies showed similar sensitivities (62% with²⁰¹Tl and 69% with tetrofosmin) and specificities (88% and 100%, respectively). When analysis of regional wall motion was combined with perfusion study, a slightly higher sensitivity was obtained (77%), with similar specificity. The regional wall motion score was concordant with the regional perfusion score in only 42% of the segments at rest and 50% during exercise.

Conclusions

These results suggest that stress tetrofosmin perfusion tomography and stress²⁰¹Tl tomography provided similar diagnostic accuracy for detection of coronary artery disease. The combined assessment of perfusion and function that is feasible with tetrofosmin may enhance diagnostic accuracy in patients with coronary artery disease.     

The value of Tc-99m MIBI SPECT during isosorbide dinitrate infusion in assessment of viable myocardium in patients with myocardial infarction

Tc-99m MIBI myocardial SPECT has shown promise for evaluation of coronary artery disease. But its role in predicting myocardial viability is still under investigation. The purpose of this study was to evaluate the value of Tc-99m MIBI myocardial SPECT during isosorbide dinitrate (ISDN) infusion in the assessment of myocardial viability. Thirty-seven patients with previous myocardial infarction (the infarct age ranged from ≤ 30 days to 900 days) were studied, of them 13 patients had Tc-99m MIBI studies before and after coronary artery bypass grafting (CABG). The results showed that out of 134 segments with hypoperfusion at resting SPECT, 56 segments (41.8%) had an increase in Tc-99m MIBI uptake during ISDN infusion. Among them, 17 segments (30.4%) were normalized, 6 segments (10.7%) were significantly improved and 33 segments (58.9%) were improved. The degree of improvement in perfusion was related to the age of the myocardial infarction. In 13 patients with CABG, of 31 segments with improvement in perfusion post CABG, 25 segments (80.6%) showed perfusion improvement during ISDN infusion, and of 28 segments with improved wall motion post CABG, 23 segments (82.1 %) showed improvement in perfusion during ISDN infusion. Tc-99m MIBI SPECT during ISDN infusion may therefore be a useful approach for assessing myocardial viability.     

Serial assessment of left ventricular function during dobutamine stress by means of electrocardiographygated myocardial SPECT: Combination with dual-isotope myocardial perfusion SPECT for detection of ischemic heart disease

BACKGROUND: Technetium-labeled myocardial perfusion tracers allow simultaneous assessment of myocardial perfusion and left ventricular function by electrocardiography (ECG)-gated myocardial single photon emission computed tomography (SPECT). The purpose of this study was to evaluate left ventricular performance during dobutamine stress by means of ECG-gated myocardial perfusion SPECT with short-time data collection. METHODS AND RESULTS: After administration of Tc-99m sestamibi or tetrofosmin (600-740 MBq), 67 patients with ischemic heart disease, including 35 with prior myocardial infarction, were examined by ECG-gated myocardial perfusion SPECT at rest and during dobutamine stress (at dosages of 4, 8, 12, 16, and 20 microg/kg/min, with increments every 8 minutes). The ECG-gated data collection time was 5 minutes for each dobutamine dosage. After acquisition of gated SPECT data at the highest dose, thallium 201 chloride (111 MBq) was injected, and dual-isotope SPECT was also performed to assess the myocardial ischemia. In 32 patients without prior myocardial infarction, the sensitivity of individual stenosed-vessel detection with dual-isotope perfusion SPECT, with wall motion abnormality obtained from gated SPECT, and with the combined method was 55.9%, 52.9%, and 73.5%, respectively, based on coronary angiography. ECG-gated SPECT during dobutamine infusion revealed regional wall motion abnormalities (worsening or biphasic response) in 19 (57.6%) of 33 infarcted areas with culprit coronary arterial stenosis. The prevalence of reversible perfusion defects on dual-isotope SPECT was higher in segments with wall motion abnormalities than in segments with normal wall motion response (89.5% vs 42.9%, P <.02). CONCLUSIONS: Myocardial perfusion and left ventricular function during dobutamine infusion were analyzed in a single examination by means of the combined method. This procedure has the potential to provide comprehensive information with which to evaluate patients with ischemic heart disease.     

Reduction of infracardiac intestinal activity by a small amount of soda water in technetium-99m tetrofosmin myocardial perfusion scintigraphy with adenosine stress

Background  In technetium (Tc)-99m myocardial perfusion imaging (MPI), intestinal activity often interferes with the assessment of myocardial perfusion of the inferior wall. We examined whether a small amount of soda water prevents intestinal activity and improves image quality of the inferior wall in Tc-99m tetrofosmin MPI. Methods and Results  Ninety-five patients referred for 1-day rest/stress Tc-99m tetrofosmin MPI were assigned to one of two groups automatically, according to the data when they underwent MPI: the soda water group (n=63) ingested 100 mL soda water just before image acquisition after adenosine stress, and the control group (n=32) underwent no intervention. The frequency of intestinal activity was assessed visually on planar images. The inferior myocardial wall and the abdominal activity adjacent to the myocardium were assessed quantitatively on three different planar images during stress, and the mean inferior wall-to-abdomen (1/A) count ratio was calculated. The frequency of intestinal activity was 69.8% in the soda water group, and 90.6% in the control group (P=.038). The I/A count ratio was significantly higher in the soda water group than in the control group (1.98±0.51 vs 1.50±0.35, respectively, P<.0001, ±SD). Conclusions  The intake of 100 mL of soda water improves intestinal activity and improves the image quality of the inferior wall.     

Perfusion and functional abnormalities outside the septal region in patients with left bundle branch block assessed with gated SPECT.

BACKGROUND: The presence of a left bundle branch block (LBBB) pattern on the electrocardiogram may frequently lead to perfusion defects in the septum not necessarily due to ischemic heart disease, but probably due to abnormal septal wall motion. The introduction of gated single photon emission computed tomography (SPECT) allows the evaluation of myocardial perfusion and function in one study. Accordingly, we analysed perfusion and function and the relation between perfusion and regional function in the septal region in patients with a LBBB without evidence of a previously sustained myocardial infarction. METHODS: We selected 37 patients with a LBBB without a history of a previous myocardial infarction, which was confirmed by echocardiography and/or coronary angiography. All patients underwent technetium-99m tetrofosmin gated SPECT myocardial imaging. Twelve control patients with a low likelihood of coronary artery disease and a normal technetium-99m tetrofosmin gated SPECT myocardial perfusion scintigram were selected as a reference population. The left ventricle (LV) was divided into 18 segments, which were scored for perfusion and function (wall motion and wall thickening) on a 4-point scale. RESULTS: The average LV end-diastolic volume was higher and the average LV ejection fraction was lower in patients with LBBB as compared to controls (142+/-90 vs. 81+/-18 ml, and 48+/-19 vs 62+/-7%, p=0.03 and p=0.02, respectively). Not only in the septum, but also in the other segments, reduced myocardial perfusion and abnormal wall motion/wall thickening was observed in the patients with LBBB (p<0.0001 vs controls). Patients with LBBB showed no correlation between perfusion and function in the septum, and between perfusion in septum and global LV function (r=0.21, p=0.2; r=0.10, p=0.6, respectively). Conversely, a good correlation was found between perfusion and function, either regional or global, in the remote segments (both r=0.79, p<0.0001). CONCLUSIONS: We conclude that patients with LBBB without a previous myocardial infarction show cardiomyopathic changes with perfusion and wall motion abnormalities, involving the entire left ventricle. The severity of diminished septal perfusion is not directly associated with the severity of septal wall motion abnormalities or global LV function. However, in the myocardial segments remote from the septum, reduced perfusion is closely associated with functional abnormalities.     

Baseline/post-nitrate Tc-99m tetrofosmin mismatch for the assessment of myocardial viability in patients with severe left ventricular dysfunction: Comparison with baseline Tc-99m tetrofosmin scintigraphy/FDG PET imaging

BACKGROUND: Positron emission tomography (PET) flow/metabolic mismatch is considered the nuclear medicine gold standard for the assessment of myocardial viability. The aim of this study was to investigate whether baseline/nitrate technetium 99m tetrofosmin single photon emission computed tomography (SPECT) mismatch may provide equivalent clinical information. METHODS AND RESULTS: We studied 23 patients (aged 62 +/- 10 years, 19 men) with previous myocardial infarction (16 anterior, 4 inferior, and 3 anterior plus inferior) and postischemic heart failure (gated SPECT [G-SPECT] ejection fraction, 26% +/- 8%). All patients underwent Tc-99m tetrofosmin G-SPECT at rest and after nitrates (intravenous isosorbide dinitrate, 0.2 mg/mL, 10 mL/h) as well as a fluorine 18 fluoro-2-deoxy-d-glucose (FDG) PET scan. Regional wall motion analysis was performed with quantitative G-SPECT (QGS). Myocardial dysfunction was defined as a regional QGS score of 2 or greater. Regional perfusion was assessed by quantitative perfusion score (QPS) providing percent Tc-99m tetrofosmin uptake in a 20-segment model. Semiquantitative analysis of FDG uptake was performed by use of polar maps generated by Siemens ECAT HR + software. In areas with a perfusion rate lower than 80%, PET viability was identified by a normalized FDG percent uptake/baseline Tc-99m tetrofosmin percent uptake ratio greater than 1.2. We analyzed 460 segments; 298 (64%) were dysfunctional by QGS analysis. Of these, 170 were viable by PET imaging whereas 128 were nonviable. Regional Tc-99m tetrofosmin uptake was higher in viable than in nonviable segments both at rest (60% +/- 24% vs 42% +/- 12%, P <.01) and after nitrates (67% +/- 20% vs 41% +/- 18%, P <.01). According to receiver operating characteristic curve analysis, a cutoff value of 63% for resting as well as post-nitrate G-SPECT provided the highest diagnostic accuracy for the detection of myocardial viability (67% and 72% at rest and after nitrates, respectively). When the same algorithm used for the comparison with PET (normalized nitrate percent uptake/baseline percent uptake) was applied to G-SPECT, we obtained the highest agreement with PET (accuracy, 93%; sensitivity, 95%; specificity, 92%). CONCLUSIONS: In patients with severe left ventricular dysfunction, perfusion data alone, both at rest and after nitrates, do not allow an accurate estimate of myocardial viability. In dysfunctioning segments, the analysis of rest/post-nitrate Tc-99m tetrofosmin mismatch provides results similar to those obtained by PET flow/metabolic mismatch.     

ATP负荷表模式采集首次通过心功能测定和心肌显像对冠心病的诊断价值

目的：探讨在ATP负荷下联合应用表模式采集首次通过心功能测定与心肌灌注显像诊断冠心病的价值。方法：对照组36例和冠心病组97例,在ATP负荷下,以^99Tc^m－甲氧基异丁基异腈（MIBI）为示踪剂,先用模式采集首次通过法测定心功能,90min后进行心肌灌注断层显像,并将其中52例与静息显像进行比较。结果：ATP负荷后心肌灌注显像诊断冠心病的灵敏度,特异性和准确性较静息状态差异有显著性（P＜0．05和P＜0．01）,而左心室射血分数（LVEF）诊断冠心病的灵敏度与准确性差异亦有显著性（P＜0．05）,但特异性差异无显著性（P＞0．05）。心肌梗死组都有不同程度心功能减低与心室扩张,甚至出现心肺血流动力学的改变,应用电影显示有52．38％的患者梗死节段存在不同程度的室壁运动。结论：该方法能同时评价心肌流灌注,心脏舒缩功能,心肺血流动力学及判断心室重构,室壁瘤形成与心肌活力,提高了对冠心病的诊断价值。