Technetium-99m Tetrofosmin Single-photon Emission Research Articles

Intramyocardial Injection of Autologous Bone Marrow Mononuclear Cells in Patients With Chronic Myocardial Infarction and Severe Left Ventricular Dysfunction

The present study investigated the safety, feasibility, and potential efficacy of autologous bone marrow cell injection in patients with chronic myocardial infarction and severe left ventricular (LV) dysfunction. In 15 patients (63 +/- 9 years; 14 men) bone marrow was aspirated from the iliac crest. Using the NOGA system (Biosense-Webster, Waterloo, Belgium), 94 +/- 14 x 10(6) bone marrow-derived mononuclear cells were injected into the infarction border zone. Bone marrow cell injection was performed without periprocedural complications in all patients. At 2.5 months, 1 patient died from worsening heart failure. New York Heart Association class improved from 3.5 +/- 0.5 at baseline to 2.7 +/- 0.8 at 3 months (p <0.01) and 2.9 +/- 0.8 at 6 months (p <0.01 vs baseline). LV ejection fraction (technetium-99m tetrofosmin single-photon emission computed tomography) increased from 23 +/- 8% to 27 +/- 9% at 3 months (p = 0.02) and regional wall thickening improved from 12.8 +/- 5.9% to 15.3 +/- 7.2% at 3 months (p = 0.02). Injected myocardial segments displayed a significant improvement in regional wall thickening (6.6 +/- 6.3% vs 11.7 +/- 7.0% at 3 months, p <0.01) and perfusion score (3.5 +/- 0.7 vs 3.0 +/- 0.9 at 3 months, p = 0.02) and a trend toward an improved fluorine-18 fluorodeoxyglucose score (2.9 +/- 0.9 vs 2.6 +/- 1.0 at 3 months, p = 0.06). Regional wall thickening (16.5 +/- 8.9% vs 19.1 +/- 9.1% at 3 months, p = NS), perfusion score (1.8 +/- 0.4 vs 1.7 +/- 0.5 at 3 months, p = NS), and fluorodeoxyglucose score (1.7 +/- 0.4 vs 1.6 +/- 0.4 at 3 months, p = NS) did not improve in noninjected myocardial segments. In conclusion, bone marrow cell injection in patients with chronic myocardial infarction and severe LV dysfunction is safe and feasible and appears to be associated with a decrease in heart failure symptoms and an improved LV function.

Sustained effect of autologous bone marrow mononuclear cell injection in patients with refractory angina pectoris and chronic myocardial ischemia: Twelve-month follow-up results

Cell therapy has recently been introduced to treat patients with refractory angina. Because most studies have only included short-term follow-up, the effects of cell therapy over a longer period are unknown. In 25 patients (mean age 64 +/- 10 years, 21 men) with refractory angina, a total of 84 +/- 29 x 10(6) bone marrow-derived mononuclear cells was injected intramyocardially in regions with ischemia on technetium-99m tetrofosmin single-photon emission computed tomography. Anginal symptoms and quality of life were evaluated at baseline and at 3, 6, and 12 months. Gated single-photon emission computed tomography was performed at baseline and at 3 and 12 months to assess myocardial perfusion and left ventricular function. Bone marrow cell injection was performed without any complication. At 7 months, one patient died of intracranial hemorrhage. Canadian Cardiovascular Society class improved from 3.4 +/- 0.5 to 2.3 +/- 0.6 at 3 months, 2.4 +/- 0.6 at 6 months, and 2.7 +/- 0.8 at 12 months (P < .01). Quality of life improved from 53% +/- 10% to 71% +/- 11% at 3 months, 72% +/- 14% at 6 months, and 68% +/- 14% at 12 months (P < .01). The number of segments with ischemia per patient decreased from 4.7 +/- 3.3 to 2.1 +/- 2.6 at 3 months and 1.6 +/- 2.5 at 12 months (P < .01). Left ventricular ejection fraction increased from 47% +/- 13% to 53% +/- 17% at 3 months and 51% +/- 17% at 12 months (P < .01). Regional wall motion improved from 5.9 +/- 1.7 to 6.6 +/- 2.2 mm at 3 months and 6.4 +/- 2.0 mm at 12 months (P = .01). Autologous bone marrow cell injection in patients with ischemia is safe and results in a sustained beneficial effect on anginal symptoms, myocardial perfusion, and left ventricular function.

The Value of Upsloping ST Depression in Diagnosing Myocardial Ischemia

We evaluated the value of upsloping ST-segment depression in predicting the severity of myocardial ischemia. Comparison of the exercise electrocardiographic changes was made to myocardial perfusion images and coronary angiograms as the criteria for ischemia. We retrospectively reviewed 621 patients who underwent exercise technetium-99m tetrofosmin single photon emission computed tomography (SPECT) for the assessment of suspected or known coronary artery disease followed by coronary angiography within a 3-month period. The test sensitivity and specificity of 1 mm horizontal or downsloping ST depression in predicting reversible ischemia as assessed by gated SPECT imaging (GSI) were 65% and 87%, respectively. The corresponding values were 67% and 94% compared to coronary angiography. The sensitivity and specificity of gated SPECT imaging compared to coronary angiography were 78% and 89%. On the other hand when 1 mm upsloping ST depression at 70 ms past the J-point was regarded as abnormal, along with horizontal and downsloping, the sensitivity and specificity were 82% and 90% compared to myocardial perfusion imaging, and 77% and 92% as assessed by coronary angiography. We conclude that upsloping ST-segment depression is associated with an increased risk of coronary artery disease and is a valuable predictor of myocardial ischemia.

Cardiovascular Disease Risk Stratification With Stress Single-Photon Emission Computed Tomography Technetium-99m Tetrofosmin Imaging in Patients With the Metabolic Syndrome and Diabetes Mellitus

The metabolic syndrome represents a constellation of risk factors caused by insulin resistance, dyslipidemia, hypertension, and obesity, resulting in elevated coronary disease risk. From a multicenter prospective registry of 7,849 patients, the relation among the metabolic syndrome, diabetes, and risk stratification with stress technetium-99m tetrofosmin single photon-emission computed tomography (SPECT) was evaluated. The percentage of stress myocardial defects was calculated as < or = 5%, 5.1% to 10%, 10.1% to 15%, and > 15%. A Cox proportional-hazards model was used to estimate cardiovascular death or myocardial infarction (n = 752). Of 7,849 patients, 42% had the metabolic syndrome. Patients with the metabolic syndrome had an 84% 2-year event-free survival rate, lower than patients with normal metabolic status (p <0.0001). In patients with the metabolic syndrome, the percentage of moderate to severely abnormal SPECT findings ranged from 11% to 44% for those with 3 to 5 risk factors for the metabolic syndrome. There was an additive relation between the number of risk factors for the metabolic syndrome and the extent and severity of abnormalities in SPECT findings (p <0.0001). Patients with 5 risk factors for the metabolic syndrome were at the greatest risk, with hazard ratios from 7.8- to 14.1-fold for mild to severely abnormal SPECT findings. For diabetic patients requiring combined oral and insulin therapy, relative risk ratios increased from 15 to 21.4 for patients with > 5% to > 15% stress myocardial perfusion defects. In conclusion, cardiovascular prognosis is affected by the degree of metabolic dysfunction, and stress-induced reductions in myocardial perfusion provide an accurate means for near-term risk stratification.

Relation of Myocardial Perfusion Defects and Nonsignificant Coronary Lesions by Angiography With Insights from Intravascular Ultrasound and Coronary Pressure Measurements

Several studies have demonstrated a correlation between myocardial ischemia and severity of coronary lesions as determined by intravascular ultrasound (IVUS) and fractional flow reserve (FFR) measurements. However, their value for the assessment of mild coronary stenoses that are associated with myocardial perfusion abnormalities has not been well studied. The objective of this study was to prospectively compare the results of myocardial perfusion as determined by exercise/dipyridamole myocardial single-photon emission computed tomography with IVUS and FFR measurements in patients who had angiographically mild coronary stenosis (< 50% diameter stenosis by quantitative coronary angiography). Forty-eight patients who had stable coronary disease (61 +/- 11 years of age; 6 women) were included. All had mild coronary stenosis in the proximal/middle segment of > or = 1 coronary artery and had undergone maximal exercise myocardial technetium-99m tetrofosmin single-photon emission computed tomography within 48 hours before coronary angiography. IVUS measurements included lesion lumen area, external elastic membrane area, lesion plaque burden (calculated as external elastic membrane minus lumen area, divided by external elastic membrane, and multiplied by 100), and lumen area stenosis (calculated as reference lumen area minus lesion lumen area, divided by reference lumen area, multiplied by 100). Fifty-three coronary lesions were studied, with a mean percent diameter stenosis of 34.9 +/- 7.9% on angiography. Myocardial perfusion defects were demonstrated by single-photon emission computed tomography in 11 patients (12 myocardial regions) with no differences in lesion percent diameter stenosis compared with those without perfusion defects. The presence of reversible perfusion defects was associated with a higher lesion plaque burden as evaluated by IVUS (67.4 +/- 8.1% vs 60.2 +/- 9.3%, p = 0.01). FFR values did not differ in the presence or absence of perfusion defects (0.90 +/- 0.06 vs 0.92 +/- 0.07, respectively; p = NS). In conclusion, plaque burden as determined by IVUS may partly explain the presence of myocardial perfusion defects in cases of angiographically nonsignificant coronary lesions. However, the high FFR values associated with these lesions suggest that other mechanisms, such as endothelial/microvascular dysfunction, might also account for perfusion abnormalities in these patients.

Nuclear medicine imaging for the assessment of primary and recurrent head and neck carcinoma using routinely available tracers.

This article reviews the literature on the use of fluorine-18 fluorodeoxyglucose positron emission tomography (FDG PET) and thallium-201, technetium-99m sestamibi and technetium-99m tetrofosmin single-photon emission tomography (SPET) for the diagnosis and staging of primary and recurrent squamous cell carcinoma of the head and neck (SCCHN). A search of the MEDLINE and CancerLit databases covering articles entered between 1989 and February 2003 was performed. In the case of FDG PET, only full-ring PET studies that included comparison with conventional morphological imaging were considered. Due to the wide variation in methodology, a straightforward meta-analysis of FDG PET literature was impossible. Instead, indicative summary receiver-operating curves of FDG PET and morphological imaging techniques were generated and a paired comparison of the sensitivities and specificities of FDG PET and morphological imaging performed. Compared with conventional morphological imaging, FDG PET proved as sensitive and specific for the detection of primary SCCHN but more sensitive and specific for the detection of cervical lymph node involvement (CLNI) and recurrence of SCCHN. Additional studies addressing the role of FDG PET in screening for distant metastases and synchronous primary tumours are mandatory. Following negative conventional evaluations, FDG PET identifies occult primary tumours in 20-50% of patients presenting with CLNI. As regards the use of 201Tl, 99mTc-sestamibi and 99mTc-tetrofosmin, more studies are required to define whether these imaging agents could form part of the current diagnostic armamentarium in SCCHN patients. It is concluded that FDG PET either is superior to or offers added value when compared with conventional morphological imaging techniques for the purpose of diagnosis and staging of primary and recurrent SCCHN.

Technetium-99m Tetrofosmin Single Photon Emission Computed Tomography to Detect Metastatic Papillary Thyroid Carcinoma in Patients with Elevated Human Serum Thyroglobulin Levels but Negative I-131 Whole Body Scan

AIM: The aim of this study was to evaluate the effectiveness of technetium-99m tetrofosmin (Tc-99m TF) single photon emission computed tomography (SPECT) of the neck and chest to detect metastatic lesions in papillary thyroid carcinoma (PTC) after near total thyroidectomy and radioiodine (I-131) treatment in patients who present with elevated serum human thyroglobulin (hTg) levels but negative I-131 whole body scan (WBS). MATERIALS AND METHODS: Twenty patients with PTC treated by near total thyroidectomy and I-131 treatments were included in this study. All 20 patients had negative I-131 WBS results and elevated hTg levels (hTg 2.0 μIU/ml) under thyroid-stimulating hormone (TSH) stimulation (TSH 30 μIU/ml). Nineteen of the 20 cases were confirmed to have metastases by operation/biopsy histopathological findings or clinical follow-up longer than 1 year by additional morphological imaging techniques. The remaining patient has been followed up closely and has been disease free for 10 months. Tc-99m TF SPECT was performed to detect metastatic lesions. RESULTS: Tc-99m TF SPECT demonstrated lesions in 11/19 patients; a sensitivity of 57.9%. Tc-99m TF SPECT failed to demonstrate lesions in eight patients including smaller lymph nodes and miliary lung metastases. CONCLUSIONS: We conclude that Tc-99m TF SPECT is a useful additional tool to detect metastatic lesions in PTC with elevated hTg but negative I-131 WBS. However, smaller lymph nodes and miliary lung metastases may be missed.

Myocardial viability inchronic ischemic heart disease: Comparison of contrast-enhanced magnetic resonance imaging with 18F-fluorodeoxyglucose positron emission tomography

ObjectivesWe sought to compare contrast-enhanced magnetic resonance imaging (ceMRI) with nuclear metabolic imaging for the assessment of myocardial viability in patients with chronic ischemic heart disease and left ventricular (LV) dysfunction. BackgroundContrast-enhanced MRI has been shown to identify scar tissue in ischemically damaged myocardium. MethodsTwenty-six patients with chronic coronary artery disease and LV dysfunction (mean ejection fraction 31 ± 11%) underwent 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET), technetium-99m tetrofosmin single-photon emission computed tomography (SPECT), and ceMRI. In a 17-segment model, the segmental extent of hyperenhancement (SEH) by ceMRI, defined as the relative amount of contrast-enhanced tissue per myocardial segment, was compared with segmental FDG and tetrofosmin uptake by PET and SPECT. ResultsIn severely dysfunctional segments (n = 165), SEH was 9 ± 14%, 33 ± 25% (p < 0.05), and 80 ± 23% (p < 0.05) in segments with normal metabolism/perfusion, metabolism/perfusion mismatch, and matched defects, respectively. Segmental glucose uptake by PET was inversely correlated to SEH (r = −0.86, p < 0.001). By receiver operator characteristic curve analysis, the area under the curve was 0.95 for the differentiation between viable and non-viable segments. At a cutoff value of 37%, SEH optimally differentiated viable from non-viable segments defined by PET. Using this threshold, the sensitivity and specificity of ceMRI to detect non-viable myocardium as defined by PET were 96% and 84%, respectively. ConclusionsContrast-enhanced MRI allows assessment of myocardial viability with a high accuracy, compared with FDG-PET, in patients with chronic ischemic heart disease and LV dysfunction.

Detection of Recurrent or Residual Nasopharyngeal Carcinomas After Radiotherapy with Technetium-99m Tetrofosmin Single Photon Emission Computed Tomography and Comparison with Computed Tomography—A Preliminary Study

The effectiveness of technetium-99m tetrofosmin (Tc-TF) single photon emission computed tomography (SPECT) of the head and neck for detecting recurrence of nasopharyngeal carcinomas (NPC) was evaluated and compared with computed tomography (CT). Both Tc-TF SPECT and CT of the head and neck were performed in 36 NPC patients 4 months after radiotherapy. All 36 then underwent histopathological examinations of nasopharyngeal biopsies. Based on the histopathological results, the sensitivity, specificity, and accuracy of visually interpreted Tc-TF SPECT images, to differentiation of recurrent NPC from benign lesions, were 64%, 96%, and 86%, respectively. The sensitivity, specificity, and accuracy of CT for detecting recurrent NPC were 73%, 88%, and 83%, respectively. The Tc-TF SPECT has a better specificity but a lower sensitivity to differentiate benign lesions and recurrent/residual NPC when compared with CT. Combined Tc-TF SPECT and CT sensitivity and specificity were 100% and 88%, respectively. There are much better either test alone. However, further studies, including a larger NPC patient population, are warranted to determine the exact role and clinical usefulness of Tc-TF SPECT to differentiate benign lesions and recurrent/residual NPC.

Detection of Recurrent Nasopharyngeal Carcinomas After Radiotherapy with Technetium-99m Tetrofosmin Single Photon Emission Computed Tomography in Patients with Indeterminate Magnetic Resonance Imaging Findings

The aim of this study is to evaluate the effectiveness of technetium-99m tetrofosmin (Tc-99m TF) single photon emission computed tomography (SPECT) of head and neck for detecting suspected recurrence of nasopharyngeal carcinomas (NPCs) when magnetic resonance imaging (MRI) findings are indeterminate. MRI was performed 4 months after radiotherapy and 26 NPC patients with indeterminate MRI findings were included. MRI, Tc-99m TF SPECT, and biopsy were performed within 1 week. The final results were based on histopathologic findings and clinical follow-up for at least 6 months. For detecting recurrent NPC in indeterminate MRI findings, the sensitivity, specificity, and accuracy of Tc-99m TF SPECT were 92.3%, 100.0%, and 96.2%, respectively. Based on this result, we can suggest Tc-99m TF SPECT is effective to detect recurrent NPC when MRI findings are indeterminate. However, further studies including a larger NPC patient population are warranted to determine the exact role and clinical usefulness of Tc-99m TF SPECT to differentiate benign lesions and recurrent NPC when MRI findings are indeterminate.

Prediction of mortality in heart transplant recipients by stress technetium-99m tetrofosmin myocardial perfusion imaging

Cardiac allograft vasculopathy is a major cause of mortality in heart transplant recipients. The aim of this study was to assess the prognostic value of stress myocardial perfusion imaging in heart transplant recipients. We studied 166 patients (age 54 ± 10 years, 140 men) by symptom-limited bicycle exercise or dobutamine (up to 40 μg/kg/min) stress myocardial perfusion imaging 7.4 ± 2.5 years after heart transplantation. An intravenous dose of 370 MBq of technetium-99m tetrofosmin was injected at peak stress and 24 hours after the stress test. An abnormal test was defined as reversible or fixed perfusion defects. Perfusion abnormalities were detected in 55 patients (33%). During a median follow-up of 2.5 years, 54 deaths (33%) occurred, 16 of which were due to cardiac causes. The incidence of perfusion abnormalities was higher in patients with subsequent cardiac death than in patients without subsequent cardiac death (69% vs 29%, p = 0.01). In an incremental multivariate Cox analysis, cardiac death was not predicted by age, gender, duration of transplantation, number of rejection episodes, or cytomegalovirus infection. In the next step, stress test parameters were added. The peak rate-pressure product was the only significant predictor at this step (risk ratio 0.84, 95% confidence interval 0.73 to 0.97, chi-square 7.7, p = 0.006). In the final step, the presence of abnormal myocardial perfusion was an independent predictor of cardiac death (risk ratio 3.5, 95% confidence interval 1.6 to 11.7, chi-square 4.7, incremental to clinical and stress test variables, p = 0.01). It is concluded that stress myocardial perfusion imaging with technetium-99m tetrofosmin single-photon emission computed tomography provides incremental data for the prediction of cardiac death in heart transplant recipients.

Correlation of Abnormal Response of Left Ventricular Ejection Fraction after Exercise and Left Ventricular Cavity-to-Myocardium Count Ratio of Technetium-99m-Tetrofosmin Single Photon Emission Computed Tomography in Patients with Coronary Artery Disease. A Preliminary Report.

The aim of this study was to assess the value of the left ventricular cavity-to-myocardium count ratio (C/M ratio) of technetium-99m (Tc-99m) tetrofosmin single photon emission computed tomography (SPECT) to identify abnormal left ventricular ejection fraction (LVEF) responses after exercise in patients with coronary artery diseases (CAD). We studied 50 patients with recent CAD undergoing rest and exercise first-pass ventriculography to calculate LVEF and rest and exercise Tc-99m tetrofosmin myocardial perfusion SPECT to calculate left ventricular C/M ratios. Group A, consisting of 25 CAD patients with normal responses (increased LVEF> or =5% after exercise), had significantly higher rest and exercise C/M ratios than those of the group B, consisting of 25 CAD patients with abnormal responses (increased LVEF <5% after exercise) after exercise. However, the C/M ratios between exercise and rest did not differ significantly between groups A and B. In addition, there was significant correlation between LVEF and C/M ratios in all of the patients. C/M ratios of Tc-99m tetrofosmin myocardial perfusion SPECT are useful parameters for identifying patients with abnormal LVEF responses among patients with CAD.

Relationship between exercise-induced ST segmental depression and myocardial ischemia assessed by technetium-99m tetrofosmin SPECT imaging in patients with inferior Q wave myocardial infarction.

ST segment depression (STD) is a standard electrocardiographic sign of myocardial ischemia. Although STD may represent reciprocal changes in patients with previous myocardial infarction, studies of reciprocal changes during exercise testing are scarce. From December 1999 to December 2000, 160 patients (119 males, 41 females, mean age 54 +/- 8 years), undergoing, maximal or symptom-limited exercise treadmill test (Bruce-protocol), myocardial perfusion scintigraphy using technetium-99m tetrofosmin single photon emission computed tomography (SPECT) imaging, within 30 days of an uncomplicated inferior Q wave myocardial infarction. The location of STD at the electrocardiogram (ECG) was defined as anterior (V1-4), high lateral (I, aVL), and lateral (V5-6). Ischemia was defined as reversible perfusion abnormalities. STD occurred in anterior leads in 29 patients (18.1%), in the lateral leads in 41 patients (25.6%), in the high lateral leads in 20 patients (12.5%). In 70 patients (43.8%) no significant STD occurred during the exercise test. ST segment elevation occurred in 28 patients (17.5%) in inferior leads. High lateral STD was associated with inferior ST elevation in 16 patients (80%), whereas only eight patients (19.5%) with lateral STD and nine patients (31%) with anterior STD were associated with inferior ST elevation. Ischemia was detected in 63 of 90 patients (70%) with and in 10 of 70 patients (14.3%) without STD (p < 0.0001). Patients with high lateral STD had a higher prevalence of fixed perfusion defects in the inferior wall (95 vs. 27.8%) and in posterolateral wall (75 vs. 18.9%) compared with other patients (p = 0.003 and 0.002, respectively). Ischemia was more prevalent in patients with lateral STD than without (87.8 vs. 14.3%, p < 0.0001). In patients with inferior Q wave, the presence of exercise-induced STD in lateral and anterior leads appears to be a sign of myocardial ischemia, and may require invasive evaluation; on the other hand, the presence of STD in high lateral leads should be recognized as a reciprocal change for ST elevation in the inferior leads, and may not be an indication for invasive evaluation.

Discordance between dipyridamole stress technetium-99m tetrofosmin single photon emission computed tomography and coronary angiography in patients with Kawasaki disease.

Kawasaki disease (KD) is an acute vasculitis syndrome of unknown etiology that mainly affects the coronary arteries. The purpose of this study was to assess the agreement between dipyridamole stress technetium-99m tetrofosmin (Tc-TF) myocardial perfusion single photon emission computed tomography (SPECT) and coronary angiography in these patients. Twenty-nine children with KD were included in this study. All of the 29 children also received dipyridamole stress Tc-TF myocardial perfusion SPECT within 1 month of their coronary angiographic studies. The results showed that (1) 89.7% of children had negative coronary angiographic findings without significant coronary stenoses, and 10.3% of children had positive coronary angiographic findings with significant coronary stenosis; (2) 44.8% of children had negative Tc-TF myocardial perfusion SPECT findings without abnormal myocardial perfusion, and 55.2% of children had positive Tc-TF myocardial perfusion SPECT findings with abnormal myocardial perfusion; (3) 44.8% of children had both normal coronary angiographic and Tc-TF myocardial perfusion SPECT findings, and 10.3% of children had both abnormal coronary angiographic and Tc-TF myocardial perfusion SPECT findings; and (4) There was no significant agreement between coronary angiographic and Tc-TF myocardial perfusion SPECT findings. We concluded that poor agreement exists between coronary angiographic and Tc-TF myocardial perfusion SPECT findings with coronary stenoses and abnormal myocardial perfusion in children with KD.

Early identification of impaired myocardial reperfusion with serial assessment of ST segments after percutaneous transluminal coronary angioplasty during acute myocardial infarction

To evaluate the relation between ST-segment analysis and microvascular reperfusion in patients with acute myocardial infarction (AMI), we studied 51 patients with first AMI who were successfully treated by percutaneous transluminal coronary angioplasty (PTCA). The lead showing the greatest ST-segment elevation on the 12-lead electrocardiogram (ECG) was serially investigated until 24 hours after PTCA. Successful reperfusion was determined by technetium-99m tetrofosmin single-photon emission computed tomography. Impaired reperfusion (group 1: <4 change in the sum of the defect score from before to immediately after PTCA) was observed in 24 patients, and successful reperfusion (group 2) was observed in 27 patients. Although ST-segment elevation was reduced significantly at 30 minutes after PTCA in group 2 (2.2 ± 1.4 to 1.7 ± 1.3 mm, p = 0.01), there was no significant change in group 1 (1.9 ± 1.9 to 2.4 ± 1.7 mm). Ten of 14 patients (71%) with persistent ST-segment elevation (ΔST >0 mm change in ST segment from before to 30 minutes after PTCA >0) were in group 1, whereas 23 of 37 patients (62%) with ST-segment resolution (ΔST ≤0) were in group 2. The sensitivity and specificity of persistent ST-segment elevation for predicting impaired microvascular reperfusion were 42% and 85%, respectively. Thus, persistent ST-segment elevation 30 minutes after primary PTCA was a highly specific electrocardiographic marker of impaired reperfusion in patients with AMI.

Interhospital observer agreement in interpretation of exercise myocardial Tc-99m tetrofosmin SPECT studies

Background. We sought to determine the degree of interhospital agreement in the interpretation of exercise myocardial technetium-99m tetrofosmin single photon emission computed tomography (SPECT).Methods and Results. Five experienced hospital laboratories were asked to submit 2 sets of myocardial Tc-99m tetrofosmin SPECT images obtained in 150 patients undergoing coronary angiography: group A used a uniform color scale for all hospitals, and group B used the individual color scale in place at each hospital (uniform color scale, nonuniform color scale, and black-and-white scale). Thus a total of 300 images were interpreted by each center without knowledge of any other patient data. Angiographically significant coronary artery disease (≤50% diameter stenosis) was present in 90 patients (60%). By a majority decision (3 or more centers), the sensitivity was found to be similar for groups A and B (82% and 84%, respectively), but the specificity was significantly higher for group A (87% vs 73%; P = .021). Four or all 5 of the centers agreed on abnormal or normal results of SPECT images in 87% of patients in group A (κ 0.626) and in 78% of patients in group B (κ 0.528). The κ value of 0.617 was obtained for the uniform color scale, 0.467 for the uniform black-and-white scale, and 0.444 for the nonuniform color scale. Agreement on the left anterior descending artery territory (81% for group A and 78% for group B) was similar to that of the right coronary artery territory (79% for A and 75% for B) and to that of the left circumflex artery territory (91% for A and 85% for B). Agreement was similar in patients with 1-, 2-, and 3-vessel coronary artery disease (91%, 88%, and 86% for group A and 81%, 82%, and 82% for group B, respectively).Conclusions. In the interpretation of myocardial Tc-99m tetrofosmin SPECT images, good interinstitutional observer agreement was found, mainly when the uniform display method was adopted.

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 μg/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. (J Nucl Cardiol 2000;7:649-54.)

Accuracy of exercise testing in the assessment of the severity of myocardial ischemia as determined by means of technetium-99m tetrofosmin SPECT scintigraphy

Background. The separation of patients with suspected or known coronary artery disease into low- and high-risk subgroups by means of noninvasive testing is highly relevant in the selection of patients who require further diagnostic or therapeutic investigation. We evaluated whether exercise electrocardiographic variables during exercise testing might be a means of predicting the severity of myocardial ischemia as assessed with myocardial scintigraphy. Methods and Results. We retrospectively reviewed 816 consecutive patients (mean age, 57 ± 10 years) who underwent exercise technetium-99m tetrofosmin single photon emission computed tomography (SPECT) for the assessment of suspected or known coronary artery disease. Eight independent significant predictors of the extent and severity of reversible perfusion defects (ischemic perfusion score), which when integrated in a diagnostic algorithm satisfactorily discriminated patients with no reversible perfusion defects (sensitivity, 75%; specificity, 80%) and patients with severe impaired myocardial perfusion (≥11 ischemic perfusion score; sensitivity, 77%; specificity, 82%), were identified by means of stepwise discriminant analysis. However, patients with mildly to moderately impaired myocardial perfusion (≥1 but <11 ischemic perfusion score) were poorly discriminated (sensitivity, 50%; specificity, 78%). The set of variables that were significant (P > .0001) for prediction included sex, myocardial infarction, exercise angina, the maximal amount of ST segment depression, rate-pressure product threshold criteria, slope of ST segment depression, ST/heart rate index, and peak exercise heart rate. Conclusions. The results of the use of clinical and electrocardiographic exercise variables satisfactorily agrees with the results from scintigraphy only for patients with no reversible perfusion defects and with severely impaired myocardial perfusion. However, it fails as an approach with universal applicability. (J Nucl Cardiol 2000;7:575-83.)

Exercise-rest Tc-99m tetrofosmin SPECT in patients with chronic ischemic left ventricular dysfunction: Direct comparison with TI-201 reinjection

Background. This study was designed to compare the results of exercise-rest technetium-99m tetrofosmin single photon emission computed tomography (SPECT) with those of thallium-201 reinjection at rest after exercise-redistribution imaging in the same patients with chronic ischemic left ventricular (LV) dysfunction. Methods. Within 1 week, 33 patients with chronic myocardial infarction and LV dysfunction underwent exercise-rest tetrofosmin SPECT and TI-201 reinjection at rest after exercise-redistribution imaging. In each patient, regional tetrofosmin and TI-201 activity was quantitatively measured in 22 myocardial segments. Regional LV function was assessed in corresponding segments by echocardiography. Results. Agreement in the evaluation of regional perfusion status between tetrofosmin and TI-201 imaging was observed in 78% of the 726 total segments, with a κ value of 0.61. In segments with normal function at echocardiography ( n = 436), no difference between TI-201 and tetrofosmin uptake was observed. In hypokinetic segments ( n = 138), exercise tetrofosmin uptake was lower ( P < .01) as compared with exercise TI-201 activity, whereas no difference was observed between tetrofosmin uptake at rest as compared with TI-201 activity on redistribution and reinjection images. In segments with severe functional impairment (akinetic or dyskinetic, n = 152), tetrofosmin uptake on exercise images was reduced ( P < .01) as compared with exercise TI-201 activity; furthermore, tetrofosmin uptake at rest was lower ( P < .01) as compared with TI-201 activity on both redistribution and reinjection images. In these segments, concordance in the detection of myocardial viability between tetrofosmin and TI-201 imaging was observed in 138 (91%) of the 152 segments, with a κ value of 0.77. Conclusions. In patients with chronic coronary artery disease and LV dysfunction quantitative exercise-rest tetrofosmin and TI-201 reinjection SPECT provide similar information in the assessment of perfusion status and in the detection of myocardial viability.

Early detection of the no-reflow phenomenon in reperfused acute myocardial infarction using technetium-99m tetrofosmin imaging.

Evaluation of myocardial perfusion in the early stage of acute myocardial infarction (MI) is clinically important for adjunctive therapies to minimize infarct size. To determine the role of early scintigraphic detection of impaired myocardial reperfusion after primary coronary angioplasty (PTCA) in patients with acute MI, semiquantitative technetium-99m tetrofosmin single-photon emission tomographic (SPET) imaging was performed before primary PTCA (before; area at risk), 60 min after PTCA (after) and at 1 month (1 M; final infarct) in 35 patients with acute MI. The left ventricle was divided into 13 segments and the defect score was calculated as the sum of the perfusion defect of each segment, from 3 (complete defect) to 0 (normal perfusion). A significant myocardial perfusion change after PTCA was defined as a change in the defect score (before minus after PTCA) of >/=4. The echocardiographic asynergic score was defined as the number of asynergic (severe hypokinetic or akinetic) segments corresponding to the analogous segments on SPET images, and recovery of wall motion was calculated as absolute change in the asynergic score (before PTCA minus 1 M). Among the 35 patients, 15 (43%) had a change in the defect score of <4 (no reflow: group 1) while 20 had a change in the defect score of >/=4 (reflow: group 2). There were no significant differences between the two groups with respect to the time between admission to PTCA, revascularization time, collateral grade or Thrombolysis in Myocardial Infarction (TIMI) flow grade before PTCA. Despite the lack of a difference in area at risk between the two groups (group 1 = 12.8+/-4.3 and group 2 = 15.1+/-4.7), final infarct size in group 1 was significantly larger compared with that in group 2 (8.1+/-4.3 vs 4.9+/-3.0, P<0.001). Recovery of wall motion was significantly smaller in group 1 than in group 2 (4.3+/-1.7 to 3.5+/-1.5 vs 4. 1+/-2.1 to 1.6+/-1.6, P<0.001). In conclusion, a small change (<4) in defect score (scintigraphic no-reflow phenomenon) after primary PTCA indicates persisting impaired myocardial perfusion or irreversible cellular damage just after PTCA which is associated with poor recovery of wall motion, as compared with that observed in cases of reflow (>/=4 in defect score).