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.     

Enhanced detection of reversible perfusion defects by Tc-99m sestamibi compared to Tc-99m tetrofosmin during vasodilator stress SPECT imaging in mild-to-moderate coronary artery disease

OBJECTIVES: We prospectively compared dipyridamole single-photon emission computed tomography (SPECT) imaging with Tc-99m sestamibi and Tc-99m tetrofosmin for the detection of reversible perfusion defects in patients with mild-to-moderate coronary artery disease. BACKGROUND: Tc-99m tetrofosmin has a lower first-pass myocardial extraction fraction compared to Tc-99m sestamibi and thus could underestimate mild perfusion defects. METHODS: Eighty-one patients with 50% to 90% stenosis in one or two major epicardial vessels without previous myocardial infarction, and seven with <5% probability of coronary artery disease underwent dipyridamole SPECT imaging with both agents. The SPECT data were analyzed quantitatively. RESULTS: Tc-99m sestamibi detected reversible perfusion defects in a greater number of segments (total 363 and 285, p < 0.001, and mean +/- SD, 2.2 +/- 3.0 and 1.8 +/- 2.5 per patient, p = 0.008, for Tc-99m sestamibi and Tc-99m tetrofosmin, respectively), demonstrated a larger extent of perfusion defect (mean +/- SD, 15.8% +/- 12.3% and 12.0% +/- 11.4%, p < 0.03, for Tc-99m sestamibi and Tc-99m tetrofosmin, respectively) and more often correctly identified patients with disease in more than one coronary artery (p = 0.02). There was better defect contrast with Tc-99m sestamibi (defect/normal wall count ratios were 0.60 +/- 0.15 vs. 0.73 +/- 0.14 for Tc-99m sestamibi and Tc99m tetrofosmin, respectively, p = 0.01, for reversible defects seen in identical segments with both agents; and 0.73 +/- 0.16 vs 0.79 +/- 0.17, respectively, p <0.01, for reversible defects detected with either agent alone). There was no significant difference in diagnostic sensitivity or image quality. CONCLUSIONS: These differences between two commonly used tracers may have significant diagnostic and prognostic implications.     

Discordant results in Tc-99m tetrofosmin and Tc-99m sestamibi parathyroid scintigraphies

Parathyroid scintigraphies have been used to detect pathological parathyroid glands either before as well as after the parathyroid resection surgery in patients with hyperparathyroidism. One of the most utilized techniques to perform the studies is the double-phase images with Tc-99m sestamibi, which has been shown to be very accurate in the localization of enlarged parathyroid glands. Similar to Tc-99m sestamibi, Tc-99m tetrofosmin is a radiopharmaceutical initially developed to perform myocardial perfusion study that has been used to perform parathyroid scintigraphies. Although most of the papers suggest that the overall sensitivities of both radiopharmaceuticals are similar, there are some papers questioning the accuracy of Tc-99m tetrofosmin to detect abnormal parathyroid glands. In the present article, we report a case with discordant results by both methods.     

Tc-99m tetrofosmin myocardial distribution 4 hours post injection

The recommended protocol for Tc99m tetrofosmin myocardial imaging suggests either a one- or two day imaging protocol so that stress and rest studies are sufficiently separated in time to allow optimum myocardium to background uptake ratios to differentiate between myocardial ischaemia and/or infarction. The biokinetic data for tetrofosmin suggest that no significant changes occur in myocardial distribution up to 180 minutes post injection. It is, therefore, necessary for two doses of the radiopharmaceutical and two separate studies to evaluate the myocardial status during stress and rest. This study assessed the differences between the 1 and 4 hour post injection SPET images obtained following peak exercise in 20 consecutively chosen patients. In addition, these images were compared to the rest images obtained on the following day after a second dose of the radiopharmaceutical was administered. In 4 patients, a one and four hour post injection study was also done during the rest phase. The results demonstrate significant changes in Tc-99m tetrofosmin distribution between the one hour and four hour post injection images. These differences are present during the stress as well as rest studies.     

Detection of occult thymoma during exercise thallium 201, technetium 99m tetrofosmin imaging for coronary artery disease

Thallium (Tl) 201 and technetium (Tc) 99m tetrofosmin single-photon emission CT are routinely used in the evaluation of coronary artery disease. Mediastinal tumors demonstrate Tl 201 and Tc 99m tetrofosmin uptake. We report a 56-year-old man who developed chest pain after a previously successful angioplasty and stent of the left anterior descending coronary artery. He underwent a Tl 201, Tc 99m tetrofosmin exercise study. Abnormal mediastinal activity was visualized in both the Tl 201 and Tc 99m tetrofosmin images. Subsequently, the patient underwent resection of a stage II thymoma. Unanticipated focal extracardiac accumulation during myocardial scintiscanning should lead to further investigation to exclude mediastinal tumor.     

Utility of myocardial scintigraphy with Tc-99m methoxy-isobutyl-isonitrile in the diagnosis of coronary disease

We have studied 24 patients (21 males and 3 females) with coronary artery disease. Stress and rest myocardial scintigraphy was performed in all cases with 15-20 mCi of Tc99m methoxy-isobutyl-isonitrile. The examination was done in 2 sessions. Usually the stress scan was obtained and within 2-4 days the rest study was obtained. All patients underwent selective coronary arteriography within a week of the scintigraphy and, in 13 cases, rest radiologic ventriculography was also performed. In 5 patients coronary arteriography and myocardial scintigraphy were normal. In 19 cases the coronary arteriography showed lesions, the myocardial scintigraphy showed ischemia or necrosis in 17 of them and was normal in two. To localize the pathologic vessel the myocardium was divided into 3 segments and segmentary analysis localized the abnormal coronary artery in 51 out of 72 cases. The best availability of the new myocardial agent and the results obtained make it a good tracer for myocardial studies.     

Comparison of double phase Tc-99m MIBI and Tc-99m tetrofosmin scintimammography for characterization of breast lesions: Visual and quantitative analyses

The aim of the current study was to compare the diagnostic reliability of visual and quantitative indices of double phase Tc-99m MIBI scintimammography (M-SMM) and Tc-99m Tetrofosmin scintimammography (TF-SMM) for detection of breast cancer. Double phase M-SMM and TF-SMM (early; 10 minutes, delayed; hour) were performed after injection of 925 MBq of radiotracers in 75 highly suspected breast cancer patients (malignant:49, benign:26). For visual analysis, five scoring methods were used. For quantitative analysis, early, delayed lesions to non-lesion ratios (L/Ns), and washout rate (%, WR) were calculated. When over grade of visual grade was used as cut-off value in the detection of primary breast cancer, M-SMM and TF-SMM showed similar diagnostic accuracies. The optimal quantitative indices of M-SMM for the detection of breast cancer were 2.06 for early L/N and 1.72 for delayed L/N. Those of TF-SMM were 3.13 for early, and 2.56 for delayed image. Visual and quantitative analyses showed similar results. However, delayed L/N of M-SMM was superior to that of TF-SMM for the detection of breast cancer. In conclusion, the double phase M-SMM and TF-SMM showed favorable diagnostic accuracy in differentiating benign from malignant breast lesions, visually and quantitatively. The optimal visual interpretation grades for the detection of primary breast cancer of double phase M-SMM and TF-SMM were grade and 5. The optimal quantitative indices of M-SMM for the detection of breast cancer were 2.06 for early L/N and 1.72 for delayed L/N. Those of TF-SMM were 3.13 for early, and 2.56 for delayed image.     

Appendicitis: evaluation by Tc-99m leukocyte scan

Diagnosing appendicitis may be difficult. We report the use of a new technetium-99m-albumin colloid white blood cell (TAC-WBC) scan in the evaluation of appendicitis. In a synthesis requiring 75 minutes, autologous neutrophils and macrophages from 40 mL of whole blood were labelled with technetium-99m-albumin colloid and administered to 100 patients with possible appendicitis. The entire process, from labelling the cells to completion of the scan took a maximum of 5 1/4 hours. Two patients had second scans on separate hospitalizations. Twenty-six patients had appendicitis; 12 had perforations, five of whom had an abscess. Eighty-five scans were read as either positive or negative for appendiceal pathology with a sensitivity of 89%, a specificity of 92%, and an accuracy of 92% in diagnosing appendicitis. Seventeen scans were indeterminant; eight of these patients had appendicitis. The value of the TAC-WBC scan in the evaluation of appendicitis lies in its ability to be used emergently, its high negative predictive value for men and women (NPV = 97%), and its high positive predictive value for men (PPV = 93%). At present, the scan does not appear to be reliable in diagnosing appendicitis in women (PPV = 43%). It is most useful in those patients in whom diagnosis is uncertain, and should not be used in patients with clear-cut appendicitis in whom its use will delay definitive surgical care.     

A comparison of Tl-201, Tc-99m sestamibi, and Tc-99m tetrofosmin myocardial perfusion scintigraphy in patients with mild to moderate coronary stenosis.

BACKGROUND: Thallium 201, technetium 99m sestamibi (MIBI), and Tc-99m tetrofosmin differ in their myocardial uptake characteristics. This may make the technetium tracers less sensitive for detecting mild to moderate coronary stenosis. METHODS AND RESULTS: We identified 163 patients with angiographic mild to moderate stenosis (50%-89%) and coexistent severe disease (88/163 patients) from a previous study of patients who received either thallium, MIBI, or tetrofosmin for myocardial perfusion scintigraphy. Summed segmental uptake scores were used to assess myocardial perfusion of territories supplied by the mildly to moderately stenotic vessels. Mean (+/- SD) summed stress uptake scores in the left anterior descending artery territory were 21.4 +/- 3.8, 21.6 +/- 4.2, and 22.1 +/- 2.3 for thallium, MIBI, and tetrofosmin, respectively (P = .7); mean summed difference uptake scores were 1.2 +/- 1.8, 1.1 +/- 1.9, and 1.0 +/- 1.1, respectively (P = .8). In the non-left anterior descending artery territory, mean summed stress uptake scores were 32.5 +/- 6.3, 34.0 +/- 6.3, and 34.5 +/- 4.7 for thallium, MIBI, and tetrofosmin, respectively (P = .4), whereas mean summed difference scores were 1.9 +/- 2.6, 1.7 +/- 2.2, and 1.7 +/- 2.3, respectively (P = .9). CONCLUSION: There were no significant differences between the tracers for the summed uptake scores. This suggests that the 3 tracers are comparable in clinical practice for assessing the extent and severity of perfusion abnormalities arising from mild to moderate coronary artery stenosis, especially in the presence of coexistent severe disease.     

Usefulness of Tc-99m HMPAO-labeled WBC heart scan to predict impaired ventricular function and coronary artery dilation in children with Kawasaki disease

Forty-nine children with Kawasaki disease were included in this study. Based on the severity of carditis as determined by Tc-99m HMPAO-labeled WBC heart scan, the children were separated into two groups. Group A (n=24) had significant carditis and group B (n=25) did not have significant carditis. The left and right ventricular ejection fractions (LVEF and RVEF) were evaluated by equilibrium multigated blood pooling ventriculography. Diameters of the left and right coronary arteries (LCA and RCA) were measured by two-dimensional echocardiography. The results showed that group A had lower LVEF and RVEF, but larger diameters of the LCA and RCA than those of group B patients. The sensitivity of significant carditis to predict left ventricular dysfunction, right ventricular dysfunction, LCA dilation and RCA dilation was 88.9, 70.6, 75, and 71.4%, respectively; the specificities were 100, 100, 100, and 67.9%, respectively. Our findings suggest that significant carditis determined by Tc-99m HMPAO-labeled WBC heart scan can accurately predict impaired ventricular function and coronary artery dilation.     

Tc-99m tetrofosmin myocardial SPECT perfusion imaging: comparison of rest-stress and stress-rest protocols

Aim. The purpose of this study was to evaluate the diagnostic value of Tc-99m tetrofosmin SPECT myocardial perfusion scintigraphy rest/stress and stress/rest protocols for the assessment of coronary artery disease (CAD). Methods. 65 patients underwent both rest and stress SPECT imaging in a one-day protocol and coronary angiography within 2 months before or after scintigraphy. Scintigraphic data was obtained according to two different protocols; 1) rest-stress (n=18) and 2) stress-rest (n=47). Results. Scintigraphic evidence for myocardial ischaemia was found in 36 patients (55%). The overall sensitivity to detect CAD (>50% luminal stenosis) was 94% (34/36), specificity 66% (19/24), positive predictive value 77%, negative predictive value 90%. The sensitivity to detect CAD for protocols 1 and 2 were 100% and 93%, specificity 56% and 70%, positive predictive value 69% and 81% and negative predictive value 100% and 88%, respectively. The left anterior descending coronary artery showed a sensitivity (overall, protocol 1 & 2) of 78%, 75% (3/4) and 79% (15/19) and a specificity of 71%, 64% (9/14) and 75% (21/28). The right coronary artery showed a sensitivity (overall, protocol 1 & 2) of 91%, 100% (6/6) and 88% (14/16) and a specificity of 70%, 92% (11/12) and 61% (19/31). The left circumflex coronary artery showed a sensitivity (overall, protocol 1 & 2) of 50%, 67% (2/3) and 46% (6/13) and a specificity of 94%, 100% (15/15) and 91% (31/34). Conclusion. Tc-99m tetrofosmin appears to be a valuable tool in predicting significant CAD. The sensitivity and the positive predictive value are high, making this test highly appropriate for the diagnosis of CAD. The diagnostic value of the individual coronary arteries is high to moderate. No significant differences were found between both protocols.     

Tc-99m tetrofosmin reverse perfusion pattern with ST segment depression after dipyridamole infusion in a patient with unstable angina and no evident coronary artery stenoses

Reverse redistribution is a well-known pattern found when performing thallium myocardial scintigraphy, and it has been implicated as an indicator of myocardial ischemia. Much more rarely, when using technetium compounds, which do not redistribute, a similar pattern is noted after the second injection of the radiotracer. This pattern has been termed "reverse perfusion pattern," and its full implications are not yet clear and are still being investigated.     

Preparation and evaluation of Tc-99m hydroxyethyl starch as a potential radiopharmaceutical for lymphoscintigraphy: comparison with Tc-99m human serum albumin, Tc-99m dextran, and Tc-99m sulfur microcolloid

Tc-99m hydroxyethyl starch (Tc-99m HES) prepared with a labeling efficiency greater than 95% was evaluated in rabbits for visualization of lymphatic channels and lymph nodes, and the findings compared with Tc-99m human serum albumin (Tc-99m HSA), Tc-99m dextran (Tc-99m DXT), and Tc-99m sulfur microcolloid (Tc-99m SMC). Tc-99m HES showed good visualization of lymphatic channels and regional nodes and it had the highest clearance rate from the injection site (p less than 0.01). Tc-99m HES showed greater uptake by the nodes than Tc-99m DXT (p less than 0.001) at 90 minutes post-injection. The concentration of Tc-99m HES in the lymphatic channels was higher than that of Tc-99m SMC at 90 minutes post-injection (p less than 0.001). Preliminary clinical studies of Tc-99m HES yielded high quality lymphoscintigrams of the leg, and the pelvic and para-aortic lymph nodes in less than 10 minutes post-injection. In addition, partially and completed obstructed lymphatics could be differentiated from normal lymphatic pathways. In conclusion, Tc-99m HES is a promising radiopharmaceutical for imaging of lymphatic channels and nodes.     

Prediction of all-cause mortality in women with known or suspected coronary artery disease by stress technetium-99m tetrofosmin myocardial perfusion imaging

We studied the incremental value of stress technetium-99m tetrofosmin imaging for predicting all-cause mortality in 503 women (aged 58 +/- 12 years) with known or suspected coronary artery disease. The annual mortality rate was 1.4% with normal perfusion and 4% with abnormal perfusion (p <0.01) during a follow-up of 3.5 +/- 1.2 years. In an incremental multivariate analysis model, clinical predictors of mortality were age, diabetes mellitus, smoking, and a lower systolic blood pressure during stress. An abnormal scan was incremental to clinical data in predicting mortality.