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Sample records for 201tl gated myocardial

  1. Spontaneous changes in /sup 201/Tl myocardial perfusion imaging after myocardial infarction

    SciTech Connect

    Buda, A.J.; Dubbin, J.D.; MacDonald, I.L.; Strauss, H.D.; Orr, S.A.; Meindok, H.

    1982-12-01

    To examine regional myocardial perfusion after myocardial infarction, 26 patients underwent exercise electrocardiographic testing with /sup 201/Tl myocardial perfusion imaging 3 weeks and 3 months after infarction. At 3 weeks, 9 of 26 patients (35%) had myocardial ischemia by exercise electrocardiographic testing, whereas 18 of 26 (69%) had ischemia by /sup 201/Tl imaging. The /sup 201/Tl scintigrams were scored by dividing each image, in 3 views, into 5 segments, using a 5-point scoring scheme. The exercise /sup 201/Tl score was 44.3 +/- 1.2 and increased to 47.3 +/- 1.2 in the redistribution study (p less than 0.001). Three months after infarction, although there was a significantly greater rate-pressure product which would predict a larger ischemic defect and a decrease in the stress /sup 201/Tl score, the stress score was improved (48.3 +/- 1.1, p less than 0.001). The redistribution score was similar, that is, 48.9 +/- 1.0. The improvement in /sup 201/Tl myocardial perfusion was associated with a loss of stress-induced ischemia in 8 patients (30%). These results indicate that spontaneous improvements in /sup 201/Tl myocardial perfusion imaging may occur after myocardial infarction.

  2. Dipyridamole 201Tl scintigraphy in the evaluation of prognosis after myocardial infarction

    SciTech Connect

    Okada, R.D.; Glover, D.K.; Leppo, J.A. )

    1991-09-01

    Dipyridamole 201Tl imaging has been proposed as an alternative to exercise ECG testing for the prehospital discharge evaluation of patients recovering from myocardial infarction. The rationale is that many postinfarction patients with exercise-induced ischemia experience later cardiac events, and the sensitivity of predischarge exercise ECG testing in patients with multivessel disease ranges from only 45% to 62%. In addition, several groups of investigators have shown the sensitivity of submaximum exercise 201Tl imaging to be less than ideal. This report summarizes the current status of dipyridamole 201Tl imaging in the period of 1-13 days after myocardial infarction. Although the number of studies performed to date is limited, the following conclusions can be drawn: dipyridamole 201Tl imaging after myocardial infarction was associated with no serious side effects, and those present could be quickly reversed with aminophylline; redistribution with dipyridamole 201Tl images definitely correlates with prognosis after uncomplicated myocardial infarction; dipyridamole 201Tl imaging is definitely useful in patients unable to exercise for a variety of reasons; and future studies are definitely indicated to further define the role of dipyridamole 201Tl imaging for assessing prognosis, especially in those patients undergoing interventional therapy after acute myocardial infarction.

  3. Value of planar 201Tl imaging in risk stratification of patients recovering from acute myocardial infarction

    SciTech Connect

    Gibson, R.S.; Watson, D.D. )

    1991-09-01

    Although exercise ECG testing has been shown to have important prognostic value after acute myocardial infarction, exercise 201Tl scintigraphy offers several potential advantages, including: (1) increased sensitivity for detecting residual myocardial ischemia; (2) the ability to localize ischemia to a specific area or areas subtended by a specific coronary artery; (3) the ability to identify exercise-induced left ventricular dysfunction, which is manifested by increased lung uptake or transient left ventricular dilation; and (4) more reliable risk stratification of individual patients. The more optimal prognostic efficiency of 201Tl scintigraphy partially results from the fact that the error rate in falsely classifying patients as low risk is significantly smaller with 201Tl scintigraphy than with stress ECG. Because of these substantial advantages, there seems to be adequate rationale for recommending exercise perfusion imaging rather than exercise ECG alone as the preferred method for evaluating mortality and morbidity risks after acute myocardial infarction.

  4. Abnormal 201Tl myocardial single photon emission computed tomography in energetic male patients with myocardial bridge.

    PubMed

    Huang, W S; Chang, H D; Yang, S P; Tsao, T P; Cheng, C Y; Cherng, S C

    2002-11-01

    Myocardial bridge is a relatively benign condition where a major coronary artery is bridged by a band of muscle and narrows during systole, particularly during rapid heart rates. Its clinical presentation and electrocardiogram (ECG) changes overlap with that of coronary artery disease. 201Tl myocardial perfusion imaging is thus frequently prescribed for further evaluation. This retrospective study was carried out to determine the 201Tl image patterns in patients with myocardial bridge. A total of 17 male patients (aged from 30 to 63 years) who had a positive exercise ECG and angiographic evidence of myocardial bridge in the mid-third of the left anterior descending coronary artery were recruited. Most of them were robust and received routine physical check-ups. They had no known heart disease or medication that affected cardiac function. The patients' clinical presentations, echocardiograph and exercise ECG findings were analysed. 201Tl single photon emission computed tomography (SPECT) was performed by intravenous injection of 201Tl (111 MBq) immediately following stress (treadmill or dipyridamole induced) and 4 h after stress, using a fixed, right angle camera equipped with a low energy, general purpose collimator. The images were interpreted independently by two experienced nuclear medicine physicians. Nine of the 17 patients had anterior chest pain during exercise. All patients had an abnormal ECG during exercise, including ST-T wave depression in leads II, III and aVF, and v4-6. Except for eight patients revealing reversible perfusion defect (R), 16 of the 17 patients also exhibited a partial reversible perfusion defect (PR) or a significant reverse redistribution (RR) scan pattern in the anterior or inferior walls of the left ventricle. Myocardial bridge should be taken into consideration in energetic male patients who had abnormal exercise ECGs and the corresponding patterns of Tl SPECT abnormalities including R, PR and RR.

  5. Cold pressor /sup 201/Tl myocardial scintigraphy in the diagnosis of coronary artery disease

    SciTech Connect

    Ahmad, M.; Dubiel, J.P.; Haibach, H.

    1982-12-01

    /sup 201/Tl myocardial scintigraphy was performed during cold pressor stimulation in 36 patients aged 36 to 69 years. Thirty-one patients had coronary artery disease and 5 patients did not, as confirmed by coronary cineangiography. /sup 201/Tl (1.5 to 2 mCi) was injected at 30 seconds of the cold pressor stimulation. The product of systolic pressure X heart rate increased from a baseline of 77.4 +/- 16 (standard deviation (SD)) to 103.6 +/- 17 at 30 seconds of the cold pressor test (p less than 0.0005). Transient perfusion deficits developed in 24 of 31 patients with coronary artery disease (sensitivity 77%), and all 5 patients without coronary artery disease had normal scintigrams. The sensitivity in detecting coronary artery disease was 40% in patients with 1 vessel disease, 91% in patients with 2 vessel disease, and 100% in patients with 3 vessel disease. Exercise electrocardiograms (available in 29 of 36 patients) were positive for ischemia in 18 of 24 patients with coronary artery disease and in 1 of 5 patients without coronary artery disease (sensitivity 75% and specificity less than 80%). Exercise /sup 201/Tl scintigrams, obtained in 16 patients, were positive in 11 patients with coronary artery disease and positive cold pressor /sup 201/Tl scintigrams. Five patients without coronary artery disease and with normal cold pressor /sup 201/Tl scintigrams had normal exercise /sup 201/Tl scintigrams. Coronary cineangiography performed during cold pressor stimulation in 6 patients who had positive cold pressor and exercise /sup 201/Tl scintigrams did not show coronary spasm. Our data indicate that cold pressor thallium-201 scintigraphy offers promise as a noninvasive test in the diagnosis of coronary artery disease and may be used in patients in whom exercise testing is not feasible.

  6. The effects of 201Tl myocardial perfusion scintigraphy studies on oxidative damage in patients.

    PubMed

    Cicek, E; Yildiz, M; Delibas, N; Bahçeli, S

    2009-01-01

    The aim of this study was to investigate gamma radiation-induced oxidative damage in erythrocytes after 201Tl myocardial perfusion scintigraphy. Twenty patients (8 women and 12 men) who performed 201Tl myocardial perfusion scintigraphy were included in this study. The blood samples were taken from patients just before, 1 hour after and three hours after injection of the radiopharmaceutical. Malondialdehyde (MDA) and antioxidant enzymes such as glutathione peroxidase (GPX), superoxide dismutase (SOD) and catalase (CAT) levels were measured to evaluate the gamma radiation induced oxidative damage. The enzyme activities of SOD, GPX and CAT were decreased 1 hour after (p = 0.042, p = 0.697 and p = 0.653 respectively) and 3 hours after (p = 0.003, p = 0.573 and p = 0.002 respectively) injection of the radiopharmaceutical. Malondialdehyde levels were increased 1 hour after (p = 0.10) and 3 hours after (p = 0.47) injection of the radiopharmaceutical. In this study, we found that radiation due to 201Tl myocardial perfusion scintigraphy decreased the erythrocyte antioxidant levels and increased MDA levels.

  7. Thrombolysis in acute myocardial infarction using intracoronary streptokinase: assessment by /sup 201/Tl scintigraphy

    SciTech Connect

    Schuler, G.; Schwarz, F.; Hofmann, M.; Mehmel, H.; Manthey, J.; Maeurer, W.; Rauch, B.; Herrmann, H.J.; Kuebler, W.

    1982-09-01

    Twenty-one patients with acute myocardial infarction, admitted to the hospital within 4 hours after the onset of symptoms, were studied by seven-pinhole /sup 201/Tl scintigraphy before and 1 hour and 24 hours after intracoronary fibrinolysis using streptokinase. The size of the /sup 201/Tl perfusion defect was assessed from myocardial cross sections reconstructed from the original seven-pinhole data and expressed as a fraction of left ventricular circumference. Recanalization was achieved in 16 patients within 3.9 +/- 1.6 hours after onset of symptoms (group A). In these patients, the size of the perfusion defect had decreased from 36 +/- 17% to 19% +/- 15% (p less than 0.001) at 24 hours. No significant change was detected by redistribution at 1 hour after the intervention. In five patients, intracoronary fibrinolysis was unsuccessful, and the vessel remained occluded (group B). The /sup 201/Tl perfusion defect affected 40 +/- 15% of the left ventricular circumference before the intervention; it remained virtually unchanged at 1 hour (37 +/- 16%) and at 24 hours (41 +/- 15%) after fibrinolysis. The perfusion defect was most reduced in patients with extensive collaterals supplying the ischemic area or with subtotal occlusion of the affected coronary artery. We conclude that successful intracoronary fibrinolysis may reduce the size of the /sup 201/Tl perfusion defect in many patients with acute myocardial infarction. One important factor in the final result may be the presence of residual coronary flow supplied by extensive collaterals or by subtotal occlusion of the affected coronary artery when reperfusion is achieved around 4 hours after the onset of symptoms.

  8. Quantification of myocardial blood flow using (201)Tl SPECT and population-based input function.

    PubMed

    Koshino, Kazuhiro; Fukushima, Kazuhito; Fukumoto, Masaji; Hori, Yuki; Moriguchi, Tetsuaki; Zeniya, Tsutomu; Nishimura, Yoshihiro; Kiso, Keisuke; Iida, Hidehiro

    2014-11-01

    Thallium-201 ((201)Tl) single photon emission computed tomography (SPECT) is an important tool in the diagnosis of ischemic heart disease. Absolute quantification of myocardial blood flow (MBF) has the potential to provide more useful information on myocardial perfusion than semi-quantitative assessments. This study aimed to validate the quantification of MBF using (201)Tl cardiac SPECT based on a population-averaged input function (STD-IF) and one-point blood sample technique. (201)Tl emission and computed tomography (CT)-based attenuation scans were performed on 11 healthy volunteers at rest using a SPECT/CT scanner. Individual input functions (IND-IFs) during the emission scans were based on arterial blood samples. The STD-IF technique was validated as follows: (1) optimal time to calibrate a STD-IF was determined to minimize differences between the calibrated STD-IF and the IND-IFs. (2) Tissue time-activity curves (TTACs) were generated based on a single-tissue compartment model for MBFtrue = 0.5, 1.0, 1.5, and 2.0 mL/min/g, a constant distribution volume of 45 mL/mL, and IND-IFs. The pseudo STD-IF for each subject was generated using the leave-one-out technique. Using the optimal calibration time and the pseudo STD-IFs, MBF values were estimated on the TTACs with an autoradiography method. Optimal mid-scan time (MST) with a fixed duration of 20 min was determined to minimize intersubject variation in estimated MBF errors, and (3) Global and regional MBF values estimated with pseudo STD-IFs were compared to those with IND-IFs using the optimal calibration time and MST. The optimal calibration time and MST were both 20 min after (201)Tl injection. Global MBF determined using both IND-IFs and pseudo STD-IF showed significant correlations with rate-pressure products, R (2) = 0.645; p < 0.01 and R (2) = 0.303; p < 0.05, respectively. The mean percent error in regional MBF using pseudo STD-IFs was 0.69 ± 7.80 % (-12.80 to 14.25 %). No significant

  9. Comparison of myocardial /sup 201/Tl clearance after maximal and submaximal exercise: implications for diagnosis of coronary disease: concise communication

    SciTech Connect

    Massie, B.M.; Wisneski, J.; Kramer, B.; Hollenberg, M.; Gertz, E.; Stern, D.

    1982-05-01

    Recently the quantitation of regional /sup 201/Tl clearance has been shown to increase the sensitivity of the scintigraphic detection of coronary disease. Although /sup 201/Tl clearance rates might be expected to vary with the degree of exercise, this relationship has not been explored. We therefore evaluated the rate of decrease in myocardial /sup 201/Tl activity following maximal and submaximal stress in seven normal subjects and 21 patients with chest pain, using the seven-pinhole tomographic reconstruction technique. In normals, the mean /sup 201/Tl clearance rate declined from 41% +/- 7 over a 3-hr period with maximal exercise to 25% +/- 5 after 3 hr at a submaximal level (p less than 0.001). Similar differences in clearance rates were found in the normally perfused regions of the left ventricle in patients with chest pain, depending on whether or not a maximal end point (defined as either the appearance of ischemia or reaching 85% of age-predicted heart rate) was achieved. In five patients who did not reach these end points, 3-hr clearance rates in uninvolved regions averaged 25% +/- 2, in contrast to a mean of 38% +/- 5 for such regions in 15 patients who exercised to ischemia or an adequate heart rate. These findings indicate that clearance criteria derived from normals can be applied to patients who are stressed maximally, even if the duration of exercise is limited, but that caution must be used in interpreting clearance rates in those who do not exercise to an accepted end point.

  10. Accuracy of serial myocardial perfusion scintigraphy with /sup 201/Tl for prediction of graft patency early and late after coronary artery bypass surgery. A controlled prospective study

    SciTech Connect

    Pfisterer, M.; Emmenegger, H.; Schmitt, H.E.; Mueller-Brand, J.; Hasse, J.; Graedel, E.; Laver, M.B.; Burckhardt, D.; Burkart, F.

    1982-11-01

    To assess the accuracy of serial myocardial perfusion scintigraphy with /sup 201/Tl to predict graft patency early and late coronary artery bypass surgery, rest and exercise /sup 201/Tl and coronary arteriography were performed preoperatively and 2 weeks and 1 year after operation. The scintigraphic results were compared with graft patency, symptoms, left ventricular function and physical work capacity in a consecutive series of 55 patients with a total of 154 grafts. Serial /sup 201/Tl had an 80% sensitivity, 88% specificity and 86% overall accuracy in detecting or excluding graft occlusion, which was predicted by reversible ischemia as well as persistent new scar segments. Occluded grafts were correctly localized by /sup 201/Tl scintigraphy in 61%. Postoperative apical /sup 201/Tl defects were frequent (two-thirds of cases), and were the result of intraoperative transapical venting of the left ventricle. After coronary bypass graft surgery, ejection fraction at rest was unchanged. Left ventricular end-diastolic pressure and physical work capacity improved significantly. In the presence of new perfusion defects detected postoperatively, physical work capacity was reduced significantly. New /sup 201/Tl defects in addition to typical or atypical angina provided a high probability of graft occlusion, while in the absence of new /sup 201/Tl defects all grafts were patent in more than 90% of patients, all of whom had no or only atypical chest pain. We conclude that serial /sup 201/Tl imaging after coronary artery bypass surgery is an accurate noninvasive method that can be used routinely to assess graft function, to localize spatially occluded grafts and to identify patients with a high likelihood of graft occlusion who may need invasive studies.

  11. Clinical implications of increased lung uptake of /sup 201/Tl during exercise scintigraphy 2 weeks after myocardial infarction

    SciTech Connect

    Gibson, R.S.; Watson, D.D.; Carabello, B.A.; Holt, N.D.; Beller, G.A.

    1982-05-01

    To determine the prevalence and clinical significance of increased lung /sup 201/Tl uptake during submaximal exercise myocardial scintigraphy performed 2 weeks after acute myocardial infarction, 61 patients underwent submaximal exercise testing (target heart rate, 120 beats/min), multigated blood pool imaging at rest and coronary angiography before hospital discharge. Thallium lung uptake on the initial anterior projection image was graded qualitatively by comparing the intensity of /sup 201/Tl activity in the lungs with that in the mediastinum. In 39 patients (64 percent), it was normal (equal to mediastinal activity) and in 22 (36 percent), it was increased (greater than mediastinal activity). Compared with patients with normal lung uptake, those with increased uptake had a greater prevalence of prior infarction (13 versus 36 percent, probability (p) less than 0.05), less global cardiac reserve as assessed by the four level New York Heart Association classification (p less than 0.05), more advanced Killip class in the coronary care unit (p less than 0.05), a higher Norris coronary prognostic index (2.6 +/- 1.9 versus 4.6 +/- 2.3 (mean +/- standard deviation), p less than 0.01), failure to achieve the target heart rate because of dyspnea, fatigue or angina (36 versus 86 percent, p less than 0.01), a greater prevalence of exercise-induced S-T segment depression (18 versus 45 percent, p less than 0.05), a greater number of anterior /sup 201/Tl myocardial defects (p less than 0.05); a lower radionuclide ejection fraction at rest (50.4 +/- 6.1 versus 39.6 +/- 9.3 percent, p less than 0.01) and a greater number of asynergic left ventricular segments (p less than 0.05). Thus, the occurrence of increased lung /sup 201/Tl uptake during submaximal exercise scintigraphy in the early postinfarction period is frequent and appears to be a marker of severe and functionally more important coronary artery disease associated with left ventricular dysfunction.

  12. Detection of coronary artery stenosis in children with Kawasaki disease. Usefulness of pharmacologic stress sup 201 Tl myocardial tomography

    SciTech Connect

    Kondo, C.; Hiroe, M.; Nakanishi, T.; Takao, A. )

    1989-09-01

    This study determined the feasibility and accuracy of quantitative 201Tl myocardial single-photon emission computed tomography (SPECT) after dipyridamole infusion to detect coronary obstructive lesions in children with Kawasaki disease. 201Tl distribution after dipyridamole infusion was measured in 23 normal children, and with these normal values, quantitative analysis of SPECT was performed in 49 patients. Thirty-four patients had coronary stenosis 90% or greater on angiograms. Side effects resulting from systemic vasodilation were observed in about 70%. Angina pectoris and ischemic ST changes were observed only in patients with coronary stenosis. These symptoms disappeared after aminophylline infusion. Results of visual and quantitative analysis of SPECT were compared. SPECT data were shown on two-dimensional polar maps, and the extent and severity scores were calculated. The sensitivity of SPECT for detection of overall coronary stenosis was 91% (visual analysis) and 88% (quantitative analysis). The specificity of SPECT was 60% visually and 93% quantitatively. The sensitivity of quantitative analysis to detect individual coronary stenosis was similar to that of visual analysis. However, the specificity of visual analysis to detect individual coronary artery stenosis was significantly less than that of quantitative analysis. From these data, we conclude that quantitative analysis of myocardial SPECT after dipyridamole infusion is a safe and accurate diagnostic method for identifying coronary stenosis in children with Kawasaki disease.

  13. Noninvasive detection and localization of coronary stenoses in patients: comparison of resting dipyridamole and exercise /sup 201/Tl myocardial perfusion imaging

    SciTech Connect

    Josephson, M.A.; Brown, B.G.; Hecht, H.S.; Hopkins, J.; Pierce, C.D.; Petersen, R.B.

    1982-06-01

    Two noninvasive tests to detect and localize coronary stenoses were compared in a fully blinded protocol. /sup 201/Tl myocardial perfusion imaging (MPI) following maximal treadmill exercise and pharmacologic coronary vasodilation with intravenous dipyridamole (DP) was performed in 33 patients. /sup 201/Tl imaging defects in six myocardial perfusion regions were correlated with stenoses in their respective vascular distributions. Disease severity was determined with coronary arteriograms using a computer-assisted method. 198 myocardial regions were evaluated; 101 were supplied by at least one major artery with a greater than or equal to 50% stenosis (luminal diameter narrowing). The sensitivity and specificity for detecting a greater than or equal to 50% stenosis were 85% and 64% (p less than 0.005), respectively, for DP and 84% and 68% (p less than 0.005) for exercise-/sup 201/Tl imaging. A particular combination of anterior and septal imaging defects was useful in detecting left anterior descending artery stenoses proximal to its first septal branch. DP administration was safe in this group of patients; however, 42% experienced transient chest pain. Although the overall sensitivity and specificity of the two methods were not significantly different, DP-MPI appeared more sensitive than exercise-MPI (70% vs 52%, p less than 0.01) in detecting coronary stenoses in the 40% to 60% range. DP-/sup 201/Tl MPI provides a useful alternative test for potential coronary disease patients unable to perform maximal exercise.

  14. Estimation of infarct size by myocardial emission computed tomography with /sup 201/Tl and its relation to creatine kinase-MB release after myocardial infarction in man

    SciTech Connect

    Tamaki, S.; Nakajima, H.; Murakami, T.

    1982-11-01

    We evaluated emission computed tomography (ECT) /sup 201/Tl myocardial imaging in estimating infarct size (IS). In 18 patients in whom IS was estimated enzymatically at the time of the acute episode, planar /sup 201/Tl perfusion scintigraphy and ECT with a rotating gamma camera were performed 4 weeks after the first myocardial infarction. From the size of /sup 201/Tl perfusion defects, the infarct area in planar images and the infarct volume in reconstructed ECT images were measured by computerized planimetry. When scintigraphic IS was compared with the accumulated creatine kinase-MB isoenzyme release (CK-MBr), infarct volume determined from ECT correlated closely with CK-MBr (r . 0.89), whereas infarct area measured from planar images correlated less satisfactorily with the enzymatic IS (for an average infarct area from three views, r . 0.69; for the largest infarct area, r . 0.73). Although conventional scintigraphic evaluation is useful for detecting and localizing infarction, quantification of ischemic injury with this two-dimensional technique has a significant inherent limitation. The ECT approach can provide a more accurate three-dimensional quantitative estimate of infarction, and can corroborate the enzymatic estimate of IS.

  15. Echocardiography versus (201)Tl semi-quantitative gated single photon emission tomography for the evaluation of cardiac disease associated with late stage Duchenne muscular dystrophy.

    PubMed

    Fujita, Atsushi; Arahata, Hajime; Sugawara, Miwa; Watanabe, Akihiro; Kawano, Yuji; Sasagasako, Naokazu; Fujii, Naoki

    2016-01-01

    In Duchenne muscular dystrophy (DMD) patients cardiac abnormalities are often detected. In adult DMD patients cardiac disease (CD) is a cause of death which increases by age and is related to respiratory dysfunction. Studies have demonstrated that CD in early DMD can be detected by echocardiography (EC) or semi-quantitative gated single photon emission tomography ((201)Tl SQGS), and the accuracy of these two tests is similar. As the disease advances, evaluation of CD by EC becomes difficult due to thoracic deformity and scoliosis. We compared (201)Tl SQGS and EC in the evaluation of cardiac function in late stage DMD, based on the ejection fraction (EF) value calculated by both tests. Twenty-three males with late stage DMD, 12 to 35 years of age (22.2±7.5), were studied by (201)Tl SQGS and EC. The mean EF value by (201)Tl SQGS was 60.8%±14.1%, which differed from that obtained by EC (52.7%±9.8%, P=0.003). Eleven patients less than 20 years old did not demonstrate a significant difference between the two tests (P=0.06), however, 12 patients over 20 years of age had significantly different results between tests (P=0.002). Although our patients were few we indicated that in DMD patients, aged older than 20 years, at an advanced stage of the disease, the EF values calculated by EC were lower than those by (201)Tl SQGS possibly due to thoracic deformity.

  16. Stress/injection protocols for myocardial scintigraphy with 99Tcm-sestamibi compared with 201Tl: implications of early post-stress kinetics.

    PubMed

    Hurwitz, G A; Blais, M; Powe, J E; Champagne, C L

    1996-05-01

    Stress/injection protocols developed for myocardial perfusion imaging with 201Tl may not be optimal for 99Tcm-sestamibi (MIBI), an agent with lower myocardial extraction and higher abdominal uptake; prolongation of exercise after radiotracer injection might improve these relative drawbacks of MIBI. We compared the kinetics of MIBI and 201Tl by acquiring dynamic planar images for 5-7 min after a bolus injection (n = 180 studies) with stress performed by supine bicycle exercise alone, intravenous dipyridamole or combined stress. Routine or prolonged protocols involved continuation of exercise for 1 or 2.5 min respectively after tracer appearance in the heart. Subsequently, the perfusion images obtained were categorized as normal or showing significant defects. Myocardial uptake of MIBI, normalized for injected dose, body weight and camera sensitivity, was only 40% of that for 201Tl; there were no differences based on test mode or scan result for either perfusion tracer. During the second minute after injection, the cavity/myocardial ratios, an index of blood pool activity, were elevated with MIBI by 25% when compared with 201Tl (P < 0.001). During the third minute, cavity activity was again higher with MIBI, but only in those subjects with abnormal scans. The prolonged exercise phase did not prevent progressive accumulation in the abdomen, but did allow cavity levels to decline before termination of exercise. The prolonged protocol may ensure that myocardial uptake of MIBI is completed during peak blood flow, and therefore is recommended for stress with exercise or with dipyridamole and exercise in combination.

  17. Quantification of infarct size by /sup 201/Tl single-photon emission computed tomography during acute myocardial infarction in humans. Comparison with enzymatic estimates

    SciTech Connect

    Mahmarian, J.J.; Pratt, C.M.; Borges-Neto, S.; Cashion, W.R.; Roberts, R.; Verani, M.S.

    1988-10-01

    We prospectively investigated whether /sup 201/Tl single-photon emission computed tomography (SPECT) could accurately diagnose the presence and quantify the extent of acute myocardial infarction when compared with infarct size assessed by plasma MB-creatine kinase activity. Thirty patients with enzymatic evidence of infarction were imaged within 12-36 hours of chest pain (mean, 23.4 hours). No patient had a previous infarction, and none underwent intervention seeking to restore coronary patency. Infarct size was quantified with computer-generated polar maps of the myocardial radioactivity and expressed as a percentage of the total left ventricular volume. To assess left and right ventricular performance, blood-pool gated radionuclide angiography was performed immediately after SPECT. All 30 patients had perfusion defects consistent with myocardial infarction. Scintigraphic and enzymatic estimates of infarct size correlated well for the group as a whole (r = 0.78, p less than 0.001, SEE = 9.1) but especially for those patients with anterior infarction (r = 0.91, p less than 0.001, SEE = 7.9). The poor correlation observed in patients with inferior infarction (r = 0.50, p less than 0.05, SEE = 10.0) was believed to be related to the frequent occurrence of right ventricular involvement because SPECT assessed only left ventricular damage, whereas the enzymatic method estimated the myocardial injury in both ventricles. A quantitative index of right ventricular infarct size, derived from the relation between the scintigraphic and enzymatic estimates, had a strong inverse correlation with right ventricular ejection fraction (r = -0.89, p less than 0.001, SEE = 3.6).

  18. Microvascular obstruction on delayed enhancement cardiac magnetic resonance imaging after acute myocardial infarction, compared with myocardial (201)Tl and (123)I-BMIPP dual SPECT findings.

    PubMed

    Mori, Hiroaki; Isobe, Satoshi; Sakai, Shinichi; Yamada, Takashi; Watanabe, Naoki; Miura, Manabu; Uchida, Yasuhiro; Kanashiro, Masaaki; Ichimiya, Satoshi; Okumura, Takahiro; Murohara, Toyoaki

    2015-08-01

    The hypo-enhanced regions within the hyper-enhanced infarct areas detected by cardiac magnetic resonance (CMR) imaging reflect microvascular obstruction (MO) after acute myocardial infarction (AMI). The combined myocardial thallium-201 ((201)Tl)/iodine-123-15-(p-iodophenyl)-3-(R,S)-methylpentadecanoic acid ((123)I-BMIPP) dual single-photon emission computed tomography (SPECT) is a useful tool for detecting myocardial reversibility after AMI. We evaluated whether MO could be an early predictor of irreversible myocardial damage in comparison with (201)Tl and (123)I-BMIPP dual SPECT findings in AMI patients. Sixty-two patients with initial AMI who successfully underwent coronary revascularization were enrolled. MO was defined by CMR imaging. Patients were divided into 2 groups as follows: MO group (n=32) and non-MO group (n=30). Scintigraphic defect scores were calculated using a 17-segment model with a 5-point scoring system. The mismatch score (MMS) was calculated as follows: the total sum of (Σ) (123)I-BMIPP defect score minus Σ(201)Tl defect score. The percentage mismatch score (%MMS) was calculated as follows: MMS/(Σ(123)I-BMIPP score)×100 (%). The percentage infarct size (%IS) was significantly greater in the MO group than in the non-MO group (32.2±13.8% vs. 18.3±12.1%, p<0.001). The %MMS significantly correlated with the %IS and the percentage MO (r=-0.26, p=0.03; r=-0.45, p<0.001, respectively). The %MMS was significantly greater in the non-MO group than in the MO group (45.4±42.4% vs. 13.3±28.0%, p=0.001), and was an independent predictor for MO (OR 0.97, 95%CI 0.94-0.99, p=0.02). Our results reconfirm that, in comparison with myocardial dual scintigraphy, MO is an important structural abnormality. CMR imaging is useful for the early detection of irreversible myocardial damage after AMI. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  19. NOTE: Comparison of correction techniques for simultaneous 201Tl/99mTc myocardial perfusion SPECT imaging: a dog study

    NASA Astrophysics Data System (ADS)

    Knesaurek, Karin; Machac, Josef

    2000-11-01

    We compared two correction methods for simultaneous 201Tl/99mTc dual-isotope single-photon emission computed tomography (SPECT). Both approaches use the information from the third energy window placed between the photopeak windows of the 201Tl and 99mTc. The first approach, described by Moore et al, corrects only for the contribution of the 99mTc to the 201Tl primary 70 keV window. We developed the three-window transformation dual-isotope correction method, which is a simultaneous cross-talk correction. The two correction methods were compared in a simultaneous 201Tl/99mTc sestamibi cardiac dog study. Three separate acquisitions were performed in this dog study: two single-isotope and one dual-isotope acquisition. The 201Tl single-isotope images were used as references. The total number of counts, and the contrast between the left ventricular cavity (LVC) and the myocardium, were used in 70 keV short-axis slices as parameters for evaluating the results of the dual-isotope correction methods. Three consecutive short-axis slices were used to calculate averaged contrast and the averaged total number of counts. The total number of the counts was 667 000 ± 500 and 414 500 ± 400 counts for the dual-isotope (201Tl + 99mTc) and single-isotope (201Tl-only) 70 keV images, respectively. The corrected dual-isotope images had 514 700 ± 700 and 368 000 ± 600 counts for Moore's correction and our approach, respectively. Moore's method improved contrast in the dual-isotope 70 keV image to 0.14 ± 0.03 from 0.11 ± 0.02, which was the value in the 70 keV non-corrected dual-isotope image. Our method improved the same contrast to 0.22 ± 0.03. The contrast in the 201Tl single-isotope 70 keV image was 0.28 ± 0.02. Both methods improved the 70 keV dual-isotope images. However, our approach provided slightly better images than Moore's correction when compared with 201Tl-only 70 keV images.

  20. Serial /sup 201/Tl myocardial imaging after dipyridamole infusion: diagnostic utility in detecting coronary stenoses and relationship to regional wall motion

    SciTech Connect

    Leppo, J.; Boucher, C.A.; Okada, R.D.; Newell, J.B.; Strauss, H.W.; Pohost, G.M.

    1982-09-01

    After a 4-minute i.v. dipyridamole infusion, 0.14 mg/kg/min, serial /sup 201/Tl scans were obtained in 60 patients undergoing cardiac catheterization. Forty patients had significant (greater than or equal to 50% stenosis) coronary artery disease (CAD), and 20 patients had normal coronary arteries or trivial lesions. The images were graded qualitatively for thallium activity by three observers. Sensitivity was 93% (37 of 40) and specificity was 80% (16 of 20). The sensitivity and specificity of the /sup 201/Tl study were not affected by the extent of CAD, the presence of Q waves, or propranolol therapy. Twenty-seven of 37 patients who had initial defects (73%) had complete thallium redistribution of one or more defects. Patient-by-patient analysis using a regression model of all patients showed that the fate of a segmental thallium defect predicted abnormal wall motion by angiography better than ECG Q waves. The presence of propranolol therapy or collaterals did not significantly affect the thallium redistribution results. We conclude that qualitative interpretation by multiple observers of thallium images after dipyridamole infusion is a highly sensitive and specific test for CAD. After dipyridamole, as with exercise stress, the extent of thallium redistribution is related to the degree of myocardial wall motion abnormality.

  1. Validation and evaluation of model-based crosstalk compensation method in simultaneous /sup 99m/Tc stress and /sup 201/Tl rest myocardial perfusion SPECT

    NASA Astrophysics Data System (ADS)

    Song, X.; Frey, E. C.; Wang, W. T.; Du, Y.; Tsui, B. M. W.

    2004-02-01

    Simultaneous acquisition of /sup 99m/Tc stress and /sup 201/Tl rest myocardial perfusion SPECT has several potential advantages, but the image quality is degraded by crosstalk between the Tc and Tl data. We have previously developed a crosstalk model that includes estimates of the downscatter and Pb X-ray for use in crosstalk compensation. In this work, we validated the model by comparing the crosstalk from /sup 99m/Tc to the Tl window calculated using a combination of the SimSET-MCNP Monte Carlo simulation codes. We also evaluated the model-based crosstalk compensation method using both simulated data from the 3-D MCAT phantom and experimental data from a physical phantom with a myocardial defect. In these studies, the Tl distributions were reconstructed from crosstalk contaminated data without crosstalk compensation, with compensation using the model-based crosstalk estimate, and with compensation using the known true crosstalk, and were compared with the Tl distribution reconstructed from uncontaminated Tl data. Results show that the model gave good estimates of both the downscatter photons and Pb X-rays in the simultaneous dual-isotopes myocardial perfusion SPECT. The model-based compensation method provided image quality that was significantly improved as compared to no compensation and was very close to that from the separate acquisition.

  2. [The significance of 201Tl/123I MIBG (metaiodobenzylguanidine) mismatched myocardial regions for predicting ventricular tachycardia in patients with idiopathic dilated cardiomyopathy].

    PubMed

    Maeno, M; Ishida, Y; Shimonagata, T; Hayashida, K; Toyama, T; Hirose, Y; Nagata, M; Miyatake, K; Uehara, T; Nishimura, T

    1993-10-01

    123I-MIBG (MIBG) regional defects in myocardial regions with preserved 201Tl (Tl) uptake have been observed in patients with idiopathic dilated cardiomyopathy (DCM). To evaluate whether the presence of Tl/MIBG mismatched regions is related to the occurrence of ventricular tachycardia (VT), we performed myocardial dual SPECT imaging with Tl (111 MBq) and MIBG (111 MBq) in 17 patients with DCM, 11 (Gp A) with and 6 (Gp B) without VT. Myocardial dual SPECT imaging was performed at 15 minutes after and 4 hours after the tracer injection. The regional tracer uptake was scored visually in 6 segments of the basal, middle, and apical short-axial images and in 2 apical segments of the midventricular vertical long-axial image by a four-point scoring system (0 = normal, 1 = moderate, 2 = severe and 3 = complete defect). Then, the severity of tracer maldistributions was assessed by the difference between total defect scores (TDSs) of Tl and MIBG (delta TDS). TDS was not different between Gps A and B in both Tl and MIBG images. However, delta TDS was larger in Gp A than in Gp B (13.5 +/- 6.5 vs. 5.8 +/- 3.0, p < 0.05). Also, the number of segments with the mismatched tracer uptake was larger in Gp A than in Gp B (12.5 +/- 3.0 vs. 8.3 +/- 1.5, p < 0.01). In the electrophysiologic study, we found that the fractionated area corresponded to the mismatched region in 3 of 5 patients in Gp A. These results suggest that regional sympathetic denervation is a possible factor which provocates VT, and myocardial dual SPECT imaging with Tl and MIBG is a useful method for predicting VT in patients with DCM.

  3. Effect of time and exercise on the clearance rate of (201)Tl in normal and ischemic myocardium.

    PubMed

    Backus, Barbra E; Hezemans, Rachel E L; Verburg, Frederik A; Keijsersa, Ruth G M; Konijnenberg, Mark W; Verzijlbergen, J Fred

    2010-06-01

    Simultaneous dual isotope (SDI) acquisition of (201)Tl rest/(99m)Tc-sestamibi stress-myocardial perfusion single photon emission computed tomography is a desirable new procedure in nuclear cardiology. In this protocol (201)Tl is injected at rest but imaging is performed not earlier than after exercise. Therefore, one must be convinced that throughout exercise (201)Tl remains distributed in an identical pattern as at rest. Before SDI can be applied clinically, (201)Tl rest MPS before and after exercise test needs to be compared for equality. The aim of this study was to assess the effect of time and exercise on the clearance of preinjected (201)Tl in normal and ischemic myocardium. In 122 patients rest (201)Tl and delayed (n =20) or poststress (n= 102) (201)Tl imaging was performed. Quantitative analysis of mean counts-per-pixel was performed for each segment in a 17-segment model. Differences between rest and delayed or poststress (201)Tl MPS were calculated. Patients with a poststress (201)Tl image were divided into normal (N= 66) and ischemic (N= 36) groups. Visual analysis was performed by two independent observers scoring the 17 segments on a scale of 0-4. The overall difference between rest (201)Tl and poststress (201)Tl MPS was - 15.4%. Normal and ischemic patients showed 16.2 and 14.0% (P =0.17) washout, respectively. Visual assessment by two independent observers revealed no regional differences between rest (201)Tl and delayed or poststress (201)Tl MPS. (201)Tl poststress MPS shows significant washout of thallium. This washout is not segmental, but global over the myocardium. No significant differences are found between normal and ischemic myocardium. The poststress (201)Tl MPS is a reliable reflection of rest perfusion. SDI acquisition of (201)Tl rest/(99m)Tc-sestamibi stress-MPS is clinically applicable.

  4. [Redistribution of 201 Tl after myocardial scintigraphy with dipyridamole: value in the detection of coronary stenosis and ventricular kinetic anomalies].

    PubMed

    Demangeat, J L; Wolff, F

    1985-12-01

    One hundred and eight-four patients suspected of having coronary artery disease underwent coronary and left ventricular angiography and Tl 201 myocardial scintigraphy with dipyridamole including images of redistribution after 3-4 hours. The results of scintigraphy were assessed visually in all cases and by quantitative analysis in 91 patients. Comparison of early (DIP) and late (REDIS) images showed three types of response: 1) no hypofixation on either (10 patients), 2) a constant defect (59 patients), 3) a reversible defect (115 patients, including 21 cases of "paradoxical" redistribution). The value of the redistribution images was assessed in the diagnosis of coronary stenosis and in the evaluation of ventricular wall function in post-stenotic zones. The following results were obtained: Visual analysis of the DIP scintigraphy alone gave 17 false positive and 8 false negative results (sens: 95%, spec: 41%). The false negative results were all observed in patients at high risk. The DIP/REDIS scintigraphy (considered normal if both images were normal) gave 20 false positive but only 1 false negative result (sens: 99%, spec: 32%). In addition, the negative predictivity increased from 60 to 90%. The considerable reduction in the number of false negative results was due to the detection of "paradoxical" redistribution. The finding indicates that late films must be taken systematically even if the early scintigraphy is normal. Quantitative analysis of DIP scintigraphy was less sensitive and more specific than visual analysis (sens: 82.7%, spec: 68.7%; NVP: 46%). The same was observed when the redistribution films were processed (DIP/REDIS): significantly increased sensitivity and negative predictive value at the cost of a lower specificity (sens: 96%, spec: 41%; NPV: 70%). No significant differences were observed between the type of scintigraphic defect (constant or reversible) and the probability of coronary stenosis (positive predictive value 93 and 86% respectively

  5. Comparison of an adaptive neuro-fuzzy inference system and an artificial neural network in the cross-talk correction of simultaneous 99 m Tc / 201Tl SPECT imaging using a GATE Monte-Carlo simulation

    NASA Astrophysics Data System (ADS)

    Heidary, Saeed; Setayeshi, Saeed; Ghannadi-Maragheh, Mohammad

    2014-09-01

    The aim of this study is to compare the adaptive neuro-fuzzy inference system (ANFIS) and the artificial neural network (ANN) to estimate the cross-talk contamination of 99 m Tc / 201 Tl image acquisition in the 201 Tl energy window (77 ± 15% keV). GATE (Geant4 Application in Emission and Tomography) is employed due to its ability to simulate multiple radioactive sources concurrently. Two kinds of phantoms, including two digital and one physical phantom, are used. In the real and the simulation studies, data acquisition is carried out using eight energy windows. The ANN and the ANFIS are prepared in MATLAB, and the GATE results are used as a training data set. Three indications are evaluated and compared. The ANFIS method yields better outcomes for two indications (Spearman's rank correlation coefficient and contrast) and the two phantom results in each category. The maximum image biasing, which is the third indication, is found to be 6% more than that for the ANN.

  6. High spin spectroscopy of 201Tl

    NASA Astrophysics Data System (ADS)

    Das Gupta, S.; Bhattacharyya, S.; Pai, H.; Mukherjee, G.; Bhattacharya, Soumik; Palit, R.; Shrivastava, A.; Chatterjee, A.; Chanda, S.; Nanal, V.; Pandit, S. K.; Saha, S.; Sethi, J.; Thakur, S.

    2013-10-01

    The high spin structure of 201Tl has been studied by γ-ray spectroscopic method using the 198Pt(7Li,4n)201Tl reaction at 45 MeV beam energy. The level scheme of 201Tl has been considerably extended through the observation of 31 new transitions. Several new band structures have been established. The 9/2- oblate band has been significantly extended beyond the particle alignment frequencies. The band structures and the other excited states have been compared with the neighboring odd-A Tl isotopes and with the even-even core nucleus 200Hg. The total Routhian surface calculations have been performed to study the deformation and shape changes as a function of spin in this nucleus.

  7. Photon emission probabilities of 201Tl

    NASA Astrophysics Data System (ADS)

    Kawada, Y.; Hino, Y.; Gatot, W.

    1990-01-01

    Precise measurements of the gamma- and X-ray emission probabilities per decay of 201Tl have been performed using a photon spectrometer with a reverse electrode Ge coaxial detector (LO-AX). The source activity was determined by the 4πβ-γ coincidence technique, and the influence of the coincidence sum effects between the K X-rays and the gamma rays was assessed. Radioactive impurities such as 200Tl and 202Tl were also taken into account.

  8. Regional cardiac wall motion from gated myocardial perfusion SPECT studies

    NASA Astrophysics Data System (ADS)

    Smith, M. F.; Brigger, P.; Ferrand, S. K.; Dilsizian, V.; Bacharach, S. L.

    1999-06-01

    A method for estimating regional epicardial and endocardial wall motion from gated myocardial perfusion SPECT studies has been developed. The method uses epicardial and endocardial boundaries determined from four long-axis slices at each gate of the cardiac cycle. The epicardial and endocardial wall position at each time gate is computed with respect to stationary reference ellipsoids, and wall motion is measured along lines normal to these ellipsoids. An initial quantitative evaluation of the method was made using the beating heart from the dynamic mathematical cardiac torso (MCAT) phantom, with and without a 1.5-cm FWHM Gaussian blurring filter. Epicardial wall motion was generally well-estimated within a fraction of a 3.56-mm voxel, although apical motion was overestimated with the Gaussian filter. Endocardial wall motion was underestimated by about two voxels with and without the Gaussian filter. The MCAT heart phantom was modified to model hypokinetic and dyskinetic wall motion. The wall motion analysis method enabled this abnormal motion to be differentiated from normal motion. Regional cardiac wall motion also was analyzed for /sup 201/Tl patient studies. Estimated wall motion was consistent with a nuclear medicine physician's visual assessment of motion from gated long-axis slices for male and female study examples. Additional research is required for a comprehensive evaluation of the applicability of the method to patient studies with normal and abnormal wall motion.

  9. /sup 201/Tl scintigraphy after surgical repair of hemodynamically significant primary coronary artery anomalies

    SciTech Connect

    Rajfer, S.I.; Oetgen, W.J.; Weeks, K.D. Jr.; Kaminski, R.J.; Rocchini, A.P.

    1982-06-01

    Nine patients with hemodynamically significant congenital coronary artery anomalies underwent surgical repair at our institution during the period 1960 to 1979. Four received diagnoses of anomalous left coronary artery arising from the pulmonary artery, while five patients had coronary artery fistulae. Stress /sup 201/Tl scintigraphy was performed on these patients 0.5 to 18 years after surgical correction as a means of assessing the adequacy of myocardial perfusion. No perfusion defects were visualized on any of the thallium studies. The surgical procedure used did not appear to influence the results of /sup 201/Tl stress imaging. Thus, these nine patients with surgically corrected primary coronary artery anomalies had no evidence of ischemia as assessed by stress thallium scintigraphy. Serial preoperative and postoperative thallium studies are now indicated to determine the role of this procedure in the management of hemodynamically significant congenital coronary artery anomalies.

  10. Differential renal uptake of 201Tl: requirements for acquisition, display and quantification.

    PubMed

    Hurwitz, G A; Powe, J E; Mattar, A G; Reid, R H; Driedger, A A; Rendak, I; Hogendoorn, P

    1991-10-01

    Renal uptake of 201Tl may have a role in screening for renal asymmetry in hypertensive patients (HP) who are referred for myocardial scintigraphy. The qualitative aspects of digitized planar images, and quantified differential renal uptake (DRU) of 201Tl were rated by comparing a simple technique (S) for outlining each kidney with an interpolative background subtracted technique (IB). These parameters were assessed in an initial series of patients by varying the length of acquisition (from 1 to 5 min), delay in acquisition (from 10 to 210 min after injection), and image preparation (nine-point smoothing). Six blinded observers rated the quality of coded images. Image quality was improved (P less than 0.01) by increasing the length of acquisition to at least 2 min, by smoothing of the images and by imaging within 2 h of 201Tl injection. Variability in quantification of DRU was suboptimal with acquisition for only 1 min and was more adversely affected with S than with IB. Clinical application of the quantitative technique was assessed in 180 HP and 32 normotensive controls. With IB, the normal range for DRU was slightly greater than for S. The two techniques were comparable in identifying abnormal cases and found 21 +/- 3% (S) and 19 +/- 3% (IB) of HP as lying outside the normal 99% confidence interval. Both quantitative techniques showed excellent agreement with renal angiography (n = 24). Furthermore, preliminary experience with surface markers and with 180 degrees tomography suggests the potential for simultaneous correction for renal depth. These data justify the use of adjunctive renal imaging during myocardial scintigraphy with 201Tl.

  11. Impaired Coronary Flow Reserve Is the Most Important Marker of Viable Myocardium in the Myocardial Segment-Based Analysis of Dual-Isotope Gated Myocardial Perfusion Single-Photon Emission Computed Tomography

    PubMed Central

    Lee, Won Woo; So, Young; Kim, Ki-Bong

    2014-01-01

    Objective The aim of this study was to investigate the most robust predictor of myocardial viability among stress/rest reversibility (coronary flow reserve [CFR] impairment), 201Tl perfusion status at rest, 201Tl 24 hours redistribution and systolic wall thickening of 99mTc-methoxyisobutylisonitrile using a dual isotope gated myocardial perfusion single-photon emission computed tomography (SPECT) in patients with coronary artery disease (CAD) who were re-vascularized with a coronary artery bypass graft (CABG) surgery. Materials and Methods A total of 39 patients with CAD was enrolled (34 men and 5 women), aged between 36 and 72 years (mean 58 ± 8 standard in years) who underwent both pre- and 3 months post-CABG myocardial SPECT. We analyzed 17 myocardial segments per patient. Perfusion status and wall motion were semi-quantitatively evaluated using a 4-point grading system. Viable myocardium was defined as dysfunctional myocardium which showed wall motion improvement after CABG. Results The left ventricular ejection fraction (LVEF) significantly increased from 37.8 ± 9.0% to 45.5 ± 12.3% (p < 0.001) in 22 patients who had a pre-CABG LVEF lower than 50%. Among 590 myocardial segments in the re-vascularized area, 115 showed abnormal wall motion before CABG and 73.9% (85 of 115) had wall motion improvement after CABG. In the univariate analysis (n = 115 segments), stress/rest reversibility (p < 0.001) and 201Tl rest perfusion status (p = 0.024) were significant predictors of wall motion improvement. However, in multiple logistic regression analysis, stress/rest reversibility alone was a significant predictor for post-CABG wall motion improvement (p < 0.001). Conclusion Stress/rest reversibility (impaired CFR) during dual-isotope gated myocardial perfusion SPECT was the single most important predictor of wall motion improvement after CABG. PMID:24642696

  12. Influence of acquisition orbit on phase analysis of gated single photon emission computed tomography myocardial perfusion imaging for assessment of left ventricular mechanical dyssynchrony.

    PubMed

    Misaka, Tomofumi; Hosono, Makoto; Kudo, Takashi; Ito, Takamichi; Syomura, Tsutomu; Uemura, Masanobu; Okajima, Kaoru

    2017-04-01

    The association between left ventricular (LV) dyssynchrony parameters, given by phase analysis of gated single photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI), and acquisition orbits is unclear. The aim of this study was to assess the dependence of LV dyssynchrony parameters on acquisition orbits. Ninety-nine patients who underwent (201)Tl-gated SPECT MPI were categorized into minor hypoperfusion or major hypoperfusion groups. Forty-four patients who underwent (99m)Tc-tetrofosmin-gated SPECT MPI were categorized into minor hypoperfusion or major hypoperfusion groups. The major hypoperfusion group with (201)Tl was divided into inferior or non-inferior wall hypoperfusion subgroups, and anteroseptal or non-anteroseptal wall hypoperfusion subgroups. Gated SPECT MPI data over a 360° acquisition orbit (360° images) and a 180° acquisition orbit (180° images) were reconstructed, and histogram bandwidth (HBW) and phase standard deviation (PSD) were compared. Between 360° and 180° images with (201)Tl, there were significant differences in HBW and PSD both globally (HBW 34.8 ± 16.6 vs. 29.1 ± 10.2; PSD 8.8 ± 4.9 vs. 7.0 ± 2.3, p < 0.05 for both) and in the inferior wall (HBW 29.5 ± 15.5 vs. 23.3 ± 9.0; PSD 7.6 ± 4.6 vs. 5.6 ± 2.4, p < 0.001 for both) in the major hypoperfusion group, and also in the inferior wall in all subgroups of the major hypoperfusion group. In contrast, no segment had any significant differences in HBW or PSD between 360° and 180° images with (99m)Tc. Differences in acquisition orbit had a significant influence on HBW and PSD with (201)Tl-gated SPECT MPI in the inferior wall in patients with major hypoperfusion myocardium.

  13. Effect of coronary blood flow on uptake and washout of /sup 99m/Tc DMPE and /sup 201/Tl

    SciTech Connect

    Nishiyama, H.; Adolph, R.J.; Deutsch, E.

    1982-12-01

    After intravenous administration of /sup 99m/Tc DMPE the flow-dependent kinetics were studied in dogs during induced ischemia and during induced maximal reactive hyperemia. A control group was also studied. Mean time-activity curves obtained from the myocardial wall were compared within the same intervention group and also with other groups. During reactive hyperemia, there was a rapid and absolute increase in uptake followed by a rapid washout, whereas during ischemia there was a slow and decreased uptake followed by a slow washout. The magnitude of /sup 99m/Tc DMPE uptake during reactive hyperemia was slightly less than that of /sup 201/Tl, but the decreased uptake with ischemia was about equal for the two agents. Following maximal uptake in the myocardium the effective half-life of /sup 99m/Tc DMPE was one-third to one-fourth that of /sup 201/Tl. The similar kinetics of /sup 99m/Tc DMPE compared to /sup 201/Tl suggests its usefulness in the evaluation of ischemic heart disease.

  14. Giant dipole resonance in 201Tl at low temperature

    NASA Astrophysics Data System (ADS)

    Dang, N. Dinh; Hung, N. Quang

    2012-10-01

    The thermal pairing gap obtained by embedding the exact solutions of the pairing problem into the canonical ensemble is employed to calculate the width and strength function of the giant dipole resonance (GDR) within the phonon damping model. The results of calculations describe reasonably well the data for the GDR width as well as the GDR linearized strength function, recently obtained for 201Tl in the temperature region between 0.8 and 1.2 MeV, for which other approaches that neglect the effect of nonvanishing thermal pairing fail to describe.

  15. Imaging considerations for a technetium-99m myocardial perfusion agent

    SciTech Connect

    English, R.J.; Jones, A.G.; Davison, A.; Lister-James, J.; Campbell, S.; Holman, B.L.

    1986-03-01

    Myocardial perfusion imaging with /sup 201/Tl chloride suffers from a number of physical, geometric, and dosimetric constraints that could be diminished if an agent labeled with /sup 99m/Tc were available. The cationic complex /sup 99m/Tc hexakis-(t-butylisonitrile)technetium(I) ((/sup 99m/Tc)TBI) has been shown to concentrate in the myocardial tissue of both animals and humans, with preliminary clinical studies demonstrating a number of technical attributes not possible with /sup 201/Tl. Technetium-99m-TBI is a promising myocardial imaging agent that may permit high quality planar, gated, and tomographic imaging of both myocardial ischemia and infarction with reduced imaging times and improved resolution.

  16. Dipyridamole thallium-201 myocardial scintigraphy

    SciTech Connect

    Not Available

    1988-09-01

    Thallium-201 (/sup 201/Tl) myocardial scintigraphy is a sensitive technique for detecting coronary artery disease. Standardized exercise testing is the most common method for inducing myocardial stress for /sup 201/Tl imaging. Unfortunately, a significant number of patients are unable to undergo adequate treadmill or bicycle exercise. In these patients, pharmacologic stress with dipyridamole provides a safe, efficacious, and reliable alternative.

  17. Markers of left ventricular dysfunction induced by exercise, dipyridamole or combined stress on ECG-gated myocardial perfusion scans.

    PubMed

    Hurwitz, G A; O'Donoghue, J P; MacDonald, A C; Laurin, N R; Powe, J E

    1993-04-01

    An index of left ventricular contraction can be extracted from the cavitary time-activity curve of electrocardiographic (ECG)-gated myocardial perfusion scans. To assess the induction of stress-induced myocardial depression, we compared contraction indexes derived from immediate poststress and delayed 201Tl images with indexes of ventricular dilation and lung uptake in the prediction of severe coronary artery disease (defined as two or more 90% stenoses). Stress procedures were performed in 93 patients with symptom-limited supine bicycle exercise alone, and in 227 with intravenous dipyridamole, combined where possible with exercise. The immediate and delayed contraction indexes reflected left ventricular dysfunction on ventriculography (P < 0.0001), but additionally the immediate index was reduced (P < 0.0001) in severe coronary disease. Stress-induced hypokinesis was seen frequently after each of the test modes. The relationship with angiographic findings was better defined for indexes of contraction than for lung uptake or ventricular dilation (P < 0.01). The prediction of severe coronary disease was optimized by combining the poststress contraction index and lung uptake. These data support the use of ECG-gated myocardial scans in evaluating the functional consequences of stress/imaging procedures.

  18. Serial right ventricle /sup 201/Tl imaging after exercise: relation to anatomy of the right coronary artery

    SciTech Connect

    Brown, K.A.; Boucher, C.A.; Okada, R.D.; Strauss, H.W.; McKusick, K.A.; Pohost, G.M.

    1982-12-01

    The relation of the appearance of the right ventricle on serium /sup 201/Tl myocardial imaging to coronary artery anatomy was examined in 88 consecutive patients undergoing exercise /sup 201/Tl testing and coronary angiography for the evaluation of chest pain. Transient defects in the right ventricle were found in 8 patients. All had high grade (greater than or equal to 90%) stenosis of the proximal right coronary artery. Nonvisualization of right ventricular (RV) activity occurred in 10 patients. Nine of the 10 (90%) had significant (greater than or equal to 50% stenosis) disease of the proximal right coronary artery and 7 (70%) had high grade stenosis. The right ventricle appeared normal in 70 patients. Twenty-nine (41%) of these patients had significant proximal right coronary artery disease. Right ventricular appearance was not affected by the presence or absence of disease of the left anterior descending or left circumflex artery or by the appearance of the left ventricle. Thus, with serial RV thallium-201 myocardial imaging after exercise, we found that (1) RV transient defects suggest the presence of high grade proximal right coronary artery stenosis, (2) non-visualization of RV activity also predicts significant proximal right coronary disease, and (3) the right ventricle frequently appears normal despite proximal right coronary artery disease and therefore this finding does not exclude such disease.

  19. Visual and semi-quantitative assessment of brain tumors using (201)Tl-SPECT.

    PubMed

    Nose, Ayumi; Otsuka, Hideki; Nose, Hayato; Otomi, Yoichi; Terazawa, Kaori; Harada, Masafumi

    2013-01-01

    To evaluate the usefulness of (201)Tl-SPECT in differentiating benign from malignant brain tumors. Eighty-eight patients (44 males and 44 females) with 58 high-grade (WHO grade III-IV) and 30 low-grade (WHO grade I-II) tumors were evaluated with (201)Tl-SPECT. (1) Visual assessment was performed by board-certificated radiologists using (201)Tl-SPECT. Tumors were classified in two groups (Tl-positive and Tl-negative) and scored using the five grade evaluation system. Receiver operating characteristic (ROC) analysis was performed in the Tl-positive group. (2) Semi-quantitative assessment involved measurement of early and delayed (201)Tl uptake, and the retention index (RI) was applied as follows: RI=delayed uptake ratio/early uptake ratio. Three combinations of RI using mean and maximum values of the region of interest were calculated. (1) Seventy-four Tl-positive and 14 Tl-negative tumors. The area under the ROC curve (AUC) estimated by three radiologists exceeded a value of 0.7. The value was greater when estimated by the more experienced radiologist. (2) In all RIs, the difference of RI between high-grade tumors and low-grade tumors was statistically significant. A visual and semi-quantitative assessment using (201)Tl-SPECT was found to be useful for differentiating benign from malignant brain tumors.

  20. Left-ventricular dyssynchrony evaluated by Tl-201 gated SPECT myocardial perfusion imaging: a comparison with Tc-99m sestamibi.

    PubMed

    Chen, Chien-Cheng; Huang, Wen-Sheng; Hung, Guang-Uei; Chen, Wan-Chen; Kao, Chia-Hung; Chen, Ji

    2013-03-01

    Phase analysis of gated single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) has been validated as a reliable tool to assess left-ventricular (LV) mechanical dyssynchrony. The initial results were all confirmed from studies using technetium-99m (Tc-99m) sestamibi or tetrofosmin as the radiotracers. The purpose of this study was to evaluate the feasibility of phase analysis in thallium-201 (Tl-201) gated SPECT MPI. Seventeen patients referred from a cardiology clinic for evaluation of coronary artery disease were studied. All patients underwent both Tl-201 and Tc-99m sestamibi gated SPECT MPI within 1 week. An additional 34 patients with Tl-201 gated SPECT and 22 patients with Tc-99m sestamibi gated SPECT, who had a low likelihood of coronary artery disease, normal LV function, and normal perfusion on MPI, were used as normal controls. LV dyssynchrony parameters, including phase standard deviation (PSD) and phase histogram bandwidth (PHB), were measured using a standard phase analysis tool and compared between Tl-201 and Tc-99m sestamibi images. The LV dyssynchrony parameters correlated well (r=0.93 for PSD and r=0.84 for PHB) between Tl-201 and Tc-99m sestamibi images. The dyssynchrony parameters of Tl-201 were significantly larger than those of Tc-99m sestamibi (PSD: 24.5±12.0 vs. 17.4±9.7, P<0.001; PHB: 74.7±35.5 vs. 50.6±25.0, P<0.001). In comparison with normal controls, Tl-201 and Tc-99m sestamibi images showed concordant results. LV dyssynchrony parameters correlated well between Tl-201 and Tc-99m sestamibi images, even though the values were significantly larger for Tl-201 than for Tc-99m sestamibi. Tl-201 images showed results similar to those of Tc-99m sestamibi in the diagnosis of LV dyssynchrony.

  1. /sup 201/Tl perfusion study of ''ischemic'' ulcers of the leg: prognostic ability compared with Doppler ultrasound

    SciTech Connect

    Siegel, M.E.; Stewart, C.A.; Kwong, P.; Sakimura, I.

    1982-04-01

    Thallium 201 perfusion analysis was compared with Doppler ultrasound as a means of determining the healing potential of an ischemic ulcer of the leg in 27 patients. The degree of hyperemia was determined by comparative point counting of the /sup 201/Tl distribution in and about the ulcer. Using established Doppler criteria and a hyperemia ratio greater than 1.5:1, ultrasound alone correctly predicted healing in 15 out of 23 cases and /sup 201/Tl in 20 out of 23. Ultrasound correctly predicted non-healing in 3 out of 6 cases, compared with 5 out of 6 for /sup 201/Tl. The positive predictive value of the /sup 201/Tl study was 63%, versus 27% for ultrasound, and the negative predictive value was 95% for /sup 201/Tl and 83% for ultrasound. The accuracy of /sup 201/Tl and ultrasound was 86% and 62%, respectively. This limited study suggests that /sup 201/Tl perfusion scanning is a useful noninvasive test of ulcer healing potential and may be more sensitive than Doppler ultrasound.

  2. Myocardial metabolic, hemodynamic, and electrocardiographic significance of reversible thallium-201 abnormalities in hypertrophic cardiomyopathy

    SciTech Connect

    Cannon, R.O. 3d.; Dilsizian, V.; O'Gara, P.T.; Udelson, J.E.; Schenke, W.H.; Quyyumi, A.; Fananapazir, L.; Bonow, R.O. )

    1991-05-01

    Exercise-induced abnormalities during thallium-201 scintigraphy that normalize at rest frequently occur in patients with hypertrophic cardiomyopathy. However, it is not known whether these abnormalities are indicative of myocardial ischemia. Fifty patients with hypertrophic cardiomyopathy underwent exercise {sup 201}Tl scintigraphy and, during the same week, measurement of myocardial lactate metabolism and hemodynamics during pacing stress. Thirty-seven patients (74%) had one or more {sup 201}Tl abnormalities that completely normalized after 3 hours of rest; 26 had regional myocardial {sup 201}Tl defects, and 26 had apparent left ventricular cavity dilatation with exercise, with 15 having coexistence of these abnormal findings. Of the 37 patients with reversible {sup 201}Tl abnormalities, 27 (73%) had metabolic evidence of myocardial ischemia during rapid atrial pacing compared with four of 13 patients (31%) with normal {sup 201}Tl scans (p less than 0.01). Eleven patients had apparent cavity dilatation as their only {sup 201}Tl abnormality; their mean postpacing left ventricular end-diastolic pressure was significantly higher than that of the 13 patients with normal {sup 201}Tl studies (33 +/- 5 versus 21 +/- 10 mm Hg, p less than 0.001). There was no correlation between the angiographic presence of systolic septal or epicardial coronary arterial compression and the presence or distribution of {sup 201}Tl abnormalities. Patients with ischemic ST segment responses to exercise had an 80% prevalence rate of reversible {sup 201}Tl abnormalities and a 70% prevalence rate of pacing-induced ischemia. However, 69% of patients with nonischemic ST segment responses had reversible {sup 201}Tl abnormalities, and 55% had pacing-induced ischemia. Reversible {sup 201}Tl abnormalities during exercise stress are markers of myocardial ischemia in hypertrophic cardiomyopathy and most likely identify relatively underperfused myocardium.

  3. 201Tl+-labelled Prussian blue nanoparticles as contrast agents for SPECT scintigraphy

    NASA Astrophysics Data System (ADS)

    Perrier, M.; Busson, M.; Massasso, G.; Long, J.; Boudousq, V.; Pouget, J.-P.; Peyrottes, S.; Perigaud, Ch.; Porredon-Guarch, C.; de Lapuente, J.; Borras, M.; Larionova, J.; Guari, Y.

    2014-10-01

    Prussian blue (PB) and its analogues on the nanometric scale are exciting nano-objects that combine the advantages of molecular-based materials and nanochemistry. Herein, we demonstrate that ultra-small PB nanoparticles of 2-3 nm can be easily labelled with radioactive 201Tl+ to obtain new nanoprobes as radiotracers for 201-thallium-based imaging.Prussian blue (PB) and its analogues on the nanometric scale are exciting nano-objects that combine the advantages of molecular-based materials and nanochemistry. Herein, we demonstrate that ultra-small PB nanoparticles of 2-3 nm can be easily labelled with radioactive 201Tl+ to obtain new nanoprobes as radiotracers for 201-thallium-based imaging. Electronic supplementary information (ESI) available: Experimental details and procedures, toxicological data, PXRD, TEM images, kinetics and adsorption isotherms, SPECT/CT images, Tl+ captation profiles. See DOI: 10.1039/c4nr03044c

  4. Using adaptive neuro-fuzzy inference system technique for crosstalk correction in simultaneous 99mTc/201Tl SPECT imaging: A Monte Carlo simulation study

    NASA Astrophysics Data System (ADS)

    Heidary, Saeed; Setayeshi, Saeed

    2015-01-01

    This work presents a simulation based study by Monte Carlo which uses two adaptive neuro-fuzzy inference systems (ANFIS) for cross talk compensation of simultaneous 99mTc/201Tl dual-radioisotope SPECT imaging. We have compared two neuro-fuzzy systems based on fuzzy c-means (FCM) and subtractive (SUB) clustering. Our approach incorporates eight energy-windows image acquisition from 28 keV to 156 keV and two main photo peaks of 201Tl (77±10% keV) and 99mTc (140±10% keV). The Geant4 application in emission tomography (GATE) is used as a Monte Carlo simulator for three cylindrical and a NURBS Based Cardiac Torso (NCAT) phantom study. Three separate acquisitions including two single-isotopes and one dual isotope were performed in this study. Cross talk and scatter corrected projections are reconstructed by an iterative ordered subsets expectation maximization (OSEM) algorithm which models the non-uniform attenuation in the projection/back-projection. ANFIS-FCM/SUB structures are tuned to create three to sixteen fuzzy rules for modeling the photon cross-talk of the two radioisotopes. Applying seven to nine fuzzy rules leads to a total improvement of the contrast and the bias comparatively. It is found that there is an out performance for the ANFIS-FCM due to its acceleration and accurate results.

  5. Clinical relevance of 201Tl-chloride SPET in the differential diagnosis of brain tumours.

    PubMed

    Staffen, W; Hondl, N; Trinka, E; Iglseder, B; Unterrainer, J; Ladurner, G

    1998-04-01

    Magnetic resonance imaging (MRI) and computed tomography (CT) may not be reliable in the differential diagnosis of tumour necrosis, scar and recurrent tumour. We compared 201Tl-chloride SPET with CT and MRI for the differential diagnosis of these cerebral lesions. Brain SPET was performed in 40 patients after the intravenous injection of 201Tl-chloride. All 40 patients also had a CT or MRI scan, and a histological diagnosis was available for 27 of the patients. For each patient, the ratio of counts in the lesion region of interest (ROI) to counts in the contralateral ROI was calculated and found to be between 0.58 and 9.60. The ratios for high-grade gliomas, metastases and meningiomas were high (> 2.7), especially in tumours with good vascularization. A low ratio (< 1.7) was noted in patients with low-grade astrocytoma, necrosis or ischaemic lesions. There were two exceptional cases of ischaemic lesions in the luxury perfusion stage (ratios of 3.61 and 3.87), as verified by HMPAO-SPET. We found that 201Tl-chloride SPET helps to differentiate between malignant tumours, poorly vascularized benign lesions and necrosis. Differentiation between low-grade astrocytoma and non-malignant lesions was not possible, but there was a trend towards differentiating between low-grade astrocytoma and ischaemic infarction. The timing of the investigation is important to avoid false-positive results in hyperperfused ischaemic tissue.

  6. Comparison of 8-frame and 16-frame thallium-201 gated myocardial perfusion SPECT for determining left ventricular systolic and diastolic parameters.

    PubMed

    Kurisu, Satoshi; Sumimoto, Yoji; Ikenaga, Hiroki; Watanabe, Noriaki; Ishibashi, Ken; Dohi, Yoshihiro; Fukuda, Yukihiro; Kihara, Yasuki

    2017-07-01

    The myocardial perfusion single photon emission computed tomography synchronized with the electrocardiogram (gated SPECT) has been widely used for the assessment of left ventricular (LV) systolic and diastolic functions using Quantitative gated SPECT. The aim of this study was to compare the effects of 8-frame and 16-frame thallium-201 (Tl-201) gated SPECT for determining LV systolic and diastolic parameters. The study population included 42 patients with suspected coronary artery disease who underwent gated SPECT by clinical indication. LV systolic and diastolic parameters were assessed on 8-frame and 16-frame gated SPECT. There were good correlations in end-diastolic volume (r = 0.99, p < 0.001), end-systolic volume (ESV) (r = 0.97, p < 0.001) and ejection fraction (EF) (r = 0.95, p < 0.001) between 8-frame and 16-frame gated SPECT. Bland-Altman plot showed a significant negative slope of -0.08 in EDV indicating a larger difference for larger EDV. Eight-frame gated SPECT overestimated ESV by 2.3 ml, and underestimated EF by -4.2% than 16-frame gated SPECT. There were good correlations in peak filling rate (PFR) (r = 0.87, p < 0.001), one third mean filling rate (r = 0.87, p < 0.001) and time to PFR (r = 0.61, p < 0.001) between 8-frame and 16-frame gated SPECT. Eight-frame gated SPECT underestimated PFR by -0.22 than 16-frame gated SPECT. Eight-frame gated SPECT estimated as much MFR/3 and TPFR as 16-frame gated SPECT. According to the data, the study suggested that 8-frame Tl-201 gated SPECT could underestimate systolic and/or diastolic parameter when compared with 16-frame gated SPECT.

  7. Estimation of potential excess cancer incidence in pediatric 201Tl imaging.

    PubMed

    Kaste, Sue C; Waszilycsak, George L; McCarville, M Beth; Daw, Najat C

    2010-01-01

    Little information is available regarding doses of ionizing radiation from medical imaging in the growing population of children undergoing therapy for cancer who are at risk of developing second cancers. The purpose of our study was to estimate the potential excess lifetime cancer incidence and mortality associated with thallium bone imaging in pediatric patients. We retrospectively reviewed the medical records of pediatric patients treated between August 1991 and December 2003 for newly diagnosed osteosarcoma who underwent 201Tl imaging as part of the treatment protocol. According to age at diagnosis and doses of 201Tl, we estimated the excess cancer incidence and cancer mortality for boys and girls at 5 and 15 years old. The study cohort consisted of 73 patients, 32 males (median age at diagnosis, 14.8 years; age range, 8.1-20.1 years) and 41 females (median age at diagnosis, 13.3 years; age range, 6.0-20.7 years). Patients underwent a total of three 201Tl studies with a median dose of 4.4 mCi (162.8 MBq) (range, 2.2-8.4 mCi [81.4-310.8 MBq]) per study. Total median cumulative patient radiation dose for 201Tl studies was 18.6 rem (186 mSv) (range, 8.4-44.2 rem [84-442 mSv]) for males and 21.5 rem (215 mSv) (range, 7.0-43.8 rem [70-438 mSv]) for females. Estimated excess cancer incidence was 6.0 per 100 (male) and 13.0 per 100 (female) if exposed by 5 years of age; 2.0 per 100 (male) and 3.1 per 100 (female) by 15 years of age. Estimated excess cancer mortality was 3.0 per 100 for males and 5.2 per 100 for females at 5 years of age; 1.0 per 100 (male) and 1.4 per 100 (female) exposed at 15 years of age. Further reduction of doses in younger patients is needed to consider 201Tl a viable option for imaging osteosarcoma.

  8. Monte Carlo evaluation of accuracy and noise properties of two scatter correction methods for /sup 201/Tl cardiac SPECT

    NASA Astrophysics Data System (ADS)

    Narita, Y.; Iida, H.; Ebert, S.; Nakamura, T.

    1997-12-01

    Two independent scatter correction techniques, transmission dependent convolution subtraction (TDCS) and triple-energy window (TEW) method, were evaluated in terms of quantitative accuracy and noise properties using Monte Carlo simulation (EGS4). Emission projections (primary, scatter and scatter plus primary) were simulated for three numerical phantoms for /sup 201/Tl. Data were reconstructed with ordered-subset EM algorithm including noise-less transmission data based attenuation correction. Accuracy of TDCS and TEW scatter corrections were assessed by comparison with simulated true primary data. The uniform cylindrical phantom simulation demonstrated better quantitative accuracy with TDCS than with TEW (-2.0% vs. 16.7%) and better S/N (6.48 vs. 5.05). A uniform ring myocardial phantom simulation demonstrated better homogeneity with TDCS than TEW in the myocardium; i.e., anterior-to-posterior wall count ratios were 0.99 and 0.76 with TDCS and TEW, respectively. For the MCAT phantom, TDCS provided good visual and quantitative agreement with simulated true primary image without noticeably increasing the noise after scatter correction. Overall TDCS proved to be more accurate and less noisy than TEW, facilitating quantitative assessment of physiological functions with SPECT.

  9. Activity determination of a 201Tl solution by 4πβ-γ and sum-peak coincidence methods

    NASA Astrophysics Data System (ADS)

    Ruzzarin, A.; da Silva, M. A. L.; Iwahara, A.; da Silva, R. L.; Filho, O. L. T.; Poledna, R.; Lopes, R. T.

    2016-07-01

    201Tl is used in nuclear medicine in cardiac imaging for evaluating the injury level in cardiac muscle at rest and exercise. In this work the activity concentration of a 201 Tl radioactive solution has been absolutely determined using the 4πβ-γ coincidence and sum-peak coincidence methods. The presence of 202Tl radioactive impurity that imposes some difficult in the activity measurements was taken into account in the measurements. In the sum-peak method a planar germanium detector was used. The half-lives were evaluated by the reference source method and the results obtained were (3.033 ± 0.004) d and (12.320 ± 0.163) d, respectively, for 201Tl and 202Tl.

  10. A noninvasive method for evaluating portal circulation by administration of /sup 201/Tl per rectum

    SciTech Connect

    Tonami, N.; Nakajima, K.; Hisada, K.; Tanaka, N.; Kobayashi, K.

    1982-11-01

    A new method for evaluating portal systemic circulation by administration of /sup 201/Tl per rectum was performed in 13 control subjects and in 65 patients with various liver diseases. In normal controls, the liver was visualized on the 0--5-min image whereas the images of other organs such as the heart, spleen, and lungs were very poor. In patients with liver cirrhosis associated with portal-systemic shunt, and in many other patients with hepatocellular damage, the liver was not so clearly visualized, whereas radioactivity in other organs, especially the heart, became evident. The heart-to-liver uptake ratio at 20 min after administration (H/L ratio) was significantly higher in liver cirrhosis than in normals and patients with chronic hepatitis (p less than 0.001). The patients with esophageal varices showed a significantly higher H/L ratio compared with that in cirrhotic patients without esophageal varices (p less than 0.001). The H/L ratio also showed a significant difference (p less than 0.01) between Stage 1 and Stage 3 esophageal varices. Since there were many other patients with hepatocellular damage who had high H/L ratios similar to those in liver cirrhosis, the effect that hepatocellular damage has on the liver uptake of /sup 201/Tl is also considered. Our present data suggest that this noninvasive method seems to be useful in evaluating portal-to-systemic shunting.

  11. Sex-specific criteria for interpretation of thallium-201 myocardial uptake and washout studies

    SciTech Connect

    Rabinovitch, M.; Suissa, S.; Elstein, J.; Staniloff, H.; Tang, A.; Rush, C.; Aldis, A.; Tannous, R.; Turek, M.; Addas, A.

    1986-12-01

    A study was undertaken to determine the effect of gender on criteria for the quantitative analysis of exercise-redistribution /sup 201/Tl myocardial scintigraphy. The studies of 26 normal females and 23 normal males were subjected to bilinear interpolative background subtraction and horizontal profile analysis. Significant sexual differences were found in both regional uptake ratios and washout rates. These differences primarily reflected a proportionately decreased anterior and upper septal uptake in females, and faster washout in females. Faster myocardial /sup 201/Tl washout rates in females could not be clearly ascribed to either a physiological or artifactual explanation. It is concluded that since important differences exist between males and females in the detected pattern of /sup 201/Tl myocardial uptake and washout, sex-specific criteria may enhance the predictive accuracy of exercise-redistribution /sup 201/Tl myocardial scintigraphy.

  12. Effect of eating on thallium myocardial imaging

    SciTech Connect

    Wilson, R.A.; Sullivan, P.J.; Okada, R.D.; Boucher, C.A.; Morris, C.; Pohost, G.M.; Strauss, H.W.

    1986-02-01

    To determine if eating between initial and delayed thallium images alters the appearance of the delayed thallium scan, a prospective study was performed; 184 subjects sent for routine thallium imaging were randomized into two groups, those who ate a meal high in carbohydrates between initial and delayed thallium myocardial images (n = 106), and those who fasted (n = 78). The /sup 201/Tl images were interpreted in blinded fashion for global myocardial and pulmonary clearance of /sup 201/Tl myocardial defects. The eating group had a significantly lower incidence of transient myocardial defects compared to the noneating group (7 percent vs 18 percent, respectively; p less than 0.05). The time between initial and delayed images and the incidence of exercise-induced ischemic ST-segment depression or pathologic Q waves on the electrocardiogram were not significantly different between the two groups. These data suggest that eating a high-carbohydrate meal between initial and delayed /sup 201/Tl images causes increased /sup 201/Tl myocardial clearance rates and may alter /sup 201/Tl myocardial redistribution over time.

  13. Effect of thallium-201 blood levels on reversible myocardial defects

    SciTech Connect

    Nelson, C.W.; Wilson, R.A.; Angello, D.A.; Palac, R.T.

    1989-07-01

    To determine if /sup 201/Tl plasma blood levels correlate with the presence of reversible myocardial defects during exercise testing, 14 patients with stable coronary artery disease underwent two separate exercise /sup 201/Tl stress tests. Between initial and delayed imaging, on one test the patients drank an instant breakfast drink (eating) and on the other they drank an equivalent volume of water as a control (H/sub 2/O). Thallium-201 imaging was performed immediately postexercise, immediately after eating/H/sub 2/O and 210 min after eating/H/sub 2/O. Between initial and immediate post eating/H/sub 2/O images 201Tl reversible defects occurred in 27/38 regions in the H/sub 2/O test versus 15/38 regions in the eating test (p = 0.02). Over this early time period, plasma /sup 201/Tl activity was significantly higher in the H/sub 2/O test than eating test (p less than 0.05). In conclusion, early reversal of /sup 201/Tl defects may, in part, be the result of higher plasma /sup 201/Tl activity early after initial postexercise /sup 201/Tl imaging.

  14. A rapid improved method for gamma-spectrometric determination of 202Tl impurities in [201Tl]-labelled radiopharmaceuticals.

    PubMed

    Bonardi, Mauro; Groppi, Flavia; Birattari, Claudio

    2002-11-01

    Despite the cyclotron production method and the efficiency of the radiochemical procedures adopted, the long-lived radio-isotopic impurity 202Tl is always present in [201Tl]-labelled radio-pharmaceuticals, together with other short-lived impurities like, 200Tl. Rapid determination of the 202Tl impurity, can be achieved using HPGe gamma spectrometry and a detector shielded by a 5 mm thick envelope of lead. In this way, dead-time correction errors, Compton and X-ray background, are very efficiently avoided and suppressed. The same method could be applied routinely in nuclear medicine, to determine the radioisotopic purity of 201Tl by means of an ionisation chamber dose calibrator.

  15. Superimposed display of coronary artery on gated myocardial perfusion scintigraphy.

    PubMed

    Nishimura, Yoshihiro; Fukuchi, Kazuki; Katafuchi, Tetsuro; Sagou, Masayoshi; Oka, Hisashi; Ishida, Yoshio; Murase, Kenya

    2004-09-01

    Fusion of images of vascular anatomy and of myocardial perfusion images might be helpful for understanding the relationship between ischemia and the responsible vessels. The aim of this study was to develop a simple means of superimposing the images obtained from coronary angiography and gated myocardial perfusion SPECT. Right and left oblique views from conventional coronary angiography and left ventriculography (LVG) were stored as 512 x 512 x 8-bit digital datasets and combined. We reconstructed images from routine gated myocardial perfusion imaging (MPI) by using (99m)Tc-tetrofosmin to match the oblique positions between the image from MPI and combined angiographic images. We then generated a 3-dimensional (3D) surface map by using the quantitative gated SPECT (QGS)/quantitative perfusion SPECT (QPS) program. Both the combined angiographic images and the 3D surface map were rescaled and unified by registering the internal landmarks between the 2 images. After subtraction of the LVG image, the coronary angiogram and the 3D surface map were fused into 1 image. All processes were performed with the QGS/QPS program and commercially available graphic software. We applied this method to datasets from a cardiac phantom and from several patients with coronary artery disease. In the phantom study, our technique could obtain a 3D surface map in which the oblique angle was identified as that of radiography and could realize image registration and superimposition of radiography on scintigraphy. The preliminary results from the patients indicated that the markedly stenotic vessels showed good coincidence with the regional myocardial perfusion abnormalities on the unified images. In addition, these images could show the relationship between the coronary artery and regional wall motion in the gated mode. We developed a simple method of superimposing the image of the coronary artery tree on images from gated MPI. The technique yielded useful information about myocardial

  16. Contamination and radiation exposure from sup 201 Tl in patients undergoing dialysis after a nuclear medicine study

    SciTech Connect

    Serrano, M.; Olson, A.; Man, C.; Galonsky, R.; Stein, R. )

    1991-03-01

    Our institution is a major kidney research and transplant center. Hemodialysis patients that are scheduled for renal transplant are given a 201Tl stress test. Possible radiation exposure and contamination are of concern to attending personnel. We investigated this situation and found measurable activity in the effluent of patients receiving dialysis but no significant contamination of equipment. We determined that dialysis personnel received minimal radiation exposure.

  17. Delayed redistribution in thallium 201 SPECT myocardial perfusion studies

    SciTech Connect

    Ziessman, H.A.; Keyes, J.W. Jr.; Fox, L.M.; Green, C.E.; Fox, S.M. )

    1989-11-01

    Stress {sup 201}Tl myocardial perfusion studies are useful in differentiating viable, reversibly ischemic from infarcted myocardium. A perfusion defect that shows redistribution 2 to 4 h after {sup 201}Tl injection is diagnostic of ischemia, while a fixed defect suggests infarction. However, occasional patients with a fixed defect at 4 h have redistribution at 24 h. This study evaluates the frequency and significance of this delayed redistribution with SPECT {sup 201}Tl. Patients with either no or incomplete redistribution at 4 h had repeat imaging 18 to 48 h later. Delayed redistribution was seen in 8/26 (31 percent). Four had incomplete and four had no redistribution at 4 h. Delayed redistribution with SPECT {sup 201}Tl is more common than generally appreciated, and we recommend delayed images in patients with fixed perfusion defects or incomplete redistribution at 4-h imaging, particularly in patients with previous infarctions for whom a revascularization procedure is being considered.

  18. Fast washout of thallium-201 from area of myocardial infarction: possible artifact of background subtraction

    SciTech Connect

    Brown, K.A.; Benoit, L.; Clements, J.P.; Wackers, F.J.

    1987-06-01

    A recent report described a pattern of reverse redistribution on poststreptokinase /sup 201/Tl studies which was believed to be due to rapid washout of /sup 201/Tl from the infarct area related to reperfusion of the infarct vessel. We have also observed the phenomenon of rapid washout of /sup 201/Tl from the area of infarction in the absence of thrombolytic therapy. This study was undertaken to test the hypothesis that rapid washout of /sup 201/Tl from an area of infarction is an artifact of background subtraction usually employed in analysis of washout. A total of 61 patients with previous myocardial infarction who underwent cardiac catheterization and exercise /sup 201/Tl imaging were examined. Thallium-201 images were analyzed using a validated quantitative method employing interpolative background correction. Abnormally increased /sup 201/Tl washout was noted in 11 infarct segments in 10 (18%) patients. Infarct segments with rapid washout had significantly less initial uptake, and more severe associated wall motion abnormalities than infarct segments with normal washout. When quantitative analysis was repeated without background subtraction, no segments with rapid washout were observed. A phantom model was constructed to further test our hypothesis. The frequency of observed rapid washout was directly related to the severity of the initial defect and was entirely dependent upon utilizing background correction during the quantitative analysis. Our study suggests that rapid washout of /sup 201/Tl in an area of previous infarction reflects an artifact of background subtraction involved with standard quantitative analysis.

  19. 201Tl heart-liver radioactivity uptake ratio and prediction of decompensation in patients with cirrhosis.

    PubMed

    Lee, Min-Ho; Tae, Hae-Jin; Jun, Dae-Won; Ryu, Seong-Eon; Choi, Yun-Young; Kwak, Min-Jeong; Kang, Ju-Seop

    2013-03-01

    The present study aimed to determine the predictive value of the heart-liver uptake ratio (H/L ratio) of rectally administered (201)Tl scintigraphy for hepatic decompensation, which was conducted in 107 patients with cirrhosis. We retrospectively assessed the predictive value of a noninvasive parameter, H/L ratio, for decompensation during a median follow-up period of 45.4 months using follow-up data from 1996 through 2008 for 107 patients with compensated cirrhosis. Logistic regression analysis and odds ratio estimates were used to estimate independent value of the H/L ratio on the risk of decompensation with 95% confidence intervals. At first visit, all subjects were confirmed as patients with compensated cirrhosis, 39 by liver biopsy and 68 by standard laboratory and radiological criteria. At end of the evaluation time, 81 patients remained compensated, whereas 26 patients decompensated as evidenced by ascites in 23, hepatic encephalopathy in 8, and variceal bleeding in 1 patient. First-visit parameters except bilirubin level, alanine aminotransferase (ALT), and H/L ratio and last visit parameters except ALT and aspartate aminotransferase-ALT ratio were significantly different between the 2 groups as ascertained by Wilcoxon rank sum test (P < 0.05). Among those parameters, we found that the last visit H/L ratio was a strongly reliable predictor of decompensation with an odds ratio estimates of 14.443, area under the receiver operating characteristic curve of 0.825, cutoff of 0.4, sensitivity of 73.1 %, and specificity of 71.6%. This evidence indicates that in patients with compensated cirrhosis, an increased H/L ratio at follow-up may be a useful predictive parameter showing a high risk of progression to a decompensated state.

  20. Myocardial perfusion and left ventricular function indices assessed by gated myocardial perfusion SPECT in methamphetamine abusers.

    PubMed

    Dadpour, Bita; Dabbagh Kakhki, Vahid R; Afshari, Reza; Dorri-Giv, Masoumeh; Mohajeri, Seyed A R; Ghahremani, Somayeh

    2016-12-01

    Methamphetamine (MA) is associated with alterations of cardiac structure and function, although it is less known. In this study, we assessed possible abnormality in myocardial perfusion and left ventricular function using gated myocardial perfusion SPECT. Fifteen patients with MA abuse, on the basis of Diagnostic and Statistical Manual of Mental Disorders, 4th ed. (DSM-IV) MA dependency determined by Structured Clinical Interview for DSM-IV, underwent 2-day dipyridamole stress/rest Tc-sestamibi gated myocardial perfusion SPECT. An average daily dose of MA use was 0.91±1.1 (0.2-4) g. The duration of MA use was 3.4±2.1 (1-7) years. In visual and semiquantitative analyses, all patients had normal gated myocardial perfusion SPECT, with no perfusion defects. In all gated SPECT images, there was no abnormality in left ventricular wall motion and thickening. All summed stress scores and summed rest scores were below 3. Calculated left ventricular functional indices including the end-diastolic volume, end-systolic volume, and left ventricular ejection fraction were normal. Many cardiac findings because of MA mentioned in previous reports are less likely because of significant epicardial coronary artery stenosis.

  1. Usefulness of the Chang attenuation correction method with use of a CT-based μ map by FBP reconstruction in (201)Tl SPECT-MPI.

    PubMed

    Nakamura, Yuya; Tomiguchi, Seiji

    2015-06-01

    Attenuation correction (AC) on nuclear images of non-uniform domains is generally performed by a change of the computed tomography (CT) values to μ values, which are then inserted as components into the detection probability of iterative reconstruction techniques (OS-EM Iterative AC). We established an AC technique which uses a CT μ map based on the Chang AC. Our purpose in this study was to confirm the appropriateness of the Chang AC with the OS-EM and the FBP method (OS-EM Chang AC and FBP Chang AC) by evaluating the results obtained in a phantom and clinical study for (201)Tl single-photon emission-computed tomography-myocardial perfusion imaging (SPECT-MPI). Myocardial phantom study and retrospective clinical study were performed. Evaluations for image quality (uniformity and contrast) and image quantitative values [accurate left ventricular (LV) volume and radioactivity] were performed for both studies. FBP Chang AC showed good image uniformity and proper contrast in phantom and clinical study. Accurate LV volume and radioactivity in the myocardium were also obtained by the phantom study. On the other hand, the number of iterations influenced the image quality both in OS-EM Iterative AC and OS-EM Chang AC in the phantom study. Different numbers of iterations were necessary for obtaining good contrast ratio in each of the anterior and inferior wall, and accurate LV volume. The number of iterations influences the image quality and quantitative values on OS-EM Iterative Chang AC and OS-EM Chang AC images. In addition, it is difficult to set an appropriate number of iterations for the iterative reconstruction of these images in phantom and clinical studies. Therefore, FBP Chang AC is considered to be clinically useful.

  2. Automated quantitative coronary computed tomography correlates of myocardial ischaemia on gated myocardial perfusion SPECT.

    PubMed

    de Graaf, Michiel A; El-Naggar, Heba M; Boogers, Mark J; Veltman, Caroline E; Broersen, Alexander; Kitslaar, Pieter H; Dijkstra, Jouke; Kroft, Lucia J; Al Younis, Imad; Reiber, Johan H; Bax, Jeroen J; Delgado, Victoria; Scholte, Arthur J

    2013-08-01

    Automated software tools have permitted more comprehensive, robust and reproducible quantification of coronary stenosis, plaque burden and plaque location of coronary computed tomography angiography (CTA) data. The association between these quantitative CTA (QCT) parameters and the presence of myocardial ischaemia has not been explored. The aim of the present investigation was to evaluate the association between QCT parameters of coronary artery lesions and the presence of myocardial ischaemia on gated myocardial perfusion single-photon emission CT (SPECT). Included in the study were 40 patients (mean age 58.2 ± 10.9 years, 27 men) with known or suspected coronary artery disease (CAD) who had undergone multidetector row CTA and gated myocardial perfusion SPECT within 6 months. From the CTA datasets, vessel-based and lesion-based visual analyses were performed. Consecutively, lesion-based QCT was performed to assess plaque length, plaque burden, percentage lumen area stenosis and remodelling index. Subsequently, the presence of myocardial ischaemia was assessed using the summed difference score (SDS ≥2) on gated myocardial perfusion SPECT. Myocardial ischaemia was seen in 25 patients (62.5%) in 37 vascular territories. Quantitatively assessed significant stenosis and quantitatively assessed lesion length were independently associated with myocardial ischaemia (OR 7.72, 95% CI 2.41-24.7, p < 0.001, and OR 1.07, 95% CI 1.00-1.45, p = 0.032, respectively) after correcting for clinical variables and visually assessed significant stenosis. The addition of quantitatively assessed significant stenosis (χ(2) = 20.7) and lesion length (χ(2) = 26.0) to the clinical variables and the visual assessment (χ(2) = 5.9) had incremental value in the association with myocardial ischaemia. Coronary lesion length and quantitatively assessed significant stenosis were independently associated with myocardial ischaemia. Both quantitative parameters have incremental value

  3. Voxel-based analysis of (201)Tl SPECT for grading and diagnostic accuracy of gliomas: comparison with ROI analysis.

    PubMed

    Kuwako, Tomoyuki; Mizumura, Sunao; Murakami, Ryusuke; Yoshida, Tamiko; Shiiba, Masato; Sato, Hidetaka; Fukushima, Yoshimitsu; Teramoto, Akira; Kumita, Shin-Ichiro

    2013-07-01

    The aim of this retrospective study was to assess the utility of a voxel-based analysis (VBA) method for (201)Tl SPECT in glioma, compared to conventional ROI analysis. We recruited 24 patients with glioma (high-grade 15; low-grade 9), for whom pre-operative (201)Tl SPECT and MRI were performed. SPECT images were coregistered with MRI. The uptake ratio (UR) images of tumor to contralateral normal tissue were measured on early and delayed images, and the (201)Tl retention index (RI) map was calculated from the early and delayed uptake ratio maps. In the ROI analysis, tumors were traced on a UR map, and the mean and maximal uptake ratio values on the early images were, respectively, defined as the mean and maximal UR. The mean and maximal RI values (mean and maximal RI) were calculated by division of the mean and maximal UR, respectively, on the delayed image by the mean and maximal UR on the early image. For the RI map calculated voxel by voxel, the maximal RI value was defined as VBA-RI. We evaluated sensitivity and accuracy of differential analysis with the mean and maximal UR, RI, and VBA-RI. The high- and low-grade groups showed no significant difference in mean and maximal RI (0.98 ± 0.12 vs. 1.05 ± 0.09 and 0.98 ± 0.18 vs. 1.05 ± 0.14, respectively). The AUC and accuracy of the mean and maximal RI were 0.681 and 66.7 %, and 0.622 and 62.5 %, respectively. In contrast, VBA-RI was higher in high-grade than in low-grade glioma (1.69 ± 0.27 vs. 0.68 ± 0.66, p < 0.001). The AUC and accuracy of VBA-RI were 0.963 and 95.8 %, which are higher than those obtained for mean (p < 0.05) and maximal RI (p < 0.01). There was no significant difference in ROC between the VBA-RI and the mean UR (0.911, p = 0.456) and maximal UR (0.933, p = 0.639); however, the AUC, sensitivity, and diagnostic accuracy of VBA-RI were all higher than those of the mean and maximal UR. The voxel-based analysis method of (201)Tl SPECT may improve diagnostic performance for gliomas, compared

  4. Assessment of resistance to paclitaxel of murine tumors by (99m)Tc-MIBI/(201)Tl dual-radionuclide imaging.

    PubMed

    Oriuchi, N; Jibu, T; Milas, L; Choe, J; Kuang, L; Kim, E E; Hunter, N R; Wallace, S; Podoloff, D A

    2000-02-01

    This study investigated P-glycoprotein (Pgp) expression by murine tumors with and without resistance to paclitaxel and the role of (99m)Tc-2-methoxyisobutylisonitrile (MIBI)/(201)Tl imaging in predicting the effect of paclitaxel. Antitumor effect of paclitaxel and biodistribution of the radiopharmaceuticals were evaluated in mice bearing four tumor types. Pgp expression did not correlate with the antitumor efficacy of paclitaxel. Although the absolute uptake of (99m)Tc-MIBI did not correlate with Pgp expression, (99m)Tc-MIBI could predict paclitaxel sensitivity by its higher uptake.

  5. Dynamic, equilibrium and human studies of adsorption of 201Tl by Prussian blue.

    PubMed

    Bhardwaj, Nidhi; Bhatnagar, Aseem; Pathak, D P; Singh, A K

    2006-03-01

    Prussian blue is the recommended but infrequently required antidote for radiocesium and thallium chemical poisoning. Conceivably, its most frequent application will be the decontamination of radiothallium (thallous chloride) from human body following myocardial scintigraphy. Dosage schedule and physicochemical parameters of interaction with radiothallium, however, need to be defined, as the known data is inadequate on this account. The objective of the present study is to create physiologically relevant and mathematically rigorous data on interaction of Prussian blue with Tl, to estimate dosage schedule of Prussian blue suitable for myocardial scintigraphy, and to perform preliminary human studies to evaluate the efficacy of the antidote in reducing the considerable radiation burden imparted by this radiotracer. Adsorption efficacy of Prussian blue for radiothallium was found to be more than 95% at basic (intestinal) pH even at low concentrations and in presence of the physiological cations, potassium and sodium. Isotherm analysis and derivations using Langmuir, Bajpai, Lagergreen, and Freundlich equations suggest a favorable adsorption of Tl on Prussian blue with qmax being 5,000 MBq g. Based on these findings and clinical considerations, particularly preferential gall bladder excretion and enterohepatic recycling of radioactive thallous chloride, a dose of 100 mg Prussian blue with every major meal for 3 days was considered adequate for the purpose. Our experience with the first two patients (serving as their own self-controls) suggests that Prussian blue therapy is a safe and effective method to significantly reduce radiation burden imparted by thallium myocardial scintigraphy.

  6. Characteristics of regional myocardial stunning after exercise in gated myocardial SPECT.

    PubMed

    Paul, Asit Kr; Hasegawa, Shinji; Yoshioka, Jun; Mu, Xiuli; Maruyama, Kaoru; Kusuoka, Hideo; Nishimura, Tsunehiko

    2002-01-01

    A number of studies have demonstrated prolonged left ventricular (LV) global dysfunction after exercise-induced ischemia in gated myocardial single photon emission tomography (SPECT) as a manifestation of exercise-induced stunning. This study investigated the residual effects of exercise on postexercise LV regional function and its implications on the detection of stunning in gated SPECT. Fifty-three subjects with known or suspected coronary artery disease and 10 control subjects underwent myocardial SPECT according to a same-day exercise-rest protocol. Both postexercise and resting images were gated and acquired 1 hour after injection of technetium 99m tetrofosmin. The LV global ejection fraction and segmental systolic wall thickening were quantitated with the use of an automatic program. Segmental perfusion was assessed semiquantitatively on summed nongated tomograms. Wall thickening index (WTI), the ratio of systolic wall thickening of a segment to that of a corresponding control segment, was significantly lower after exercise than at rest in the reversible defect (RD) segments (0.66 +/- 0.24 vs 0.78 +/- 0.24; P <.0001). In patients with exercise-induced ischemia, the difference in WTI between rest and after exercise was significantly greater in the RD segments, which represented ischemia, than in the non-RD segments. Postexercise WTIs were not different from the resting values in subjects with no perfusion abnormalities or who had fixed defects (infarction). Significant postexercise dysfunction was present in 44% of the RD segments, compared with 5% of the normal and 3% of the fixed defect segments. Postexercise segmental dysfunction was correlated with the segmental reversibility score, the difference in defect scores between exercise and rest images (n = 82, Spearman rank correlation coefficient = -0.78, P <.0001). Among 19 patients with ischemia, 9 (47%) exhibited concurrent segmental and global dysfunction, but segmental dysfunction persisted in the absence

  7. KEY COMPARISON: BIPM comparison BIPM.RI(II)-K1.Tl-201 of activity measurements of the radionuclide 201Tl

    NASA Astrophysics Data System (ADS)

    Ratel, G.; Michotte, C.

    2004-01-01

    Since 1979, six national metrology institutes (NMI) and another laboratory have submitted 16 samples of known activity of 201Tl to the International Reference System (SIR) for activity comparison at the Bureau International des Poids et Mesures (BIPM), with comparison identifier BIPM.RI(II)-K1.Tl-201. The activities ranged from about 3.5 MBq to 207 MBq. The degrees of equivalence between each equivalent activity measured in the SIR and the key comparison reference value (KCRV) have been calculated and the results are given in the form of a matrix for six NMIs. A graphical presentation is also given. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by Section II of the Consultative Committee for Ionizing Radiation (CCRI(II)), according to the provisions of the Mutual Recognition Arrangement (MRA).

  8. Kinetic analysis of 18F-fluorodihydrorotenone as a deposited myocardial flow tracer: Comparison to thallium-201.

    SciTech Connect

    Marshall, Robert C.; Powers-Risius, Patricia; Reutter, Bryan W.; O'Neil, James P.; La Belle, Michael; Huesman, Ronald H.; VanBrocklin, Henry F.

    2004-03-01

    The goal of this investigation was to assess the accuracy of 18F-fluorodihydrorotenone (18F-FDHR) as a new deposited myocardial flow tracer and compare the results to those for 201Tl. Methods. The kinetics of these flow tracers were evaluated in 22 isolated, erythrocyte- and albumin-perfused rabbit hearts over a flow range encountered in patients. The two flow tracers plus a vascular reference tracer (131I-albumin) were introduced as a bolus through a port just above the aortic cannula. Myocardial extraction, retention, washout, and uptake parameters were computed from the venous outflow curves using the multiple indicator dilution technique and spectral analysis. Results. The mean initial extraction fractions of 18F-FDHR (0.85 +- 0.07) and 201Tl (0.87 +- 0.05) were not significantly different, although the initial extraction fraction for 18F-FDHR declined with flow (P < 0.0001), whereas the initial extraction fraction of 201Tl did not. Washout of 201Tl was faster (P < 0.001) and more affected by flow (P < 0.05) than 18F-FDHR washout. Except for initial extraction fraction, 18F-FDHR retention was greater (P < 0.001) and less affected by flow (P < 0.05) than 201Tl retention. Reflecting its superior retention, net uptake of 18F-FDHR was better correlated with flow than 201Tl uptake at both one and fifteen minutes after tracer introduction (P < 0.0001 for both comparisons). Conclusion. The superior correlation of 18F-FDHR uptake with flow indicates that it is a better flow tracer than 201Tl in the isolated rabbit heart. Compared to the other currently available positron-emitting flow tracers (82Rb, 13N-ammonia, and 15O-water), 18F-FDHR has the potential of providing excellent image resolution without the need for an on-site cyclotron.

  9. Radionuclide imaging in myocardial sarcoidosis. Demonstration of myocardial uptake of /sup 99m/Tc pyrophosphate and gallium

    SciTech Connect

    Forman, M.B.; Sandler, M.P.; Sacks, G.A.; Kronenberg, M.W.; Powers, T.A.

    1983-03-01

    A patient had severe congestive cardiomyopathy secondary to myocardial sarcoidosis. The clinical diagnosis was confirmed by radionuclide ventriculography, /sup 201/Tl, /sup 67/Ga, and /sup 99m/Tc pyrophosphate (TcPYP) scintigraphy. Myocardial TcPYP uptake has not been reported previously in sarcoidosis. In this patient, TcPYP was as useful as gallium scanning and thallium imaging in documenting the myocardial process.

  10. Left ventricular wall function abnormalities in patients with ankylosing spondylitis evaluated by gated myocardial perfusion scintigraphy.

    PubMed

    Yalcin, H; Guler, H; Gunay, E; Yeral, N; Turhanoglu, A; Bolaç, E; Yalcin, F

    2011-01-01

    Ankylosing spondilitis (AS) is a chronic inflammatory disease with prominent inflammation in joints and extraarticular organs. AS patients have approximately two times more risk of mortality than the normal population. One reason for this increase in mortality is increased cardiovascular risk. In this study, we have aimed to evaluate myocardial perfusion and left ventricular function using (99m)Tc-MIBI gated myocardial perfusion single photon emission computed tomography (SPECT). The study group consisted of 28 AS patients (19 men, 9 women), and mean age 39.46±10.98 years. All patients underwent (99m)Tc-MIBI gated myocardial perfusion SPECT with the same day protocol. We detected various risk factors including smoking habits in 12, family history of cardiovascular disease in 12, hypertension in 3, hyperlipidemia in 9 patients. We performed a myocardial perfusion SPECT for each patient and found normal perfusion pattern in SPECT images. Out of 28 patients, eight patients had normal perfusion but wall motion abnormalities. We detected that myocardial perfusion is preserved in the patients with AS. However, left ventricular wall motion abnormalities are seen. We concluded that ankylosing spondylitis may be associated with microvascular dysfunction and gated myocardial perfusion scintigraphy could be valuable in AS patients for the evaluation of LV function even if the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) score are low and the disease duration shorter. Copyright © 2010 Elsevier España, S.L. and SEMNIM. All rights reserved.

  11. Dielectric properties and charge transfer in (TlInSe2)0.1(TlGaTe2)0.9 for the DC and AC current

    NASA Astrophysics Data System (ADS)

    Mustafaeva, S. N.; Asadov, M. M.; Dzhabbarov, A. I.

    2014-06-01

    The experimental results of studying the temperature and frequency dependences of dc and ac conductivity as well as the dispersion of dielectric coefficients of the grown single crystals of the (TlInSe2)0.1(TlGaTe2)0.9 solid solution are presented. The nature of dielectric losses and the hopping charge transfer mechanism have been established, and parameters of localized states, such as the density of states near the Fermi level and their spread, the average time and the hopping length of charge carriers, and the concentration of deep traps responsible for dc and ac conductivity, have been evaluated.

  12. Tomographic myocardial perfusion scintigraphy in children with Kawasaki disease

    SciTech Connect

    Spielmann, R.P.; Nienaber, C.A.; Hausdorf, G.; Montz, R.

    1987-12-01

    Myocardial infarction and stenotic coronary lesions are serious late complications in children with Kawasaki disease. For the noninvasive assessment of myocardial perfusion, dipyridamole-redistribution /sup 201/Tl emission computed tomography (ECT) was performed in seven children (age 2 8/12-8 7/12 yr) 3-20 mo after the acute stage of the disease. In all patients, coronary aneurysms had been demonstrated by cross-sectional echocardiography. The scintigrams of six children showed no significant regional reduction of myocardial thallium uptake. These children had remained asymptomatic since the acute stage of Kawasaki disease. Persistent and transient thallium defects were present in one child with documented myocardial infarction. For this patient, obstruction of corresponding coronary vessels was confirmed by contrast angiography. It is suggested, that /sup 201/Tl ECT after dipyridamole-induced vasodilation may be used as a safe alternative to invasive coronary angiography for follow-up investigations in patients with Kawasaki disease.

  13. Signal Quality Analysis of Ambulatory Electrocardiograms to Gate False Myocardial Ischemia Alarms.

    PubMed

    Abdelazez, Mohamed; Quesnel, Patrick X; Chan, Adrian D C; Yang, Homer

    2017-06-01

    The objective of this study is to propose and validate an alarm gating system for a myocardial ischemia monitoring system that uses ambulatory electrocardiogram. The PeriOperative ISchemic Evaluation study recommended the selective administration of β blockers to patients at risk of cardiac events following noncardiac surgery. Patients at risk are identified by monitoring ST segment deviations in the electrocardiogram (ECG); however, patients are encouraged to ambulate to improve recovery, which deteriorates the signal quality of the ECG leading to false alarms. The proposed alarm gating system computes a signal quality index (SQI) to quantify the ECG signal quality and rejects alarms with a low SQI. The system was validated by artificially contaminating ECG records with motion artifact records obtained from the long-term ST database and MIT-BIH noise stress test database, respectively. Without alarm gating, the myocardial ischemia monitoring system attained a Precision of 0.31 and a Recall of 0.78. The alarm gating improved the Precision to 0.58 with a reduction of Recall to 0.77. The proposed system successfully gated false alarms with future work exploring the misidentification of fiducial points by myocardial ischemia monitoring systems. The reduction of false alarms due to the proposed system will decrease the incidence of the alarm fatigue condition typically found in clinicians. Alarm fatigue condition was rated as the top patient safety hazard from 2012 to 2015 by the Emergency Care Research Institute.

  14. Effects of hemoglobin level on myocardial washout rate of thallium-201 in patients with normal myocardial perfusion assessed by single-photon emission computed tomography.

    PubMed

    Kurisu, Satoshi; Sumimoto, Yoji; Ikenaga, Hiroki; Watanabe, Noriaki; Ishibashi, Ken; Dohi, Yoshihiro; Fukuda, Yukihiro; Kihara, Yasuki

    2017-04-05

    Myocardial perfusion single-photon emission computed tomography (SPECT) is often performed even in patients with suspected coronary artery disease complicated by anemia. We assessed the effects of hemoglobin level on myocardial washout rate of Thallium-201 (Tl-201) in patients with normal myocardial perfusion assessed by SPECT. The study population consisted of 231 patients with summed stress score of zero on SPECT. The mean myocardial washout rate of Tl-201 in the left ventricle was calculated from the stress and the redistribution Bull's eye map. Hematological test was performed within 2 weeks before gated SPECT. There were 135 male and 96 female patients with a mean age of 72.6 ± 9.0 years. The mean hemoglobin was 12.9 ± 1.9 mg/dl; the median was 13.2 mg/dl and the range was 8.0-16.5 mg/dl. There was a significant inverse correlation between hemoglobin level and myocardial washout rate of Tl-201 (r = -0.45, p < 0.001). Univariate linear regression analysis showed that age, female, body mass index, serum creatinine, hemoglobin, end-diastolic volume, and ejection fraction were associated with myocardial washout rate of Tl-201. Multivariate analysis showed that only hemoglobin was the independent predictor of myocardial washout rate of Tl-201 (β = -0.35, p < 0.001). Our data suggested that anemia was a major determinant of increased myocardial washout rate of Tl-201 in patients with normal myocardial perfusion on SPECT.

  15. Non-ECG-gated myocardial perfusion MRI using continuous magnetization-driven radial sampling.

    PubMed

    Sharif, Behzad; Dharmakumar, Rohan; Arsanjani, Reza; Thomson, Louise; Bairey Merz, C Noel; Berman, Daniel S; Li, Debiao

    2014-12-01

    Establishing a high-resolution non-ECG-gated first-pass perfusion (FPP) cardiac MRI technique may improve accessibility and diagnostic capability of FPP imaging. We propose a non-ECG-gated FPP imaging technique using continuous magnetization-driven golden-angle radial acquisition. The main purpose of this preliminary study is to evaluate whether, in the simple case of single-slice two-dimensional imaging, adequate myocardial contrast can be obtained for accurate visualization of hypoperfused territories in the setting of myocardial ischemia. A T1-weighted pulse sequence with continuous golden-angle radial sampling was developed for non-ECG-gated FPP imaging. A sliding-window scheme with no temporal acceleration was used to reconstruct 8 frames/s. Canines were imaged at 3T with and without coronary stenosis using the proposed scheme and a conventional magnetization-prepared ECG-gated FPP method. Our studies showed that the proposed non-ECG-gated method is capable of generating high-resolution (1.7 × 1.7 × 6 mm(3) ) artifact-free FPP images of a single slice at high heart rates (92 ± 21 beats/min), while matching the performance of conventional FPP imaging in terms of hypoperfused-to-normal myocardial contrast-to-noise ratio (proposed: 5.18 ± 0.70, conventional: 4.88 ± 0.43). Furthermore, the detected perfusion defect areas were consistent with the conventional FPP images. Non-ECG-gated FPP imaging using optimized continuous golden-angle radial acquisition achieves desirable image quality (i.e., adequate myocardial contrast, high spatial resolution, and minimal artifacts) in the setting of ischemia. © 2014 Wiley Periodicals, Inc.

  16. Non-ECG-Gated Myocardial Perfusion MRI Using Continuous Magnetization-Driven Radial Sampling

    PubMed Central

    Sharif, Behzad; Dharmakumar, Rohan; Arsanjani, Reza; Thomson, Louise; Merz, C. Noel Bairey; Berman, Daniel S.; Li, Debiao

    2014-01-01

    Purpose Establishing a high-resolution non-ECG-gated first-pass perfusion (FPP) cardiac MRI technique may improve accessibility and diagnostic capability of FPP imaging. We propose a non-ECG-gated FPP imaging technique using continuous magnetization-driven golden-angle radial acquisition. The main purpose of this preliminary study is to evaluate whether, in the simple case of single-slice 2D imaging, adequate myocardial contrast can be obtained for accurate visualization of hypoperfused territories in the setting of myocardial ischemia. Methods A T1-weighted pulse sequence with continuous golden-angle radial sampling was developed for non-ECG-gated FPP imaging. A sliding-window scheme with no temporal acceleration was used to reconstruct 8 frames/second. Canines were imaged at 3T with and without coronary stenosis using the proposed scheme and a conventional magnetization-prepared ECG-gated FPP method. Results Our studies showed that the proposed non-ECG-gated method is capable of generating high-resolution (1.7×1.7×6 mm3) artifact-free FPP images of a single slice at high heart rates (92±21 beats/minute), while matching the performance of conventional FPP imaging in terms of hypoperfused-to-normal myocardial contrast-to-noise ratio (proposed: 5.18±0.70, conventional: 4.88±0.43). Furthermore, the detected perfusion defect areas were consistent with the conventional FPP images. Conclusion Non-ECG-gated FPP imaging using optimized continuous golden-angle radial acquisition achieves desirable image quality (i.e., adequate myocardial contrast, high spatial resolution, and minimal artifacts) in the setting of ischemia. PMID:24443160

  17. Thallium 201 Exercise Scintigraphy for Detection of Multivessel Coronary Artery Disease After Transmural Myocardial Infarction

    PubMed Central

    Ahmadpour, Hedayatolah; Siegel, Michael E.; Colletti, Patrick; Haywood, L. Julian

    1984-01-01

    Fifty patients with prior transmural myocardial infarction were studied with cardiac catheterization, coronary angiography, and thallium 201 exercise perfusion scintigraphy. Obstructive coronary disease involved two or three vessels in 37 patients. The sensitivity of a positive electrocardiographic test during exercise for detecting multivessel coronary disease was only 40 percent (15/37), and the sensitivity of a reversible defect on 201Tl perfusion scintigraphy was 48 percent (18/37). The combination of exercise testing and 201Tl scintigraphy detected multivessel coronary disease in 75 percent (28/37) (P < .05). New perfusion defects occurred in 61 percent (13/21) of patients with inferior myocardial infarction and multivessel coronary disease whereas it occurred in only 35 percent (5/14) of patients with prior anterior infarction and multivessel coronary disease (P < .05). 201Tl exercise perfusion scintigraphy appears to be more sensitive for detecting significant multivessel coronary disease in the presence of previous inferior infarction compared with previous anterior infarction. Combined graded exercise testing and 201Tl perfusion scintigraphy can reliably detect the presence of significant multivessel coronary disease after transmural myocardial infarction. ImagesFigure 3 PMID:6512876

  18. [Variables that influence the indication of a second myocardial perfusion gated-SPECT after a normal stress-rest gated SPECT].

    PubMed

    Romero-Farina, G; Candell-Riera, J; Aguadé-Bruix, S; Cuberas-Borrós, G; Pizzi, M N; Santos, A; de León, G; García-Dorado, D

    2014-01-01

    The objective of this study was to investigate predictor variables at the moment of normal stress-rest myocardial perfusion gated SPECT for indication of a second gated SPECT. A prospective, single center cohort study was conducted. We evaluated 2326 consecutive patients (age 63.6 ± 13 years, 57.3% females) without perfusion defects and with normal left ventricular ejection fraction on a myocardial perfusion gated SPECT. Clinical and stress test variables were studied to predict indication of a second gated SPECT and presence of reversible perfusion defects in the second gated SPECT. During a mean follow-up of 3.6 ± 2 years a second gated SPECT was performed in 286 patients (12.3%). Independent predictor variables of a second gated SPECT were presence of three or more cardiovascular risk factors (χ(2): 5.510; HR: 1.4; p=0.019), previous acute myocardial infarction (χ(2): 3.867; HR: 1.4; p=0.049), previous coronary revascularization (χ(2): 41.081; HR: 2.5; p<0.001), and a positive stress test (χ(2): 8.713; HR: 1.5; p=0.003). Observation of perfusion defects in the 280 patients in whom a second stress-rest gated SPECT was performed was more likely in male patients (χ(2): 4.322; HR: 1.9; p=0.038) who had a first pure pharmacological gated-SPECT (χ(2): 7.182; HR: 2.6; p=0.007). In patients with a first normal myocardial perfusion gated SPECT, various clinical factors and variables derived from the stress test affect the indication of a second gated SPECT and the presence of ischemia in the latter. Copyright © 2013 Elsevier España, S.L. and SEMNIM. All rights reserved.

  19. Evaluating microvascular obstruction after acute myocardial infarction using cardiac magnetic resonance imaging and 201-thallium and 99m-technetium pyrophosphate scintigraphy.

    PubMed

    Onishi, Takayuki; Kobayashi, Isshi; Onishi, Yuko; Kawashima, Tomoyuki; Muramoto, Hirotaka; Nakamura, Hiroaki; Nagata, Yasutoshi; Umezawa, Shigeo; Niwa, Akihiro

    2010-11-01

    Few studies have compared the ability of cardiac magnetic resonance (CMR) with that of scintigraphy using 201-thallium (201-Tl) and 99m-technetium pyrophosphate (99m-Tc PYP) to evaluate microvascular obstructions (MOs). In the present study the relationship between the scintigraphic and CMR characteristics of MOs after acute myocardial infarction (MI) was examined. The 14 patients (age 69±8 years, 11 males) underwent 201-Tl/99m-Tc PYP SPECT 7±3 days, initial CMR 16±12 days, and follow-up CMR 193±20 days after a reperfused first acute MI. Each image was analyzed using a 17-segment model. Segmental extent of delayed enhancement (DE), wall motion (WM) and degree of 201-Tl uptake were scored in 238 segments. Of 91 MI segments, MO was recognized in 22 (25%) segments on CMR. WM was significantly better in proportion to 201-Tl uptake (P=0.01) in MO segments. All 8 MO segments with WM improvement at follow-up had 99m-Tc PYP uptake, although only 3 (21%) of 14 MO segments that did not show WM improvement at follow-up had 99m-Tc PYP uptake (P=0.001). 99m-Tc PYP and 201-Tl scintigraphy have the potential to predict WM status and improvement of the MO region after reperfused acute MI.

  20. Assessment of systolic thickening with thallium-201 ECG-gated single-photon emission computed tomography: A parameter for local left ventricular function

    SciTech Connect

    Mochizuki, T.; Murase, K.; Fujiwara, Y.; Tanada, S.; Hamamoto, K.; Tauxe, W.N. )

    1991-08-01

    The authors measured left ventricular (LV) systolic thickening expressed as a systolic thickening ratio in 28 patients, using 201Tl ECG-gated SPECT. Five normals, 15 patients with prior myocardial infarction, 5 with hypertrophic cardiomyopathy, and 3 with dilated cardiomyopathy were studied. The systolic thickening ratio was calculated as ((end-systolic--end-diastolic pixel counts) divided by end-diastolic pixel counts), using the circumferential profile technique of both end-diastolic and end-systolic short axial images. Functional images of the systolic thickening ratio were also displayed with the bull's-eye method. The mean systolic thickening ratio thus calculated were as follows: normals, 0.53 {plus minus} 0.05 (mean {plus minus} 1 s.d.); non-transmural prior myocardial infarction, 0.33 {plus minus} 0.09; transmural prior myocardial infarction, 0.14 {plus minus} 0.05; hypertrophic cardiomyopathy in relatively nonhypertrophied areas, 0.56 {plus minus} 0.11; hypertrophic cardiomyopathy in hypertrophied areas, 0.23 {plus minus} 0.07; and dilated cardiomyopathy, 0.19 {plus minus} 0.02. The systolic thickening ratio analysis by gated thallium SPECT offers a unique approach for assessing LV function.

  1. Comparison of myocardial imaging with iodine-123-iodophenyl-9-methyl pentadecanoic acid and thallium-201-chloride for assessment of patients with exercise-induced myocardial ischemia

    SciTech Connect

    Chouraqui, P.; Maddahi, J.; Henkin, R.; Karesh, S.M.; Galie, E.; Berman, D.S. )

    1991-03-01

    Iodine-123-iodophenyl-9-methyl-pentadecanoic acid (({sup 123}I)MPDA) and thallium-201 ({sup 201}Tl) were sequentially injected in 11 patients during exercise-induced myocardial ischemia. Simultaneous dual-energy planar images were obtained at 5 min, 3 and 5 hr. All studies were concordantly either positive (8/11) or negative (3/11) by both radionuclides. Exact agreement for segmental uptake was 93%, 94% and 94% for 5-min, 3- and 5-hr images, respectively. Exact agreement for defect reversibility by 3 and 5 hr were 95% and 92%. The initial defect contrasts and myocardial-to-lung ratios were similar by both agents but myocardial-to-liver ratio was lower by ({sup 123}I)MPDA at 5 min, which became similar to {sup 201}Tl at 5 hr. Normal percent myocardial clearances of both agents were comparable and significantly higher than those in defect zones. Thus ({sup 123}I)MPDA is suitable for myocardial imaging and correlates closely with {sup 201}Tl for initial postexercise myocardial uptake and defect reversibility. Defect reversibility appears to result from differential myocardial clearance from normal and ischemic regions.

  2. A prospective comparison of rubidium-82 PET and thallium-201 SPECT myocardial perfusion imaging utilizing a single dipyridamole stress in the diagnosis of coronary artery disease

    SciTech Connect

    Go, R.T.; Marwick, T.H.; MacIntyre, W.J.; Saha, G.B.; Neumann, D.R.; Underwood, D.A.; Simpfendorfer, C.C. )

    1990-12-01

    The purpose of the present study is to prospectively compare myocardial perfusion imaging with rubidium-82 ({sup 82}Rb) by positron emission tomography (PET) with thallium-201 ({sup 201}Tl) imaging by single-photon emission tomography (SPECT) by recording both studies with a single dipyridamole handgrip stress, and reading both sets of images with the same display technique. In a series of 202 patients with previous coronary arteriography, the sensitivity, specificity, and accuracy of {sup 82}Rb PET were 93%, 78%, and 90% and for {sup 201}Tl SPECT 76%, 80%, and 77%, respectively. When 70 patients with previous therapeutic interventions were excluded, the remaining 132 patients showed a sensitivity, specificity, and accuracy of 95%, 82% and 92% for {sup 82}Rb PET and 79%, 76%, and 78% for {sup 201}Tl SPECT. The improved contrast resolution of PET resulted in markedly superior images and a more confident identification of defects.

  3. Use of thallium-201 redistribution scintigraphy in the preoperative differentiation of reversible and nonreversible myocardial asynergy.

    PubMed

    Rozanski, A; Berman, D S; Gray, R; Levy, R; Raymond, M; Maddahi, J; Pantaleo, N; Waxman, A D; Swan, H J; Matloff, J

    1981-11-01

    Thallium-201 (201Tl) redistribution scintigraphy might differentiate reversibly from nonreversibly asynergic myocardial segments and thus predict the response of these segments to coronary artery bypass grafting (CABG). To test this hypothesis, 25 consecutive patients undergoing CABG, preoperative stress-redistribution 201Tl scintigraphy, and both pre- and postoperative resting equilibrium radionuclide ventriculography were evaluated. For both types of scintigraphic study, each patient was imaged in the same three views. Because of the effects of CABG on septal motion, this region was considered separately. Postoperative improvement was noted in 54% of 72 preoperative asynergic segments. Improvement was common not only in hypokinetic but also in akinetic and dyskinetic segments, and occurred in a similar proportion of studies performed early (less than 2 weeks) or late (3-6 months) after CABG. Thallium-201 redistribution scintigraphy was highly predictive of the pattern of postoperative asynergy: The redistribution pattern was normal in 90% of segments with reversible asynergy and abnormal in 76% of segments with nonreversible asynergy. The presence or absence of pathologic Q waves was less sensitive in this differentiation. Septal segments, however, frequently demonstrated abnormal wall motion postoperatively, despite normal 201Tl redistribution scintigraphy. Resting left ventricular ejection fraction (LVEF) was generally unchanged postoperatively, but in some patients with multiple areas of reversible asynergy it did improve. Thus, 201Tl redistribution scintigraphy appears to reliably distinguish viable from nonviable asynergic myocardial zones, and predicts the response of these segments to CABG.

  4. Prognosis of normal stress-only gated-SPECT myocardial perfusion imaging: a single center study.

    PubMed

    Ferreira, Maria João Vidigal; Cunha, Maria João; Albuquerque, Anabela; Moreira, Ana Paula; Ramos, Domingos; Costa, Gracinda; Lima, João; Pego, Mariano

    2013-10-01

    It has been advocated that using the stress followed by rest protocol, if the stress images were normal there is no need of rest images, reducing radiation exposure and costs. Our purpose was to assess the prognosis of a group of patients with normal stress-only gated-SPECT myocardial perfusion imaging. This was retrospective study that includes 790 patients with normal myocardial stress only perfusion gated SPECT images. Images were considered as normal if a homogeneous myocardial distribution of the tracer was associated with a normal ejection fraction. The mean follow-up was of 42.8 ± 13.3 months. The considered events were death of all causes, myocardial infarction and myocardial revascularization. During this period there were 85 events (10.8 %), including 57 deaths of all causes (67.1 %), 9 myocardial infarctions (10.6 %), 19 revascularizations (2.4 %). In the first year of follow-up there were 32 events (4.0 %) and excluding non cardiac deaths there were 8 events (1.0 %). Using Cox survival analysis, diabetes (HR = 2.2; CI = 1.4-3.4; p ≤ 0.0005), the history of coronary artery disease (CAD) (HR = 2.1; CI = 1.3-3.2; p ≤ 0.001), age (HR = 1.0; CI = 1.0-1.0; p ≤ 0.05) and type of stress protocol were related with events (exercise test vs. adenosine) (Exercise test: HR = 0.5; CI = 0.3-0.8; p ≤ 0.01). In a multivariate analysis the independent predictors were diabetes, CAD and the type of stress protocol. Based on these results, normal stress-only images are associated with an excellent prognosis even in patients at higher risk, diabetics and patients with known CAD.

  5. Caffeine reduces dipyridamole-induced myocardial ischemia

    SciTech Connect

    Smits, P.; Aengevaeren, W.R.; Corstens, F.H.; Thien, T. )

    1989-10-01

    The mechanism of action of coronary vasodilation after dipyridamole may be based on inhibition of cellular uptake of circulating endogenous adenosine. Since caffeine has been reported to be a competitive antagonist of adenosine we studied the effect of caffeine on the outcome of dipiridamole-{sup 201}Tl cardiac imaging in one patient. During caffeine abstinence dipyridamole induced myocardial ischemia with down-slope ST depressions on the ECG, and reversible perfusion defects on the scintigrams. When the test was repeated 1 wk later on similar conditions, but now shortly after infusion of caffeine (4 mg/kg), the ECG showed nodepressions, and the scintigrams only slight signs of ischemia. We conclude that when caffeine abstinence is not sufficient, the widespread use of coffee and related products may be responsible for false-negative findings in dipyridamole-201Tl cardiac imaging.

  6. Clinical assessment of myocardial viability using MRI during a constant infusion of Gd-DTPA.

    PubMed

    Pereira, R S; Wisenberg, G; Prato, F S; Yvorchuk, K

    2000-12-01

    This study assessed the accuracy and feasibility of magnetic resonance imaging (MRI) during a constant infusion of gadolinium diethylenetriaminepentaacetic acid (Gd-DTPA) for the determination of myocardial viability in patients with recent acute myocardial infarction (AMI). Nine patients were studied within 10 days of AMI. Rest-redistribution 201Thallium (201Tl) single photon emission computed tomography (SPECT) was used as a gold standard for viability. Using MRI, regional perfusion was assessed using dynamic imaging during a bolus injection of Gd-DTPA and viability was assessed during a continuous infusion. Finally, cine MR images were acquired at baseline, during low-dose dobutamine infusion and after recovery. To assess viability, the left ventricle was divided into 16 segments and signal intensity in corresponding MRI and redistribution SPECT segments were compared. Wall thickening index (WTI) was determined at each step during the dobutamine study. The results revealed that in five patients, reduced perfusion in infarcted regions was observed qualitatively during dynamic first pass imaging. There was a significant inverse correlation between 201Tl uptake and MRI signal intensity, i.e. infarcted tissue (low 201Tl uptake) had increased MR signal intensity. Segments were separated into normal (201Tl uptake > 90%) and infarcted (< 601%). lnfarcted MRI segments had greater signal intensity than normal segments (179 +/- 50 vs. 102 +/- 14%; P < 0.0001). WTI in normal segments increased by 18 +/- 8.5% (P < 0.0001) from baseline to 10 microg/kg per min of dobutamine while infarcted tissue WTI decreased 2.8 +/- 7.2% (P = 0.17). Thus regions of myocardium that were infarcted as defined by reduced 201Tl uptake and absent contractile reserve showed greatly increased MRI signal intensity during a constant infusion of Gd-DTPA. The use of MRI during a constant infusion of Gd-DTPA is accurate and feasible for the determination of myocardial necrosis in a clinical setting.

  7. Assessment of myocardial viability in patients with myocardial infarction using twenty-four hour thallium-201 late redistribution imaging.

    PubMed

    Yang, Xiang-Jun; He, Yong-Ming; Zhang, Bin; Wu, Yi-Wei; Hui, Jie; Jiang, Ting-Bo; Song, Jian-Ping; Liu, Zhi-Hua; Jiang, Wen-Ping

    2006-01-01

    Rest thallium-201 (201Tl) myocardial perfusion imaging has been widely used for evaluation of myocardial ischemia/viability after myocardial infarction, but the ideal timing for imaging after injection to maximally estimate viability is not well established. Thirty-six patients with myocardial infarction underwent the initial, 3 h, and 24 h redistribution imaging after intravenous injection of 148-185 MBq 201Tl. The initial and 3 h images, the initial and 24 h images, and the 3 and 24 h images were compared double-blinded. Out of the 184 abnormal segments based on the initial imaging, 56 (30%) segments improved by at least 1 grade on the 3 h imaging while 78 (42%) segments improved by at least 1 grade on the 24 h imaging. The 24 h late imaging detected more viable myocardium than the 3 h imaging did, with a significant difference (chi2= 5.680, p = 0.017). There were 158 abnormal segments on the 3 h imaging, with average 28% (44) segments improved by at least 1 grade on the 24 h imaging. There were 128 initial abnormal segments with no improvement on the 3 h imaging. Out of these segments, the 24 h late redistribution imaging detected additional redistribution in 26 segments, taking up 20%. Twenty-four hour late 201Tl imaging will demonstrated additional redistribution in patients who have incompletely reversible defects on early redistribution imaging at 3h.

  8. How reliable is myocardial imaging in the diagnosis of acute myocardial infarction

    SciTech Connect

    Willerson, J.T.

    1983-01-01

    Myocardial scintigraphic techniques available presently allow a sensitive and relatively specific diagnosis of acute myocardial infarction when they are used correctly, although every technique has definite limitations. Small myocardial infarcts (less than 3 gm.) may be missed, and there are temporal limitations in the usefulness of the scintigraphic techniques. The development of tomographic methodology that may be used with single-photon radionuclide emitters (including technetium and /sup 201/Tl will allow the detection of relatively small abnormalities in myocardial perfusion and regions of myocardial infarction and will help to provide a more objective interpretation of the myocardial scintigrams. The use of overlay techniques allowing simultaneous assessment of myocardial perfusion, infarct-avid imaging, and radionuclide ventriculograms will provide insight into the relevant aspects of the extent of myocardial damage, the relationship of damage to myocardial perfusion, and the functional impact of myocardial infarction on ventricular performance.

  9. False-negative dipyridamole-thallium-201 myocardial imaging after caffeine infusion

    SciTech Connect

    Smits, P.; Corstens, F.H.; Aengevaeren, W.R.; Wackers, F.J.; Thien, T. )

    1991-08-01

    The vasodilator effect of intravenously administered dipyridamole may be caused by an increase in endogenous plasma adenosine levels. The authors evaluated the effect of caffeine, an adenosine receptor antagonist, on the diagnostic results of dipyridamole-201Tl myocardial imaging in eight patients with coronary artery disease. Caffeine infusion significantly attenuated the dipyridamole-induced fall in blood pressure and the accompanied increase in heart rate. The infusion of dipyridamole alone resulted in chest pain and ST-segment depressions on the electrocardiogram in four patients, whereas none of these problems occurred when the tests were repeated after caffeine. In six of eight patients, caffeine was responsible for false-negative dipyridamole-201Tl tests. Semiquantitive scores of the dipyridamole-induced 201Tl perfusion defects were decreased by caffeine from 9.0 {plus minus} 0.9 to 2.0 {plus minus} 1.1 points (p less than 0.05). Computerized analysis revealed a caffeine-mediated reduction in the percent reversibility of the images from 46% {plus minus} 16% to 6% {plus minus} 10% (p less than 0.05). They conclude that the use of caffeinated products prior to dipyridamole-201Tl testing may be responsible for false-negative findings.

  10. Effects of heart rate on myocardial thallium-201 uptake and clearance

    SciTech Connect

    Nordrehaug, J.E.; Danielsen, R.; Vik-Mo, H. )

    1989-12-01

    The effects of heart rate on the myocardial uptake and clearance of {sup 201}Tl were studied prospectively in seven healthy men, mean age 43 +/- 7 (s.d.) yr. Initial and delayed (3 hr) thallium images were obtained in three views after three bicycle exercise tests: to maximal, 80% and 60% of predicted maximal heart rate. The mean of three views initial myocardial {sup 201}Tl uptake was higher at maximal than at both 80% and 60% of predicted maximal heart rate, being 81% (p less than 0.01) and 60% (p less than 0.01) of maximal activity, respectively. The myocardial activity in the delayed images was identical. There was a linear relationship between heart rate and the initial myocardial activity, r = 0.86 (p less than 0.001). The mean (range) {sup 201}Tl clearance was 58% (51-65), 47% (34-56), and 34% (22-49) (all differences p less than 0.01), respectively. Concordance among the three individual views in estimating clearance was best for the highest exercise level. There was a linear relationship between heart rate and clearance, r = 0.80 (p less than 0.001). Clearance was altered by only 1.67 x 10%/heart bpm (0.024 hr/heart beat). Clearance in the liver, spleen and lungs increased at submaximal exercise levels. Thus, a linear relationship between heart rate and clearance is the result of changes in the initial exercise myocardial {sup 201}Tl activity. Submaximal exercise may reduce reproducibility of clearance estimation, and the change of myocardial clearance with heart rate seems less than previously suggested.

  11. Decontamination of rat and human skin experimentally contaminated with (99m)Tc, (201)Tl and (131)I radionuclides using "Dermadecon" - a skin decontamination kit: an efficacy study.

    PubMed

    Nishad, Dhruv Kumar; Bhalla, Supriya; Khanna, Kushagra; Sharma, Braj Gaurav; Rawat, Harish Singh; Mittal, Gaurav; Bhatnagar, Aseem

    2017-05-03

    Radioactive skin contamination is one of the most likely risks which occurs after accidental or occupational radiological accidents apart from internal contamination. In such cases where the radioactive contamination has occurred, the person who is contaminated should be decontaminated as early as possible to reduce the damaging health effects of radiation. In the present study, the decontamination efficiency of a developed skin decontamination kit "dermadecon" has been evaluated in animal models and human subjects using gamma scintigraphy. Decontamination efficiency (percentage of the radioactive contaminant removed) was calculated for each radioactive isotope of the study and compared with control where general washing procedure was followed using liquid and soap. The effectiveness of the kit was calculated in animal model with respect to (99m)Tc-sodium-pertechnetate ((99m)TcO(4-)), (201)TlCl and (131)I and was found 92.84 ± 4.9%, 91.18 ± 3.23% and 94.67 ± 2.92%, respectively. Whereas, in case of human skin, the decontamination efficiency for (99m)TcO(4-) was observed to be 95.00 ± 3.21%. On the basis of findings from the study, it can be concluded that the decontamination agents of the used skin decontamination kit are effective for removal of localized radioactive contaminants from skin, as compared with normal decontamination using soap and water.

  12. The Diagnostic Value of Tc-99m MIBI Gated Myocardial Perfusion SPECT in Detection of Silent Myocardial Ischemia in Asymptomatic Patients with Type 2 Diabetes Mellitus

    PubMed Central

    Ak, Coskun; Sahin, Ali; Capoglu, Ilyas

    2008-01-01

    Objective: In this study, we aimed to evaluate the diagnostic value of Technetium-99m methoxyisobutylisonitrile (Tc-99m MIBI) gated myocardial perfusion SPECT (MPS) in the detection of coronary artery disease (CAD) and silent myocardial ischemia (SMI) in patients with asymptomatic type 2 diabetes mellitus (DM). Materials and Methods: For this purpose, 35 patients with type 2 DM and 15 volunteers with no cardiac symptoms (control group) were included in this study. Exercise tolerance tests (ETT), echocardiography and Tc-99m MIBI gated MPS were performed in patients and volunteers. Computed tomography coronary angiography (CTCA) was performed in patients with coronary ischemia or infarct detected by Tc-99m MIBI gated MPS. The results were analyzed and compared visually and statistically. Results: The present study revealed a high rate of silent myocardial ischemia (25.71%, N=9) in 35 patients with type 2 DM. Severe CAD in CTCA was detected in four of nine patients with ischemia or infarct by Tc-99m MIBI gated MPS (44.4%). Left ventricular diastolic dysfunction, ischemic pattern and high risk of CAD were detected in the same four patients by echocardiography, ETT and biochemical analysis, respectively. At the end of the statistical evaluation, we found that Tc-99m MIBI gated MPS showed significant correlations with CTCA, echocardiography, ETT, Hba1c level, risk of CAD and diabetic age in diabetic patients with CAD. Conclusion: We propose that Tc-99m MIBI gated MPS is a reliable and non-invasive method that can be used to detect silent myocardial ischemia and CAD in patients with type 2 DM. PMID:25610029

  13. Imaging Three-Dimensional Myocardial Mechanics Using Navigator-gated Volumetric Spiral Cine DENSE MRI

    PubMed Central

    Zhong, Xiaodong; Spottiswoode, Bruce S.; Meyer, Craig H.; Kramer, Christopher M.; Epstein, Frederick H.

    2010-01-01

    A navigator-gated 3D spiral cine displacement encoding with stimulated echoes (DENSE) pulse sequence for imaging 3D myocardial mechanics was developed. In addition, previously-described 2D post-processing algorithms including phase unwrapping, tissue tracking, and strain tensor calculation for the left ventricle (LV) were extended to 3D. These 3D methods were evaluated in 5 healthy volunteers, using 2D cine DENSE and historical 3D myocardial tagging as reference standards. With an average scan time of 20.5 ± 5.7 minutes, 3D data sets with a matrix size of 128 × 128 × 22, voxel size of 2.8 × 2.8 × 5.0 mm3, and temporal resolution of 32 ms were obtained with displacement encoding in three orthogonal directions. Mean values for end-systolic mid-ventricular mid-wall radial, circumferential, and longitudinal strain were 0.33 ± 0.10, −0.17 ± 0.02, and −0.16 ± 0.02, respectively. Transmural strain gradients were detected in the radial and circumferential directions, reflecting high spatial resolution. Good agreement by linear correlation and Bland-Altman analysis was achieved when comparing normal strains measured by 2D and 3D cine DENSE. Also, the 3D strains, twist, and torsion results obtained by 3D cine DENSE were in good agreement with historical values measured by 3D myocardial tagging. PMID:20574967

  14. Normal Myocardial Perfusion Gated SPECT and Positive Stress Test: Different Prognoses in Women and Men.

    PubMed

    Romero-Farina, Guillermo; Candell-Riera, Jaume; Ferreira-González, Ignacio; Aguadé-Bruix, Santiago; Pizzi, Nazarena; García-Dorado, David

    2015-06-01

    The aim of this study was to analyze different prognoses in women and men with normal myocardial perfusion gated SPECT, according to stress test results. Differences between women and men in terms of hard events (HE) (non-fatal acute myocardial infarction or cardiac death) and HE plus coronary revascularization (HE + CR) were analyzed in 2,414 consecutive patients (mean age 62.8 ± 13.5 years, 1,438 women) with a normal stress-rest gated SPECT, taking into account their stress test results. Four hundred and seven patients (16.9%) (15.9% women and 17.5% men) had a positive stress test (ST-segment depression ≥1 mm and/or angina). During a follow-up of 5.1 ± 3.4 years, there were more significant HE (6.5% vs 2.3%; P = .005) and HE + CR (11.6% vs 4.8%, P = .001) in men with a positive stress test than in men with a negative stress test. These differences were not observed in women. In multivariate regression models, HE and HE + CR were also more frequent in men with a positive stress test (HR:3.3 [95% CI 1.1% to 9.5%]; HR:4.2 [95% CI 1.8% to 9.9%]; respectively) vs women with a positive stress test. Although patients with normal gated SPECT studies have a favorable outcome, men with an abnormal stress test have a more adverse prognosis than women.

  15. Imaging of cocaine-induced global and regional myocardial ischemia

    SciTech Connect

    Oster, Z.H.; Som, P.; Wang, G.J.; Weber, D.A. )

    1991-08-01

    Severe and often fatal cardiac complications have been reported in cocaine users with narrowed coronary arteries caused by atherosclerosis as well as in young adults with normal coronaries. The authors have found that in normal dogs cocaine induces severe temporary hypoperfusion of the left ventricle as indicated by a significantly lower 201Tl concentration compared to the baseline state. The most significant decrease in uptake occurred 5 min after injection and was more pronounced in the septal and apical segments. Following intravenous administration of cocaine, instead of gradual disappearance of 201Tl from the left ventricle, there was continuous increase in 201Tl concentration in the left ventricle. These imaging experiments indicate that the deleterious effects of cocaine on the heart are probably due to spasm of the coronaries and decreased myocardial perfusion. Since spasm of the large subpericardial vessels does not seem to explain the magnitude of the increased coronary resistance and decreased coronary flow after cocaine as described in the literature, it is suggested that microvascular spasm of smaller vessels plays a major role in the temporary decrease in perfusion. The data may also suggest that severe temporary myocardial ischemia is probably the initiating factor for the cardiac complications induced by cocaine.

  16. Optimization of Acquisition Parameters for Simultaneous ,^^201rm Tl; and ,^^99rm mrm Tc Dual-Isotope Myocardial Imaging

    NASA Astrophysics Data System (ADS)

    Wang, Wen-Tung; Tsui, B. M. W.; Lalush, D. S.; Tocharoenchai, C.; Frey, E. C.

    2005-10-01

    In /sup 201/Tl//sup 99m/Tc dual-isotope simultaneous-acquisition (DISA) myocardial imaging, crosstalk due to Tc photons results in significant contamination of the Tl data. The objective of this work is to seek the acquisition parameters (i.e., energy window width and center) that have the optimal tradeoff between minimizing the crosstalk and maximizing the detection efficiency. The optimization criterion was based on maximizing an ideal observer signal-to-noise ratio (SNR) for the myocardial defect detection task using single-isotope and DISA projection images acquired from a torso phantom. For single-isotope images, the optimal energy windows (width/center: 26 keV/75 keV and 28 keV/165 keV for /sup 201/Tl, 30 keV/142 keV for /sup 99m/Tc) are wider than typical windows. For DISA imaging, the optimal windows varied with the /sup 99m/Tc to /sup 201/Tl activity ratio and are thus likely to depend on the uptake ratio in each patient. Using the optimal ratio 2.25-2.75 (148 MBq /sup 201/Tl and 333-407 MBq /sup 99m/Tc) with the corresponding optimal windows (22 keV/72 keV, 24 keV/167 keV, and 24 keV/140 keV) gives /sup 201/Tl images with substantially increased SNRs as well as /sup 99m/Tc images with SNRs same as those of 370 MBq /sup 99m/Tc-only images. However, without the addition of crosstalk compensation, the use of the optimal activity and energy windows alone is likely not sufficient to restore the DISA Tl SNR to that of Tl-only image.

  17. Detection and characterization of acute myocardial infarction in man with use of gated magnetic resonance.

    PubMed

    McNamara, M T; Higgins, C B; Schechtmann, N; Botvinick, E; Lipton, M J; Chatterjee, K; Amparo, E G

    1985-04-01

    To evaluate the capability of magnetic resonance imaging (MRI) in the detection and characterization of alterations in signal intensity and T2 relaxation time in acutely infarcted relative to normal myocardium 16 adult patients and normal volunteers were studied by electrocardiographically gated proton MRI. The seven volunteers were entirely asymptomatic and had no history of cardiovascular abnormality. The nine patients had each suffered an acute myocardial infarction within 5 to 12 days before the MRI studies. The diagnosis in each patient was confirmed by electrocardiographic (ECG) criteria and elevated levels of fractionated creatine kinase (CK) isoenzymes. Electrocardiographically gated MRI was performed with a superconducting system operating at 0.35 tesla. MRI demonstrated infarcted myocardium as a region of high signal intensity relative to that of adjacent normal myocardium; regions of high intensity corresponded anatomically to the site of infarction as defined by the ECG changes. The mean percent difference between normal and infarcted myocardium was substantially greater on 56 msec images (70.2 +/- 21.3%) compared with 28 msec images (27.1 +/- 13.6%). Region of interest analysis revealed that infarcted myocardium had a significantly (p less than .01) prolonged T2 relaxation time (mean T2 = 80.9 msec) relative to that in normal myocardium (mean T2 = 42.3 msec) and relative to the mean T2 of left ventricular myocardium in the volunteers (mean T2 = 42.4 msec). An additional finding for each patient with myocardial infarction was a high intraluminal flow signal on 56 msec images, but this was also observed in normal subjects and is therefore a nonspecific finding.(ABSTRACT TRUNCATED AT 250 WORDS)

  18. Ischemic left ventricular dysfunction assessed on ECG-gated thallium-201 myocardial perfusion images.

    PubMed

    Hurwitz, G A; Laurin, N R; Powe, J E; Driedger, A A; MacDonald, A C

    1990-05-01

    Ischemic dysfunction of the left ventricle can be suggested by ancillary data derived from thallium-201 myocardial perfusion images. In this study, qualitative and quantitative assessments of global and segmental contraction derived from ECG-gated left anterior oblique images were analyzed to define more precisely transient ischemic hypokinesis. Immediate (4 mins post stress) and delayed (2 to 4 h) images were compared in 200 patients; 165 had coronary angiography and 35 had a low probability of coronary artery disease based on pretest and test outcome variables. For both immediate and delayed images, a quantitative index of left ventricular contraction (derived from the time-activity curve of the left ventricular cavity and validated in a previous study), correlated well with contrast ventriculography scores. The index derived from the immediate image also was related to the severity/extent of coronary artery lesions and to thallium-201 lung uptake. The ratio of indices (immediate/delayed) was depressed (P less than 0.001) in patients with two or three critically diseased vessels, and reflected the qualitative assessment of stress-induced dysfunction on cinematic images. These data suggest that the quantitative index derived from ECG-gated perfusion scans may be a valuable indicator of stress-induced ventricular contractile dysfunction.

  19. Defect images in stress thallium-201 myocardial scintigraphy in patients with complete left bundle branch block: comparison of exercise stress and pharmacological stress.

    PubMed

    Sasaki, Hideki; Shimizu, Mitsuyuki; Ogawa, Kazuhiko; Okazaki, Fumiko; Mizokami, Tsuneo; Kusaka, Masafumi; Uehara, Yoshiki; Taniguchi, Ikuo; Mochizuki, Seibu

    2007-04-01

    Stress thallium-201 (201Tl) myocardial scintigraphy can demonstrate perfusion abnormalities, especially in the septum in patients with complete left bundle branch block (CLBBB) even with angiographically normal coronary arteries. Differences in the images between exercise and pharmacological stress 201Tl myocardial scintigraphy were evaluated in patients with CLBBB and normal coronary arteries. Forty-five patients with CLBBB underwent exercise stress using treadmill or pharmacological (adenosine triphosphate) stress 201Tl myocardial scintigraphy from October 1997 to February 2003. Patients with myocardial diseases were excluded, such as cardiomyopathy and coronary artery diseases detected by echocardiography and/or cardiac catheterization. The myocardial segment was classified according to the American Heart Association style for coronary artery disease. Peak blood pressure levels and heart rates were significantly higher in the exercise stress group than in the pharmacological stress group (p < 0.001). The rate of defects in stress images was significantly higher in the exercise stress group (72.4%; 21/29 cases) than in the pharmacological stress group (18.8%; 3/16 cases) (p < 0.01). The rate of redistribution of observed defects in delayed images was 76.2% (16/21 cases) in the exercise stress group, and 0% (0/3 cases)in the pharmacological stress group (p < 0.01). The myocardial segments showing defects were different between the exercise stress group and the pharmacological stress group. Patients with CLBBB showed different frequencies of defects by stress 201Tl myocardial scintigraphy according to the stress method. Moreover, defects also occured in areas other than the septum. Blood pressure and heart rate were involved in the mechanisms of defects in left bundle branch block.

  20. Exercise thallium-201 myocardial scintigraphy in the follow-up of aortocoronary bypass graft surgery.

    PubMed Central

    Wainwright, R J; Brennand-Roper, D A; Maisey, M N; Sowton, E

    1980-01-01

    The predictive accuracy of exercise thallium-201 (201Tl) myocardial scintigraphy in the evaluation of aortocoronary bypass graft surgery was assessed in 48 patients undergoing angiographic investigation 15 months (mean time) after myocardial revascularisation. 201Tl scintigrams detected 61 out of 77 (79%) patent grafts but only 21 out of 42 (50%) occluded grafts, though, for grafts supplying non-infarcted myocardium, the predictive accuracy of graft patency and graft occlusion was 85 per cent and 81 per cent, respectively. Stress electrocardiography failed to detect 15 out of 21 patients with scintigraphic evidence of regional myocardial ischaemia. Residual ischaemia in the proximal left anterior descending coronary distribution was commonly detected in 201Tl scintigrams despite a patent, well-functioning left anterior descending graft to the distal coronary segment. Additional residual ischaemia attributable to ungrafted coronary disease was detected by scintigraphy in 32 (67%) patients and most commonly occurred in the distribution of the diagonal branch of the left anterior descending especially in the presence of a patent distal left anterior descending graft. Thus, independent grafts to the diagonal branch of the left anterior descending are recommended at the time of aortocoronary bypass graft surgery. Images PMID:6965585

  1. Risk stratification after myocardial infarction. Clinical overview

    SciTech Connect

    O'Rourke, R.A. )

    1991-09-01

    Many patients with an acute myocardial infarction can be stratified into subgroups that are at high risk for morbidity and mortality on the basis of clinical characteristics that indicate recurrent myocardial ischemia, persistent left ventricular dysfunction, and/or recurrent cardiac arrhythmias. In patients with uncomplicated myocardial infarction the assessment of symptoms, physical findings, and ECG changes during predischarge exercise testing often identifies patients at increased risk for further cardiac events. Because of the suboptimum sensitivity and specificity of the exercise ECG for detecting myocardial ischemia, myocardial perfusion imaging with 201Tl and/or assessment of global and segmental ventricular function by two-dimensional echocardiography or radionuclide cineangiography during or immediately after exercise are often added to the predischarge risk stratification.

  2. Thallium-201 is comparable to technetium-99m-sestamibi for estimating cardiac function in patients with abnormal myocardial perfusion imaging.

    PubMed

    Wu, Ming-Che; Tsai, Cheng-Ting; Lin, Hui-Chun; Sun, Fang-Ju; Lin, Ku-Hung

    2015-11-01

    We analyzed the left-ventricular functional data obtained by cardiac-gated single-photon emission computed tomography myocardial perfusion imaging (MPI) with thallium-201 (Tl-201) and technetium-99m-sestamibi (MIBI) protocols in different groups of patients, and compared the data between Tl-201 and MIBI. Two hundred and seventy-two patients undergoing dipyridamole stress/redistribution Tl-201 MPI and 563 patients undergoing 1-day rest/dipyridamole stress MIBI MPI were included. Higher mean stress ejection fraction (EF), rest EF, and change in EF (ΔEF) were noticed in the normal MPI groups by both Tl-201 and MIBI protocols. Higher mean EF was observed in the females with normal MPI results despite their higher mean age. Comparisons between the Tl-201 and MIBI groups suggested a significant difference in all functional parameters, except for the rest end diastolic volume/end systolic volume and ΔEF between groups with negative MPI results. For the positive MPI groups, there was no significant difference in all parameters, except for the change in end diastolic volume and change in end systolic volume after stress between both protocols. The Tl-201 provides comparable left-ventricular functional data to MIBI cardiac-gated single-photon emission computed tomography in patients with positive MPI results, and may therefore be undertaken routinely for incremental functional information that is especially valuable to this patient group. Copyright © 2015. Published by Elsevier Taiwan.

  3. Prognostic Value of Functional Variables as Assessed by Gated Thallium-201 Myocardial Perfusion Single Photon Emission Computed Tomography for Major Adverse Cardiac Events in Patients with Coronary Artery Disease.

    PubMed

    Shen, Thau-Yun; Chang, Ming-Che; Hung, Guang-Uei; Kao, Chia-Hung; Hsu, Bailing

    2013-05-01

    Gated single photon emission computed tomography (SPECT) using thallium-201 (Tl-201) has the capacity to evaluate the earlier post-stress (PS) function compared to technetium-99m labeled tracers, and may be more sensitive in detecting transient ventricular dysfunction caused by stress-induced ischemia. The purpose of this study was to assess the prognostic value of functional variables obtained from Tl-201 gated SPECT as a predictor of major adverse cardiac events (MACE). Four hundred and thirty-eight subjects who had known or suspected coronary artery disease and underwent clinically indicated dipyridamole-stress electrocardiography-gated Tl-201 SPECT were included in this study. Functional variables, including PS-ejection fraction (EF), PS-end systolic volume (ESV), PS-regional wall motion abnormality (RWA), reversible RWA and EF worsening, were generated to study the correlation with MACE (cardiac death, nonfatal infarction, unstable angina and coronary revascularization). Sixty-eight of the total 438 patients (15.5%) had MACE during the period of follow-up (a median time of 31 months), including 2 cardiac deaths, 9 non-fatal infarctions, 9 unstable angina and 48 coronary revascularizations. These events occurred significantly more frequently in patients with reversible RWA (28.8% vs. 7.1%, p < 0.0001), EF worsening (34.8% vs. 12.1%, p < 0.0001), PS-RWA (29.9% vs. 11.4%, p < 0.0001) and PS-EF < 45% (27.8% vs. 14.4%, p = 0.034). Using the Cox proportional hazards regression analysis, reversible RWA and EF worsening were two independent predictors of MACE, providing incremental prognostic value over clinical and perfusion-alone information. The functional assessment with Tl-201 gated SPECT was a useful prognosticator for patients who had known or suspected coronary artery disease. Coronary artery disease; Gated SPECT; Major adverse cardiac events; Tl-201.

  4. Segmental quantitative analysis of digital thallium-201 myocardial scintigrams in diagnosis of coronary artery disease. Comparison with rest and exercise electrocardiography and coronary arteriography.

    PubMed Central

    Wainwrwight, R J; Maisey, M N; Sowton, E

    1981-01-01

    One hundred and forty-nine patients with suspected ischaemic heart disease were evaluated by exercise thallium-201 myocardial scintigraphy (201Tl SMS), single lead exercise electrocardiography, and coronary arteriography. Myocardial distribution of tracer was assessed semi-quantitatively from digital 201Tl scintigrams and compared with tracer distribution in subjects with normal hearts. Fifty-two of 54 (96%) patients with normal coronary arteries had normal myocardial scintigrams whereas three patients had a positive ischaemic exercise electrocardiogram and were scan normal. Conversely, 36 of 95 (38%) patients with coronary artery disease had a positive ischaemic electrocardiogram compared with 94 of 95 (99%) patients who had a positive myocardial scintigram. Disease in specific coronary arteries could be deduced from the topography of myocardial tracer deficit. Disease was predicted correctly in 76 out of 80 (95%) of left anterior descending coronary stenoses, in 48 out of 64 (75%) of right coronary artery stenoses, and in 55 out of 64 (85%) of left circumflex coronary artery stenosis, despite the presence of infarcted myocardium in other territories. Similarly, single vessel disease was predicted correctly in 14 out of 17 (82%) patients and multiple vessel disease in 64 out of 77 (83%) patients. 201Tl SMS with segmental quantitative analysis is a highly sensitive and specific technique in the diagnosis of coronary artery disease and may be useful screening procedure to select patients for further investigation, particularly those with evidence of life-threatening severe left coronary artery disease. PMID:7317214

  5. Estimation of infarct size by myocardial emission computed tomography with thallium-201 and its relation to creatine kinase-MB release after myocardial infarction in man

    SciTech Connect

    Tamaki, S.; Nakajima, H.; Murakami, T.

    1982-11-01

    Emission computed tomography (ECT) for thallium-201 (/sup 201/Tl) myocardial imaging was evaluated in estimating infarct size (IS). In 18 patients in whom IS was estimated enzymatically at the time of the acute episode, planar /sup 201/Tl perfusion scintigraphy and ECT with a rotating gamma camera were performed 4 weeks after the first myocardial infarction. From the size of /sup 201/Tl perfusion defects, the infarct area in planar images and the infarct volume in reconsturcted ECT images were measured by computerized planimetry. When scintigraphic IS was compared with the accumulated creatine kinase-MB isoenzyme release (CK-MBr), infarct volume determined from ECT correlated closely with CK-MBr (r=0.89), whereas infarct area measured from planar images correlated less satisfactorily with the enzymatic IS (for an average infarct area from three views, r=0.69; for the largest infarct area, r=0.73). Although conventional scintigraphic evaluation is useful for detecting and localizing infarction, quantification of ischemic injury with this two-dimensional technique has a significant inherent limitation. The ECT approach can provide a more accurate three-dimensional quantitative estimate of infarction, and can corroborate the enzymatic estimate of IS.

  6. Evaluation of the post-coronary artery bypass patient by myocardial perfusion scintigraphy and computed tomography

    SciTech Connect

    Engelstad, B.L.; Wagner, S.; Herfkens, R.; Botvinick, E.; Brundage, B.; Lipton, M.

    1983-09-01

    The clinical utility of /sup 201/Tl scintigraphy and of computed tomography for the noninvasive assessment of graft patency and regional myocardial perfusion was evaluated in 24 patients who had undergone aortocoronary bypass surgery. Perfusion defects on /sup 201/Tl scintigraphy (reversible or new, fixed) correlated (100% sensitivity, 78% specificity) with occlusion or stenosis of a graft or significant new native vessel disease. Graft occlusion was accurately demonstrated by dynamic computed tomography (100% sensitivity, 96% specificity) but did not uniformly correlate with regional perfusion. Perfusion defects in the distribution of patent grafts resulted from progressive native vessel disease or graft stenosis without complete occlusion. The absence of exercise-induced perfusion defects in regions of occluded grafts was attributed to suboptimal exercise, collateralization, or noncritical native vessel stenosis. The two studies provide complementary anatomic and physiologic information in the evaluation of the postbypass patient.

  7. Clinical evaluation of 360 degrees and 180 degrees data sampling techniques for transaxial SPECT thallium-201 myocardial perfusion imaging.

    PubMed

    Go, R T; MacIntyre, W J; Houser, T S; Pantoja, M; O'Donnell, J K; Feiglin, D H; Sufka, B J; Underwood, D A; Meaney, T F

    1985-07-01

    The most serious controversy regarding the application of transaxial SPECT technology to 201Tl myocardial perfusion imaging is the choice between 360 degrees compared with 180 degrees data sampling techniques. The present study utilized the original 360 degrees sampled raw data of 25 patients who had both SPECT 201Tl myocardial perfusion imaging and coronary angio/ventriculography for back projection reprocessing to accomplish the 360 degrees/180 degrees comparison. The results show a high incidence, 36% (9/25), of false-positive segmental perfusion abnormality and a high incidence, 24% (6/25), of moderate to severe degree of image distortion with the 180 degrees data sampled reconstructed images. These were not observed in the 360 degrees data sampled reconstructed images. The above findings confirmed our previous preliminary conclusion that even though the 180 degrees data sampling technique has the advantage of providing improved image contrast and reduction in acquisition time it is not a reliable technique and should be abandoned. The 360 degrees data sampling is the technique of choice for transaxial SPECT 201Tl myocardial perfusion imaging.

  8. Correlation of left ventricular dyssynchrony with myocardial stunning using dual single photon emission computed tomography of (123)iodine-beta-methyl iodophenyl pentadecanoic acid and (201)thallium scintigraphy after reperfusion therapy.

    PubMed

    Maruyama, Yoshiaki; Masaki, Nobuyuki; Shimizu, Yuji; Honda, Norinari; Yoshimoto, Nobuo

    2009-11-01

    Left ventricular (LV) dyssynchrony after reperfusion therapy has been closely examined as a cause of chronic remodeling, but the details have not been clarified. The present study measured LV dyssynchrony appearing immediately after reperfusion therapy using real-time three-dimensional echocardiography (RT-3DE), and assessed the significance of this phenomenon in relation to dual single photon emission computed tomography (SPECT) of (123)iodine beta methyliodophenyl pentadecanoic acid ((123)I-BMIPP) and (201)thallium ((201)Tl). Subjects comprised 58 patients with first-time acute myocardial infarction who received reperfusion therapy and underwent RT-3DE and dual SPECT of (123)I-BMIPP and (201)Tl within two weeks of onset. Two dyssynchrony parameters were measured using RT-3DE in the acute phase and six months later. After evaluating the correlation of these dyssynchrony parameters to resting (201)Tl uptake, (201)Tl washout, (123)I-BMIPP uptake, and (201)Tl-(123)I-BMIPP discrepancy (Tl-BMIPP discrepancy), we compared scintigraphic parameters in the chronic phase between groups with improved dyssynchrony and those without. Acute dyssynchrony exhibited a significant positive correlation to Tl-BMIPP discrepancy and it was significantly increased in the group with improved dyssynchrony in the chronic phase, revealing close relationship between dyssynchrony and Tl-BMIPP discrepancy. Then the subjects were divided into positive Tl-BMIPP discrepancy and negative discrepancy groups, and the parameters of cardiac function were compared between them. In the chronic phase, improved cardiac function was observed in the group with positive Tl-BMIPP discrepancy compared to negative discrepancy. LV dyssynchrony after reperfusion therapy correlates positively with Tl-BMIPP discrepancy, reflecting acute myocardial stunning, in which ventricular contraction improves during the chronic phase.

  9. Relationship between myocardial perfusion-gated SPECT and the performance of coronary revascularization in patients with ischemic cardiomyopathy.

    PubMed

    Romero-Farina, Guillermo; Candell-Riera, Jaume; Aguadé-Bruix, Santiago; Ferreira-Gonzalez, Ignacio; Igual, Albert; García-Dorado, David

    2012-10-01

    Ischemic cardiomyopathy (ICM) is a disease with high morbidity and mortality. There are several published studies on the evolution and prognosis of patients with ICM. However, reports on the therapeutic management in clinical practice are scarce. The aim of this study was to analyze coronary revascularization (CR) performance in patients with ICM and suitable coronary anatomy according to myocardial perfusion stress-rest gated SPECT results. Eighty-seven consecutive patients (mean age, 62.4 y; 20 women), with ischemic heart disease, left ventricular ejection fraction of 40% or less, coronary anatomy suitable for CR, and without previous CR, were evaluated by means of stress-rest gated SPECT. Sixty-four percent of patients had scintigraphic criteria of viability and 62.1% showed scintigraphic ischemia in stress-rest gated SPECT. Forty-five percent of patients were revascularized, and the remainder received medical treatment only. Coronary revascularization was more frequent in patients with scintigraphic viability (P = 0.012), in those with scintigraphic ischemia (P = 0.007), and in those with low left ventricular end-systolic volume (P = 0.006). Cox regression analysis identified multivessel disease [hazard ratio (HR), 3.3; 95% confidence interval (CI), 4-7.8], summed difference score greater than 4 (HR, 3.9; 95% CI, 1.5-9.8), and left ventricular end-systolic volume less than 120 mL (HR, 3.2; 95% CI, 1.3-8.2) as the best independent predictors of CR treatment. In patients with ICM and suitable coronary arteries who are able to perform a stress myocardial perfusion-gated SPECT, the presence of multivessel disease and myocardial ischemia and the absence of severely increased left ventricular volume were associated to a decision of CR.

  10. Optimal left ventricular lead position assessed with phase analysis on gated myocardial perfusion SPECT

    PubMed Central

    Boogers, Mark J.; Chen, Ji; van Bommel, Rutger J.; Borleffs, C. Jan Willem; Dibbets-Schneider, Petra; van der Hiel, Bernies; Al Younis, Imad; Schalij, Martin J.; van der Wall, Ernst E.; Garcia, Ernest V.

    2010-01-01

    Purpose The aim of the current study was to evaluate the relationship between the site of latest mechanical activation as assessed with gated myocardial perfusion SPECT (GMPS), left ventricular (LV) lead position and response to cardiac resynchronization therapy (CRT). Methods The patient population consisted of consecutive patients with advanced heart failure in whom CRT was currently indicated. Before implantation, 2-D echocardiography and GMPS were performed. The echocardiography was performed to assess LV end-systolic volume (LVESV), LV end-diastolic volume (LVEDV) and LV ejection fraction (LVEF). The site of latest mechanical activation was assessed by phase analysis of GMPS studies and related to LV lead position on fluoroscopy. Echocardiography was repeated after 6 months of CRT. CRT response was defined as a decrease of ≥15% in LVESV. Results Enrolled in the study were 90 patients (72% men, 67±10 years) with advanced heart failure. In 52 patients (58%), the LV lead was positioned at the site of latest mechanical activation (concordant), and in 38 patients (42%) the LV lead was positioned outside the site of latest mechanical activation (discordant). CRT response was significantly more often documented in patients with a concordant LV lead position than in patients with a discordant LV lead position (79% vs. 26%, p<0.01). After 6 months, patients with a concordant LV lead position showed significant improvement in LVEF, LVESV and LVEDV (p<0.05), whereas patients with a discordant LV lead position showed no significant improvement in these variables. Conclusion Patients with a concordant LV lead position showed significant improvement in LV volumes and LV systolic function, whereas patients with a discordant LV lead position showed no significant improvements. PMID:20953608

  11. A Comparison between Quantitative Gated Myocardial Perfusion Scintigraphy and Strain Echocardiography as Indicators of Ventricular Functions in Patients with Anterior Myocardial Infarction

    PubMed Central

    Karacavus, Seyhan; Celik, Ahmet; Tutus, Ahmet; Kula, Mustafa; Oguzhan, Abdurrahman; Ozdogru, Ibrahim; Kalay, Nihat

    2014-01-01

    The purpose of this study is to compare the strain echocardiographic and scintigraphic parameters for evaluating of the left ventricular (LV) functions in patients with anterior myocardial infarction (MI). Fifty-four patients (male/female: 36/18; mean age 62 ± 13 years) with anterior MI were prospectively enrolled. All patients were performed gated myocardial perfusion scintigraphy gated single-photon emission computed tomography (GSPECT) and echocardiography (EC). GSPECT data were processed and analyzed using 4D-MSPECT (4DM, Invia Medical Imaging Solutions, Ann Arbor, MI, USA). The echocardiographic strain (S) and strain rate (SR) values were calculated. The results obtained by these techniques were compared each other. A total of 918 segments of LV wall were evaluated. In all patients, 385 segments were automatically scored as normokinetic, 206 as hypokinetic, 122 as akinetic, 205 as dyskinetic and 300 as normal thickening, 348 as decrease thickening and 270 as no thickening. The means of S and SR values in thickening and motion score groups according to GSPECT were statistically different from each other (P < 0.001). There was a negative significant correlation between LV wall thickening sum score and S and SR and between LV wall motion sum score and S and SR (P < 0.001). There was a good correlation between GSPECT and echocardiographic LV-ejection fraction (r = 0.7, P < 0.001). GSPECT and strain EC are similar in quantitative grading of the severity of regional and global myocardial dysfunction in patients with anterior MI and these techniques provide valuable diagnostic information. PMID:25538490

  12. Prevalence and prognostic significance of exercise-induced silent myocardial ischemia detected by thallium scintigraphy and electrocardiography in asymptomatic volunteers

    SciTech Connect

    Fleg, J.L.; Gerstenblith, G.; Zonderman, A.B.; Becker, L.C.; Weisfeldt, M.L.; Costa, P.T. Jr.; Lakatta, E.G. )

    1990-02-01

    Although a silent ischemic electrocardiographic response to treadmill exercise in clinically healthy populations is associated with an increased likelihood of future coronary events (i.e., angina pectoris, myocardial infarction, or cardiac death), such a response has a low predictive value for future events because of the low prevalence of disease in asymptomatic populations. To examine whether detection of reduced regional perfusion by thallium scintigraphy improved the predictive value of exercise-induced ST segment depression, we performed maximal treadmill exercise electrocardiography (ECG) and thallium scintigraphy (201Tl) in 407 asymptomatic volunteers 40-96 years of age (mean = 60) from the Baltimore Longitudinal Study on Aging. The prevalence of exercise-induced silent ischemia, defined by concordant ST segment depression and a thallium perfusion defect, increased more than sevenfold from 2% in the fifth and sixth decades to 15% in the ninth decade. Over a mean follow-up period of 4.6 years, cardiac events developed in 9.8% of subjects and consisted of 20 cases of new angina pectoris, 13 myocardial infarctions, and seven deaths. Events occurred in 7% of individuals with both negative 201Tl and ECG, 8% of those with either test positive, and 48% of those in whom both tests were positive (p less than 0.001). By proportional hazards analysis, age, hypertension, exercise duration, and a concordant positive ECG and 201Tl result were independent predictors of coronary events. Furthermore, those with positive ECG and 201Tl had a 3.6-fold relative risk for subsequent coronary events, independent of conventional risk factors.

  13. Detection of right ventricular pressure overloading by thallium-201 myocardial scintigraphy. Results in 57 patients with chronic respiratory diseases

    SciTech Connect

    Weitzenblum, E.; Moyses, B.; Dickele, M.C.; Methlin, G.

    1984-02-01

    The diagnostic value of thallium 201 (/sup 201/Tl) myocardial imaging was studied in 57 patients with chronic respiratory diseases, most with COPD (n . 46), by comparing the results to hemodynamic findings. In healthy subjects, the right ventricle (RV) is not visualized; therefore, any recorded activity of the RV was considered as indicating RV hypertrophy due to RV pressure overloading (RVPO). RV activity was graded from 0 (no activity) to 3 (activity greater than or equal to that of the left ventricle). Patients were divided into three groups according to the level of the pulmonary artery mean pressure (PPA): PPA less than or equal to 20 mm Hg (no pulmonary arterial hypertension (PAH) ) . group 1, n . 20; PPA ranging from 21 to 30 mm Hg (mild to moderate PAH) . group 2, n . 20; PPA greater than 30 mm Hg (marked PAH) . group 3, n . 17. RV was visualized in 14 patients in group 3 (82 percent) and in 13 patients in group 2 (65 percent). For all patients with PAH (2 + 3) the sensitivity of /sup 201/Tl imaging for the diagnosis of RVPO was of 73 percent, higher than that of ECG and echocardiography (both 51 percent). The sensitivity of /sup 201/Tl, even if moderate (65 percent) was better than that of ECG (30 percent) or echo (40 percent) in patients with mild-to-moderate PAH (group 2). A high RV activity (grade 3) was observed in only three patients. The specificity of this method (obtained from results in group 1) was of 80 percent vs 89 percent for echo and 100 percent for ECG. These results suggest that 201Tl myocardial imaging is a rather sensitive method and could be of interest for the noninvasive diagnosis of RVPO in COPD patients.

  14. All-Systolic Non-ECG-gated Myocardial Perfusion MRI: Feasibility of Multi-Slice Continuous First-Pass Imaging

    PubMed Central

    Sharif, Behzad; Arsanjani, Reza; Dharmakumar, Rohan; Bairey Merz, C. Noel; Berman, Daniel S.; Li, Debiao

    2015-01-01

    Purpose To develop and test the feasibility of a new method for non-ECG-gated first-pass perfusion (FPP) cardiac MR capable of imaging multiple short-axis slices at the same systolic cardiac phase. Methods A magnetization-driven pulse sequence was developed for non-ECG-gated FPP imaging without saturation-recovery preparation using continuous slice-interleaved radial sampling. The image reconstruction method, dubbed TRACE, employed self-gating based on reconstruction of a real-time image-based navigator combined with reference-constrained compressed sensing. Data from ischemic animal studies (n=5) was used in a simulation framework to evaluate temporal fidelity. Healthy subjects (n=5) were studied using both the proposed and conventional method to compare the myocardial contrast-to-noise ratio (CNR). Patients (n=2) underwent adenosine stress studies using the proposed method. Results Temporal fidelity of the developed method was shown to be sufficient at high heart-rates. The healthy volunteers studies demonstrated normal perfusion and no artifacts. Compared to the conventional scheme, myocardial CNR for the proposed method was slightly higher (8.6±0.6 vs. 8.0±0.7). Patient studies showed stress-induced perfusion defects consistent with invasive angiography. Conclusions The presented methods and results demonstrate feasibility of the proposed approach for high-resolution non-ECG-gated FPP imaging and indicate its potential for achieving desirable image quality (high CNR, no dark-rim artifacts) with a 3-slice spatial coverage, all imaged at the same systolic phase. PMID:26052843

  15. Determinants of the response of left ventricular ejection fraction to vasodilator stress in electrocardiographically gated (82)rubidium myocardial perfusion PET.

    PubMed

    Brown, Tracy L Y; Merrill, Jennifer; Volokh, Lana; Bengel, Frank M

    2008-02-01

    Myocardial perfusion imaging with (82)Rb PET allows for ECG-gated studies to be obtained early after radiotracer injection, capturing ventricular function close to peak pharmacologic action of dipyridamole. This is different from gated SPECT and may potentially provide additional diagnostic information. We sought to identify potential correlates of the PET-derived ejection fraction response to vasodilator stress. One hundred ten consecutive patients undergoing (82)Rb PET myocardial perfusion imaging during evaluation for coronary artery disease were included. Using a GE Discovery STRx PET-CT scanner, ECG-gated images (eight bins) were obtained at rest and 4 min after dipyridamole infusion, 90 s after infusion of 1,480-2,220 MBq of (82)Rb. Summed rest, stress, and difference scores (SRS, SSS, and SDS) were determined using a five-point scoring system and 20-segment model. Ejection fraction was calculated using automated QGS software. Significant reversibility (SDS > or = 4) was found in 23 patients (21%). Mean LVEF in all patients was 47 +/- 13% at rest and 53 +/- 13% during dipyridamole. LVEF increased in 89 patients, and decreased in 17 patients during vasodilation. The change in LVEF was inversely correlated with SDS (r = -0.26; p = 0.007). Additionally, it was inversely correlated with resting LVEF (r = -0.20; p = 0.03) and SSS (r = -0.25; p = 0.009). No significant correlations were observed with SRS, heart rate, blood pressure, age, hypertension, hypercholesterolemia, or pretest likelihood of disease. At multivariate regression analysis, SDS was an independent predictor of the change in LVEF. Gated (82)Rb PET during pharmacologic stress allows for assessment of the functional response to vasodilation. The magnitude of LVEF increase is determined by stress perfusion/reversible perfusion defects. Functional response to hyperemia may thus be incorporated in future evaluations of diagnostic and prognostic algorithms based on (82)Rb PET.

  16. Diagnostic accuracy of supine and prone thallium-201 stress myocardial perfusion single-photon emission computed tomography to detect coronary artery disease in inferior wall of left ventricle.

    PubMed

    Katayama, Takuji; Ogata, Nobuhiko; Tsuruya, Yoshio

    2008-05-01

    Prone thallium-201 ((201)Tl) myocardial perfusion single-photon emission computed tomography (SPECT) reduces false-positive rates when evaluating inferior wall abnormalities by minimizing diaphragmatic attenuation. The present study investigates the diagnostic validity of prone (201)Tl stress myocardial perfusion SPECT for detecting coronary artery disease in the inferior wall of the left ventricle in Japanese patients. Of the 104 consecutive patients who underwent (201)Tl stress myocardial perfusion SPECT to diagnose coronary artery disease, we evaluated 46 who underwent image acquisition in both the supine and prone positions, and coronary angiography within 3 months thereafter. Images were acquired in the routine supine position immediately following (201)Tl (111 MBq) injection and 4 h following early acquisition. Images were acquired in the prone position only during the early phase following supine acquisition. We evaluated the SPECT images of the inferior half segments of the left ventricle using a five-point defect scoring system. According to the coronary angiographic findings, we investigated the diagnostic accuracy of stress-rest supine, stress supine, stress prone, and combined supine-prone images. Reduced uptake in the stress supine image of the combined images was considered as attenuation when uptake was normal in the prone image. The sensitivity of the stress-rest supine, stress supine, stress prone, and stress-combined supine-prone images was 77%, 86%, 55%, and 55%, and the specificity was 71%, 54%, 79%, and 83%, respectively. Diagnostic accuracy was the highest in stress-rest supine images. Prone images tended to improve the specificity of detecting coronary artery disease in the inferior wall, but not diagnostic accuracy compared with stress-rest supine images because of decreased sensitivity.

  17. Evaluation of ECG-gated [(11)C]acetate PET for measuring left ventricular volumes, mass, and myocardial external efficiency.

    PubMed

    Hansson, Nils Henrik; Tolbod, Lars; Harms, Johannes; Wiggers, Henrik; Kim, Won Yong; Hansen, Esben; Zaremba, Tomas; Frøkiær, Jørgen; Jakobsen, Steen; Sørensen, Jens

    2016-08-01

    Noninvasive estimation of myocardial external efficiency (MEE) requires measurements of left ventricular (LV) oxygen consumption with [(11)C]acetate PET in addition to LV stroke volume and mass with cardiovascular magnetic resonance (CMR). Measuring LV geometry directly from ECG-gated [(11)C]acetate PET might enable MEE evaluation from a single PET scan. Therefore, we sought to establish the accuracy of measuring LV volumes, mass, and MEE directly from ECG-gated [(11)C]acetate PET. Thirty-five subjects with aortic valve stenosis underwent ECG-gated [(11)C]acetate PET and CMR. List mode PET data were rebinned into 16-bin ECG-gated uptake images before measuring LV volumes and mass using commercial software and compared to CMR. Dynamic datasets were used for calculation of mean LV oxygen consumption and MEE. LV mass, volumes, and ejection fraction measured by CMR and PET correlated strongly (r = 0.86-0.92, P < .001 for all), but were underestimated by PET (P < .001 for all except ESV P = .79). PET-based MEE, corrected for bias, correlated fairly with PET/CMR-based MEE (r = 0.60, P < .001, bias -3 ± 21%, P = .56). PET-based MEE bias was strongly associated with LV wall thickness. Although analysis-related improvements in accuracy are recommended, LV geometry estimated from ECG-gated [(11)C]acetate PET correlate excellently with CMR and can indeed be used to evaluate MEE.

  18. Relationship between gated myocardial perfusion SPECT findings and hemodynamic, electrocardiographic, and heart rate changes after Dipyridamole infusion.

    PubMed

    Gholoobi, Arash; Ayati, Narjess; Baghyari, Alireza; Mouhebati, Mohsen; Atar, Baharak; Dabbagh Kakhki, Vahid Reza

    2017-02-01

    After dipyridamole infusion, electrocardiographic (ECG), blood pressure and heart rate (HR) changes were seen. We tried to investigate whether there is a relationship between hemodynamic, ECG and HR changes after dipyridamole infusion and gated myocardial perfusion SPECT findings. We studied 206 consecutive patients which underwent a 2-day protocol Dipyridamole Stress/Rest Tc99m-Sestamibi gated myocardial perfusion SPECT. Systolic blood pressure (SBP), diastolic blood pressure (DBP), HR and ECG were recorded. HR was mildly increased while SBP and DBP were mildly decreased after Dipyridamole infusion. There was only statistically significant difference between ECG changes as well as transient ischemic dilation (TID) ratio between normal scans and scans with ischemia (P = 0.02 and P = 0.01 respectively). There was correlation between these variables and summed stress score (SSS) and summed difference score (SDS). Patients with ischemia in their scans, 44.3% had ST depression after Dipyridamole infusion. Also ST depression most frequently was seen in patients with left anterior descending artery disease. From patients with abnormal scan + ST depression after Dipyridamole infusion (33 patient), 27 patient (81.81%) had ischemia. There was an association between TID ratio as well as ECG changes after Dipyridamole infusion and SSS, SDS and coronary artery territory abnormality. Difference between calculated left ventricular ejection fraction using stress and rest images had significant correlation with SSS and SDS. ST depression after Dipyridamole infusion and TID ratio had association with ischemia, SSS and SDS. So in equivocal Gated SPECT findings, they could be very useful for interpretation.

  19. The comparison of 2-18F-2-deoxyglucose and 15-(ortho-123I-phenyl)-pentadecanoic acid uptake in persisting defects on thallium-201 tomography in myocardial infarction

    SciTech Connect

    Henrich, M.M.; Vester, E.; von der Lohe, E.; Herzog, H.; Simon, H.; Kuikka, J.T.; Feinendegen, L.E. )

    1991-07-01

    The myocardial uptake of glucose and fatty acids into 201Tl redistribution defects were studied in 32 patients with myocardial infarction by tomography using 2-18F-2-deoxyglucose (FDG) and 15-(ortho-123I-phenyl)-pentadecanoic acid (oPPA). A total of 1153 segments were analyzed, 408 (35%) of which showed a persistent thallium-defect in stress-redistribution images. Of the segments with a decreased 201Tl uptake in these redistribution tomograms, 50.5% had a decreased uptake of both FDG and oPPA; in 21.8% FDG as well as oPPA uptake was within normal range. Normal FDG uptake but decreased oPPA uptake was detected in 17.4%, whereas 10.3% of the segments had normal oPPA uptake but decreased FDG uptake (chi-square test, p less than 0.001). A significant correlation of FDG and oPPA uptake (r = 0.51) was found in the segments with persistent 201Tl defect. Thus, a substantial fraction of persistent thallium-defects after healed myocardial infarction exhibit FDG as well as oPPA uptake, probably due to residual fatty acid metabolism in partially ischemic regions.

  20. [Estimation of I-123 metaiodobenzylguanidine (MIBG) myocardial washout].

    PubMed

    Saito, T; Watanabe, N; Saitoh, T; Asakura, T; Kanke, M; Owada, K; Hoshi, K; Kimura, K; Maruyama, Y

    1990-11-01

    A crosstalk from I-123 to Tl-201 (Tl) window was 35 +/- 30% (mean +/- SD) and 30 +/- 10% in a myocardial phantom and the images of 6 patients respectively. However, the crosstalk from Tl to I-123 was approximately 1% in each. I-123 MIBG (MIBG) and Tl myocardial SPECT images were recorded in 3 normal volunteers (N), 10 patients with myocardial infarction (MI), and 4 with dilated cardiomyopathy (DCM). The MIBG and Tl imagings were performed on the other day to avoid the crosstalk. Myocardial washout rates (WR) of Tl and MIBG were derived from 15 min and 4 hour images. WR of Tl was approximately 36% in each group. On the other hand, WR of MIBG in DCM (52 +/- 7%) and MI (41 +/- 14%) groups were statistically higher than in N (24 +/- 7%) group. Thus WR of MIBG would be useful to detect abnormalities in adrenergic nervous system.

  1. Tomographic thallium-201 myocardial perfusion scintigrams after maximal coronary artery vasodilation with intravenous dipyridamole: comparison of qualitative and quantitative approaches

    SciTech Connect

    Francisco, D.A.; Collins, S.M.; Go, R.T.; Ehrhardt, J.C.; Van Kirk, O.C.; Marcus, M.L.

    1982-08-01

    Eighty-six patients had thallium-201 (/sup 201/Tl) myocardial perfusion scintigrams after intense coronary artery dilation with i.v. dipyridamole. Tomographic and planar /sup 201/Tl scintigrams were obtained in each patient. Tomographic scintigrams were interpreted using quantitative or visual criteria; planar scintigrams were assessed using visual criteria only. When visual criteria were used, interobserver variability was 40% for tomographic scintigrams and 44% for planar scintigrams. In the 24 patients with normal or nonsignificant CAD, quantitative analysis of the tomograms (range approach) indicated that one of 24 (4%) had a positive image (specificity 96%%); in contrast, when visual criteria were used to interpret the tomographic or planar /sup 201/Tl scintigrams, eight of 24 (33%) had positive scintigrams (specificity 67%). In the 51 abnormal patients, the sensitivity of detecting CAD was 46 of 51 (90%) for tomographic scintigrams interpreted quantitatively, 39 of 51 (76%) for tomographic scintigrams interpreted visually and 41 of 51 (80%) for planar scintigrams assessed visually. The tomographic imaging procedure (quantitative interpretation) also demonstrated a high sensitivity (89%) and specificity (100%) in 28 patients (10 normal and 18 CAD), with a clinical diagnosis of unstable angina pectoris. Overall, the predictive accuracy of an abnormal scintigram with quantitative tomographic imaging (98%) was significantly better (p<0.05) than either qualitative planar or pinhole imaging. (JMT)

  2. Scintigraphic anatomy of coronary artery disease in digital thallium-201 myocardial images.

    PubMed Central

    Wainwright, R J

    1981-01-01

    One hundred and eight patients with single and multiple vessel coronary artery disease confirmed by arteriography were evaluated by exercise thallium-201 (201Tl) myocardial scintigraphy to determine the scintigraphic appearances of specific coronary stenoses. In general proximal stenoses caused more widespread, but not necessarily more severe, myocardial tracer deficit than distal stenoses. In particular, proximal dominant right coronary artery disease was specifically associated with extensive inferior wall tracer deficit in the anterior scintigram, whereas proximal left circumflex disease caused similar tracer depletion best visualised in the left lateral scintigram. A triad of uptake defects was caused by left anterior descending coronary artery disease: viz. apical tracer deficit (anterior view) in 71% lesions, septal tracer deficit (left anterior oblique view) in 83% of lesions, and anterolateral wall tracer deficit (left lateral projection) in 72% of lesions. The last defect has been termed a 'diagonal window' because it was associated with independent disease of the main diagonal branch of the left anterior descending coronary artery or with disease in the main left anterior descending artery situated proximal to this branch. Diagonal window tracer deficit was the most useful scintigraphic sign distinguishing proximal from distal disease in the left anterior descending coronary artery. False negative scintigraphic defects occurred more commonly in patients with triple vessel disease and in association with well-developed coronary collateral vessels. Certain scintigraphic patterns of 201Tl myocardial accumulation appear invaluable in the noninvasive localisation of stenoses within specific coronary arteries and thus may be useful in predicting life-threatening coronary artery disease which should be confirmed by definite coronary arteriography. The digital 201Tl myocardial scintigram also provides an independent functional guide to the interpretation of

  3. Aortic knob width reflects left ventricular diastolic function assessed by gated myocardial perfusion single photon emission computed tomography in patients with normal myocardial perfusion.

    PubMed

    Kurisu, Satoshi; Higaki, Tadanao; Sumimoto, Yoji; Ikenaga, Hiroki; Watanabe, Noriaki; Ishibashi, Ken; Dohi, Yoshihiro; Fukuda, Yukihiro; Kihara, Yasuki

    2017-04-01

    Aortic knob width on chest radiography represents the extent of aortic dialation and tortuosity of the aortic arch. We tested the hypothesis that aortic knob width reflected left ventricular (LV) diastolic function assessed by gated myocardial perfusion single photon emission computed tomography (SPECT) in patients with normal myocardial perfusion. One hundred and thirty patients with preserved LV ejection fraction and normal myocardial perfusion were enrolled in this study. Aortic knob width was measured along the horizontal line from the point of the lateral edge of the trachea to the left lateral wall of the aortic knob. The peak filling rate (PFR) and the one-third mean filling rate (1/3 MFR) were obtained as LV diastolic parameters. There were 114 male and 16 female patients. Age ranged from 43 to 88 years (69.9 ± 8.9 years). Aortic knob width ranged from 24.2 to 53.4 mm (37.6 ± 5.7 mm). There was a significant correlation between age and aortic knob width (r = 0.34, p < 0.001). Aortic knob width was inversely correlated with both PFR (r = -0.53, p < 0.001) and 1/3 MFR (r = -0.42, p < 0.001). Multivariate linear regression analysis revealed that serum creatinine (β = -0.16, p = 0.045) and aortic knob width (β = -0.45, p < 0.001) were significant predictors of PFR, and that age (β = -0.20, p = 0.02) and aortic knob width (β = -0.33, p < 0.001) were significant predictors of 1/3 MFR. Our data suggested that aortic knob width on chest radiography was a simple marker of LV diastolic function in patients with normal myocardial perfusion.

  4. [Myocardial perfusion scintigraphy 2012 in Germany. Results of the 6th Query].

    PubMed

    Lindner, O; Burchert, W; Schäfers, M; Schaefer, W

    2014-01-01

    The working group Cardiovascular Nuclear Medicine of the German Society of Nuclear Medicine presents the results of the 6th survey on myocardial perfusion scintigraphy (MPS) of the reporting year 2012. 278 questionnaires (177 private practices (PP), 78 hospitals (HO), 23 university hospitals (UH)) were evaluated. MPS of 105,941 patients were reported. 95% [2005 = 80%] of MPS studies were conducted with (99m)Tc perfusion radiopharmaceuticals and only 5% with 201Tl. 79% [2009 = 76%] of the MPS were performed in PP, 15% [2009 = 17%] in HO, and 6% [2009 = 7%] in UH. Data from 108 centres which participated in all surveys from 2005 to 2012 showed an increase in MPS numbers of 4.0% (PP +6.1%, HO +18.2%, UH -18.3%). 29% of all participants (27% of PP, 31% of HO, and 26% of UH) noticed no change and 26% of all participants (28% of PP, 17% of HO and 35% of UH) an increase in their MPS requests since the 2009 query. The type of stress was pharmacological in 39% [2009 = 31%]. Of these 61% with adenosine (39% with exercise), 22% with regadenoson (51% with exercise), 14% with dipyridamole (60% with exercise), and 3% with dobutamine. Gated SPECT was performed in 73% [2009 = 56%] of all rest, in 70% [2009 = 56%] of all stress and in 67% [47%] of all stress and rest MPS. Only 36% [2009 = 33%] of the centres performed a quantification of all their studies with scores, whereas 41% [2009 = 52%] did not apply any quantification. 60% [2009 = 49%] of the MPS were requested by ambulatory care cardiologists. The survey on MPS in Germany reveals a good conformity of imaging procedures with the current guideline. A positive development in MPS practice and referral can be stated. However, there is still some potential of MPS processing considering the quantitative perfusion analysis.

  5. Development of 4D mathematical observer models for the task-based evaluation of gated myocardial perfusion SPECT.

    PubMed

    Lee, Taek-Soo; Frey, Eric C; Tsui, Benjamin M W

    2015-04-07

    This paper presents two 4D mathematical observer models for the detection of motion defects in 4D gated medical images. Their performance was compared with results from human observers in detecting a regional motion abnormality in simulated 4D gated myocardial perfusion (MP) SPECT images. The first 4D mathematical observer model extends the conventional channelized Hotelling observer (CHO) based on a set of 2D spatial channels and the second is a proposed model that uses a set of 4D space-time channels. Simulated projection data were generated using the 4D NURBS-based cardiac-torso (NCAT) phantom with 16 gates/cardiac cycle. The activity distribution modelled uptake of (99m)Tc MIBI with normal perfusion and a regional wall motion defect. An analytical projector was used in the simulation and the filtered backprojection (FBP) algorithm was used in image reconstruction followed by spatial and temporal low-pass filtering with various cut-off frequencies. Then, we extracted 2D image slices from each time frame and reorganized them into a set of cine images. For the first model, we applied 2D spatial channels to the cine images and generated a set of feature vectors that were stacked for the images from different slices of the heart. The process was repeated for each of the 1,024 noise realizations, and CHO and receiver operating characteristics (ROC) analysis methodologies were applied to the ensemble of the feature vectors to compute areas under the ROC curves (AUCs). For the second model, a set of 4D space-time channels was developed and applied to the sets of cine images to produce space-time feature vectors to which the CHO methodology was applied. The AUC values of the second model showed better agreement (Spearman's rank correlation (SRC) coefficient = 0.8) to human observer results than those from the first model (SRC coefficient = 0.4). The agreement with human observers indicates the proposed 4D mathematical observer model provides a good predictor of the

  6. Development of 4D mathematical observer models for the task-based evaluation of gated myocardial perfusion SPECT

    NASA Astrophysics Data System (ADS)

    Lee, Taek-Soo; Frey, Eric C.; Tsui, Benjamin M. W.

    2015-04-01

    This paper presents two 4D mathematical observer models for the detection of motion defects in 4D gated medical images. Their performance was compared with results from human observers in detecting a regional motion abnormality in simulated 4D gated myocardial perfusion (MP) SPECT images. The first 4D mathematical observer model extends the conventional channelized Hotelling observer (CHO) based on a set of 2D spatial channels and the second is a proposed model that uses a set of 4D space-time channels. Simulated projection data were generated using the 4D NURBS-based cardiac-torso (NCAT) phantom with 16 gates/cardiac cycle. The activity distribution modelled uptake of 99mTc MIBI with normal perfusion and a regional wall motion defect. An analytical projector was used in the simulation and the filtered backprojection (FBP) algorithm was used in image reconstruction followed by spatial and temporal low-pass filtering with various cut-off frequencies. Then, we extracted 2D image slices from each time frame and reorganized them into a set of cine images. For the first model, we applied 2D spatial channels to the cine images and generated a set of feature vectors that were stacked for the images from different slices of the heart. The process was repeated for each of the 1,024 noise realizations, and CHO and receiver operating characteristics (ROC) analysis methodologies were applied to the ensemble of the feature vectors to compute areas under the ROC curves (AUCs). For the second model, a set of 4D space-time channels was developed and applied to the sets of cine images to produce space-time feature vectors to which the CHO methodology was applied. The AUC values of the second model showed better agreement (Spearman’s rank correlation (SRC) coefficient = 0.8) to human observer results than those from the first model (SRC coefficient = 0.4). The agreement with human observers indicates the proposed 4D mathematical observer model provides a good predictor of the

  7. Association between non-perfusion parameters and presence of ischemia in gated-SPECT myocardial perfusion imaging studies.

    PubMed

    Peix, Amalia; Cabrera, Lázaro O; Padrón, Kenia; Rodríguez, Lydia; Fernández, Jesús; López, Giselle; Carrillo, Regla; Mena, Erick; Fernández, Yoel; Dondi, Maurizio; Páez, Diana

    2016-11-17

    Combined assessment of perfusion and function improves diagnostic and prognostic power of gated-SPECT in patients with coronary artery disease. The aim of this study was to investigate whether the presence of stress-induced ischemia is associated with abnormal resting left ventricular (LV) function and intraventricular dyssynchrony. Gated-SPECT myocardial perfusion imaging (MPI) at rest and 15 min post-stress was performed in 101 patients, who were divided into three groups: those with stress-induced ischemia (Group 1, n = 58), those with normal scans (Group 2, n = 28), and those with scar but no ischemia (Group 3, n = 15). More extensive perfusion defects were found in patients of Groups 1 and 3 [Summed stress score (SSS): 13 ± 8 and 21 ± 9, respectively]. In Group 2, the mean SSS was 1.5. The mean change in LV ejection fraction (LVEF at stress - LVEF at rest) was higher in Group 1 v. Group 2 patients: -5.54% ± 6.24% vs -2.46% ± 5.56%, p = 0.02. Group 3 patients also had higher values, similar to Group 1: -6.47% ± 8.82%. Patients with ischemia had almost 50% higher end-diastolic volumes than patients with normal MPI. Similarly, end-systolic volumes were almost twice as high in this group (p < 0.0001). In addition, the histogram bandwidth, a measure of intraventricular dyssynchrony, was greater in Group 1. Baseline differences in left ventricular volumes and degree of dyssynchrony are associated with inducible ischemia on stress testing in a gated-SPECT MPI. Stress-induced ischemia increases the degree of intraventricular dyssynchrony.

  8. Comparison of diagnostic performance of four software packages for phase dyssynchrony analysis in gated myocardial perfusion SPECT.

    PubMed

    Okuda, Koichi; Nakajima, Kenichi; Matsuo, Shinro; Kashiwaya, Soichiro; Yoneyama, Hiroto; Shibutani, Takayuki; Onoguchi, Masahisa; Hashimoto, Mitsumasa; Kinuya, Seigo

    2017-12-01

    Phase analysis of gated myocardial perfusion single-photon emission computed tomography (SPECT) for assessment of left ventricular (LV) dyssynchrony was investigated using the following dedicated software packages: Corridor4DM (4DM), cardioREPO (cREPO), Emory Cardiac Toolbox (ECTb), and quantitative gated SPECT (QGS). The purpose of this study was to evaluate the normal values of 95% histogram bandwidth, phase standard deviation (SD), and entropy and to compare the diagnostic performance of the four software packages. A total of 122 patients with normal myocardial perfusion and cardiac function (58.9 ± 12.3 years, 60 women, ejection fraction (EF) 74.3 ± 5.7%, and end-diastolic volume (EDV) 83.5 ± 3.6 mL) and 34 patients with suspected LV dyssynchrony (64.1 ± 12.2 years, 9 women, EF 52.0 ± 18.0%, and EDV 145.0 ± 6.8 mL) who underwent Tc-99m methoxy-isobutyl-isonitrile/tetrofosmin gated SPECT were retrospectively evaluated. Dyssynchrony indices of the 95% histogram bandwidth, phase SD, and entropy were computed with the four software programs. Diagnostic performance of LV phase dyssynchrony assessments was determined by receiver operator characteristic (ROC) analysis. The area under the ROC curve (AUC) was used to compare the software programs. The optimal cutoff point was determined by ROC curve based on the Youden index. The average of normal bandwidth significantly differed among the four software programs except in the comparison of 4DM and ECTb. Moreover, the normal phase SD significantly differed among the four software programs except in the comparison of cREPO and ECTb. The software programs showed high correlation levels for bandwidth, phase SD, and entropy (r ≥ 0.73, p < 0.001). ROC AUCs of bandwidth, phase SD, and entropy were ≥0.850, ≥0.858, and ≥0.900, respectively. Moreover, the ROC AUCs of bandwidth, phase SD, and entropy did not significantly differ among the four software programs. Optimal cutoff

  9. KEY COMPARISON: Activity measurements of the radionuclide 201Tl for the LNE-LNHB, France, PTB, Germany and the NPL, UK in the ongoing comparison BIPM.RI(II)-K1.Tl-201

    NASA Astrophysics Data System (ADS)

    Ratel, G.; Michotte, C.; Moune, M.; Bobin, C.; Kossert, K.; Johansson, L.

    2008-01-01

    In 2005, the Laboratoire national de métrologie et essais-Laboratoire national Henri Becquerel (LNE-LNHB) and the Physikalisch-Technische Bundesanstalt (PTB) each submitted a sample of known activity of 201Tl to the International Reference System (SIR). In 2006, the National Physical Laboratory (NPL) submitted their first sample. The range of values of the activity submitted was between 2 MBq and 63 MBq. These key comparison results have been included in the re-evaluated key comparison reference value and replaced the previous results for France and Germany in the matrix of degrees of equivalence in the key comparison database that now contains seven results, identifier BIPM.RI(II)-K1.Tl-201. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCRI Section II, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).

  10. Functional evaluation of myocardial viability by 99mTc tetrofosmin gated SPECT--a quantitative comparison with 18F fluorodeoxyglucose positron emission CT (18F FDG PET).

    PubMed

    Kuwabara, Y; Watanabe, S; Nakaya, J; Fujiwara, M; Hasegawa, R; Matsuno, K; Kuroda, T; Mikami, Y; Fujii, K; Himi, T; Masuda, Y

    1999-06-01

    To validate functional analysis of gated SPECT in detecting myocardial viability, seventeen patients (male 15, female 2, mean age 58) with angiographically proven chronic ischemic heart disease (RCA 6, LAD 10, LCX 1) and eight normal volunteers (all male) were studied. All patients underwent 18F FDG PET and 99mTc tetrofosmin (TF) gated SPECT within a week. After being displayed in a polar map, myocardial perfusion was regionally determined by the mean count in 9 segments at end diastole (ED) and end systole (ES) in gated SPECT. Systolic function was determined by the count increase ratio from ED to ES (WTI: ES - ED/ED). Glucose metabolism was assessed by 18F FDG PET in the segments correspondent to those defined for SPECT. TF %uptake of < 60% was defined as hypoperfusion, and FDG %uptake of < 50% was defined as reduced glucose metabolism. The myocardial segments were classified into 3 categories: "normal" perfusion (n = 85), "mismatch" (reduced perfusion with reserved FDG uptake, n = 25) and "matched" reduced perfusion and metabolic reduction (n = 26). Mean WTI in "mismatch" segment was 0.38 +/- 0.21, and was significantly greater than that in "matched reduced" segments, 0.15 +/- 0.20 (p < 0.001). It was also greater than that in "normal" segments, 0.27 +/- 0.16. Regression analysis showed that association between WTI and FDG %uptake was significant (r = 0.57, p < 0.0005) for the ischemic segments ("mismatch" + "matched", n = 51), but the association was weak for the entire segments although it was statistically significant (r = 0.26, p = 0.02, n = 136). For the segments determined as infarct by perfusion image, systolic functional analysis by gated SPECT is helpful in differentiation of a viable myocardial region or artifact from a scar. Nevertheless, further clinical and technical assessment is required for ECG gating to eliminate overestimation of viability and to warrant clinical use.

  11. Myocardial wall thickening from gated magnetic resonance images using Laplace's equation

    NASA Astrophysics Data System (ADS)

    Prasad, M.; Ramesh, A.; Kavanagh, P.; Gerlach, J.; Germano, G.; Berman, D. S.; Slomka, P. J.

    2009-02-01

    The aim of our work is to present a robust 3D automated method for measuring regional myocardial thickening using cardiac magnetic resonance imaging (MRI) based on Laplace's equation. Multiple slices of the myocardium in short-axis orientation at end-diastolic and end-systolic phases were considered for this analysis. Automatically assigned 3D epicardial and endocardial boundaries were fitted to short-axis and long axis slices corrected for breathold related misregistration, and final boundaries were edited by a cardiologist if required. Myocardial thickness was quantified at the two cardiac phases by computing the distances between the myocardial boundaries over the entire volume using Laplace's equation. The distance between the surfaces was found by computing normalized gradients that form a vector field. The vector fields represent tangent vectors along field lines connecting both boundaries. 3D thickening measurements were transformed into polar map representation and 17-segment model (American Heart Association) regional thickening values were derived. The thickening results were then compared with standard 17-segment 6-point visual scoring of wall motion/wall thickening (0=normal; 5=greatest abnormality) performed by a consensus of two experienced imaging cardiologists. Preliminary results on eight subjects indicated a strong negative correlation (r=-0.8, p<0.0001) between the average thickening obtained using Laplace and the summed segmental visual scores. Additionally, quantitative ejection fraction measurements also correlated well with average thickening scores (r=0.72, p<0.0001). For segmental analysis, we obtained an overall correlation of -0.55 (p<0.0001) with higher agreement along the mid and apical regions (r=-0.6). In conclusion 3D Laplace transform can be used to quantify myocardial thickening in 3D.

  12. Effects of CT-based attenuation correction of rat microSPECT images on relative myocardial perfusion and quantitative tracer uptake

    SciTech Connect

    Strydhorst, Jared H. Ruddy, Terrence D.; Wells, R. Glenn

    2015-04-15

    Purpose: Our goal in this work was to investigate the impact of CT-based attenuation correction on measurements of rat myocardial perfusion with {sup 99m}Tc and {sup 201}Tl single photon emission computed tomography (SPECT). Methods: Eight male Sprague-Dawley rats were injected with {sup 99m}Tc-tetrofosmin and scanned in a small animal pinhole SPECT/CT scanner. Scans were repeated weekly over a period of 5 weeks. Eight additional rats were injected with {sup 201}Tl and also scanned following a similar protocol. The images were reconstructed with and without attenuation correction, and the relative perfusion was analyzed with the commercial cardiac analysis software. The absolute uptake of {sup 99m}Tc in the heart was also quantified with and without attenuation correction. Results: For {sup 99m}Tc imaging, relative segmental perfusion changed by up to +2.1%/−1.8% as a result of attenuation correction. Relative changes of +3.6%/−1.0% were observed for the {sup 201}Tl images. Interscan and inter-rat reproducibilities of relative segmental perfusion were 2.7% and 3.9%, respectively, for the uncorrected {sup 99m}Tc scans, and 3.6% and 4.3%, respectively, for the {sup 201}Tl scans, and were not significantly affected by attenuation correction for either tracer. Attenuation correction also significantly increased the measured absolute uptake of tetrofosmin and significantly altered the relationship between the rat weight and tracer uptake. Conclusions: Our results show that attenuation correction has a small but statistically significant impact on the relative perfusion measurements in some segments of the heart and does not adversely affect reproducibility. Attenuation correction had a small but statistically significant impact on measured absolute tracer uptake.

  13. Iterative deconvolution of simultaneous 99mTc and 201Tl projection data measured on a CdZnTe-based cardiac SPECT scanner

    NASA Astrophysics Data System (ADS)

    Kacperski, Krzysztof; Erlandsson, Kjell; Ben-Haim, Simona; Hutton, Brian F.

    2011-03-01

    We present a method of correcting self-scatter and crosstalk effects in simultaneous technetium-99m/thallium-201 stress/rest myocardial perfusion (single photon emission computed tomography) SPECT scans. The method, which is in essence a hybrid between the triple energy window method and scatter modelling, is based on a model of spatial and spectral distribution of projection counts in several selected energy windows. The parameters of the model are determined from measurements of thin rod sources in air when no in-object scatter or attenuation effects are present. The model equations are solved using the iterative maximum likelihood expectation maximization algorithm in the projection space to find estimates of the primary photopeak counts of both radionuclides. The method has been developed particularly for a novel dedicated cardiac camera based on CdZnTe pixellated detectors, although it can also be adapted to a conventional scintillator camera. The method has been validated in anthropomorphic phantom experiments. Significant improvement in defect contrast has been observed with only moderate increase in image noise. The application of the method to patient data is illustrated.

  14. Peritoneal fluid causing inferior attenuation on SPECT thallium-201 myocardial imaging in women

    SciTech Connect

    Rab, S.T.; Alazraki, N.P.; Guertler-Krawczynska, E.

    1988-11-01

    On SPECT thallium images, myocardial left ventricular (LV) anterior wall attenuation due to breast tissue is common in women. In contrast, in men, inferior wall counts are normally decreased compared to anterior counts. The purpose of this report is to describe cases of inferior wall attenuation of counts in women caused by peritoneal fluid, not myocardial disease. Twelve consecutive SPECT thallium myocardial studies performed in women on peritoneal dialysis, being evaluated for kidney transplant, were included in this study. For all studies, 3.5 mCi 201Tl were injected intravenously. Thirty-two images were acquired over 180 degrees (45 degrees RAO progressing to 45 degrees LPO) at 40 sec per stop. SPECT images were reviewed in short axis, horizontal long and vertical long axes. Data were also displayed in bullseye format with quantitative comparison to gender-matched normal files. Ten of 12 female patients studied had inferior wall defects on images, confirmed by bullseye display. All patients had approximately 2 liters of peritoneal fluid. Review of planar rotational views showed diaphragm elevation and fluid margin attenuations affecting left ventricular inferior wall. Thus, peritoneal fluid is a cause of inferior attenuation on 201Tl cardiac imaging.

  15. Fixed defect on rest/stress Tc-99m sestamibi study underestimates myocardial ischemia: comparison with 24-hour thallium-201 study for short- and intermediate-term follow-up.

    PubMed

    Kong, Grace; Lichtenstein, Meir; Gunawardana, Dishan; Better, Nathan; Roysri, Krisana; Sivaratnam, Dinesh

    2008-03-01

    We assessed whether a same day rest/stress gated Tc-99m sestamibi (MIBI) SPECT myocardial study underestimates reversible ischemia in patients with fixed perfusion defects compared with a 24-hour thallium-201 (Tl-201) study. The short- and intermediate-term outcome with or without Tl-201 reversibility was assessed. Forty-nine consecutive patients with fixed MIBI defects received an additional Tl-201 study and were evaluated. Tl-201 was given to patients with a high clinical suspicion of underestimation of reversibility. Images were interpreted semiquantitatively by 3 nuclear medicine physicians using a 17-segment, 5-point model. A summed stress score (SSS) from stress MIBI images, a summed rest score (SRS) from Tl images, and a summed difference (SDS = SSS - SRS) score were calculated. SDS >3 indicated significant Tl-201 redistribution. Composite end points included acute myocardial infarction, unstable angina needing admission, cardiac death, or revascularization within 3 and 6 months. Fifteen of 49 patients showed no Tl-201 redistribution. Thirty-four of 49 (69%) patients had significant Tl-201 redistribution, and these patients had significantly higher cardiac events (CE) at 3 months (29% vs. 7%; P = 0.039), and higher at 6 months (32% vs. 7%; P = 0.027). These patients with CE had a larger amount of Tl-201 redistribution, mean SDS 8.6 vs. 5.3 (P = 0.047). Patients with significant Tl-201 redistribution had a lower left ventricular ejection fraction (mean 37%; P = 0.001). With short- and intermediate-term follow-up, our study shows a significant association towards fixed defects on the rest/stress MIBI study underestimating CE risk when compared with a delayed Tl-201 study, especially in patients with a large amount of Tl-201 redistribution. Hence, the addition of a Tl-201 study may be useful in the management of patients with large fixed MIBI defects, especially with a depressed left ventricular ejection fraction.

  16. Comparison of Hemodynamic Effects and Negative Predictive Value of Normal Adenosine Gated Myocardial Perfusion Scan With or Without Caffeine Abstinence.

    PubMed

    Uz Zaman, Maseeh; Fatima, Nosheen; Zaman, Areeba; Zaman, Unaiza; Tahseen, Rabia

    2016-09-01

    For vasodilator stress, myocardial perfusion imaging (MPI) with at least 12-h caffeine abstinence is recommended, as it attenuates cardiovascular hyperemic response of adenosine and dipyridamole. However, many published conflicting results have shown no significant effect upon perfusion abnormalities in MPI performed without caffeine abstinence. The aim of this study was to compare the hemodynamic changes and negative predictive value (NPV) of normal MPIs with adenosine stress performed with or without caffeine abstinence. This was a prospective study that accrued 50 patients from May 2013 till September 2013 and followed till November 2014. These patients had a normal adenosine-gated MPI (GMPI) with technetium-99m methoxy isobutyl isonitrile ((99m)Tc-MIBI) after 12-h caffeine abstinence (no-caffeine). Next day, all patients had a repeat adenosine stress within 60 min after ingestion of a cup of coffee (about 80 mg of caffeine) followed by no MPI in 30 patients due to concern about radiation dose (prior-caffeine adenosine-no MPI; group A). Twenty patients opted for a repeat MPI (prior-caffeine adenosine-MPI; group B). Adenosine-induced hemodynamic response and NPV of the normal MPI with no-caffeine and prior-caffeine protocols were compared. The mean age of the study cohort was 57 ± 9 years with a male-to-female ratio of 76:24% and mean body mass index (BMI) of 26.915 ± 4.121 kg/m(2). Prevalence of hypertension, diabetes, dyslipidemia, and positive family history were 76%, 20%, 22%, and 17%, respectively. Comparison of group A with group B revealed no significant difference in demographic parameters, hemodynamic or electrocardiography (ECG) parameters, or left ventricular (LV) function parameters during adenosine intervention with prior-caffeine and no-caffeine protocols. During the follow-up, no fatal myocardial infarction (MI) was reported but 6 nonfatal MIs were reported based upon the history of short hospitalization for chest pain but without biochemical or

  17. Criteria for definition of regional functional improvement on quantitative post-stress gated myocardial SPET after bypass surgery in patients with ischaemic cardiomyopathy.

    PubMed

    Lee, Dong Soo; Cheon, Gi Jeong; Paeng, Jin Chul; Kim, Ki Bong; Chung, June-Key; Lee, Myung Chul

    2002-08-01

    Myocardial viability can be defined as functional improvement of dysfunctional myocardium after revascularization. The purpose of this study was to define the optimal criteria for definition of regional functional improvement after coronary artery bypass graft (CABG) surgery on quantitative gated single-photon emission tomography (SPET). Thirty-two patients (26 men, 6 women; age 56 +/- 13 years) with coronary artery disease (three-vessel disease, 17; two-vessel disease, 15; previous history of myocardial infarction, 9) and severe left ventricular dysfunction (LVEF < or = 35%) underwent CABG. Rest thallium-201/dipyridamole stress technetium-99m methoxyisobutylisonitrile gated myocardial SPET was performed before and 3 months after CABG. Global LV functional improvement was defined as either an improvement in LVEF of 10% ( n = 15) or an improvement in LVEF of 5% combined with a decrease in end-systolic volume of 10 ml ( n = 2) after CABG on quantitative gated SPET. Postoperative regional wall thickening improvement (DeltaRWT), regional wall motion improvement (DeltaRWM) and regional resting (DeltaRP) and stress perfusion improvement (DeltaRstrP) were used to determine global functional improvement by ROC curve analysis, and the optimal criteria for definition of viable regional dysfunctional myocardium were defined on the ROC curves. Correlations were verified by determining the number of improved myocardial regions and LVEF improvement. LVEF was improved from 25% +/- 6% to 34% +/- 11% after CABG. A total of 229 segments were dysfunctional (wall motion < or = 2 mm, thickening < or = 20%) before CABG. On ROC curve analysis using global functional improvement as an indicator of viability, the areas under the ROC curves (AUCs) of DeltaRWT and DeltaRWM were 0.717 and 0.620, respectively. The AUC of DeltaRWT was significantly larger than that of DeltaRWM ( P = 0.009) and the optimal cut-off value of DeltaRWT was 15%. The AUCs of DeltaRP and DeltaRstrP were not significant

  18. Investigation of optimal acquisition time of myocardial perfusion scintigraphy using cardiac focusing-collimator

    NASA Astrophysics Data System (ADS)

    Niwa, Arisa; Abe, Shinji; Fujita, Naotoshi; Kono, Hidetaka; Odagawa, Tetsuro; Fujita, Yusuke; Tsuchiya, Saki; Kato, Katsuhiko

    2015-03-01

    Recently myocardial perfusion SPECT imaging acquired using the cardiac focusing-collimator (CF) has been developed in the field of nuclear cardiology. Previously we have investigated the basic characteristics of CF using physical phantoms. This study was aimed at determining the acquisition time for CF that enables to acquire the SPECT images equivalent to those acquired by the conventional method in 201TlCl myocardial perfusion SPECT. In this study, Siemens Symbia T6 was used by setting the torso phantom equipped with the cardiac, pulmonary, and hepatic components. 201TlCl solution were filled in the left ventricular (LV) myocardium and liver. Each of CF, the low energy high resolution collimator (LEHR), and the low medium energy general purpose collimator (LMEGP) was set on the SPECT equipment. Data acquisitions were made by regarding the center of the phantom as the center of the heart in CF at various acquisition times. Acquired data were reconstructed, and the polar maps were created from the reconstructed images. Coefficient of variation (CV) was calculated as the mean counts determined on the polar maps with their standard deviations. When CF was used, CV was lower at longer acquisition times. CV calculated from the polar maps acquired using CF at 2.83 min of acquisition time was equivalent to CV calculated from those acquired using LEHR in a 180°acquisition range at 20 min of acquisition time.

  19. Biokinetics of radiolabeled Iodophenylpentadecanoic acid (I-123-IPPA) and thallium-201 in a rabbit model of chronic myocardial infarction measured using a series of thermoluminescent dosimeters

    NASA Astrophysics Data System (ADS)

    Medich, David Christopher

    1997-09-01

    The biokinetics of Iodophenylpentadecanoic acid (123I-IPPA) during a chronic period of myocardial infarction were determined and compared to 201Tl. IPPA was assessed as a perfusion and metabolic tracer in the scintigraphic diagnosis of coronary artery disease. The myocardial clearance kinetics were measured by placing a series of thermoluminescent dosimeters (TLDs) on normal and infarcted tissue to measure the local myocardial activity content over time. The arterial blood pool activity was fit to a bi-exponential function for 201Tl and a tri-exponential function for 123I-IPPA to estimate the left ventricle contribution to TLD response. At equilibrium, the blood pool contribution was estimated experimentally to be less than 5% of the total TLD response. The method was unable to resolve the initial uptake of the imaging agent due in part to the 2 minute TLD response integration time and in part to the 30 second lag time for the first TLD placement. A noticeable disparity was observed between the tracer concentrations of IPPA in normal and ischemic tissue of approximately 2:1. The fitting parameters (representing the biokinetic eigenvalue rate constants) were related to the fundamental rate constants of a recycling biokinetic model. The myocardial IPPA content within normal tissue was elevated after approximately 130 minutes post injection. This phenomenon was observed in all but one (950215) of the IPPA TLD kinetics curves.

  20. Validation of left ventricular function from gated single photon computed emission tomography by using a scintillator-photodiode camera: a dynamic myocardial phantom study.

    PubMed

    Kubo, N; Mabuchi, M; Katoh, C; Arai, H; Morita, K; Tsukamoto, E; Morita, Y; Tamaki, N

    2002-07-01

    A scintillator-photodiode camera is able to acquire single photon emission computed tomography (SPECT) images by using a rotating chair system. We validated the left ventricular (LV) parameters of this camera system utilizing a dynamic myocardial phantom. Gated myocardial SPECT of a dynamic myocardial phantom (Hokkaido University type; end diastolic volume (EDV), 143 ml; end systolic volume (ESV), 107 ml; ejection fraction (EF), 25%) was performed with this scintillation camera. LV parameters were calculated using pre-installed software (Mirage Myocardial Perfusion SPECT) (study 1) and the other software (QGS; Cedars-Sinai) (study 2). For comparison, SPECT from a traditional Anger camera were processed by the QGS software (study 3). The estimated volumes were similar among the three studies (EDV, 110+/-8 ml in study 1, 112+/-2 ml in study 2 and 111+/-1 ml in study 3; ESV, 86+/-8 ml in study 1, 93+/-4 ml in study 2 and 91+/-2 ml in study 3). The estimated EFs were 23+/-3%, 17+/-2%, and 18+/-1%, respectively. The calculated volume within each study was underestimated by approximately the same degree. However, each estimated EF value for each study was close to the actual value. The estimated LV function using the scintillator-photodiode camera system may be considered as a suitable alternative to the traditional Anger camera system.

  1. Optimal reproducibility of gated sestamibi and thallium myocardial perfusion study left ventricular ejection fractions obtained on a solid-state CZT cardiac camera requires operator input.

    PubMed

    Cherk, Martin H; Ky, Jason; Yap, Kenneth S K; Campbell, Patrina; McGrath, Catherine; Bailey, Michael; Kalff, Victor

    2012-08-01

    To evaluate the reproducibility of serial re-acquisitions of gated Tl-201 and Tc-99m sestamibi left ventricular ejection fraction (LVEF) measurements obtained on a new generation solid-state cardiac camera system during myocardial perfusion imaging and the importance of manual operator optimization of left ventricular wall tracking. Resting blinded automated (auto) and manual operator optimized (opt) LVEF measurements were measured using ECT toolbox (ECT) and Cedars-Sinai QGS software in two separate cohorts of 55 Tc-99m sestamibi (MIBI) and 50 thallium (Tl-201) myocardial perfusion studies (MPS) acquired in both supine and prone positions on a cadmium zinc telluride (CZT) solid-state camera system. Resting supine and prone automated LVEF measurements were similarly obtained in a further separate cohort of 52 gated cardiac blood pool scans (GCBPS) for validation of methodology and comparison. Appropriate use of Bland-Altman, chi-squared and Levene's equality of variance tests was used to analyse the resultant data comparisons. For all radiotracer and software combinations, manual checking and optimization of valve planes (+/- centre radius with ECT software) resulted in significant improvement in MPS LVEF reproducibility that approached that of planar GCBPS. No difference was demonstrated between optimized MIBI/Tl-201 QGS and planar GCBPS LVEF reproducibility (P = .17 and P = .48, respectively). ECT required significantly more manual optimization compared to QGS software in both supine and prone positions independent of radiotracer used (P < .02). Reproducibility of gated sestamibi and Tl-201 LVEF measurements obtained during myocardial perfusion imaging with ECT toolbox or QGS software packages using a new generation solid-state cardiac camera with improved image quality approaches that of planar GCBPS however requires visual quality control and operator optimization of left ventricular wall tracking for best results. Using this superior cardiac technology, Tl-201

  2. Diagnostic accuracy of gated Tc-99m sestamibi stress myocardial perfusion SPECT with combined supine and prone acquisitions to detect coronary artery disease in obese and nonobese patients.

    PubMed

    Berman, Daniel S; Kang, Xingping; Nishina, Hidetaka; Slomka, Piotr J; Shaw, Leslee J; Hayes, Sean W; Cohen, Ishac; Friedman, John D; Gerlach, James; Germano, Guido

    2006-01-01

    The diagnostic value of gated myocardial perfusion single-photon emission computed tomography (MPS) with combined supine and prone acquisitions to detect coronary artery disease (CAD) in obese and nonobese patients has not been defined. We studied 1511 patients without prior myocardial infarction or coronary revascularization who either had coronary angiography within 3 months of MPS (n = 785) or had a low pretest likelihood of CAD (n = 726). All patients underwent rest thallium 201/gated exercise or adenosine stress technetium 99m sestamibi MPS in both the supine and prone positions. According to body mass index (BMI), patients were categorized as normal weight (BMI of 18.5-24.9 kg/m2), overweight (BMI of 25.0-29.9 kg/m2), or obese (BMI > or = 30.0 kg/m2). There were no significant differences in stress, fixed, or ischemic defects among patients in different weight categories. The sensitivity of MPS was 85%, 86%, and 89% for detecting patients with 50% or greater coronary stenosis and 89%, 91%, and 92% for detecting those with 70% or greater coronary stenosis in the normal-weight, overweight, and obese groups, respectively. Normalcy rates were nearly identical among the 3 weight groups (99%, 98%, and 99%, respectively). Multivariate logistic regression analysis further confirmed that BMI was a nonsignificant predictor for the detection of CAD. In a subset of 290 patients, automated quantitative MPS analysis confirmed that combined supine and prone MPS increased specificity (86%) in identifying CAD, without a significant reduction in sensitivity (83% for > or = 50% stenosis and 88% for > or = 70% stenosis). The findings of this study suggest that MPS performed with gating and combined supine and prone acquisitions without attenuation correction had a similar diagnostic accuracy for the detection of CAD in normal-weight, overweight, and obese patients.

  3. Task-Based Evaluation of a 4D MAP-RBI-EM Image Reconstruction Method for Gated Myocardial Perfusion SPECT using a Human Observer Study

    PubMed Central

    Lee, Taek-Soo; Higuchi, Takahiro; Lautamäki, Riikka; Bengel, Frank M.; Tsui, Benjamin M. W.

    2015-01-01

    We evaluated the performance of a new 4D image reconstruction method for improved 4D gated myocardial perfusion (MP) SPECT using a task-based human observer study. We used a realistic 4D NURBS-based Cardiac-Torso (NCAT) phantom that models cardiac beating motion. Half of the population was normal; the other half had a regional hypokinetic wall motion abnormality. Noise-free and noisy projection data with 16 gates/cardiac cycle were generated using an analytical projector that included the effects of attenuation, collimator-detector response, and scatter (ADS), and were reconstructed using the 3D FBP without and 3D OS-EM with ADS corrections followed by different cut-off frequencies of a 4D linear post-filter. A 4D iterative maximum a posteriori rescaled-block (MAP-RBI)-EM image reconstruction method with ADS corrections was also used to reconstruct the projection data using various values of the weighting factor for its prior. The trade-offs between bias and noise were represented by the normalized mean squared error (NMSE) and averaged normalized standard deviation (NSDav), respectively. They were used to select reasonable ranges of the reconstructed images for use in a human observer study. The observers were trained with the simulated cine images and were instructed to rate their confidence on the absence or presence of a motion defect on a continuous scale. We then applied receiver operating characteristic (ROC) analysis and used the area under the ROC curve (AUC) index. The results showed that significant differences in detection performance among the different NMSE-NSDav combinations were found and the optimal trade-off from optimized reconstruction parameters corresponded to a maximum AUC value. The 4D MAP-RBI-EM with ADS correction, which had the best trade-off among the tested reconstruction methods, also had the highest AUC value, resulting in significantly better human observer detection performance when detecting regional myocardial wall motion

  4. Task-based evaluation of a 4D MAP-RBI-EM image reconstruction method for gated myocardial perfusion SPECT using a human observer study

    NASA Astrophysics Data System (ADS)

    Lee, Taek-Soo; Higuchi, Takahiro; Lautamäki, Riikka; Bengel, Frank M.; Tsui, Benjamin M. W.

    2015-09-01

    We evaluated the performance of a new 4D image reconstruction method for improved 4D gated myocardial perfusion (MP) SPECT using a task-based human observer study. We used a realistic 4D NURBS-based Cardiac-Torso (NCAT) phantom that models cardiac beating motion. Half of the population was normal; the other half had a regional hypokinetic wall motion abnormality. Noise-free and noisy projection data with 16 gates/cardiac cycle were generated using an analytical projector that included the effects of attenuation, collimator-detector response, and scatter (ADS), and were reconstructed using the 3D FBP without and 3D OS-EM with ADS corrections followed by different cut-off frequencies of a 4D linear post-filter. A 4D iterative maximum a posteriori rescaled-block (MAP-RBI)-EM image reconstruction method with ADS corrections was also used to reconstruct the projection data using various values of the weighting factor for its prior. The trade-offs between bias and noise were represented by the normalized mean squared error (NMSE) and averaged normalized standard deviation (NSDav), respectively. They were used to select reasonable ranges of the reconstructed images for use in a human observer study. The observers were trained with the simulated cine images and were instructed to rate their confidence on the absence or presence of a motion defect on a continuous scale. We then applied receiver operating characteristic (ROC) analysis and used the area under the ROC curve (AUC) index. The results showed that significant differences in detection performance among the different NMSE-NSDav combinations were found and the optimal trade-off from optimized reconstruction parameters corresponded to a maximum AUC value. The 4D MAP-RBI-EM with ADS correction, which had the best trade-off among the tested reconstruction methods, also had the highest AUC value, resulting in significantly better human observer detection performance when detecting regional myocardial wall motion

  5. Effects of propranolol and nifedipine on exercise-induced attack in patients variant angina: assessment by exercise thallium-201 myocardial scintigraphy with quantitative rotational tomography

    SciTech Connect

    Kugiyama, K.; Yasue, H.; Horio, Y.; Morikami, Y.; Fujii, H.; Koga, Y.; Kojima, A.; Takahashi, M.

    1986-08-01

    To examine the effects of propranolol and nifedipine on exercise-induced attack in patients with variant angina, exercise /sup 201/Tl myocardial scintigraphy with quantitative analysis by emission-computed tomography was performed in 20 patients with variant angina after oral propranolol (80 mg), nifedipine (20 mg), and placebo. Exercise-induced attack occurred in 11 patients on placebo, in 14 on propranolol, and in none on nifedipine. The exercise duration was significantly shorter in those on propranolol (p less than .05), but significantly longer in patients on nifedipine (p less than .05) than in those on placebo. The peak rate-pressure product was significantly lower in patients on propranolol (p less than .01), but did not change in those on nifedipine, as compared with that in patients on placebo. The size of the perfusion defect as measured by /sup 201/Tl tomography was significantly greater in patients on propranolol (p less than .05), but significantly less in those on nifedipine (p less than .01) than in those on placebo. In conclusion, propranolol does not suppress but rather may aggravate exercise-induced attack in patients with variant angina, while nifedipine suppresses it. This unfavorable effect of propranolol on exercise-induced attack in patients with variant angina is likely to be due to a reduction of regional myocardial blood flow.

  6. Motion-frozen Imaging by Gated Myocardial Perfusion Single Photon Emission Computed Tomography Using Multi-focus Fan Beam Collimator in Thallium-201 Study.

    PubMed

    Takahashi, Kaito; Takeuchi, Takashi; Hosokai, Yoshiyuki; Odagiri, Hayato; Saito, Haruo

    This study aimed to evaluate the statistical noise of motion-frozen (MF) image generated by gated myocardial perfusion single photon emission computed tomography (SPECT) imaging using IQ · SPECT and to determine the optimal acquisition and reconstruction parameters for MF image using IQ · SPECT. A movement cardiac phantom and static cardiac phantom were used to acquire the MF images. The acquisition times used were different in 8 and 16 frames per R-R interval, and varying reconstruction parameters (subset and iteration) were used. We determined the %CV value, contrast, and normalized mean square error (NMSE) to evaluate the image quality. The %CV value for a MF image with IQ · SPECT was lower than that for a conventional non-gated myocardial perfusion SPECT (MPS) image with low energy high resolution (LEHR). With regard to the acquisition parameters, the contrast did not change when the acquisition time was increased in 8 and 16 frames per R-R interval. NMSE converged in 56 beats/view in 8 frames per R-R interval. With regard to the reconstruction parameters, the contrast and the %CV value of the anterior and septal wall converged in update 40. The minimum NMSE in subsets 1, 2, and 3 were almost similar. Uniformity in the MF image with IQ · SPECT was higher than that in the conventional image. The results of this MF image with IQ · SPECT study suggest that the optimal acquisition parameter should be 56 beats/view in 8 frames per R-R interval, and the optimal reconstruction parameters should be subset 3 and iteration 14.

  7. Adenosine triphosphate stress 99mTc-methoxyisobutylisonitrile gated myocardial perfusion imaging efficacy in diagnosing stent restenosis following coronary stent implantation

    PubMed Central

    Zhang, Pengfei; Chen, Song; Li, Yang; Du, Qiuhong; Wang, Lijuan; Sun, Yingxian; Li, Yaming

    2016-01-01

    Coronary stent restenosis rate following implantation is considerably high. The adenosine stress gated myocardial perfusion imaging (G-MPI) method has been widely used in the diagnosis, risk stratification and prognosis evaluation of coronary heart disease; however, the high cost of adenosine limits its clinical application. The aim of the present study was to investigate the efficacy of adenosine triphosphate (ATP) stress 99mTc-methoxyisobutylisonitrile (99mTc-MIBI) G-MPI for diagnosis in-stent restenosis following coronary stent implantation. Data from 66 patients with typical angina pectoris symptoms who had undergone percutaneous coronary stent implantation >3 months prior to participation in the study were analyzed. All the patients underwent ATP stress 99mTc-MIBI G-MPI and coronary artery angiography as the criterion diagnostic standard within 1 month. The sensitivity, specificity, and accuracy of ATP stress 99mTc-MIBI G-MPI in the assessment of in-stent restenosis were calculated. In addition, Fisher's exact probability methods were used to compare differences between experimental groups. Among 66 patients with a total of 99 implanted coronary arterial branches, 39 patients (59%) with 45 coronary arteries (45%) presented in-stent restenosis. The diagnostic sensitivity, specificity, accuracy, positive predictive and negative predictive value of ATP stress 99mTc-MIBI G-MPI for assessing stent restenosis in all patients were 85, 89, 86, 92 and 80%, respectively. Similarly, these values in patients with myocardial infarction were 79, 88, 83, 88 and 78%, respectively, while in patients without myocardial infarction the values were 90, 91, 90, 95 and 83%, respectively. Therefore, the diagnostic efficacy of ATP stress 99mTc-MIBI G-MPI in patients without myocardial infarction was higher compared with those with myocardial infarction; however, no significant difference was observed between the two groups. Furthermore, the sensitivity, specificity and accuracy for

  8. Adenosine triphosphate stress (99m)Tc-methoxyisobutylisonitrile gated myocardial perfusion imaging efficacy in diagnosing stent restenosis following coronary stent implantation.

    PubMed

    Zhang, Pengfei; Chen, Song; Li, Yang; Du, Qiuhong; Wang, Lijuan; Sun, Yingxian; Li, Yaming

    2016-12-01

    Coronary stent restenosis rate following implantation is considerably high. The adenosine stress gated myocardial perfusion imaging (G-MPI) method has been widely used in the diagnosis, risk stratification and prognosis evaluation of coronary heart disease; however, the high cost of adenosine limits its clinical application. The aim of the present study was to investigate the efficacy of adenosine triphosphate (ATP) stress (99m)Tc-methoxyisobutylisonitrile ((99m)Tc-MIBI) G-MPI for diagnosis in-stent restenosis following coronary stent implantation. Data from 66 patients with typical angina pectoris symptoms who had undergone percutaneous coronary stent implantation >3 months prior to participation in the study were analyzed. All the patients underwent ATP stress (99m)Tc-MIBI G-MPI and coronary artery angiography as the criterion diagnostic standard within 1 month. The sensitivity, specificity, and accuracy of ATP stress (99m)Tc-MIBI G-MPI in the assessment of in-stent restenosis were calculated. In addition, Fisher's exact probability methods were used to compare differences between experimental groups. Among 66 patients with a total of 99 implanted coronary arterial branches, 39 patients (59%) with 45 coronary arteries (45%) presented in-stent restenosis. The diagnostic sensitivity, specificity, accuracy, positive predictive and negative predictive value of ATP stress (99m)Tc-MIBI G-MPI for assessing stent restenosis in all patients were 85, 89, 86, 92 and 80%, respectively. Similarly, these values in patients with myocardial infarction were 79, 88, 83, 88 and 78%, respectively, while in patients without myocardial infarction the values were 90, 91, 90, 95 and 83%, respectively. Therefore, the diagnostic efficacy of ATP stress (99m)Tc-MIBI G-MPI in patients without myocardial infarction was higher compared with those with myocardial infarction; however, no significant difference was observed between the two groups. Furthermore, the sensitivity, specificity and

  9. SIMULTANEOUS DUAL-RADIONUCLIDE MYOCARDIAL PERFUSION IMAGING WITH A SOLID-STATE DEDICATED CARDIAC CAMERA

    PubMed Central

    Ben-Haim, S.; Kacperski, K.; Hain, S.; Van Gramberg, D.; Hutton, B.F.; Waddington, W.A.; Sharir, T.; Roth, N.; Berman, D.S.; Ell, P.J.

    2011-01-01

    We compared simultaneous dual-radionuclide stress and rest myocardial perfusion imaging (MPI) with a novel solid-state cardiac camera and a conventional SPECT camera with separate stress and rest acquisitions. Methods 24 consecutive patients (64.5 ± 11.8 years, 16 men) were injected with 74 MBq of 201Tl (rest) and 250 MBq 99mTc-MIBI (stress). Conventional MPI acquisition times for stress and rest were 21 min and 16 min, respectively. A simultaneous dual-radionuclide (DR) 15 minute list mode gated acquisition was performed on D-SPECT (Spectrum-dynamics, Caesarea, Israel). The DR D-SPECT data were processed using a spillover and scatter correction method. We compared DR D-SPECT images with conventional SPECT images by visual analysis employing the 17-segment model and a 5-point scale (0=normal, 4=absent) to calculate the summed stress and rest scores (SSS and SRS, respectively) and the % visual perfusion defect (TPD) at stress and rest, by dividing the stress and rest scores, respectively, by 68 and multiplying by 100. TPD <5% was considered normal. Image quality was assessed on a 4-point scale (1=poor, 4=very good) and gut activity was assessed on a 4-point scale (0=none, 3=high). Results Conventional MPI was abnormal at stress in 17 patients and at rest in 9 patients. In the 17 abnormal stress studies DR D-SPECT MPI was abnormal in 113 vs. 93 abnormal segments by conventional MPI. In the nine abnormal rest studies DR D-SPECT was abnormal in 45 vs. 48 segments abnormal by conventional MPI. SSS, SRS, TPD stress and TPD rest on conventional SPECT and DR D-SPECT highly correlated (r=0.9790, 0.9694, 0.9784, 0.9710, respectively; p<0.0001 for all). In addition, 6 patients had significantly larger perfusion defects on DR D-SPECT stress images, including five of 11 patients who were imaged earlier on D-SPECT than conventional SPECT. Conclusion D-SPECT enables fast and high quality simultaneous DR MPI in a single imaging session with comparable diagnostic performance and

  10. Assessment of Heart Rate Recovery with GATED-Myocardial Perfusion Scintigraphy Outcome in Patients with Coronary Artery Disease: A Retrospective Study and Institutional Experience

    PubMed Central

    Tan, Yusuf Ziya; Özdemir, Semra; Altun, Burak; Çelik, Fatmanur

    2016-01-01

    Objective: This study aimed to investigate the effects of assessment with myocardial perfusion scintigraphy (MPS) and heart rate recovery (HRrec) measurements in combination to evaluate the current status of patients with a diagnosis or suspicion of coronary artery disease (CAD). Methods: A total of 350 patients were included in the study. CAD group consisted of 200 patients with stable angina pectoris and a known history of CAD, while the control group consisted of 150 patients with suspicious stress test who had no history of known CAD. In order to calculate the HRrec index, the treadmill exercise test was performed in all patients according to the Bruce protocol. The MPS results were evaluated for the presence or absence of myocardial ischemia and infarction by visual and quantitative (summed stress score and summed difference score) assessments. Results: When the MPS results and HRrec were evaluated together, there was no statistically significant difference in the non-CAD group. But, when GATED-MPS was evaluated alone in the triple-vessel patient group, 27 (36%) patients were found to be normal while evaluated with HRrec, four (5.3%) patients were found to be normal. Conclusion: HRrec measurements obtained during stress MPS is important in patient evaluation. Therefore, evaluation of MPS results and HRrec measurements together may provide a more accurate estimation of possible presence of CAD in patients. PMID:27751974

  11. The significance of post-stress decrease in left ventricular ejection fraction in patients undergoing regadenoson stress gated SPECT myocardial perfusion imaging.

    PubMed

    Gomez, Javier; Golzar, Yasmeen; Fughhi, Ibtihaj; Olusanya, Adebayo; Doukky, Rami

    2017-02-08

    The significance of post-stress decrease in left ventricular ejection fraction (LVEF) with regadenoson stress gated SPECT (GSPECT) myocardial perfusion imaging (MPI) has not been studied. Consecutive patients who underwent rest/regadenoson stress GSPECT-MPI followed by coronary angiography within 6 months were analyzed. Change in LVEF by GSPECT-MPI was calculated as stress LVEF minus rest LVEF; a significant decrease was tested at 5% and 10% thresholds. In a diagnostic cohort of 793 subjects, LVEF change was not predictive of severe/extensive coronary artery disease (area under the curve, 0.50; 95% confidence interval, 0.44-0.57; P = 0.946). There was no significant difference in the rates of severe/extensive coronary artery disease in patients with or without a decrease in LVEF, irrespective of MPI findings. In an outcome cohort of the 929 subjects followed for 30 ± 16 months, post-regadenoson stress decrease in LVEF was not associated with increased risk of the composite endpoint of cardiac death or myocardial infarction or in the risk of coronary revascularization. In patients selected to undergo coronary angiography following regadenoson stress GSPECT-MPI, a decrease in LVEF after regadenoson stress is not predictive of severe/extensive CAD or adverse clinical outcomes, irrespective of MPI findings.

  12. Sequential thallium-201 myocardial perfusion studies after successful percutaneous transluminal coronary artery angioplasty: delayed resolution of exercise-induced scintigraphic abnormalities

    SciTech Connect

    Manyari, D.E.; Knudtson, M.; Kloiber, R.; Roth, D.

    1988-01-01

    To characterize the sequential changes of myocardial perfusion scintigraphy in patients with coronary artery disease (CAD) after complete revascularization, 43 patients underwent exercise thallium-201 (/sup 201/Tl) myocardial perfusion scintigraphy before and at 9 +/- 5 days, 3.3 +/- 0.6, and 6.8 +/- 1.2 months after percutaneous transluminal coronary angioplasty (PTCA). Only patients with single-vessel CAD, without previous myocardial infarction, and without evidence of restenosis at 6 to 9 months after PTCA were included. Perfusion scans were analyzed blindly with the use of a new quantitative method to define regional myocardial perfusion in the topographic distribution of each coronary artery, which was shown to be reproducible (r = .94 or higher and SEE of 7% or less, between repeated measures by one and two operators). At 4 to 18 days after PTCA, the mean treadmill walking time increased by 123 +/- 42 sec, mean exercise-induced ST segment depression decreased by 0.6 +/- 0.3 mm, group maximal heart rate increased by 20 +/- 9 beats/min, and group systolic blood pressure at peak exercise increased by 24 +/- 10 mm Hg, compared with pre-PTCA values (p less than .001). However, no group differences were noted in these variables between the three post-PTCA stages. Myocardial perfusion in the distribution of the affected (dilated) coronary artery, on the other hand, improved progressively. In the 45 degree left anterior oblique view for instance, myocardial perfusion increased at 9 days after PTCA (from 68 +/- 24% before PTCA to 91 +/- 9%, p less than .001) and at 3.3 months after PTCA (101 +/- 8%, p less than .05 vs 9 days after PTCA), but no further significant changes were seen at 6.8 months after PTCA (102 +/- 8%). Similar changes were noted in the other two views. No relationship between minor complications during PTCA and delayed improvement on the /sup 201/Tl was observed.

  13. Measurement of left ventricular ejection fraction using gated 99mTc-sestamibi myocardial planar images: Comparison to contrast ventriculography

    SciTech Connect

    Parker, D.A.; Lloret, R.L.; Barilla, F.; Douthat, L.; Gheorghiade, M. )

    1991-01-01

    Using the new myocardial perfusion agent 99mTc-sestamibi and multigated acquisition on a nuclear medicine gamma camera, the left ventricular ejection fraction (LVEF) was derived in 13 patients with coronary artery disease (CAD). Cross-sectional activity profiles were used to measure the left ventricle from end-diastolic and end-systolic images. Several different geometric methods were then utilized to derive ejection fractions from the nuclear data. Comparison of the resultant ejection fractions to those obtained from contrast ventriculography showed significant correlation for all geometric methods (P less than 0.01, Sy X x = 6.2 to 9.6). The authors conclude that in patients with CAD one or more of these simple geometric methods can provide a useful estimate of the LVEF when performing 99mTc-sestamibi multigated myocardial perfusion imaging.

  14. [Interest in myocardial scintigraphy following the arterial switch procedure for transposition of the great vessels].

    PubMed

    Acar, P; Maunoury, C; Bonnet, D; Sébahoun, S; Bonhoeffer, P; Hallaj, I; Aggoun, Y; Iserin, F; Sidi, D; Kachaner, J

    2001-05-01

    Coronary artery obstruction is the main late complication of the so-called arterial switch operation designed to repair transpositions of the great arteries in newborn infants by switching the great vessels and transferring the coronary ostia onto the posterior vessel. Our aim was to study the links between myocardial perfusion and coronary artery anatomy after the arterial switch operation. Forty-five patients (5.863 years) underwent a 201Tl myocardial SPECT and a selective coronary artery angiography. The latter was normal in 20 children: 13 had also a normal myocardial scan but 7 had myocardial perfusion defects including 2 with angina who had a very low coronary reserve at positron emission tomography. Twenty-five patients had severe coronary artery lesions: 5 with a normal myocardial scan and 20 with perfusion defects. Twelve out of these 20 underwent surgical revascularization and the SPECT images went back to normal in all within 6 months after surgery. Specificity and sensitivity of myocardial SPECT in detecting coronary artery lesions were 78% and 69% whereas positive and negative predictive values were 74 and 73%. We conclude that myocardial SPECT imaging is not the right way to detect late post arterial switch coronary artery lesions. It is helpful in decision making as to submit these children to surgical revascularization and in assessing its postoperative effectiveness.

  15. Modulation of Mononuclear Phagocyte Inflammatory Response by Liposome-Encapsulated Voltage Gated Sodium Channel Inhibitor Ameliorates Myocardial Ischemia/Reperfusion Injury in Rats

    PubMed Central

    Ji, Wen-Jie; Zhang, Li; Dong, Yan; Ge, Lan; Lu, Rui-Yi; Sun, Hai-Ying; Guo, Zao-Zeng; Yang, Guo-Hong; Jiang, Tie-Min; Li, Yu-Ming

    2013-01-01

    Background Emerging evidence shows that anti-inflammatory strategies targeting inflammatory monocyte subset could reduce excessive inflammation and improve cardiovascular outcomes. Functional expression of voltage-gated sodium channels (VGSCs) have been demonstrated in monocytes and macrophages. We hypothesized that mononuclear phagocyte VGSCs are a target for monocyte/macrophage phenotypic switch, and liposome mediated inhibition of mononuclear phagocyte VGSC may attenuate myocardial ischemia/reperfusion (I/R) injury and improve post-infarction left ventricular remodeling. Methodology/Principal Findings Thin film dispersion method was used to prepare phenytoin (PHT, a non-selective VGSC inhibitor) entrapped liposomes. Pharmacokinetic study revealed that the distribution and elimination half-life of PHT entrapped liposomes were shorter than those of free PHT, indicating a rapid uptake by mononuclear phagocytes after intravenous injection. In rat peritoneal macrophages, several VGSC α subunits (NaV1.1, NaV1.3, NaV1.4, NaV1.5, NaV1.6, NaV1.7, NaVX, Scn1b, Scn3b and Scn4b) and β subunits were expressed at mRNA level, and PHT could suppress lipopolysaccharide induced M1 polarization (decreased TNF-α and CCL5 expression) and facilitate interleukin-4 induced M2 polarization (increased Arg1 and TGF-β1 expression). In vivo study using rat model of myocardial I/R injury, demonstrated that PHT entrapped liposome could partially suppress I/R injury induced CD43+ inflammatory monocyte expansion, along with decreased infarct size and left ventricular fibrosis. Transthoracic echocardiography and invasive hemodynamic analysis revealed that PHT entrapped liposome treatment could attenuate left ventricular structural and functional remodeling, as shown by increased ejection fraction, reduced end-systolic and end-diastolic volume, as well as an amelioration of left ventricular systolic (+dP/dtmax) and diastolic (-dP/dtmin) functions. Conclusions/Significance Our work for the

  16. IQ-SPECT for thallium-201 myocardial perfusion imaging: effect of normal databases on quantification.

    PubMed

    Konishi, Takahiro; Nakajima, Kenichi; Okuda, Koichi; Yoneyama, Hiroto; Matsuo, Shinro; Shibutani, Takayuki; Onoguchi, Masahisa; Kinuya, Seigo

    2017-07-01

    Although IQ-single-photon emission computed tomography (SPECT) provides rapid acquisition and attenuation-corrected images, the unique technology may create characteristic distribution different from the conventional imaging. This study aimed to compare the diagnostic performance of IQ-SPECT using Japanese normal databases (NDBs) with that of the conventional SPECT for thallium-201 ((201)Tl) myocardial perfusion imaging (MPI). A total of 36 patients underwent 1-day (201)Tl adenosine stress-rest MPI. Images were acquired with IQ-SPECT at approximately one-quarter of the standard time of conventional SPECT. Projection data acquired with the IQ-SPECT system were reconstructed via an ordered subset conjugate gradient minimizer method with or without scatter and attenuation correction (SCAC). Projection data obtained using the conventional SPECT were reconstructed via a filtered back projection method without SCAC. The summed stress score (SSS) was calculated using NDBs created by the Japanese Society of Nuclear Medicine working group, and scores were compared between IQ-SPECT and conventional SPECT using the acquisition condition-matched NDBs. The diagnostic performance of the methods for the detection of coronary artery disease was also compared. SSSs were 6.6 ± 8.2 for the conventional SPECT, 6.6 ± 9.4 for IQ-SPECT without SCAC, and 6.5 ± 9.7 for IQ-SPECT with SCAC (p = n.s. for each comparison). The SSS showed a strong positive correlation between conventional SPECT and IQ-SPECT (r = 0.921 and p < 0.0001), and the correlation between IQ-SPECT with and without SCAC was also good (r = 0.907 and p < 0.0001). Regarding diagnostic performance, the sensitivity, specificity, and accuracy were 80.8, 78.9, and 79.4%, respectively, for the conventional SPECT; 80.8, 80.3, and 82.0%, respectively, for IQ-SPECT without SCAC; and 88.5, 86.8, and 87.3%, respectively, for IQ-SPECT with SCAC, respectively. The area under the curve obtained via receiver operating

  17. [Obtaining myo-cardial perfusion images synchronized with the ECG (gated-SPEC) after injecting MIBI during exertion: comparative study with echocardiography in 95 patients for the assessment of left ventricular function].

    PubMed

    Fraile, M; Pereferrer, D; Luque, M T; Larrouse, E; Rubio, L; Valle, V; Riba, J

    1998-01-01

    Technical innovation has recently resulted in the routine use of gated-SPECT in myocardial perfusion imaging. In the present work we compare estimates of left ventricular function (LV cavity) by gated-SPECT with those of conventional echocardiography in a group of 95 ischemic patients, 49 of whom had previous myocardial infarction. Kappa analysis showed correlation coefficients of 0.67 for global function in the whole group and of 0.68 in patients with MI, as well as of 0.56 in the anterior wall, and 0.55 in the inferior wall. With these data, we believe that the technique is useful and it adds to the conventional perfusion SPECT imaging. Also, it is conveniently validated against echocardiography in our hands.

  18. Higher events rate in patients with a normal gated myocardial perfusion imaging with dipyridamole than exercise: “Run for reliability”

    PubMed Central

    Fatima, Nosheen; uz Zaman, Maseeh; Ishaq, Mohd; Rasheed, S Zahed; Baloch, Dad J; Wali, Asif; Bano, Javeria; Rehman, Kawish

    2012-01-01

    Objective: The aim of this is to evaluate the negative predictive value (NPV) of a normal gated myocardial perfusion imaging (NGMPI) with exercise and dipyridamole in a propensity matched population. Materials and Methods: This is a prospective study conducted at Nuclear Cardiology Department of Karachi Institute of Heart Diseases, Karachi from December 2008 until June 2010. A total of 809 patients with a NGMPI with adequate exercise (558/809) or dipyridamole (251/809) stress were included and followed-up for 12-30 months (mean 24 ± 3 months) for fatal or non-fatal myocardial infarctions (MI). Results: Mean ejection fraction (%), end diastolic volume (ml), and end systolic volume (ml) in exercise and dipyridamole cohorts were (72 ± 08, 66 ± 11), (68 ± 13, 81 ± 17), and (19 ± 11, 26 ± 12) respectively. On follow-up, in dipyridamole cohort 2 fatal and 6 non-fatal MIs were reported. While in exercise cohort only 2 non-fatal MIs were reported. The NPV of a NGMPI with exercise was 99.7% (95% confidence interval [CI] 98.93-99.96%) with an event rate of 0.3% (95% CI; 0.03-0.6%) and annualized event rate of 0.15%. The NPV of NGMPI with dipyridamole was 96.80% (95% CI; 2.2-4.3%) with an event rate of 3.2% (95% CI; 1.39-3.83%) and annualized event rate of approximately 1.6%. Event free survival for dipyridamole group was significantly lower than exercise analyzed by Log-rank test (14.509, P < 0.001). Conclusion: A NGMPI with dipyridamole stress has higher event rate (low-NPV) as compared with exercise and this raises concern over its credibility to label these patients into low-risk group. PMID:23919070

  19. Regional wall thickening of left ventricle evaluated by gated positron emission tomography in relation to myocardial perfusion and glucose metabolism

    SciTech Connect

    Yamashita, K.; Tamaki, N.; Yonekura, Y.; Ohtani, H.; Magata, Y.; Nohara, R.; Kambara, H.; Kawai, C.; Ban, T.; Konishi, J. )

    1991-04-01

    Regional wall thickening was assessed by electrocardiographically gated positron emission tomography (ECG-gated PET) in 26 patients with coronary artery disease. The standardized percent count increase from end-diastole to end-systole (S-percent Cl) was calculated as an index of wall thickening. The S-percent Cl was 77.8% +/- 28.9% in the segments with normal perfusion at rest, 51.9% +/- 29.5% in those with mild hypoperfusion, and 32.8% +/- 30.9% in those with severe hypoperfusion (p less than 0.001, each). Among the segments with resting hypoperfusion, the S-percent Cl was 38.9% +/- 31.5% in those without stress-induced ischemia and 48.7% +/- 30.9% in those with ischemia (p less than 0.05). Furthermore, among resting severe hypoperfusion, the S-percent Cl was 23.0% +/- 23.9% in the segments without fluorine-18-fluorodeoxyglucose (FDG) uptake and 37.8 +/- 32.9% in those with FDG uptake (p less than 0.05). These results suggest that stress-induced ischemia and FDG accumulation correlated with wall thickening. Thus, quantitative analysis of regional wall thickening seems to be useful for combined analysis of regional function, perfusion and metabolism in coronary patients.

  20. Myocardial scintigraphy with 201thallium in pediatric cardiology: A review of 52 cases

    SciTech Connect

    Bjoerkhem, G.E.; Evander, E.; White, T.; Lundstroem, N.R. )

    1990-01-01

    We report our experience of myocardial scintigraphy with 201thallium (201Tl) in 52 children, aged 4 days to 18 years, in which 80 studies were made primarily to demonstrate or exclude impaired myocardial perfusion. For analysis, the patients were divided into the following eight groups: group I, coronary artery malformations (five patients); group II, Kawasaki's syndrome (six patients); group III, arterial switch operation (seven patients); group IV, dilated cardiomyopathy (18 patients); group V, hypertrophic cardiomyopathy (four patients); group VI, myocardial dysfunction after surgery for congenital heart disease (five patients); group VII, pulmonary atresia (three patients); and group VIII, miscellaneous (four patients). Myocardial scintigraphy was performed with a planar or tomographic technique at rest or after exercise (four patients). Isotope-uptake defects, indicating impaired myocardial perfusion, were present in 14 patients, including small infants. Defects were seen in all groups except those with hypertrophic cardiomyopathy and pulmonary atresia. The absence of such defects in several of the patients with Kawasaki's syndrome was particularly valuable as it made coronary angiography unnecessary. In the other groups of patients myocardial scintigraphy was a valuable adjunct to other investigations.

  1. In-vivo regional myocardial perfusion measurements in a porcine model by ECG-gated multislice computed tomography

    NASA Astrophysics Data System (ADS)

    Stantz, Keith M.; Liang, Yun; Meyer, Cristopher A.; Teague, Shawn; Stecker, Michael; Hutchins, Gary; McLennan, Gordon; Persohn, Scott

    2003-05-01

    Purpose: To evaluate whether functional multi-slice computed tomography (MSCT) can identify regional areas of normally perfused and ischemic myocardium in a porcine model. Material and Methods: Three out bred pigs, two of which had ameroids surgically implanted to constrict flow within the LAD and LCx coronary arteries, were injected with 25 mL of iopromide (Isovue) at a rate of 5 mL/second via the femoral or jugular vein. Sixty axial scans along the short axis of the heart was acquired on a 16-slice CT scanner (Philips MX8000-IDT) triggered at end-diastole of the cardiac cycle and acquiring an image within 270 msec. A second series of scans were taken after an intravenous injection of a vasodilator, 150 μg/kg/min of adenosine. ROIs were drawn around the myocardial tissue and the resulting time-density curves were used to extract perfusion values. Results: Determination of the myocardial perfusion and fractional blood volume implementing three different perfusion models. A 5-point averaging or 'smoothing' algorithm was employed to effectively filter the data due to its noisy nature. The (preliminary) average perfusion and fractional blood volume values over selected axial slices for the pig without an artificially induced stenosis were measured to be 84 +/- 22 mL/min/100g-tissue and 0.17 +/- 0.04 mL/g-tissue, the former is consistent with PET scan and EBCT results. The pig with a stenosis in the left LAD coronary artery showed a reduced global perfusion value -- 45 mL/min/100g-tissue. Correlations in regional perfusion values relative to the stenosis were weak. During the infusion of adenosine, averaged perfusion values for the three subjects increased by 46 (+/-45) percent, comparable to increases measured with PET. Conclusion: Quantifying global perfusion values using MDCT appear encouraging. Future work will focus resolving the systematic effects from noise due to signal fluctuation from the porcine tachyardia (80-93 BPM) and provide a more robust measurement

  2. Development and validation of an automatic method to detect the latest contracting viable left ventricular segments to assist guide CRT therapy from gated SPECT myocardial perfusion imaging.

    PubMed

    Zhou, Weihua; Tao, Ningchao; Hou, Xiaofeng; Wang, Yao; Folks, Russell D; Cooke, David C; Moncayo, Valeria M; Garcia, Ernest V; Zou, Jiangang

    2017-03-28

    The purpose of this study is to use ECG-gated SPECT MPI to detect the latest contracting viable left ventricular (LV) segments to help guide the LV probe placement used in CRT therapy and to validate segment selection against the visual integration method by experts. For each patient, the resting ECG-gated SPECT MPI short-axis images were sampled in 3D to generate a polar map of the perfusion distribution used to determine LV myocardial viability, and to measure LV synchronicity using our phase analysis tool. In the visual integration method, two experts visually interpreted the LV viability and mechanical dyssynchrony from the short-axis images and polar maps of viability and phase, to determine the latest contracting viable segments using the 17-segment model. In the automatic method, the apical segments, septal segments, and segments with more than 50% scar were excluded as these are not candidates for CRT LV probe placement. Amongst the remaining viable segments, the segments, whose phase angles were within 10° of the latest phase angle (the most delayed contracting segment), were identified for potential CRT LV probe placement and ranked based on the phase angles of the segments. Both methods were tested in 36 pre-CRT patients who underwent ECG-gated SPECT MPI. The accuracy was determined as the percent agreement between the visual integration and automatic methods. The automatic method was performed by a second independent operator to evaluate the inter-operator processing reproducibility. In all the 36 patients, the LV lead positions of the 1st choices recommended by the automatic and visual integration methods were in the same segments in 35 patients, which achieved an agreement rate of 97.2%. In the inter-operator reproducibility test, the LV lead positions of the 1st choices recommended by the two operators were in the same segments in 25 patients, and were in the adjacent segments in 7 patients, which achieved an overall agreement of 88.8%. An automatic

  3. Detection of residual jeopardized myocardium 3 weeks after myocardial infarction by exercise testing with thallium-201 mycardial scintigraphy

    SciTech Connect

    Turner, J.D.; Schwartz, K.M.; Logic, J.R.; Sheffield, L.T.; Kansal, S.; Roitman, D.I.; Mantle, J.A.; Russell, R.O.; Rackley, C.E.; Rogers, W.J.

    1980-04-01

    The usefulness of thallium-201 (Tl-201) exercise myocardial scintigraphy in identifying patients with multivessel coronary artery disease (MVCAD) and residual jeopardized myocardium after myocardial infarction (MI) was evaluated in 32 patients 3 weeks after MI. All patients underwent (1) limited multilead submaximal treadmill testing, (2) thallium-201 (Tl) myocardial scintigraphy at end-exercise and at rest, and (3) coronary and left ventricular angiography. Tl-201 perfusion defects were categorized as either reversible (ischemia) or irreversible (scar). The conventional exercise test was designated positive if there was ST depression > = 1mm and/or angina. Jeopardized myocardium (JEP) was defined angiographically as a segment of myocardium with normal or hypokinetic wall motion supplied by a significantly stenotic major coronary artery. MVCAD was defined as two or more significantly stenotic coronary arteries. Significant coronary stenosis was categorized as either 50 to 69% diameter narrowing or > = 70% diameter narrowing, thereby yielding, respectively, two subgroups each of jeopardized myocardium (JEP-50 and JEP-70) and MVCAD (MV-50 and MV-70). Clinical findings of angina, heart failure or ventricular arrhythmias during the late convalescent period after MI occurred in four of 10 patients (40%) with MV-50, five of 16 (31%) with MV-70, four of 10 (40%) with JEP-50 and five of 18 (28%) with JEP-70, and thus were insensitive for detecting MVCAD and JEP. Reversible ischemia and/or a positive conventional exercise test occurred in five of 10 patients (50%) with MV-50, 13 of 16 (81%) with MV-70, four of 10 (40%) with JEP-50 and 15 of 18 (83%) with JEP-70. All eight patients with both Tl-201 reversible ischemia and a positive conventional exercise test had JEP-70. In 30 of 31 patients (97%) with angiographic asynergy, Tl-201 scar was detected. No complications were associated with exercise testing.

  4. AKAP150 participates in calcineurin/NFAT activation during the down-regulation of voltage-gated K(+) currents in ventricular myocytes following myocardial infarction.

    PubMed

    Nieves-Cintrón, Madeline; Hirenallur-Shanthappa, Dinesh; Nygren, Patrick J; Hinke, Simon A; Dell'Acqua, Mark L; Langeberg, Lorene K; Navedo, Manuel; Santana, Luis F; Scott, John D

    2016-07-01

    The Ca(2+)-responsive phosphatase calcineurin/protein phosphatase 2B dephosphorylates the transcription factor NFATc3. In the myocardium activation of NFATc3 down-regulates the expression of voltage-gated K(+) (Kv) channels after myocardial infarction (MI). This prolongs action potential duration and increases the probability of arrhythmias. Although recent studies infer that calcineurin is activated by local and transient Ca(2+) signals the molecular mechanism that underlies the process is unclear in ventricular myocytes. Here we test the hypothesis that sequestering of calcineurin to the sarcolemma of ventricular myocytes by the anchoring protein AKAP150 is required for acute activation of NFATc3 and the concomitant down-regulation of Kv channels following MI. Biochemical and cell based measurements resolve that approximately 0.2% of the total calcineurin activity in cardiomyocytes is associated with AKAP150. Electrophysiological analyses establish that formation of this AKAP150-calcineurin signaling dyad is essential for the activation of the phosphatase and the subsequent down-regulation of Kv channel currents following MI. Thus AKAP150-mediated targeting of calcineurin to sarcolemmal micro-domains in ventricular myocytes contributes to the local and acute gene remodeling events that lead to the down-regulation of Kv currents.

  5. Examining a hypothetical quantitative model for better approximation of culprit coronary artery and site of stenosis on 99mTc-sestamibi gated myocardial perfusion SPECT.

    PubMed

    Pal, Sushanta; Sen, Srabani; Das, Debasis; Basu, Sandip

    2016-10-01

    A hypothetical quantitative model of analyzing gated myocardial perfusion SPECT is proposed and examined for the feasibility of its use as a predictor of diseased coronary artery and approximating the site of stenosis to determine whether it could serve as a useful noninvasive complement for coronary angiography. The extent and severity of perfusion defects on rest gated myocardial perfusion imaging SPECT-images were assessed on a five-point scale in a standard 17-segment model and total perfusion deficit was quantified by automated software. The first step was to locate the diseased coronary artery using a quantitative method: for this, the score of each segment belonging to a particular coronary artery was determined using a systematic presumptive approach. After determination of specific coronary artery segments, the scores of the contiguous segments in three short axis slices (apical, middle, and basal) were summed for six subdivisions (anterior, anterolateral, inferolateral, inferior, anteroseptal, and inferoseptal). The site of stenosis was determined from (a) the initial approximation of the involved segments with a defect score of 2-4 and (b) subsequent calculation of the defect score of each of the six subdivisions and allocating the site through a preassigned number for each coronary artery. For each coronary artery, only the subdivision with the highest defect score was considered. Proximal, middle, and distal segments of left anterior descending artery (LAD) were considered to be represented when the summed value of a subdivision within a particular arterial territory was more than or equal to 7, between 5 and 7, 5 and 3, respectively. For the left circumflex and right coronary artery, summed scores (of respective subdivisions) of more than or equal to 5 and between 3 and 5 were preassigned to proximal and distal stenosis, respectively. The results were then correlated with the coronary angiographic data. On coronary angiography, proximal LAD occlusion

  6. The relationship between ischemia-induced left ventricular dysfunction, coronary flow reserve, and coronary steal on regadenoson stress-gated 82Rb PET myocardial perfusion imaging

    PubMed Central

    Van Tosh, Andrew; Votaw, John R.; Reichek, Nathaniel; Palestro, Christopher J.; Nichols, Kenneth J.

    2014-01-01

    Background Gated rubidium-82 (82Rb) positron emission tomography (PET) imaging studies are acquired both at rest and during pharmacologic stress. Stress-induced ischemic left ventricular dysfunction (LVD) can produce a significant decrease in left ventricular ejection fraction (LVEF) from rest to stress. We determined the prevalence on PET of stress LVD with reduced ejection fraction (EF) and its association with absolute global and regional coronary flow reserve (CFR), and with relative perfusion defect summed difference score (SDS). Methods and Results We studied 205 patients with known or suspected coronary disease (120 M, 75 F, age 69 ± 13 years) who had clinically indicated rest/regadenoson stress 82Rb PET/CT studies. Data were acquired in dynamic gated list mode. Global and 17-segment regional CFR values were computed from first-pass flow data using a 2-compartment model and factor analysis applied to auto-generated time-activity curves. Rest and stress LVEF and SDS were quantified from gated equilibrium myocardial perfusion tomograms using Emory Cardiac Toolbox software. LVD was defined as a change in LVEF of ≤−5% from rest to stress. A subgroup of 109 patients also had coronary angiography. Stress LVD developed in 32 patients (16%), with mean EF change of −10 ± 5%, vs +6 ± 7% for patients without LVD (P < .0001). EF was similar at rest in patients with and without stress LVD (57 ± 18% vs 56 ± 16%, P = .63), but lower during stress for patients with LVD (47 ± 20% vs 61 ± 16%, P = .0001). CFR was significantly lower in patients with LVD (1.61 ± 0.67 vs 2.21 ± 1.03, Wilcoxon P = .002), and correlated significantly with change in EF (r = 0.35, P < .0001), but not with SDS (r = −0.13, P = .07). The single variable most strongly associated with high risk of CAD (i.e., left main stenosis ≥50%, LAD % stenosis ≥70%, and/or 3-vessel disease) was stress EF (χ2 = 17.3, P < .0001). There was a higher prevalence of patients with territorial CFR

  7. The effect of relaxing music on heart rate and heart rate variability during ECG GATED-myocardial perfusion scintigraphy.

    PubMed

    Tan, Yusuf Ziya; Ozdemir, Semra; Temiz, Ahmet; Celik, Fatmanur

    2015-05-01

    The positive changes in human behavior caused by relaxing music demonstrate the psychological effect of music on human body. A meta-analytical study has shown that relaxing music affects blood pressure and heart rate in coronary heart patients and cancer patients. The aim of our study is to research whether there is a significant effect on heart rate and heart rate variability due to listening to relaxing music during ECG GATED MPS imaging under gamma camera. The music group (n = 50 patients) could choose from 15 different musical types including folk music (no lyric). The other 50 patients were placed in a "no music group" and did not get headphones or any music. There was a statistically significant reduction in the heart rate of patients in the music group compared to those in the control group. Relaxing music provides great benefits to both patient and clinician. There is close relationship between relaxing music and health procedure, can use every area of the health noninvasiv, safe, cheap and is a method don't have side effect. Copyright © 2015 Elsevier Ltd. All rights reserved.

  8. Precordial ST-segment depression during acute inferior myocardial infarction: clinical, scintigraphic and angiographic correlations

    SciTech Connect

    Gibson, R.S.; Crampton, R.S.; Watson, D.D.; Taylor, G.J.; Carabello, B.A.; Holt, N.D.; Beller, G.A.

    1982-10-01

    The cause and associated pathophysiology of precordial ST-segment depression during acute inferior myocardial infarction (IMI) are controversial. To investigate this problem, electrocardiographic findings in 48 consecutive patients with acute IMI were prospectively compared with results of coronary angiography, submaximal exercise thallium-201 (/sup 201/Tl) scintigraphy and multigated blood pool imaging, all obtained 2 weeks after IMI, and with clinical follow-up at 3 months. Patients were classified according to the admission ECG obtained 3.3 +/- 3.1 hours after the onset of chest pain. Twenty-one patients (group A) had no or <1.0 mm ST-segment depression, and 27 (group B) had greater than or equal to1.0 mm ST-segment depression in two or more precordial (V/sub 1-6/) leads. Patients in group B had more prolonged chest pain after admission to the coronary care unit than those in group A (2.8 +/- 3.0 vs 1.2 +/- 1.1 hours, p<0.03), greater summed ST-segment elevation in leads II, III, aV/sub F/ (6.7 +/- 4.7 vs 3.3 +/- 4.5 mm, p<0.02), higher plasma peak creatine kinase levels (1133 +/- 781 vs 653 +/- 482 IU/l, p<0.01), a higher prevalence of ''true posterior'' infarction by ECG criteria (26% vs 5%, p<0.05), a lower radionuclide ejection fraction (46 +/- 9% vs 54 +/- 6%, p<0.001), more extensive infarct-related asynergy (p<0.001) and /sup 201/Tl perfusion abnormalities (p<0.01), more complications during hospitalization (p<0.03), and more cardiac events at 3 months (p<0.02). There were no significant differences between group A and group B in the extent of underlying coronary disease, prevalence of left anterior descending coronary artery disease, exercise-induced ST-segment depression or angina, /sup 201/Tl defects or wall motion abnormalities in anterior or septal segments.

  9. Effect of eating on thallium-201 myocardial redistribution after myocardial ischemia

    SciTech Connect

    Angello, D.A.; Wilson, R.A.; Palac, R.T.

    1987-09-01

    To determine whether eating a high-carbohydrate meal between initial and delayed postexercise thallium-201 (Tl-201) imaging affects detection of Tl-201 redistribution during exercise stress testing, 16 patients with stable angina performed 2 Tl-201 treadmill exercise stress tests within a 14-day interval. Immediately after initial postexercise imaging, patients either drank a commercially available instant breakfast preparation for the intervention test or drank an equivalent volume of water for the control test. Comparable exercise workloads were achieved by exercising patients to the same heart rate for both tests. The order of the 2 (intervention and control) tests were randomized. All patients had at least 1 region of Tl-201 myocardial redistribution on either their eating or control test scans, although only 7 of the 16 had positive treadmill exercise test responses. Forty-six regions showing Tl-201 myocardial redistribution were identified in all 144 regions examined. Significantly more of these regions were identified on control test scans than on eating test scans: 11 of 46 on both test scans, 6 of 46 only on eating test scans and 29 of 46 only on control scans (p less than 0.001). Consistent with results of the quantitative regional analysis, the percentage of Tl-201 clearance over 4 hours in the 46 Tl-201 myocardial redistribution regions was 39 +/- 8% for the eating tests and 29 +/- 8% for control tests (mean +/- standard deviation, p less than 0.003). In 4 patients diagnosis of transient ischemia would have been missed because their 14 Tl-201 myocardial redistribution regions were detected only on the control test scans.

  10. Thallium-201 myocardial SPECT in a patient with mirror-image dextrocardia and left bundle branch block.

    PubMed

    Turgut, Bülent; Kitapci, Mehmet T; Temiz, N Hakan; Unlü, Mustafa; Erselcan, Taner

    2003-09-01

    A 53-year-old male patient with a previous diagnosis of situs inversus with mirror-image dextrocardia underwent thallium-201 (Tl-201) stress-redistribution myocardial perfusion single photon emission computed tomography (SPECT). Electrocardiogram (ECG) obtained on right hemithorax revealed constant complete left bundle branch block. Tl-201 stress-redistribution SPECT images revealed abnormal perfusion with reversible ischemia in the anteroseptal, septal and inferoseptal walls. Coronary angiography performed 1 month after SPECT study was normal. This case illustrates that false positive reversible perfusion defects can be seen in patients with mirror-image dextrocardia associated with constant complete left bundle branch block. To our knowledge, this is the first reported case of mirror-image dextrocardia and constant complete left bundle branch block with false positive Tl-201 SPECT findings.

  11. Association between aortic valve calcification and myocardial ischemia, especially in asymptomatic patients.

    PubMed

    Yamazato, Ryo; Yamamoto, Hideya; Tadehara, Futoshi; Teragawa, Hiroki; Kurisu, Satoshi; Dohi, Yoshihiro; Ishibashi, Ken; Kunita, Eiji; Utsunomiya, Hiroto; Oka, Toshiharu; Kihara, Yasuki

    2012-08-01

    Aortic valve calcification (AVC) is recognized as a manifestation of systemic arteriosclerosis. However, it is unclear whether AVC is associated with myocardial ischemia. Stress myocardial perfusion SPECT (MPS) is widely used for the diagnosis of myocardial ischemia. However, routine MPS is not recommended, particularly in asymptomatic patients. Accordingly, we investigated the hypothesis that the presence of AVC is strongly associated with inducible myocardial ischemia, even among asymptomatic patients. We investigated 669 consecutive patients who underwent both adenosine stress (201)Tl MPS and echocardiography. We evaluated the extent and severity of myocardial ischemia by the summed difference score (SDS). We defined the presence of myocardial ischemia as SDS ≥ 3 and moderate to severe ischemia as SDS ≥ 8. We classified the severity of AVC according to the number of affected aortic leaflets. We also compared the mean SDS and the prevalence of SDS ≥ 3 and SDS ≥ 8 among patients stratified by the severity of AVC. The presence of AVC was significantly associated with myocardial ischemia (odds ratio [OR], 1.56; 95% confidence interval [CI], 1.10-2.23; P = 0.013) and moderate to severe ischemia (OR, 2.16; 95% CI, 1.26-3.80; P = 0.0061). In 311 asymptomatic patients, AVC was strongly associated with moderate to severe ischemia (OR, 4.31; 95% CI, 1.67-12.8; P = 0.0043). However, the SDS value and the prevalence of SDS ≥ 3 and SDS ≥ 8 did not increase with increasing number of affected aortic leaflets. The presence of AVC may be associated with the presence of myocardial ischemia, particularly in asymptomatic patients. However, we found no association between the extent of AVC and inducible myocardial ischemia. The presence of AVC may be a useful anatomic marker to help identify patients at high risk of myocardial ischemia, particularly asymptomatic patients.

  12. Left ventricular dyssynchrony assessed by two three-dimensional imaging modalities: phase analysis of gated myocardial perfusion SPECT and tri-plane tissue Doppler imaging

    PubMed Central

    Ajmone Marsan, Nina; Henneman, Maureen M.; Chen, Ji; Ypenburg, Claudia; Dibbets, Petra; Ghio, Stefano; Bleeker, Gabe B.; Stokkel, Marcel P.; van der Wall, Ernst E.; Tavazzi, Luigi; Garcia, Ernest V.

    2007-01-01

    Purpose To compare left ventricular (LV) dyssynchrony assessment by phase analysis from gated myocardial perfusion SPECT (GMPS) with LV dyssynchrony assessment by tri-plane tissue Doppler imaging (TDI). Baseline LV dyssynchrony assessed with standard deviation (SD) of time-to-peak systolic velocity of 12 LV segments (Ts-SD) with TDI has proven to be a powerful predictor of response to CRT. Information on LV dyssynchrony can also be provided by GMPS with phase analysis of regional LV maximal count changes throughout the cardiac cycle. Methods Forty heart failure patients, referred for evaluation of potential eligibility for CRT, underwent both 3D echocardiography, with tri-plane TDI, and resting GMPS. From tri-plane TDI, Ts-SD was used as a validated parameter of LV dyssynchrony and compared with different indices (histogram bandwidth, phase SD, histogram skewness and kurtosis) derived from phase analysis of GMPS. Results Histogram bandwidth and phase SD showed good correlation with Ts-SD (r=0.77 and r=0.74, p<0.0001, respectively). Patients with substantial LV dyssynchrony assessed with tri-plane TDI (Ts-SD ≥33 ms) had also significantly higher values of histogram bandwidth and phase SD. Conclusions The results of this study support the use of phase analysis by GMPS to evaluate LV dyssynchrony. Histogram bandwidth and phase SD showed the best correlation with Ts-SD assessed with tri-plane TDI and appeared the most optimal variables for assessment of LV dyssynchrony with GMPS. PMID:17874098

  13. Gated myocardial perfusion single photon emission computed tomography in the clinical outcomes utilizing revascularization and aggressive drug evaluation (COURAGE) trial, Veterans Administration Cooperative study no. 424.

    PubMed

    Shaw, Leslee J; Heller, Gary V; Casperson, Paul; Miranda-Peats, Romalisa; Slomka, Piotr; Friedman, John; Hayes, Sean W; Schwartz, Ronald; Weintraub, William S; Maron, David J; Dada, Marcin; King, Spencer; Teo, Koon; Hartigan, Pamela; Boden, William E; O'Rourke, Robert A; Berman, Daniel S

    2006-09-01

    Stress gated myocardial perfusion single photon emission computed tomography (gSPECT) is increasingly used before and after intercurrent therapeutic intervention and is the basis for ongoing evaluation in the Department of Veterans Affairs clinical outcomes utilizing revascularization and aggressive drug evaluation (COURAGE) trial. The COURAGE trial is a North American multicenter randomized clinical trial that enrolled 2287 patients to aggressive medical therapy vs percutaneous coronary intervention plus aggressive medical therapy. Three COURAGE nuclear substudies have been designed. The goals of substudy 0 are to examine the diagnostic accuracy of the extent and severity of inducible ischemia at baseline in COURAGE patients compared with patient symptoms and quantitative coronary angiography and to explore the relationship between inducible ischemia and the benefit from revascularization when added to medical therapy. Substudy 1 will correlate the extent and severity of provocative ischemia with the frequency, quality, and instability of recurrent symptoms in postcatheterization patients. Substudy 2 (n = 300) will examine the usefulness of sequential gSPECT monitoring 6 to 18 months after therapeutic intervention. Together, these nuclear substudies will evaluate the role of gSPECT to determine the effectiveness of aggressive risk-factor modifications, lifestyle interventions, and anti-ischemic medical therapies with or without revascularization in reducing patients' ischemic burdens. The unfolding of evidence on the application of gSPECT in trials such as COURAGE defines a new era for nuclear cardiology. We hope the evidence that emerges from the COURAGE trial will further establish the role of nuclear imaging in the evidence-based management of patients with stable coronary disease.

  14. Myocardial perfusion gated single-photon emission computed tomography in patients with left bundle branch block: comparison between the end-diastolic images and the ungated images.

    PubMed

    Edet-Sanson, Agathe; Hitzel, Anne; Guernou, Mohamed; Véra, Pierre; Manrique, Alain

    2009-01-01

    Septal perfusion abnormalities are frequently observed in patients with left bundle branch block (LBBB). The aim of this study was to compare myocardial perfusion imaging obtained from ungated and diastolic thallium gated single-photon emission computed tomography (SPECT) images in patients with LBBB. Stress/rest SPECT was performed in 70 patients with LBBB [38 with coronary artery disease (CAD) (G1), 32 without (G2)] and 19 control participants (G3). Diastolic images were obtained as the sum of four diastolic bins. Perfusion was assessed by summed stress, rest, and difference scores for both diastolic and ungated images. In G1, there was no difference between diastolic and ungated perfusion scores. In G2, summed stress score and summed rest score were increased in diastolic versus ungated imaging, and perfusion defect extent was increased on diastolic versus ungated images at stress (diastole: 6.2 +/- 9.9% vs. ungated: 5.1 +/- 9.70/%, P = 0.01) and rest (diastole: 4.3 +/- 9.3% vs. ungated: 2.8 +/- 9.50%, P = 0.0014), with an increased extent of reversible defect (diastole: 3.4 4.7% vs. ungated: 2.3 3.7%, P = 0.01). In G2, diastolic images failed to correct septal perfusion abnormalities. The number of normal SPECT did not increase with diastolic versus ungated imaging (24 and 180% in G1, 66 and 53% in G2, respectively). Otherwise, a significant association between left ventricular dysfunction and CAD was found, stress ejection fraction being decreased in 20 patients (53%) in G1 and seven patients (22%) in G2 (CHI2 = 6.93, P < 0.01). In patients with LBBB, diastolic imaging did not provide additional information to ungated perfusion imaging, but left ventricular dysfunction was associated with CAD.

  15. Normal values of cardiac mechanical synchrony parameters using gated myocardial perfusion single-photon emission computed tomography: Impact of population and study protocol

    PubMed Central

    Mukherjee, Anirban; Singh, Harmandeep; Patel, Chetan; Sharma, Gautam; Roy, Ambuj; Naik, Nitish

    2016-01-01

    Purpose of the Study: Normal values of cardiac mechanical synchrony parameters in gated myocardial perfusion single-photon emission computed tomography (GMPS) are well established in literature from the Western population. The aim of the study is to establish normal values of mechanical synchrony with GMPS in Indian population and to find out whether it differs significantly from established values. Procedure: We retrospectively analyzed 1 day low-dose stress/high-dose rest GMPS studies of 120 patients (sixty males, 52 ± 11.7 years) with low pretest likelihood of coronary artery disease and having normal GMPS study. In GMPS, first-harmonic fast Fourier transform was used to extract a phase array using commercially available software. Phase standard deviation (PSD) and phase histogram bandwidth (PHB) were used to quantify cardiac mechanical dyssynchrony. Results: The values obtained were as follows, PSD: In men, 14.3 ± 4.7 (stress) and 8.9 ± 2.9 (rest), in women 11 ± 4 (stress) and 7.7 ± 2.7 (rest), and PHB: In men, 40.1 ± 11.9 (stress) and 30.6 ± 7.6 (rest), in women, 34.7 ± 12.6 (stress) and 25.3 ± 8.6 (rest). The value of PSD and PHB was significantly less in Indian population as compared with established values in literature. We also observed that synchrony indices derived from the low-dose stress studies are higher than high-dose rest studies. Conclusions: The value of synchrony parameters differs significantly according to population and methodology suggesting that specific population and methodology-based normal database for assessment of cardiac mechanical dyssynchrony should be established. PMID:27833309

  16. Verapamil prevents silent myocardial perfusion abnormalities during exercise in asymptomatic patients with hypertrophic cardiomyopathy

    SciTech Connect

    Udelson, J.E.; Bonow, R.O.; O'Gara, P.T.; Maron, B.J.; Van Lingen, A.; Bacharach, S.L.; Epstein, S.E.

    1989-05-01

    Recent studies indicate that reversible 201Tl perfusion defects, compatible with silent myocardial ischemia, commonly develop during exercise in asymptomatic or mildly symptomatic patients with hypertrophic cardiomyopathy (HCM). To determine whether this represents a dynamic process that may be modified favorably by medical therapy, we studied 29 asymptomatic or minimally symptomatic patients with HCM, aged 12-55 years (mean, 28), with exercise 201Tl emission computed tomography under control conditions and again after 1 week of oral verapamil (mean dosage, 453 mg/day). Treadmill time increased slightly during verapamil (21.0 +/- 3.6 to 21.9 +/- 2.7 minutes, p less than 0.005), but peak heart rate-blood pressure product was unchanged (26.3 +/- 6.0 X 10(3)) compared with 25.0 +/- 6.4 X 10(3). Two midventricular short-axis images per study were divided into five regions each, and each of these 10 regions was then analyzed on a 0-2 scale by three observers blinded with regard to the patients' therapy. Average regional scores of 1.5 or less were considered to represent perfusion defects, and a change in regional score of 0.5 or more was considered to constitute a significant change. During control studies, 15 patients (52%) developed perfusion defects with exercise (average, 3.7 regions per patient). In 14 of these patients, all perfusion defects completely reversed after 3 hours of rest; one patient had fixed defects. After administration of verapamil, exercise perfusion scores improved in 10 of the 14 patients (71%) with reversible defects; there was overall improvement in 34 of 50 (68%) regions with initially reversible perfusion defects.

  17. Effects of coronary angioplasty and reperfusion on distribution of myocardial flow

    SciTech Connect

    Wahr, D.W.; Ports, T.A.; Botvinick, E.H.; Dae, M.; Schechtmann, N.; Huberty, J.; Hattner, R.S.; O'Connell, J.W.; Turley, K.

    1985-08-01

    To assess the effects of angioplasty (PTCA) and intracoronary streptokinase (ICSK) on relative myocardial perfusion, the authors administered /sup 99m/Tc-macroaggregated albumin (MAA) to the uninvolved coronary artery before successful PTCA in 33 patients and before successful infusion of ICSK in eight patients and of /sup 111/In-MAA into the same vessel after the intervention. In 10 patients who underwent PTCA, MAA was injected into the involved, instrumented coronary artery. Computer-processed images were acquired in registry and compared. Similar scintigraphic studies were performed in six control patients and in 11 in whom planned interventions were not performed or were unsuccessful. Distribution of MAA was also compared with angiographic results and with the distribution of /sup 201/Tl on images obtained in patients at rest or on redistribution images obtained before and soon after intervention in 22 patients. In control patients and those studied after aborted or unsuccessful intervention, scintigraphic results showed excellent correlation with the angiographic anatomy and were without serial change. When MAA was injected into the uninvolved vessel, the scintigram revealed evidence of collateral perfusion with retraction of the perfusion zone from that of the involved coronary in 19 of 33 patients undergoing PTCA and in three of eight of those receiving ICSK. When MAA was injected into the involved artery, a relative increase in perfusion was seen in eight of 10 patients after PTCA. Although 30 patients demonstrated scintigraphic evidence of collateral vessels, only 10 patients had angiographic evidence of collateral circulation before intervention. The distribution of /sup 201/Tl demonstrated little change in its global pattern and regions previously supplied by collaterals were generally well perfused after intervention.

  18. Wiener filtering improves quantification of regional myocardial perfusion with thallium-201 SPECT

    SciTech Connect

    Links, J.M.; Jeremy, R.W.; Dyer, S.M.; Frank, T.L.; Becker, L.C. )

    1990-07-01

    Quantitation of myocardial perfusion with thallium-201 (201Tl) SPECT is limited by finite resolution and image noise. This study examined whether Wiener filtering could improve quantitation of the severity of myocardial perfusion deficits. In 19 anesthetized dogs, adjustable stenoses were placed on the left anterior descending (LAD, n = 12) or circumflex (LCx, n = 7) arteries. Thallium-201 SPECT images were acquired during maximal coronary vasodilation with dipyridamole, and simultaneous measurements of myocardial blood flow were made with microspheres. The relationship between SPECT and microsphere flow deficits in the LAD region was significantly better (p less than 0.05) with Wiener filtering (Y = 0.90X + 0.03, r = 0.78) than with conventional Hanning filtering (Y = 0.66X + 0.34, r = 0.61). Similarly, in the LCx region the relationship between SPECT and microsphere perfusion deficits was better (p less than 0.01) with the Wiener filter (Y = 0.91X + 0.07, r = 0.66) than with the Hanning filter (Y = 0.36X + 0.50, r = 0.40). Wiener filtering improves quantitation of the severity of regional myocardial perfusion deficits, allowing better assessment of the functional significance of coronary artery stenoses.

  19. Does perfusion pattern influence stress-induced changes in left ventricular mechanical dyssynchrony on thallium-201-gated SPECT myocardial perfusion imaging?

    PubMed

    Singh, Harmandeep; Patel, Chetan D; Sharma, Punit; Naik, Nitish; Singh, Sandeep; Narang, Rajiv

    2015-02-01

    The relationship between perfusion pattern and stress-induced changes in left ventricular mechanical dyssynchrony (LVMD) on stress-rest thallium-201-gated SPECT myocardial perfusion imaging (Tl-201 SPECT MPI) is not clear. The aim of the study is to assess the relation of perfusion pattern with stress-induced changes in LVMD on Tl-201 MPI. Data of 194 patients who underwent exercise-rest Tl-201 MPI between January to December 2012 at our institute was retrospectively evaluated. Institute Ethical committee approval was obtained. Fifty patients who underwent Tl-201 MPI for suspected CAD and had normal LV perfusion and function on MPI were taken as normal group. Patients with perfusion abnormalities (n = 144) were divided into three groups: ischemia (n = 66), infarct (n = 32), and mixed group (n = 46; ischemia and infarct both). Summed stress score, summed rest score, summed difference score (SDS), and LV ejection fraction (EF) were evaluated. Two LVMD parameters, phase standard deviation (PSD) and phase histogram bandwidth (PHB), were assessed in post-stress and rest MPI images. ΔPSD (post-stress PSD - rest PSD) and ΔPHB (post-stress PHB - rest PHB) were calculated to measure stress-induced changes in LVMD. In all the groups, mean post-stress LVMD parameters were lower as compared to LVMD parameters at rest. Post-stress PSD was significantly lower than rest PSD in all groups. Similar trend was noted with PHB values also, but it was statistically significant in the normal and ischemia group only. Post-stress worsening of at least one of the LVMD parameters was noted in 28 patients and all these patients had perfusion abnormalities. But on subgroup analysis, no difference was found in proportion of patients showing post-stress worsening of LVMD between ischemia (13.6%), infarct (25%), and mixed (23.6%) groups. No significant correlation was found between ΔPSD/ΔPHB and ΔLVEF/SDS in any group. LV mechanical dyssynchrony parameters are smaller in post-exercise stress

  20. Comparison of sulfur hexafluoride microbubble (SonoVue)-enhanced myocardial contrast echocardiography with gated single-photon emission computed tomography for detection of significant coronary artery disease: a large European multicenter study.

    PubMed

    Senior, Roxy; Moreo, Antonella; Gaibazzi, Nicola; Agati, Luciano; Tiemann, Klaus; Shivalkar, Bharati; von Bardeleben, Stephan; Galiuto, Leonarda; Lardoux, Hervé; Trocino, Giuseppe; Carrió, Ignasi; Le Guludec, Dominique; Sambuceti, Gianmario; Becher, Harald; Colonna, Paolo; Ten Cate, Folkert; Bramucci, Ezio; Cohen, Ariel; Bezante, Gianpaolo; Aggeli, Costantina; Kasprzak, Jaroslaw D

    2013-10-08

    The purpose of this study was to compare sulfur hexafluoride microbubble (SonoVue)-enhanced myocardial contrast echocardiography (MCE) with single-photon emission computed tomography (SPECT) relative to coronary angiography (CA) for assessment of coronary artery disease (CAD). Small-scale studies have shown that myocardial perfusion assessed by SonoVue-enhanced MCE is a viable alternative to SPECT for CAD assessment. However, large multicenter studies are lacking. Patients referred for myocardial ischemia testing at 34 centers underwent rest/vasodilator SonoVue-enhanced flash-replenishment MCE, standard (99m)Tc-labeled electrocardiography-gated SPECT, and quantitative CA within 1 month. Myocardial ischemia assessments by 3 independent, blinded readers for MCE and 3 readers for SPECT were collapsed into 1 diagnosis per patient per technique and were compared to CA (reference standard) read by 1 independent blinded reader. Of 628 enrolled patients who received SonoVue (71% males; mean age: 64 years; >1 cardiovascular [CV] risk factor in 99% of patients) 516 patients underwent all 3 examinations, of whom 161 (31.2%) had ≥70% stenosis (131 had single-vessel disease [SVD]; 30 had multivessel disease), and 310 (60.1%) had ≥50% stenosis. Higher sensitivity was obtained with MCE than with SPECT (75.2% vs. 49.1%, respectively; p < 0.0001), although specificity was lower (52.4% vs. 80.6%, respectively; p < 0.0001) for ≥70% stenosis. Similar findings were obtained for patients with ≥50% stenosis. Sensitivity levels for detection of SVD and proximal disease for ≥70% stenosis were higher for MCE (72.5% vs. 42.7%, respectively; p < 0.0001; 80% vs. 58%, respectively; p = 0.005, respectively). SonoVue-enhanced MCE demonstrated superior sensitivity but lower specificity for detection of CAD compared to SPECT in a population with a high incidence of CV risk factors and intermediate-high prevalence of CAD. (A phase III study to compare SonoVue® enhanced myocardial

  1. Diagnostic accuracy of thallium-201 myocardial perfusion imaging

    SciTech Connect

    Beller, G.A. )

    1991-09-01

    Myocardial thallium-201 (Tl-201) imaging performed in conjunction with exercise stress has enhanced the accuracy of detecting coronary artery disease among patients with chest pain. Sensitivity and specificity of qualitative visual Tl-201 scintigraphy for detection of coronary artery disease average 84% and 87%, respectively. Quantitative analysis of planar Tl-201 scintigrams has yielded sensitivity and specificity in the 90% range. Single photon emission computed tomographic imaging is associated with even higher sensitivity but with specificity in the 82-85% range. Perfusion defects representing ischemia can now be distinguished from scar by demonstration of delayed Tl-201 redistribution or enhanced uptake after reinjection of a second dose of Tl-201. Stenoses of the left circumflex coronary artery are less easily detected than lesions of the right and left anterior descending coronary arteries. False-positive Tl-201 perfusion defects may occur as a result of attenuation artifacts, most often caused by overlying breast tissue or by a high left hemidiaphragm. Patient motion during acquisition of single photon emission computed tomographic images results in artifactual defects on reconstruction. Abnormal Tl-201 uptake has been noted in patients with (1) left bundle branch block and normal coronary arteries, (2) hypertrophic cardiomyopathy, and (3) progressive systemic sclerosis.

  2. The Development and Initial Evaluation of a Realistic Simulated SPECT Dataset with Simultaneous Respiratory and Cardiac Motion for Gated Myocardial Perfusion SPECT

    PubMed Central

    Lee, Taek-Soo; Tsui, Benjamin M. W.

    2015-01-01

    We developed a realistic simulation dataset for simultaneous respiratory and cardiac (R&C) gated SPECT/CT using the 4D NURBS-based Cardiac-Torso (NCAT) Phantom and Monte Carlo simulation methods, and evaluated it for a sample application study. The 4D NCAT phantom included realistic respiratory motion and beating heart motion based on respiratory gated CT and cardiac tagged MRI data of normal human subjects. To model the respiratory motion, a set of 24 separate 3D NCAT phantoms excluding the heart was generated over a respiratory cycle. The beating heart motion was modelled separately with 48 frames per cardiac cycle for each of the 24 respiratory phases. The resultant set of 24×48 3D NCAT phantoms provides a realistic model of a normal human subject at different phases of combined R&C motions. An almost noise-free SPECT projection dataset for each of the 1,152 3D NCAT phantoms was generated using Monte Carlo simulation techniques and the radioactivity uptake distribution of 99mTc sestamibi in different organs. By grouping and summing the separate projection datasets, separate or simultaneous R&C gated acquired data with different gating schemes could be simulated. In the initial evaluation, we combined the projection datasets into no gating, 6 respiratory-gates only, 8 cardiac-gates only, and combined 6 respiratory-gates & 8 cardiac-gates projection datasets. Each dataset was reconstructed using 3D OS-EM without and with attenuation correction using the averaged and respiratory-gated attenuation maps, and the resulting reconstructed images were compared. These results were used to demonstrate the effects of R&C motions and the reduction of image artifact due to R&C motions by gating and attenuation corrections. We concluded that the realistic 4D NCAT phantom and Monte Carlo simulated SPECT projection datasets with R&C motions are powerful tools in the study of the effects of R&C motions, as well as in the development of R&C gating schemes and motion correction

  3. The development and initial evaluation of a realistic simulated SPECT dataset with simultaneous respiratory and cardiac motion for gated myocardial perfusion SPECT

    NASA Astrophysics Data System (ADS)

    Lee, Taek-Soo; Tsui, Benjamin M. W.

    2015-02-01

    We developed a realistic simulation dataset for simultaneous respiratory and cardiac (R&C) gated SPECT/CT using the 4D NURBS-based Cardiac-Torso (NCAT) Phantom and Monte Carlo simulation methods, and evaluated it for a sample application study. The 4D NCAT phantom included realistic respiratory motion and beating heart motion based on respiratory gated CT and cardiac tagged MRI data of normal human subjects. To model the respiratory motion, a set of 24 separate 3D NCAT phantoms excluding the heart was generated over a respiratory cycle. The beating heart motion was modeled separately with 48 frames per cardiac cycle for each of the 24 respiratory phases. The resultant set of 24  ×  48 3D NCAT phantoms provides a realistic model of a normal human subject at different phases of combined R&C motions. An almost noise-free SPECT projection dataset for each of the 1152 3D NCAT phantoms was generated using Monte Carlo simulation techniques and the radioactivity uptake distribution of 99mTc sestamibi in different organs. By grouping and summing the separate projection datasets, separate or simultaneous R&C gated acquired data with different gating schemes could be simulated. In the initial evaluation, we combined the projection datasets into ungated, 6 respiratory-gates only, 8 cardiac-gates only, and combined 6 respiratory-gates & 8 cardiac-gates projection datasets. Each dataset was reconstructed using 3D OS-EM without and with attenuation correction using the averaged and respiratory-gated attenuation maps, and the resulting reconstructed images were compared. These results were used to demonstrate the effects of R&C motions and the reduction of image artifact due to R&C motions by gating and attenuation corrections. We concluded that the realistic 4D NCAT phantom and Monte Carlo simulated SPECT projection datasets with R&C motions are powerful tools in the study of the effects of R&C motions, as well as in the development of R&C gating schemes and motion

  4. The development and initial evaluation of a realistic simulated SPECT dataset with simultaneous respiratory and cardiac motion for gated myocardial perfusion SPECT.

    PubMed

    Lee, Taek-Soo; Tsui, Benjamin M W

    2015-02-21

    We developed a realistic simulation dataset for simultaneous respiratory and cardiac (R&C) gated SPECT/CT using the 4D NURBS-based Cardiac-Torso (NCAT) Phantom and Monte Carlo simulation methods, and evaluated it for a sample application study. The 4D NCAT phantom included realistic respiratory motion and beating heart motion based on respiratory gated CT and cardiac tagged MRI data of normal human subjects. To model the respiratory motion, a set of 24 separate 3D NCAT phantoms excluding the heart was generated over a respiratory cycle. The beating heart motion was modeled separately with 48 frames per cardiac cycle for each of the 24 respiratory phases. The resultant set of 24  ×  48 3D NCAT phantoms provides a realistic model of a normal human subject at different phases of combined R&C motions. An almost noise-free SPECT projection dataset for each of the 1152 3D NCAT phantoms was generated using Monte Carlo simulation techniques and the radioactivity uptake distribution of (99m)Tc sestamibi in different organs. By grouping and summing the separate projection datasets, separate or simultaneous R&C gated acquired data with different gating schemes could be simulated. In the initial evaluation, we combined the projection datasets into ungated, 6 respiratory-gates only, 8 cardiac-gates only, and combined 6 respiratory-gates & 8 cardiac-gates projection datasets. Each dataset was reconstructed using 3D OS-EM without and with attenuation correction using the averaged and respiratory-gated attenuation maps, and the resulting reconstructed images were compared. These results were used to demonstrate the effects of R&C motions and the reduction of image artifact due to R&C motions by gating and attenuation corrections. We concluded that the realistic 4D NCAT phantom and Monte Carlo simulated SPECT projection datasets with R&C motions are powerful tools in the study of the effects of R&C motions, as well as in the development of R&C gating schemes and motion

  5. Semi-automated measurements of heart-to-mediastinum ratio on 123I-MIBG myocardial scintigrams by using image fusion method with chest X-ray images

    NASA Astrophysics Data System (ADS)

    Kawai, Ryosuke; Hara, Takeshi; Katafuchi, Tetsuro; Ishihara, Tadahiko; Zhou, Xiangrong; Muramatsu, Chisako; Abe, Yoshiteru; Fujita, Hiroshi

    2015-03-01

    MIBG (iodine-123-meta-iodobenzylguanidine) is a radioactive medicine that is used to help diagnose not only myocardial diseases but also Parkinson's diseases (PD) and dementia with Lewy Bodies (DLB). The difficulty of the segmentation around the myocardium often reduces the consistency of measurement results. One of the most common measurement methods is the ratio of the uptake values of the heart to mediastinum (H/M). This ratio will be a stable independent of the operators when the uptake value in the myocardium region is clearly higher than that in background, however, it will be unreliable indices when the myocardium region is unclear because of the low uptake values. This study aims to develop a new measurement method by using the image fusion of three modalities of MIBG scintigrams, 201-Tl scintigrams, and chest radiograms, to increase the reliability of the H/M measurement results. Our automated method consists of the following steps: (1) construct left ventricular (LV) map from 201-Tl myocardium image database, (2) determine heart region in chest radiograms, (3) determine mediastinum region in chest radiograms, (4) perform image fusion of chest radiograms and MIBG scintigrams, and 5) perform H/M measurements on MIBG scintigrams by using the locations of heart and mediastinum determined on the chest radiograms. We collected 165 cases with 201-Tl scintigrams and chest radiograms to construct the LV map. Another 65 cases with MIBG scintigrams and chest radiograms were also collected for the measurements. Four radiological technologists (RTs) manually measured the H/M in the MIBG images. We compared the four RTs' results with our computer outputs by using Pearson's correlation, the Bland-Altman method, and the equivalency test method. As a result, the correlations of the H/M between four the RTs and the computer were 0.85 to 0.88. We confirmed systematic errors between the four RTs and the computer as well as among the four RTs. The variation range of the H

  6. Real-Time Three-Dimensional Echocardiography as a Novel Approach to Quantify Left Ventricular Dyssynchrony: A Comparison Study with Phase Analysis of Gated Myocardial Perfusion Single Photon Emission Computed Tomography

    PubMed Central

    Marsan, Nina Ajmone; Henneman, Maureen M.; Chen, Ji; Ypenburg, Claudia; Dibbets, Petra; Ghio, Stefano; Bleeker, Gabe B.; Stokkel, Marcel P.; van der Wall, Ernst E.; Tavazzi, Luigi; Garcia, Ernest V.; Bax, Jeroen J.

    2010-01-01

    Background Different imaging modalities have been explored for assessment of left ventricular (LV) dyssynchrony. Gated myocardial perfusion single photon emission computed tomography (GMPS) with phase analysis is a reliable technique to quantify LV dyssynchrony and predict response to cardiac resynchronization therapy. Objective Real-time 3-dimensional echocardiography (RT3DE) is a novel imaging technique that provides a LV systolic dyssynchrony index, based on regional volumetric changes as a function of time and calculated as the SD of time to minimum systolic volume of 16 standard myocardial segments expressed in percentage of cardiac cycle. The aim of this study was to compare LV dyssynchrony evaluated with GMPS with LV dyssynchrony assessed with RT3DE. Methods The study population consisted of 40 patients with heart failure who underwent both GMPS and RT3DE. Results Good correlations between LV dyssynchrony assessed with RT3DE and GMPS were demonstrated (r = 0.76 for histogram bandwidth, r = 0.80 for phase SD, P < .0001). Patients with substantial LV dyssynchrony on GMPS (defined as ≥135 degrees for histogram bandwidth and ≥43 degrees for phase SD) had significantly higher LV systolic dyssynchrony index than patients without substantial LV dyssynchrony. Conclusions The good correlations between LV dyssynchrony assessed with GMPS and with RT3DE provide further support for the use of RT3DE for reliable assessment of LV dyssynchrony. PMID:18222645

  7. Left-ventricular systolic and diastolic dyssynchrony as assessed by multi-harmonic phase analysis of gated SPECT myocardial perfusion imaging in patients with end-stage renal disease and normal LVEF

    PubMed Central

    Chen, Ji; Kalogeropoulos, Andreas P.; Verdes, Liudmila; Butler, Javed; Garcia, Ernest V.

    2011-01-01

    Background The purpose of this study was to develop a multi-harmonic phase analysis method to measure diastolic dyssynchrony from conventional gated SPECT myocardial perfusion imaging(MPI) data and to compare it with systolic dyssynchrony in normal subjects and in patients with end-stage renal disease (ESRD) and normal left-ventricular ejection fraction (LVEF). Methods 121 consecutive patients with ESRD and normal LVEF and 30 consecutive normal controls were enrolled. Diastolic dyssynchrony parameters were calculated using 3-harmonic phase analysis. Systolic dyssynchrony parameters were calculated using the established 1-harmonic phase analysis. Results The systolic and diastolic dyssynchrony parameters were correlated, but significantly different in both control and ESRD groups, indicating they were physiologically related but measured different LV mechanisms. The systolic and diastolic dyssynchrony parameters were each significantly different between the control and the ESRD groups. Significant systolic and diastolic dyssynchrony were found in 47% and 65% of the entire ESRD group. Conclusion Multi-harmonic phase analysis has been developed to assess diastolic dyssynchrony, which measured a new LV mechanism of regional function from gated SPECT MPI and showed a significantly higher prevalence rate than systolic dyssynchrony in patients with ESRD and normal LVEF. PMID:21229401

  8. Functional significance of coronary collateral circulation during dynamic exercise evaluated by thallium-201 myocardial scintigraphy.

    PubMed Central

    Wainwright, R J; Maisey, M N; Edwards, A C; Sowton, E

    1980-01-01

    Sixty-five patients with angiographically documented coronary artery disease were investigated by thallium-201 (201Tl) scintigraphy to determine the role of the collateral circulation during dynamic exercise. Fifty-three patients had complete proximal occlusion of at least one major coronary artery. One patient had total occlusion of all three major coronary arteries. Sixty-four collateral channels were identified, graded, and compared with corresponding regions of the myocardial scintigram. Tracer uptake was also graded and classified as various degrees of protection from ischaemia. A significant correlation between good collaterals with complete protection and poor or absent collaterals with no protection was noted. Seventeen patients (20 occluded vessels) had total coronary occlusion without myocardial infarction. Collaterals conferred protection in 9/15 occlusions whereas no protection was seen in five occlusions without collaterals. There was no difference in the protective role of homocoronary and heterocoronary collateral vessels. Hypertrophy of the first septal left anterior descending perforator conferred significant protection from ischaemia in contrast to bridging collaterals and ghosting. During exercise the right coronary bed is preferentially protected from ischaemia, in contrast to the left anterior descending territory. This probably reflects the direction of a transmural flow gradient between left and right ventricles during exercise. Images PMID:7356862

  9. Experimental studies of the physiologic properties of technetium-99m agents: Myocardial transport of perfusion imaging agents

    SciTech Connect

    Meerdink, D.J.; Leppo, J.A. )

    1990-10-16

    The physiologic properties of new technetium-99m-labeled myocardial imaging agents (Tc-99m sestamibi, an isonitrile; and Tc-99m teboroxime, a boronic acid adduct of technetium dioxime) are discussed and compared to thallium-201 (Tl-201). Studies with isolated hearts, subcellular fractions and cell cultures indicate that Tc-99m sestamibi, Tc-99m teboroxime and Tl-201 do not share common transport or sequestration mechanisms. Although peak Tc-99m sestamibi myocardial extraction over time is about half that of Tl-201 at equivalent coronary blood flows, the amount of Tc-99m sestamibi that remains in the heart is similar to that of Tl-201 because of its higher retention efficiency. The high retention efficiency for Tc-99m sestamibi also results in minimal redistribution. In contrast, Tc-99m teboroxime myocardial extraction is higher than that of Tl-201, but its retention is less efficient, resulting in relatively rapid washout characteristics which may quickly result in tracer redistribution. During reperfusion after a no-flow period, Tc-99m sestamibi extraction and retention increase, but for Tc-99m teboroxime and Tl-201 these values tend to decrease. All tracers show adequate transport characteristics for perfusion imaging, and differences in transport and retention should lead to the development of new clinical protocols.27 references.

  10. Physical training of the patients with coronary heart disease: noninvasive strategies for the evaluation of its effects on the oxygentransport system and myocardial ischemia.

    PubMed

    Doba, N; Shukuya, M; Yoshida, H; Inagaki, M; Inaji, J; Hinohara, S

    1990-11-01

    To clarify the central effects of physical training on patients with coronary heart disease, 81 subjects were selected for the present study. Evaluations of the oxygen transport system function were performed according to the definition proposed by Bruce and others in terms of FAI (functional aerobic impairment), LVI (left ventricular impairment) or MRI (myocardial reserve impairment), CRI (chronotropic reserve impairment) and PCI (peripheral circulatory impairment). Remarkable improvement in left ventricular impairment was found in those patients with single vessel disease or those who experienced disappearance of chest pain after the completion of the program. In another series of study on myocardial perfusion performed on 11 patients with coronary heart disease, improvement in ischemia was also demonstrated in 7 of 8 patients who revealed redistribution pattern in 201TL exercise stress images specifying myocardial ischemia. In conclusion, exercise training could induce improvements not only the left ventricular functions characterized by increased maximal pressure rate product and maximal heart rate, but also in myocardial ischemia. Further studies are needed to specify its effects, since natural progression or regression of the disease process itself may influence the results.

  11. Evaluation of the left ventricular hemodynamic function and myocardial perfusion by gated single photon emission tomography, in patients with type 1 diabetes mellitus; prodromal signs of cardiovascular disease after four years.

    PubMed

    Chrapko, Beata; Kowalczyk, Mariusz; Nocuń, Anna; Nowakowski, Andrzej; Zaorska-Rajca, Janina

    2006-01-01

    The aim of this study was to assess the changes in hemodynamic function and myocardial perfusion of the left ventricle occurring in patients with type 1 diabetes mellitus (DM1) 47-49 months after the first assessment. We have studied 20 asymptomatic patients, five females and 15 males, aged 22-46 y. The patients were under intensive insulin treatment and had normal electrocardiogram (ECG) at rest. In all patients gated single photon emission tomography (GSPET) was performed at rest and after exercise (examination I). After 47-49 months this test was repeated (examination II). GSPET was performed 60 min after the intravenous injection of 740 MBq of technetium-99m 2-methoxy-isobutyl-isonitrile ((99m)Tc-MIBI), using a dual-headed gamma-camera. Left ventricular ejection fraction (LVEF), end diastolic volume (EDV) and end systolic volume (ESV) were calculated using quantitative GSPET (QGS). The intensity of perfusion defects was also evaluated based on a four degree QGS scale. Our results were as follows: a) In examination I, performed at rest: LVEF was 56.1%+/-7.5%, EDV 96.9+/-25.8 ml and ESV 42.6+/-16.3 ml. b) In examination I at stress: LVEF was 57.2%+/-7.5%, EDV 94.1+/-24.0 ml and ESV 40.5+/-15.5. c) In examination II performed at rest: LVEF was 58.1%+/-6.5%, EDV 112.1+/-26.1 ml and ESV 46.6+/-14.9 ml and d) In examination II at stress: LVEF 57.8%+/-5.6%, EDV 107.9+/-27.4 ml and ESV 44.9+/-14.4 ml. Significant differences were found between examinations I and II, regarding: a) EDV at rest (P<0.001) and at stress (P<0.001) and b) ESV at rest (P<0.05) and at stress (P<0.005). Correlation analysis revealed significant correlation between LVEF at rest and at stress both in examination I (r=0.83; P<0.001) and also in examination II (r=-0.897; P<0.001). Intensity of myocardial perfusion defects in examination I at rest and at stress was: 1.68+/-0.5 and 2.2+/-0.6 degrees respectively. Intensity of myocardial perfusion defects in examination II at rest and at stress was: 1

  12. Prevalence and clinical significance of painless ST segment depression during early postinfarction exercise testing

    SciTech Connect

    Gibson, R.S.; Beller, G.A.; Kaiser, D.L.

    1987-03-01

    In a recent study of 190 survivors of acute myocardial infarction, the authors sought to determine whether exercise-induced painless ST segments depression indicates residual myocardial ischemia, as defined by /sup 201/Tl scintigraphic criteria. 2 weeks after uncomplicated myocardial infarction, and whether quantitative /sup 201/Tl imaging enhances the prognostic value of such an exercise electrocardiographic response.

  13. Cardiac gated ventilation

    SciTech Connect

    Hanson, C.W. III; Hoffman, E.A.

    1995-12-31

    There are several theoretic advantages to synchronizing positive pressure breaths with the cardiac cycle, including the potential for improving distribution of pulmonary and myocardial blood flow and enhancing cardiac output. The authors evaluated the effects of synchronizing respiration to the cardiac cycle using a programmable ventilator and electron beam CT (EBCT) scanning. The hearts of anesthetized dogs were imaged during cardiac gated respiration with a 50 msec scan aperture. Multi slice, short axis, dynamic image data sets spanning the apex to base of the left ventricle were evaluated to determine the volume of the left ventricular chamber at end-diastole and end-systole during apnea, systolic and diastolic cardiac gating. The authors observed an increase in cardiac output of up to 30% with inspiration gated to the systolic phase of the cardiac cycle in a non-failing model of the heart.

  14. Quantitative analysis of planar technetium-99m-sestamibi myocardial perfusion images using modified background subtraction

    SciTech Connect

    Koster, K.; Wackers, F.J.; Mattera, J.A.; Fetterman, R.C. )

    1990-08-01

    Standard interpolative background subtraction, as used for thallium-201 ({sup 201}Tl), may create artifacts when applied to planar technetium-99m-Sestamibi ({sup 99m}Tc-Sestamibi) images, apparently because of the oversubtraction of relatively high extra-cardiac activity. A modified background subtraction algorithm was developed and compared to standard background subtraction in 16 patients who had both exercise-delayed {sup 201}Tl and exercise-rest {sup 99m}Tc-Sestamibi imaging. Furthermore, a new normal data base was generated. Normal {sup 99m}Tc-Sestamibi distribution was slightly different compared to {sup 201}Tl. Using standard background subtraction, mean defect reversibility was significantly underestimated by {sup 99m}Tc-Sestamibi compared to {sup 201}Tl (2.8 +/- 4.9 versus -1.8 +/- 8.4, p less than 0.05). Using the modified background subtraction, mean defect reversibility on {sup 201}Tl and {sup 99m}Tc-Sestamibi images was comparable (2.8 +/- 4.9 versus 1.7 +/- 5.2, p = NS). We conclude, that for quantification of {sup 99m}Tc-Sestamibi images a new normal data base, as well as a modification of the interpolative background subtraction method should be employed to obtain quantitative results comparable to those with {sup 201}Tl.

  15. USPIO-enhanced 3D-cine self-gated cardiac MRI based on a stack-of-stars golden angle short echo time sequence: Application on mice with acute myocardial infarction.

    PubMed

    Trotier, Aurélien J; Castets, Charles R; Lefrançois, William; Ribot, Emeline J; Franconi, Jean-Michel; Thiaudière, Eric; Miraux, Sylvain

    2016-08-01

    To develop and assess a 3D-cine self-gated method for cardiac imaging of murine models. A 3D stack-of-stars (SOS) short echo time (STE) sequence with a navigator echo was performed at 7T on healthy mice (n = 4) and mice with acute myocardial infarction (MI) (n = 4) injected with ultrasmall superparamagnetic iron oxide (USPIO) nanoparticles. In all, 402 spokes were acquired per stack with the incremental or the golden angle method using an angle increment of (360/402)° or 222.48°, respectively. A cylindrical k-space was filled and repeated with a maximum number of repetitions (NR) of 10. 3D cine cardiac images at 156 μm resolution were reconstructed retrospectively and compared for the two methods in terms of contrast-to-noise ratio (CNR). The golden angle images were also reconstructed with NR = 10, 6, and 3, to assess cardiac functional parameters (ejection fraction, EF) on both animal models. The combination of 3D SOS-STE and USPIO injection allowed us to optimize the identification of cardiac peaks on navigator signal and generate high CNR between blood and myocardium (15.3 ± 1.0). The golden angle method resulted in a more homogeneous distribution of the spokes inside a stack (P < 0.05), enabling reducing the acquisition time to 15 minutes. EF was significantly different between healthy and MI mice (P < 0.05). The method proposed here showed that 3D-cine images could be obtained without electrocardiogram or respiratory gating in mice. It allows precise measurement of cardiac functional parameters even on MI mice. J. Magn. Reson. Imaging 2016;44:355-365. © 2016 Wiley Periodicals, Inc.

  16. Prediction of reversible perfusion defects by quantitative analysis of post-exercise electrocardiogram-gated acquisition of technetium-99m 2-methoxyisobutylisonitrile myocardial perfusion scintigraphy.

    PubMed

    Marcassa, C; Marzullo, P; Sambuceti, G; Parodi, O

    1992-01-01

    The aim of this study was to assess the reliability of the quantitative analysis of regional wall thickening with electrocardiographic-gated technetium-99m 2-methoxyisobutylisonitrile (SESTAMIBI) in predicting the reversibility of stress-induced perfusion defects. The assumption was that a preserved resting wall thickening in a segment with stress-induced perfusion defect would predict normal resting perfusion. Twenty-five patients with suspected coronary artery disease underwent planar stress-rest SESTAMIBI scintigraphy. The wall thickening was quantitatively evaluated as percentage increase in counts from diastole to systole; a ratio defined as the wall thickening index (WTI) between patient and normal profile (mean - 2 SD) below 1 was considered abnormal. Improvement of the perfusion pattern at rest was observed in 76% (54/71) of segments with a stress-induced perfusion defect; 90% of these segments had a (WTI) greater than 0.8. Five segments (9%) showed fixed perfusion defects despite a WTI value greater than 0.8. In conclusion, quantitative analysis of regional wall thickening by electrocardiographic-gated SESTAMIBI identifies segments with reversible perfusion defects; this may overcome the need for studies at rest and may direct the detection of hypoperfused but viable myocardium.

  17. Effects of myocardial perfusion abnormalities on the accuracy of left ventricular volume and ejection fraction measured by thallium-201 gated single-photon emission tomography: comparison with echocardiography as the reference standard.

    PubMed

    Kurisu, Satoshi; Iwasaki, Toshitaka; Abe, Nobukazu; Tamura, Megumi; Ikenaga, Hiroki; Watanabe, Noriaki; Higaki, Tadanao; Shimonaga, Takashi; Ishibashi, Ken; Dohi, Yoshihiro; Fukuda, Yukihiro; Kihara, Yasuki

    2015-11-01

    We assessed the accuracy of left ventricular end-diastolic volume (EDV), end-systolic volume (ESV), and ejection fraction (EF) using quantitative gated single-photon emission computed tomography (QGS) in comparison with echocardiography as the reference standard. We also assessed the effects of total perfusion deficit (TPD) on the accuracy of QGS measurements. A total of 258 patients underwent single-photon emission computed tomography and transthoracic echocardiography within 4 weeks of each investigation for evaluating coronary artery disease. Patients were divided into four groups according to TPD scores. There were 138 patients with no/minimal TPD, 64 patients with small TPD, 35 patients with middle TPD, and 21 patients with large TPD. There were good correlations and agreements in EDV (r=0.87, 0.90, 0.71, and 0.94, respectively), ESV (r=0.92, 0.94, 0.79, and 0.94, respectively), and EF (r=0.61, 0.79, 0.61, and 0.83, respectively) between QGS and echocardiography in patients with any TPD. QGS significantly underestimated EDV and ESV in patients with no/minimal or small TPD, and significantly overestimated ESV in patients with large TPD. QGS significantly underestimated EF in patients with middle or large TPD. Our results suggest that QGS is a useful tool for assessing the left ventricular volume and function in patients with any TPD, but myocardial perfusion abnormalities should be taken into consideration when interpreting QRS measurements.

  18. Nuclear myocardial perfusion imaging using thallium-201 with a novel multifocal collimator SPECT/CT: IQ-SPECT versus conventional protocols in normal subjects.

    PubMed

    Matsuo, Shinro; Nakajima, Kenichi; Onoguchi, Masahisa; Wakabayash, Hiroshi; Okuda, Koichi; Kinuya, Seigo

    2015-06-01

    A novel multifocal collimator, IQ-SPECT (Siemens) consists of SMARTZOOM, cardio-centric and 3D iterative SPECT reconstruction and makes it possible to perform MPI scans in a short time. The aims are to delineate the normal uptake in thallium-201 ((201)Tl) SPECT in each acquisition method and to compare the distribution between new and conventional protocol, especially in patients with normal imaging. Forty patients (eight women, mean age of 75 years) who underwent myocardial perfusion imaging were included in the study. All patients underwent one-day protocol perfusion scan after an adenosine-stress test and at rest after administering (201)Tl and showed normal results. Acquisition was performed on a Symbia T6 equipped with a conventional dual-headed gamma camera system (Siemens ECAM) and with a multifocal SMARTZOOM collimator. Imaging was performed with a conventional system followed by IQ-SPECT/computed tomography (CT). Reconstruction was performed with or without X-ray CT-derived attenuation correction (AC). Two nuclear physicians blinded to clinical information interpreted all myocardial perfusion images. A semi-quantitative myocardial perfusion was analyzed by a 17-segment model with a 5-point visual scoring. The uptake of each segment was measured and left ventricular functions were analyzed by QPS software. IQ-SPECT provided good or excellent image quality. The quality of IQ-SPECT images without AC was similar to those of conventional LEHR study. Mid-inferior defect score (0.3 ± 0.5) in the conventional LEHR study was increased significantly in IQ-SPECT with AC (0 ± 0). IQ-SPECT with AC improved the mid-inferior decreased perfusion shown in conventional images. The apical tracer count in IQ-SPECT with AC was decreased compared to that in LEHR (0.1 ± 0.3 vs. 0.5 ± 0.7, p < 0.05). The left ventricular ejection fraction from IQ-SPECT was significantly higher than that from the LEHR collimator (p = 0.0009). The images of IQ-SPECT acquired in a

  19. Identification of Angiogenesis Rich-Viable Myocardium using RGD Dimer based SPECT after Myocardial Infarction

    PubMed Central

    Lee, Min Su; Park, Hyun Soo; Lee, Byung Chul; Jung, Jae Ho; Yoo, Jung Sun; Kim, Sang Eun

    2016-01-01

    Cardiac healing after myocardial ischemia is a complex biological process. Advances in understanding of wound healing response have paved the way for clinical testing of novel molecular imaging to improve clinical outcomes. A key factor for assessing myocardial viability after ischemic injury is the evaluation of angiogenesis accompanying increased expression of integrin αvβ3. Here, we describe the capability of an αvβ3 integrin-targeting SPECT agent, 99mTc-IDA-D-[c(RGDfK)]2, for identification of ischemic but viable myocardium, i.e., hibernating myocardium which is crucial to predict functional recovery after revascularization, the standard care of cardiovascular medicine. In vivo SPECT imaging of rat models with transient coronary occlusion showed significantly high uptake of 99mTc-IDA-D-[c(RGDfK)]2 in the ischemic region. Comparative measurements with 201Tl SPECT and 18F-FDG PET, then, proved that such prominent uptake of 99mTc-IDA-D-[c(RGDfK)]2 exactly matched the hallmark of hibernation, i.e., the perfusion-metabolism mismatch pattern. The uptake of 99mTc-IDA-D-[c(RGDfK)]2 was non-inferior to that of 18F-FDG, confirmed by time-course variation analysis. Immunohistochemical characterization revealed that an intense signal of 99mTc-IDA-D-[c(RGDfK)]2 corresponded to the vibrant angiogenic events with elevated expression of αvβ3 integrin. Together, these results establish that 99mTc-IDA-D-[c(RGDfK)]2 SPECT can serve as a sensitive clinical measure for myocardial salvage to identify the patients who might benefit most from revascularization. PMID:27283041

  20. Noninvasive assessment of changes in myocardial perfusion and ventricular performance following exercise training

    SciTech Connect

    Tubau, J.; Witztum, K.; Froelicher, V.; Jensen, D.; Atwood, E.; McKirnan, M.D.; Reynolds, J.; Ashburn, W.

    1982-08-01

    Seventeen coronary patients (CAD) underwent /sup 201/Tl treadmill and radionuclide (RNV) ejection fraction supine bicycle testing before and after 5.6 +/- 1.6 (mean +/- SD) months of an exercise program. Thallium data were assessed both using analog images and a computerized circumferential profile technique. Patients exercised on the treadmill to a higher workload after the exercise program, but achieved a similar pressure-rate product. When interpreting the analog thallium images, only 50% agreement was obtained for the assessment of changes in myocardial perfusion (pre/post-training). The computer technique, however, had low inter-intraobserver variability (6%) and better agreement (90.5%). Using the circumferential profile method, five patients improved (a total of 11 regions) and one patient worsened (with two regions). Before the exercise program, the ejection fraction (EF) response to supine bike exercise was normal (an increase greater than 11%) in four, flat in seven, and severely abnormal (a decrease of more than 4%) in six patients. After the exercise program, even though achieving similar or higher pressure-rate products, six patients improved their EF response, nine did not change, and two worsened. Of the five patients who improved their thallium images, one improved his EF response, two remained normal, and two did not change. One patient worsened both his thallium study and the EF response after the exercise program. Changes in thallium exercise images and the EF response to supine exercise occurred in our patients after an exercise program, but were not always concordant. Indeed, of five patients with exercise-induced ischemic ST changes before and after training, the EF response improved in three whereas myocardial perfusion was unchanged. Reasons for this lack of agreement are discussed, and have been considered in the planning of a randomized trial of the effects of an exercise program on myocardial perfusion and function.

  1. Surveillance study for creating the national clinical database relating to ECG-gated myocardial perfusion SPECT of asymptomatic ischemic heart disease in patients with type-2 diabetes mellitus: J-ACCESS 2 study design.

    PubMed

    Kusuoka, Hideo; Yamasaki, Yoshimitsu; Izumi, Tohru; Kashiwagi, Atsunori; Kawamori, Ryuzo; Shimamoto, Kazuaki; Yamada, Nobuhiro; Nishimura, Tsunehiko

    2008-01-01

    Diabetes mellitus is an independent risk factor for acute myocardial infarction. Thus, a surveillance study was conducted as part of studies to create a national database related to electrocardiogram (ECG)-gated myocardial perfusion single-photon emission computed tomography (SPECT) of ischemic heart disease. Single-photon emission computed tomography was conducted in patients with type 2 diabetes mellitus and their prognoses will be followed for 3 years, stratified by patients' clinical background and SPECT findings. A total of 513 patients from 50 institutions were enrolled in this study, 297 of whom were men (age 66.2 +/- 0.4 years, mean +/- SEM) and 261 women (age 67.8 +/- 0.5 years). They have a history of retinopathy (25.3%), neuropathy (19.9%), cerebrovascular disorder, chronic obstructive pulmonary disease, and photocoagulation. Major risk factors for present disease were hypertension (82.3%) and hyperlipidemia (79.7%). In 244 patients (129 men and 115 women), body mass index (BMI) was 25 or more. Fifty-two of them (10.1%) underwent coronary angiography; of these, 26 (50.0%) had no coronary artery lesions with 75% or more stenosis, and only 1 (1.9%) had a left main trunk with 50% or more stenosis. An overwhelming majority of patients (94.3%) underwent SPECT imaging by a 1-day stress-followed-by-rest procedure. Stress procedure was exercise in most (70.8%) patients, followed by dipyridamole infusion in 14.6%, adenosine infusion in 6.6%, and adenosine triphosphate infusion in 5.7%. Endpoint of stress examination was most often fatigue in lower limbs (40.7%), followed by completion of pharmacological stress protocol (28.7%), and achievement of target heart rate (26.3%). The largest number of patients (198, 38.6%) received (99m)Tc-tetrofosmin at an initial dosage of 200-300 MBq (mean 331 +/- 3 MBq) followed by a second dosage of 700-800 MBq (mean 748 +/- 8 MBq). Among them, 491 (95.7%) received some kind of therapeutic drug: hypoglycemic drugs were used by the

  2. Feasibility of free-breathing late gadolinium-enhanced cardiovascular MRI for assessment of myocardial infarction: navigator-gated versus single-shot imaging.

    PubMed

    Matsumoto, Hidenari; Matsuda, Tetsuya; Miyamoto, Kenichi; Nakatsuma, Kenji; Sugahara, Masataka; Shimada, Toshihiko

    2013-09-20

    The aim of this study was to evaluate the feasibility of two free-breathing late gadolinium-enhanced cardiovascular magnetic resonance (LGE-CMR) techniques (two-dimensional segmented navigator-gated [NAV-LGE] and single-shot [SS-LGE]) by comparing with breath-hold LGE-CMR (BH-LGE) as reference. A total of 200 consecutive patients underwent the three LGE-CMR imaging techniques. BH patterns were assessed with dynamic navigator MR imaging. Image quality was graded on a 5-point scale (4=optimal; 0=not assessable). In patients with sufficient BH capability (diaphragmatic movement with a deviation of <3mm), hyperenhancement was scored with a 5-point scale, and global infarct size (%left ventricle) was quantified. Compared to free-breathing LGE-CMR, BH-LGE had higher image quality grade in patients with sufficient BH capability (P<0.01 [vs. NAV-LGE]; P<0.001 [vs. SS-LGE]) but poorer image quality in patients with insufficient BH capability (P<0.001 [vs. NAV-LGE]; P<0.01 [vs. SS-LGE]). NAV-LGE had higher sensitivity for infarct detection than SS-LGE (97.1% vs. 88.4%, P<0.05), but specificity was not significantly different (97.3% vs. 94.7%, P=0.37). By Bland-Altman analysis, the average differences in global infarct size were 0.4% and 1.2%, and the limits of agreement were ± 4.0% and ± 5.9% for NAV- and SS-LGE, respectively. Although both NAV- and SS-LGE improve the image quality in patients with insufficient BH capability, NAV-LGE is superior to SS-LGE in infarct detection and infarct size measurement. NAV-LGE can be a possible first-line technique for patients with inability to perform sufficient BH. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

  3. Phase analysis of gated myocardial perfusion single-photon emission computed tomography after coronary artery bypass graft surgery: reflection of late reverse remodeling in patients with patent grafts after coronary artery bypass graft surgery.

    PubMed

    Park, Sohyun; Cheon, Gi Jeong; Paeng, Jin Chul; Won, Kyoung Sook; Kang, Keon Wook; Kim, Ki-Bong; Chung, June-Key; Lee, Dong Soo

    2016-11-01

    Phase analysis using gated myocardial perfusion single-photon emission computed tomography (GMPS) is a tool used to assess left ventricular (LV) dyssynchrony. We attempted to investigate the role of LV dyssynchrony assessed by GMPS using phase analysis for the late LV function after coronary artery bypass graft surgery (CABG) in patients with patent grafts. A total of 45 patients who received off-pump CABG with patent graft 1 year after CABG and preserved perfusion reserve were enrolled retrospectively. All patients underwent GMPS before and 3 months and 1 year after CABG. Using the Emory Cardiac Toolbox, both phase histogram bandwidth (PBW) and phase SD derived by phase analysis were used for the analysis, in addition to the conventional perfusion parameters. For the evaluation of LV function, transthoracic echocardiography was also performed. All of the patients showed perfusion improvement (paired t-test, P<0.05) after CABG. Nonetheless, 30 of 45 patients showed LV dyssynchrony 3 months after CABG. One year after CABG, however, 25 out of 45 patients showed reverse remodeling. Among those patients with reverse remodeling, 19 patients had shown LV 3 months after CABG. Using stepwise logistic regression with forward selection, PBW 3 months after CABG could predict reverse remodeling 1 year after CABG (odds ratio 1.03, P<0.05). Using receiver operating characteristic analysis, PBW 3 months after CABG had the largest area under the curve to detect reverse remodeling 1 year after CABG with a cut-off value of 82 (sensitivity 0.95, specificity 0.56, P<0.001). Postoperative LV dyssynchrony assessed by GMPS using phase analysis may reflect late reverse remodeling and potential of further functional improvement in patients with patent grafts and preserved perfusion reserve after CABG.

  4. Myocardial Ischemia

    MedlinePlus

    ... pectoris: Chest pain caused by myocardial ischemia. www.uptodate.com/home. Accessed June 1, 2015. Deedwania PC. Silent myocardial ischemia: Epidemiology and pathogenesis. www.uptodate.com/home. Accessed June 1, 2015. Mann DL, ...

  5. 20. DETAIL VIEW OF SUBMERSIBLE GATE, SHOWING GATE ARMS, GATE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    20. DETAIL VIEW OF SUBMERSIBLE GATE, SHOWING GATE ARMS, GATE PIERS, TRUNNION PIN AND GATE GAUGE, LOOKING NORTHEAST - Upper Mississippi River 9-Foot Channel, Lock & Dam No. 8, On Mississippi River near Houston County, MN, Genoa, Vernon County, WI

  6. 21. DETAIL VIEW OF SUBMERSIBLE TAINTER GATE, SHOWING GATE, GATE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    21. DETAIL VIEW OF SUBMERSIBLE TAINTER GATE, SHOWING GATE, GATE ARM, TRUNNION PIN, PIER AND GATE GAUGE, LOOKING EAST - Upper Mississippi River 9-Foot Channel, Lock & Dam No. 10, Guttenberg, Clayton County, IA

  7. 17. DETAIL VIEW OF NONSUBMERSIBLE TAINTER GATE, SHOWING GATES, GATE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    17. DETAIL VIEW OF NON-SUBMERSIBLE TAINTER GATE, SHOWING GATES, GATE ARMS, PIERS AND DAM BRIDGE, WITH ROLLER GATE HEADHOUSE IN BACKGROUND, LOOKING SOUTHEAST - Upper Mississippi River 9-Foot Channel, Lock & Dam No. 9, Lynxville, Crawford County, WI

  8. 17. DETAIL VIEW OF TAINTER GATE, SHOWING GATES, GATE ARMS, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    17. DETAIL VIEW OF TAINTER GATE, SHOWING GATES, GATE ARMS, PIERS, GATE CHAINS AND SWITCHES, AND BRIDGE GIRDERS, LOOKING SOUTHWEST - Upper Mississippi River 9-Foot Channel Project, Lock & Dam No. 5, Minneiska, Winona County, MN

  9. 18. DETAIL VIEW OF TAINTER GATE, SHOWING GATES, GATE ARMS, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    18. DETAIL VIEW OF TAINTER GATE, SHOWING GATES, GATE ARMS, PIERS, GATE CHAINS AND SWITCHES, AND BRIDGE GIRDERS, LOOKING NORTHWEST - Upper Mississippi River 9-Foot Channel Project, Lock & Dam No. 5, Minneiska, Winona County, MN

  10. A myocardial perfusion imaging system using a multifocal collimator for detecting coronary artery disease: validation with invasive coronary angiography.

    PubMed

    Ogino, Yutaka; Horiguchi, Yoriko; Ueda, Tomohiro; Shiomori, Tomofumi; Kanna, Masahiko; Kawaminami, Tomoko; Iinuma, Naoki; Sudo, Yuta; Morita, Yukiko

    2015-05-01

    Myocardial perfusion imaging (MPI) systems using a multifocal collimator can reduce scan time substantially compared with conventional MPI systems. In this study, we evaluated the diagnostic accuracy of multifocal collimator SPECT/CT in coronary artery disease (CAD) detection by comparing it with coronary artery angiography (CAG). We retrospectively analyzed 50 consecutive patients who had undergone CAG and stress (201)Tl MPI multifocal collimator SPECT/CT within a 3-month period. A summed difference score (SDS) was calculated for each vascular territory from the MPI images. On CAG, a stenotic coronary artery was defined as one with luminal narrowing of ≥75 % with quantitative coronary angiography software. We analyzed the diagnostic accuracy of coronary artery stenosis detection using the definition that a coronary artery territory was ischemic when the SDS per vessel was ≥2. We generated receiver operating characteristic (ROC) curves to evaluate the usefulness of SDS per vascular territory to find coronary artery stenoses. The area under the ROC curve was 0.86 and cut-off value was 2. Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy to detect stenoses were 85, 83, 66, 94 and 84 %, respectively. We confirmed the high accuracy of imaging with multifocal collimator SPECT/CT for detection of angiographically significant CAD.

  11. Microimaging studies of myocardial substrate utilization and perfusion in two models of non-coronary heart disease

    SciTech Connect

    Som, P.; Oster, Z.H.; Knapp, F.F. Jr.

    1987-01-01

    We have studied two animal models of non-coronary heart disease. The salt-sensitive Dahl strain hypertensive rats and their genetically matched normotensive controls and the cardiomyopathic BIO 53.58 (CM) strain Syrian hamsters with age and sex-matched RB strain controls. The CM strain hamster seems to be a very good model of human congestive cardiomyopathy and the Dahl strain hypertensive rats have also been found to be good models for studying the effects of hypertension on the myocardium. In our studies we compared the utilization of various metabolic substrates, viz., fatty acids, glucose analogs, and the early distribution of /sup 201/Tl, as an indicator of myocardial flow. The routine studies involving dissection of animals for assaying the radioactivity following the injection of radiopharmaceuticals is not suitable for assessing regional changes in metabolism and flow. The use of quantitative autoradiographic microimaging (ARG) enables the visualization of discrete regional as well as global changes from normal and to quantitate them. This paper describes the methodology and results of these investigations. 14 refs., 5 figs.

  12. The prognostic value of mechanical left ventricular dyssynchrony defined by phase analysis from gated single-photon emission computed tomography myocardial perfusion imaging among patients with coronary heart disease.

    PubMed

    Hess, Paul L; Shaw, Linda K; Fudim, Marat; Iskandrian, Ami E; Borges-Neto, Salvador

    2017-04-01

    The prognostic value of left ventricular dyssynchrony measured by gated single-photon emission computed tomography (GSPECT) myocardial perfusion imaging (MPI) and its relationship to electrical dyssynchrony measured by QRS duration are incompletely understood. The aim of this study was therefore to examine the independent and incremental prognostic value of dyssynchrony in yet the largest group of patients with coronary artery disease (CAD). Patients presenting for GSPECT- MPI between July 1993 and May 1999 in normal sinus rhythm were identified from the Duke Nuclear Cardiology Databank and the Duke Databank for Cardiovascular Disease (N = 1244). After a median of 4.2 years, 336 deaths occurred. At 8 years, the Kaplan-Meier estimates of the probability of death were 34.0% among patients with a phase bandwidth <100° and 56.8% among those with a bandwidth ≥100°. After adjustment for standard clinical variables, QRS dyssynchrony was independently associated with death (Hazard Ratio (HR), per 10°: 1.092, 95% Confidence Interval (CI) 1.048,1.139, P < .0001). Phase bandwidth was similarly associated with death after clinical adjustment (HR per 10°: 1.056, 95% CI 1.041,1.072, P < .0001). In clinically adjusted models examining QRS duration in addition to phase bandwidth, phase bandwidth had a stronger association with mortality. After accounting for left ventricular ejection fraction (LVEF), neither QRS duration nor phase bandwidth were statistically significant. Among patients with EF >35%, QRS duration and phase bandwidth together provided value above that provided by LVEF alone (P = 0.0181). When examining cardiovascular death, results were consistent with all-cause death. Among patients with CAD, mechanical left ventricular dyssynchrony measured by GSPECT MPI has a stronger relationship with outcomes than electrical dyssynchrony measured by QRS duration. After adjustment for baseline characteristics and LVEF, neither mechanical nor electrical

  13. Reproducibility of quantitative planar thallium-201 scintigraphy: quantitative criteria for reversibility of myocardial perfusion defects

    SciTech Connect

    Sigal, S.L.; Soufer, R.; Fetterman, R.C.; Mattera, J.A.; Wackers, F.J. )

    1991-05-01

    Fifty-two paired stress/delayed planar {sup 201}TI studies (27 exercise studies, 25 dipyridamole studies) were processed twice by seven technologists to assess inter- and intraobserver variability. The reproducibility was inversely related to the size of {sup 201}Tl perfusion abnormalities. Intraobserver variability was not different between exercise and dipyridamole studies for lesions of similar size. Based upon intraobserver variability, objective quantitative criteria for reversibility of perfusion abnormalities were defined. These objective criteria were tested prospectively in a separate group of 35 {sup 201}Tl studies and compared with the subjective interpretation of quantitative circumferential profiles. Overall, exact agreement existed in 78% of images (kappa statistic k = 0.66). We conclude that quantification of planar {sup 201}Tl scans is highly reproducible, with acceptable inter- and intraobserver variability. Objective criteria for lesion reversibility correlated well with analysis by experienced observers.

  14. 16. DETAIL VIEW OF SUBMERSIBLE TAINTER GATE, SHOWING GATE, GATE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    16. DETAIL VIEW OF SUBMERSIBLE TAINTER GATE, SHOWING GATE, GATE ARM, TRUNNION PIN AND PIER, LOOKING NORTHEAST - Upper Mississippi River 9-Foot Channel, Lock & Dam No. 8, On Mississippi River near Houston County, MN, Genoa, Vernon County, WI

  15. 18. DETAIL VIEW OF NONSUBMERSIBLE TAINTER GATE, SHOWING GATES, GATE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    18. DETAIL VIEW OF NON-SUBMERSIBLE TAINTER GATE, SHOWING GATES, GATE ARMS, PIERS AND DAM BRIDGE, LOOKING SOUTHEAST - Upper Mississippi River 9-Foot Channel, Lock & Dam No. 9, Lynxville, Crawford County, WI

  16. Myocardial kinetics of thallium-201 after dipyridamole infusion in normal canine myocardium and in myocardium distal to a stenosis.

    PubMed Central

    Okada, R D; Leppo, J A; Boucher, C A; Pohost, G M

    1982-01-01

    The purpose of the present study was to define myocardial and blood thallium-201 (Tl-201) kinetics after infusion of dipyridamole in normal canine myocardium and in myocardium distal to a coronary artery stenosis. Miniature radiation detector probes were implanted in the left ventricle in 39 open-chest dogs. A balloon constrictor was placed around the proximal left circumflex coronary artery. Electromagnetic flow probes were positioned proximally around both the left circumflex and left anterior descending coronary arteries. In five control dogs (group 1) the balloon occluder was not inflated; in 12 dogs (group 2) a mild stenosis was created such that resting flow was not reduced, yet the hyperemic response after 10 s of total occlusion was partially attenuated; in nine dogs (group 3) a moderate stenosis was created such that resting flow was not reduced, yet the hyperemic response was completely eliminated; and in 13 dogs (group 4) a severe stenosis was created such that resting flow was reduced. After intravenous dipyridamole (0.08 mg/kg . min-1 x 4 min), 1.5 mCi Tl-201 was injected intravenously and probe counts were collected continuously for 4 h. The mean 4-h fractional myocardial Tl-201 clearance for nonstenotic zones was 0.35, 0.27 for group 2 stenotic zones, 0.19 for group 3 stenotic zones, and 0.05 for group 4 stenotic zones (P less than 0.0001). After reaching peak activity, myocardial Tl-201 activity cleared biexponentially with a final decay constant lambda 2 = 0.0017 +/- 0.0001 min-1 (SE) for nonstenotic zones, 0.0011 +/- 0.0001 min-1 for group 2 stenotic zones, and 0.0006 +/- 0.0001 min-1 for group 3 stenotic zones (P less than 0.01). Group 4 stenotic zone Tl-201 clearances were negligible (decay constant essentially zero). Blood Tl-201 activity decayed triexponentially with a final blood lambda 3 = 0.0018 +/- 0.0001 min-1, which was almost identical to the final myocardial lambda 2 decay constant. Thus, the rate of myocardial Tl-201 clearance can

  17. Prevalence and clinical significance of residual myocardial ischemia 2 weeks after uncomplicated non-Q wave infarction: a prospective natural history study

    SciTech Connect

    Gibson, R.S.; Beller, G.A.; Gheorghiade, M.; Nygaard, T.W.; Watson, D.D.; Huey, B.L.; Sayre, S.L.; Kaiser, D.L.

    1986-06-01

    Despite having smaller infarct size and better left ventricular function, patients with non-Q wave myocardial infarction (NQMI) appear to have an unexpectedly high long-term mortality that is ultimately comparable to that of patients with Q-wave myocardial infarction (QMI). Patients with NQMI may lose their initial prognostic advantage because there is more viable tissue in the perfusion zone of the infarct-related vessel, rendering myocardium more prone to reinfarction. We tested this hypothesis in a prospective study of 241 consecutive patients 65 years of age or younger with acute uncomplicated myocardial infarction confirmed by creatine kinase levels (MB fraction). All patients received customary care and none underwent thrombolytic therapy or emergency angioplasty. Predischarge coronary angiography, radionuclide ventriculography, 24 hr Holter monitoring, and quantitative thallium-201 scintigraphy during treadmill exercise were performed 10 +/- 3 days after infarction. Infarcts were designated as QMI (n = 154) or NQMI (n = 87) by accepted criteria applied to serial electrocardiograms obtained on days 1, 2, 3, and 10. The baseline Norris coronary prognostic index, angiographic jeopardy scores, and prevalence of Lown grade ventricular arrhythmias were similar between groups despite evidence for less necrosis with NQMI vs QMI, reflected by lower peak creatine kinase levels (520 vs 1334 IU/liter; p = .0001, 4 hr sampling), higher resting left ventricular ejection fraction (53% vs 46%; p = .0001), fewer akinetic or dyskinetic segments (1.2 vs 2.4; p = .0001), and fewer persistent /sup 201/Tl defects in the infarct zone. Patients with NQMI also had more patent infarct-related vessels and a shorter time from onset of infarction to peak creatine kinase level.

  18. Myocardial viability.

    PubMed Central

    Birnbaum, Y; Kloner, R A

    1996-01-01

    Left ventricular function is a major predictor of outcome in patients with coronary artery disease. Acute ischemia, postischemic dysfunction (stunning), myocardial hibernation, or a combination of these 3 are among the reversible forms of myocardial dysfunction. In myocardial stunning, dysfunction occurs despite normal myocardial perfusion, and function recovers spontaneously over time. In acute ischemia and hibernation, there is regional hypoperfusion. Function improves only after revascularization. Evidence of myocardial viability usually relies on the demonstration of uptake of various metabolic tracers, such as thallium (thallous chloride TI 201) or fludeoxyglucose F 18, by dysfunctional myocardium or by the demonstration of contractile reserve in a dysfunctional region. This can be shown as an augmentation of function during the infusion of various sympathomimetic agents. The response of ventricular segments to increasing doses of dobutamine may indicate the underlying mechanism of dysfunction. Stunned segments that have normal perfusion show dose-dependent augmentation of function. If perfusion is reduced as in hibernating myocardium, however, a biphasic response usually occurs: function improves at low doses of dobutamine, whereas higher doses may induce ischemia and, hence, dysfunction. But in patients with severely impaired perfusion, even low doses may cause ischemia. Myocardial regions with subendocardial infarction or diffuse scarring may also have augmented contractility during catecholamine infusion due to stimulation of the subepicardial layers. In these cases, augmentation of function after revascularization is not expected. Because the underlying mechanism, prognosis, and therapy may differ among these conditions, it is crucial to differentiate among dysfunctional myocardial segments that are nonviable and have no potential to regain function, hibernating or ischemic segments in which recovery of function occurs only after revascularization, and

  19. Self-gated fat-suppressed cardiac cine MRI.

    PubMed

    Ingle, R Reeve; Santos, Juan M; Overall, William R; McConnell, Michael V; Hu, Bob S; Nishimura, Dwight G

    2015-05-01

    To develop a self-gated alternating repetition time balanced steady-state free precession (ATR-SSFP) pulse sequence for fat-suppressed cardiac cine imaging. Cardiac gating is computed retrospectively using acquired magnetic resonance self-gating data, enabling cine imaging without the need for electrocardiogram (ECG) gating. Modification of the slice-select rephasing gradients of an ATR-SSFP sequence enables the acquisition of a one-dimensional self-gating readout during the unused short repetition time (TR). Self-gating readouts are acquired during every TR of segmented, breath-held cardiac scans. A template-matching algorithm is designed to compute cardiac trigger points from the self-gating signals, and these trigger points are used for retrospective cine reconstruction. The proposed approach is compared with ECG-gated ATR-SSFP and balanced steady-state free precession in 10 volunteers and five patients. The difference of ECG and self-gating trigger times has a variability of 13 ± 11 ms (mean ± SD). Qualitative reviewer scoring and ranking indicate no statistically significant differences (P > 0.05) between self-gated and ECG-gated ATR-SSFP images. Quantitative blood-myocardial border sharpness is not significantly different among self-gated ATR-SSFP ( 0.61±0.15 mm -1), ECG-gated ATR-SSFP ( 0.61±0.15 mm -1), or conventional ECG-gated balanced steady-state free precession cine MRI ( 0.59±0.15 mm -1). The proposed self-gated ATR-SSFP sequence enables fat-suppressed cardiac cine imaging at 1.5 T without the need for ECG gating and without decreasing the imaging efficiency of ATR-SSFP. © 2014 Wiley Periodicals, Inc.

  20. Self-Gated Fat-Suppressed Cardiac Cine MRI

    PubMed Central

    Ingle, R. Reeve; Santos, Juan M.; Overall, William R.; McConnell, Michael V.; Hu, Bob S.; Nishimura, Dwight G.

    2014-01-01

    Purpose To develop a self-gated alternating repetition time balanced steady-state free precession (ATR-SSFP) pulse sequence for fat-suppressed cardiac cine imaging. Methods Cardiac gating is computed retrospectively using acquired MR self-gating data, enabling cine imaging without the need for electrocardiogram (ECG) gating. Modification of the slice-select rephasing gradients of an ATR-SSFP sequence enables the acquisition of a 1D self-gating readout during the unused short repetition time (TR). Self-gating readouts are acquired during every TR of segmented, breath-held cardiac scans. A template-matching algorithm is designed to compute cardiac trigger points from the self-gating signals, and these trigger points are used for retrospective cine reconstruction. The proposed approach is compared with ECG-gated ATR-SSFP and balanced steady-state free precession (bSSFP) in ten volunteers and five patients. Results The difference of ECG and self-gating trigger times has a variability of 13 ± 11 ms (mean ± SD). Qualitative reviewer scoring and ranking indicate no statistically significant differences (P > 0.05) between self-gated and ECG-gated ATR-SSFP images. Quantitative blood-myocardial border sharpness is not significantly different among self-gated ATR-SSFP (0.61 ± 0.15 mm−1), ECG-gated ATR-SSFP (0.61 ± 0.15 mm−1), or conventional ECG-gated bSSFP cine MRI (0.59 ± 0.15 mm−1). Conclusion The proposed self-gated ATR-SSFP sequence enables fat-suppressed cardiac cine imaging at 1.5 T without the need for ECG gating and without decreasing the imaging efficiency of ATR-SSFP. PMID:24806049

  1. Alterations in myocardial metabolism and function at rest in stable angina pectoris: relations with the amount of exercise-induced thallium-201 perfusion defect

    SciTech Connect

    De Kock, M.; Melin, J.A.; Pouleur, H.; Rousseau, M.F.

    1986-01-01

    The relation between the amount of exercise-induced ischemia and alterations in left ventricular (LV) function and metabolism at rest was studied in 18 coronary patients with stable angina pectoris. An ischemic defect area score was computed from quantitative exercise thallium-201 (Tl-201) scintigraphy; this estimation of the amount of ischemic myocardium was used to classify the patients in group I (n = 8; score less than 15%, mean 6.7 +/- 2.5%) and II (n = 10; score greater than 15%; mean 27.2 +/- 8.9%). Hemodynamics and metabolism were studied in basal state. No patient had anginal pain during the study, and the extent of angiographic coronary artery disease (CAD) was comparable in the two groups. Heart rate, aortic pressure, coronary blood flow, and myocardial oxygen uptake were also similar in both groups. However, ejection fraction was reduced in group II (51 +/- 13 vs 63 +/- 5%; p less than 0.01) and LV relaxation was impaired as shown by the increase in time-constant of isovolumic pressure fall (55 +/- 16 vs 44 +/- 6 ms in group I; p less than 0.05); the LV end-diastolic pressure was also increased in group II (19 +/- 8 vs 10 +/- 4 mmHg in group l; p less than 0.05). Furthermore, in group II, myocardial lactate uptake was reduced (4 +/- 19 vs 30 +/- 29 mumole/min in group I; p less than 0.01) and the productions of alanine and glutamine were augmented (-7.5 +/- 4.4 vs -4.6 +/- 1.6 mumole/min in group I; p less than 0.05).

  2. Myocardial uptake and washout kinetics of T1-201 with the VEX (vasodilator plus exercise) test: contribution of stress mode components and coronary stenosis severity.

    PubMed

    Hurwitz, G A; MacDonald, A C; Weingert, M E; Hessian, R C; Finnie, K J; St Clement, G; Powe, J E

    1996-07-01

    To assess the vasodilator plus exercise (VEX) test as an adjunct to myocardial perfusion imaging with respect to the accuracy of kinetics of thallium-201 (Tl-201) and other indicators of ischemia. A nuclear medicine laboratory in which patients referred for myocardial scintigraphy are triaged to undergo the stress component with symptom-limited bicycle exercise, dipyridamole or VEX as appropriate. Cases having correlating scintigraphy and angiography (n = 425) were selected retrospectively. Immediate poststress and redistribution images were quantified using a circumferential profile analysis with interpolative background subtraction. For each of nine sectors on the left anterior oblique image, multivariate analyses were performed, comparing the relative uptake and net washout of Tl-201 to the exercise workload attained, use of dipyridamole, time to redistribution, gender, and the angiographic presence and severity of stenoses at five key sites. Washout values standardized according to gender, exercise level and time to redistribution, were compared with relative uptake profiles and ST depression using receiver operating curves. For each sector, a significant contribution to Tl-201 washout was made by the exercise level (P < 0.001) and by at least one site of stenosis (P < 0.0001), but not by use of dipyridamole (P > 0.5); female gender was associated with increased washout (P < 0.01) except for the three lateral sectors. For each stress modality, standardized washout performed better than ST depression but not as well as relative uptake profiles in detecting coronary artery disease. For combined pharmacological-exercise stress, quantitative uptake profiles may assist in confirming subjective scan interpretation; washout profiles, even when standardized for gender and stress level, are suboptimal for confirming defect reversibility.

  3. Myocardial perfusion scintigraphy: techniques, interpretation, indications and reporting.

    PubMed

    Fathala, Ahmed

    2011-01-01

    Myocardial perfusion single photon emission-computed tomography (MPS) has been one of the most important and common non-invasive diagnostic cardiac test. Gated MPS provides simultaneous assessment of myocardial perfusion and function with only one study. With appropriate attention to the MPS techniques, appropriate clinical utilization and effective reporting, gated MPS will remain a useful diagnostic test for many years to come. The aim of this article is to review the basic techniques of MPS, a simplified systematic approach for study interpretation, current clinical indications and reporting. After reading this article the reader should develop an understanding of the techniques, interpretation, current clinical indications and reporting of MPS studies.

  4. Role of myocardial perfusion single photon emission computed tomography in pediatric cardiology practice

    PubMed Central

    Sundaram, P Shanmuga; Padma, S

    2009-01-01

    Diagnostic and prognostic power of myocardial perfusion imaging in patients with coronary artery disease has been demonstrated with planar imaging which was further improvised with addition of gated SPECT and newer Technetium labeled myocardial perfusion tracers like SestaMIBI, Tetrofosmin. Myocardial perfusion abnormalities at rest and after stress are considered to be the best predictors of cardiac event–free survival in adults with ischemic heart disease. This article highlights various myocardial perfusion imaging (MPI) radiopharmaceuticals, exercise procedures, pharmacological stress protocols, indications for MPI and myocardial perfusion patterns in children with some of the common congenital and acquired heart diseases. PMID:20808625

  5. 49 CFR 234.255 - Gate arm and gate mechanism.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Gate arm and gate mechanism. 234.255 Section 234... Maintenance, Inspection, and Testing Inspections and Tests § 234.255 Gate arm and gate mechanism. (a) Each gate arm and gate mechanism shall be inspected at least once each month. (b) Gate arm movement shall...

  6. 49 CFR 234.255 - Gate arm and gate mechanism.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 4 2014-10-01 2014-10-01 false Gate arm and gate mechanism. 234.255 Section 234....255 Gate arm and gate mechanism. (a) Each gate arm and gate mechanism shall be inspected at least once each month. (b) Gate arm movement shall be observed for proper operation at least once each month....

  7. 49 CFR 234.255 - Gate arm and gate mechanism.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 4 2013-10-01 2013-10-01 false Gate arm and gate mechanism. 234.255 Section 234....255 Gate arm and gate mechanism. (a) Each gate arm and gate mechanism shall be inspected at least once each month. (b) Gate arm movement shall be observed for proper operation at least once each month....

  8. 49 CFR 234.255 - Gate arm and gate mechanism.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 4 2011-10-01 2011-10-01 false Gate arm and gate mechanism. 234.255 Section 234... Maintenance, Inspection, and Testing Inspections and Tests § 234.255 Gate arm and gate mechanism. (a) Each gate arm and gate mechanism shall be inspected at least once each month. (b) Gate arm movement shall...

  9. 49 CFR 234.255 - Gate arm and gate mechanism.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 4 2012-10-01 2012-10-01 false Gate arm and gate mechanism. 234.255 Section 234....255 Gate arm and gate mechanism. (a) Each gate arm and gate mechanism shall be inspected at least once each month. (b) Gate arm movement shall be observed for proper operation at least once each month....

  10. Validation of a short-scan-time imaging protocol for thallium-201 myocardial SPECT with a multifocal collimator.

    PubMed

    Horiguchi, Yoriko; Ueda, Tomohiro; Shiomori, Tomofumi; Kanna, Masahiko; Matsushita, Hirooki; Kawaminami, Tomoko; Sudo, Yuta; Kikuchi, Shinnosuke; Sasaki, Ryo; Hoshimiya, Jun; Morita, Yukiko

    2014-10-01

    IQ-SPECT (Siemens AG, Munich, Germany) is a highly sensitive single-photon-emission computed tomography (SPECT) myocardial perfusion imaging (MPI) system that uses a multifocal collimator. We searched for a suitable protocol for short-time imaging by IQ-SPECT in thallium-201 (Tl-201) MPI by evaluating phantom images and also by comparing human IQ-SPECT images with conventional SPECT images as reference standards. We assessed the image quality using the normalized mean square error (NMSE) and drew up count profiles in Tl-201 SPECT images acquired with IQ-SPECT in a phantom study. We also performed Tl-201 stress myocardial SPECT/CT in 21 patients and compared delayed images acquired by using IQ-SPECT with 36 or 17 views per head with images obtained by using conventional SPECT. The NMSE of SPECT images from IQ-SPECT with 36 views was approximately one-fifth of that with 17 views. The myocardial count profile of images with 17 views was lower than those of images with 36 or 104 views in some regions. Defect scores were significantly lower, and image quality scores higher, in images from conventional SPECT than in those from IQ-SPECT with 17 views. Defect scores and image quality scores were equivalent in images from conventional SPECT and those from IQ-SPECT with 36 views. Agreement with the results of conventional SPECT in terms of coronary artery territory-based defect judgment was the best in IQ-SPECT with 36 views with computed tomography-derived attenuation correction (CTAC): the kappa values for IQ-SPECT with 36 views were 0.76 (without CTAC) and 0.83 (with CTAC), and those for IQ-SPECT with 17 views were 0.62 (without CTAC) and 0.59 (with CTAC). The difference in quantitative tracer uptake between conventional SPECT images and IQ-SPECT images was significantly greater for IQ-SPECT images with 17 views than for those with 36 views. Scanning with 36 views per head with CTAC may be appropriate for Tl-201 MPI using IQ-SPECT, because it provides images equivalent to

  11. Application of Three-Class ROC Analysis to Task-Based Image Quality Assessment of Simultaneous Dual-Isotope Myocardial Perfusion SPECT (MPS)

    PubMed Central

    He, Xin; Song, Xiyun; Frey, Eric C.

    2009-01-01

    The diagnosis of cardiac disease using dual-isotope myocardial perfusion SPECT (MPS) is based on the defect status in both stress and rest images, and can be modeled as a three-class task of classifying patients as having no, reversible, or fixed perfusion defects. Simultaneous acquisition protocols for dual-isotope MPS imaging have gained much interest due to their advantages including perfect registration of the 201Tl and 99mTc images in space and time, increased patient comfort, and higher clinical throughput. As a result of simultaneous acquisition, however, crosstalk contamination, where photons emitted by one isotope contribute to the image of the other isotope, degrades image quality. Minimizing the crosstalk is important in obtaining the best possible image quality. One way to minimize the crosstalk is to optimize the injected activity of the two isotopes by considering the three-class nature of the diagnostic problem. To effectively do so, we have previously developed a three-class receiver operating characteristic (ROC) analysis methodology that extends and unifies the decision theoretic, linear discriminant analysis, and psychophysical foundations of binary ROC analysis in a three-class paradigm. In this work, we applied the proposed three-class ROC methodology to the assessment of the image quality of simultaneous dual-isotope MPS imaging techniques and the determination of the optimal injected activity combination. In addition to this application, the rapid development of diagnostic imaging techniques has produced an increasing number of clinical diagnostic tasks that involve not only disease detection, but also disease characterization and are thus multiclass tasks. This paper provides a practical example of the application of the proposed three-class ROC analysis methodology to medical problems. PMID:18955172

  12. Three-class ROC analysis: a sequential decision model developed for the diagnostic task rest-stress myocardial perfusion SPECT imaging

    NASA Astrophysics Data System (ADS)

    He, Xin; Frey, Eric C.

    2008-03-01

    Previously we have developed a decision model for three-class ROC analysis where classification is made three simultaneously, i.e., with a single decision. In this paper, an alternative sequential decision model was developed for the specific three-class diagnostic procedure of rest-stress myocardial perfusion SPECT (MPS) imaging. This sequential decision model was developed based on the fact that sometimes this diagnostic task is performed using a two-step process. First, the stress ( 99m Tc) image is read to determine whether a patient is normal or abnormal based on the presence of a defect in the stress image. If a defect is found, the rest ( 201Tl) image is then read to determine whether this is a reversible defect or a fixed defect based on the presence of defect on the rest image. In fact, in some MPS protocols where sequential stress/rest imaging is performed, the rest imaging is not performed if there is no defect in the stress image. Therefore, the three-class task is decomposed to a sequence of two two-class tasks. For this task we determined, by maximizing the expected utility of both steps of the decision process, that log likelihood ratios were the optimal decision variables and provide the optimal ROC surface under the assumption that incorrect decisions have equal utilities under the same hypothesis. The properties of the sequential decision model were then studied. We found that the sequential decision model shares most of the features of a 2-class ROC curve. While this model was developed in the context of rest-stress MPS, it may have applications to other two-step diagnostic tasks.

  13. 21. DETAIL VIEW OF SUBMERSIBLE TAINTER GATE, SHOWING GATE ARM, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    21. DETAIL VIEW OF SUBMERSIBLE TAINTER GATE, SHOWING GATE ARM, GATE PIER, TRUNNION PIN AND GATE GAUGE, LOOKING SOUTHEAST - Upper Mississippi River 9-Foot Channel, Lock & Dam No. 9, Lynxville, Crawford County, WI

  14. 6. DETAIL VIEW OF ENTRANCE GATES, SHOWING IRON GATE, STONE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    6. DETAIL VIEW OF ENTRANCE GATES, SHOWING IRON GATE, STONE WORK, AND GATE STOP FROM SOUTHEAST OF NORTHWEST ELEMENTS. - William Enston Home, Entrance Gate, 900 King Street, Charleston, Charleston County, SC

  15. Parallelizable adiabatic gate teleportation

    NASA Astrophysics Data System (ADS)

    Nakago, Kosuke; Hajdušek, Michal; Nakayama, Shojun; Murao, Mio

    2015-12-01

    To investigate how a temporally ordered gate sequence can be parallelized in adiabatic implementations of quantum computation, we modify adiabatic gate teleportation, a model of quantum computation proposed by Bacon and Flammia [Phys. Rev. Lett. 103, 120504 (2009), 10.1103/PhysRevLett.103.120504], to a form deterministically simulating parallelized gate teleportation, which is achievable only by postselection. We introduce a twisted Heisenberg-type interaction Hamiltonian, a Heisenberg-type spin interaction where the coordinates of the second qubit are twisted according to a unitary gate. We develop parallelizable adiabatic gate teleportation (PAGT) where a sequence of unitary gates is performed in a single step of the adiabatic process. In PAGT, numeric calculations suggest the necessary time for the adiabatic evolution implementing a sequence of L unitary gates increases at most as O (L5) . However, we show that it has the interesting property that it can map the temporal order of gates to the spatial order of interactions specified by the final Hamiltonian. Using this property, we present a controlled-PAGT scheme to manipulate the order of gates by a control qubit. In the controlled-PAGT scheme, two differently ordered sequential unitary gates F G and G F are coherently performed depending on the state of a control qubit by simultaneously applying the twisted Heisenberg-type interaction Hamiltonians implementing unitary gates F and G . We investigate why the twisted Heisenberg-type interaction Hamiltonian allows PAGT. We show that the twisted Heisenberg-type interaction Hamiltonian has an ability to perform a transposed unitary gate by just modifying the space ordering of the final Hamiltonian implementing a unitary gate in adiabatic gate teleportation. The dynamics generated by the time-reversed Hamiltonian represented by the transposed unitary gate enables deterministic simulation of a postselected event of parallelized gate teleportation in adiabatic

  16. Quantum gate decomposition algorithms.

    SciTech Connect

    Slepoy, Alexander

    2006-07-01

    Quantum computing algorithms can be conveniently expressed in a format of a quantum logical circuits. Such circuits consist of sequential coupled operations, termed ''quantum gates'', or quantum analogs of bits called qubits. We review a recently proposed method [1] for constructing general ''quantum gates'' operating on an qubits, as composed of a sequence of generic elementary ''gates''.

  17. Kinetics and dosimetry of thallium-201 in human testes

    SciTech Connect

    Rao, D.V.; Shepstone, B.J.; Wilkins, H.B. ||

    1995-04-01

    Thallous chloride ({sup 201}Tl) is a well-known imaging agent. It has been shown to accumulate in the testes. In view of this, the testicular kinetics of {sup 201}Tl is investigated in humans and the absorbed dose to the organ calculated. Thallous chloride {sup 201}Tl was injected intravenously into four patients for myocardial perfusion studies. After clinical evaluation, the testicular uptake and clearance of {sup 201}Tl were monitored for about 1 wk using a gamma camera. Testicular uptake of {sup 201}Tl was rapid with a mean biological uptake half-time of 0.67 hr and mean biological clearance half-time of 280 hr. The mean maximum testicular uptake of {sup 201}Tl was about 0.4% of the injected activity. These data were utilized to calculate the average absorbed dose to the testes. The absorbed dose to the testes was calculated to be 3.5 x 10{sup {minus}4} Gy/MBq (1.3 rad/mCi) of injected activity. When the relative biological effectiveness of the Auger emitter {sup 201}Tl is taken into account, the equivalent dose to the testes is 9.5 x 10{sup {minus}4} Sv/MBq (3.5 rem/mCi). 14 refs., 1 fig., 2 tabs.

  18. Gated strip proportional detector

    DOEpatents

    Morris, Christopher L.; Idzorek, George C.; Atencio, Leroy G.

    1987-01-01

    A gated strip proportional detector includes a gas tight chamber which encloses a solid ground plane, a wire anode plane, a wire gating plane, and a multiconductor cathode plane. The anode plane amplifies the amount of charge deposited in the chamber by a factor of up to 10.sup.6. The gating plane allows only charge within a narrow strip to reach the cathode. The cathode plane collects the charge allowed to pass through the gating plane on a set of conductors perpendicular to the open-gated region. By scanning the open-gated region across the chamber and reading out the charge collected on the cathode conductors after a suitable integration time for each location of the gate, a two-dimensional image of the intensity of the ionizing radiation incident on the detector can be made.

  19. Gated strip proportional detector

    DOEpatents

    Morris, C.L.; Idzorek, G.C.; Atencio, L.G.

    1985-02-19

    A gated strip proportional detector includes a gas tight chamber which encloses a solid ground plane, a wire anode plane, a wire gating plane, and a multiconductor cathode plane. The anode plane amplifies the amount of charge deposited in the chamber by a factor of up to 10/sup 6/. The gating plane allows only charge within a narrow strip to reach the cathode. The cathode plane collects the charge allowed to pass through the gating plane on a set of conductors perpendicular to the open-gated region. By scanning the open-gated region across the chamber and reading out the charge collected on the cathode conductors after a suitable integration time for each location of the gate, a two-dimensional image of the intensity of the ionizing radiation incident on the detector can be made.

  20. Range gated imaging experiments using gated intensifiers

    SciTech Connect

    McDonald, T.E. Jr.; Yates, G.J.; Cverna, F.H.; Gallegos, R.A.; Jaramillo, S.A.; Numkena, D.M.; Payton, J.; Pena-Abeyta, C.R.

    1999-03-01

    A variety of range gated imaging experiments using high-speed gated/shuttered proximity focused microchannel plate image intensifiers (MCPII) are reported. Range gated imaging experiments were conducted in water for detection of submerged mines in controlled turbidity tank test and in sea water for the Naval Coastal Sea Command/US Marine Corps. Field experiments have been conducted consisting of kilometer range imaging of resolution targets and military vehicles in atmosphere at Eglin Air Force Base for the US Air Force, and similar imaging experiments, but in smoke environment, at Redstone Arsenal for the US Army Aviation and Missile Command (AMCOM). Wavelength of the illuminating laser was 532 nm with pulse width ranging from 6 to 12 ns and comparable gate widths. These tests have shown depth resolution in the tens of centimeters range from time phasing reflected LADAR images with MCPII shutter opening.

  1. Optical Logic Gates

    NASA Technical Reports Server (NTRS)

    Du Fresne, E. R.; Dowler, W. L.

    1985-01-01

    Logic gates for light signals constructed from combinations of prisms, polarizing plates, and quarterwave plates. Optical logic gate performs elementary logic operation on light signals received along two optical fibers. Whether gate performs OR function or exclusive-OR function depends on orientation of analyzer. Nonbinary truth tables also obtained by rotating polarizer or analyzer to other positions or inserting other quarter-wave plates.

  2. Myocardial imaging. Coxsackie myocarditis

    SciTech Connect

    Wells, R.G.; Ruskin, J.A.; Sty, J.R.

    1986-09-01

    A 3-week-old male neonate with heart failure associated with Coxsackie virus infection was imaged with Tc-99m PYP and TI-201. The abnormal imaging pattern suggested myocardial infarction. Autopsy findings indicated that the cause was myocardial necrosis secondary to an acute inflammatory process. Causes of abnormal myocardial uptake of Tc-99m PYP in pediatrics include infarction, myocarditis, cardiomyopathy, bacterial endocarditis, and trauma. Myocardial imaging cannot provide a specific cause diagnosis. Causes of myocardial infarction in pediatrics are listed in Table 1.

  3. 15. DETAIL VIEW OF SUBMERSIBLE TAINTER GATE, SHOWING GATES AND ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    15. DETAIL VIEW OF SUBMERSIBLE TAINTER GATE, SHOWING GATES AND GATE ARMS, PIERS AND DAM BRIDGE, LOOKING NORTHEAST - Upper Mississippi River 9-Foot Channel, Lock & Dam No. 8, On Mississippi River near Houston County, MN, Genoa, Vernon County, WI

  4. 4. DETAIL VIEW OF TAINTER GATE PIER AND TAINTER GATE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    4. DETAIL VIEW OF TAINTER GATE PIER AND TAINTER GATE NO. 7 AND NON-SUBMERSIBLE TAINTER GATES, LOOKING WEST (UPSTREAM) - Upper Mississippi River 9-Foot Channel Project, Lock & Dam 26R, Alton, Madison County, IL

  5. 19. DETAIL VIEW OF SUBMERSIBLE TAINTER GATE, SHOWING GATE ARM, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    19. DETAIL VIEW OF SUBMERSIBLE TAINTER GATE, SHOWING GATE ARM, PIER, TRUNNION PIN AND GATE GAUGE, LOOKING NORTH - Upper Mississippi River 9-Foot Channel, Lock & Dam No. 8, On Mississippi River near Houston County, MN, Genoa, Vernon County, WI

  6. 20. DETAIL VIEW OF TAINTER GATE, SHOWING GATE ARMS, PIERS, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    20. DETAIL VIEW OF TAINTER GATE, SHOWING GATE ARMS, PIERS, TRUNNION PINS, AND GATE GAUGE, LOOKING SOUTHWEST - Upper Mississippi River 9-Foot Channel Project, Lock & Dam No. 5, Minneiska, Winona County, MN

  7. 16. DETAIL VIEW OF TAINTER GATE, SHOWING GATES, PIERS, BRIDGE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    16. DETAIL VIEW OF TAINTER GATE, SHOWING GATES, PIERS, BRIDGE GIRDERS AND ROLLER GATE BULKHEADS STORED ON PIER ABUTMENTS, LOOKING WEST - Upper Mississippi River 9-Foot Channel Project, Lock & Dam No. 5, Minneiska, Winona County, MN

  8. 12. DETAIL VIEW OF ROLLER GATE, SHOWING GATE FLANGE AND ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    12. DETAIL VIEW OF ROLLER GATE, SHOWING GATE FLANGE AND TUBE, ROLLER TRACK, CHAIN AND GATE HEATER, LOOKING EAST - Upper Mississippi River 9-Foot Channel Project, Lock & Dam No. 5, Minneiska, Winona County, MN

  9. 10. DETAIL VIEW OF ROLLER GATE, SHOWING GATE FLANGE AND ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    10. DETAIL VIEW OF ROLLER GATE, SHOWING GATE FLANGE AND TUBE, ROLLER TRACK AND GATE HEATER, LOOKING SOUTHWEST - Upper Mississippi River 9-Foot Channel, Lock & Dam No. 8, On Mississippi River near Houston County, MN, Genoa, Vernon County, WI

  10. Sliding-gate valve

    DOEpatents

    Usnick, George B.; Ward, Gene T.; Blair, Henry O.; Roberts, James W.; Warner, Terry N.

    1979-01-01

    This invention is a novel valve of the slidable-gate type. The valve is designed especially for long-term use with highly abrasive slurries. The sealing surfaces of the gate are shielded by the valve seats when the valve is fully open or closed, and the gate-to-seat clearance is swept with an inflowing purge gas while the gate is in transit. A preferred form of the valve includes an annular valve body containing an annular seat assembly defining a flow channel. The seat assembly comprises a first seat ring which is slidably and sealably mounted in the body, and a second seat ring which is tightly fitted in the body. These rings cooperatively define an annular gap which, together with passages in the valve body, forms a guideway extending normal to the channel. A plate-type gate is mounted for reciprocation in the guideway between positions where a portion of the plate closes the channel and where a circular aperture in the gate is in register with the channel. The valve casing includes opposed chambers which extend outwardly from the body along the axis of the guideway to accommodate the end portions of the gate. The chambers are sealed from atmosphere; when the gate is in transit, purge gas is admitted to the chambers and flows inwardly through the gate-to-seat-ring, clearance, minimizing buildup of process solids therein. A shaft reciprocated by an external actuator extends into one of the sealed chambers through a shaft seal and is coupled to an end of the gate. Means are provided for adjusting the clearance between the first seat ring and the gate while the valve is in service.

  11. IMAGING DIAGNOSIS-MULTIMODALITY FINDINGS IN AN ADULT DOG WITH PRIMARY SARCOMA OF THE PULMONARY ARTERY AND MYOCARDIAL METASTASES.

    PubMed

    Stieger-Vanegas, Susanne M; Bottorff, Bryan; Sisson, David; Löhr, Christiane V

    2016-07-01

    Intravascular pulmonary artery sarcomas in combination with myocardial metastasis are rare in dogs. We describe the radiographic, echocardiographic, and electrocardiographic-gated (ECG-gated) computed tomographic angiography (CTA) findings in a dog with pulmonary artery sarcoma. All imaging studies demonstrated severe main pulmonary artery enlargement. Echocardiography and ECG-gated CTA revealed a mass occluding the lumen of the right pulmonary artery. In addition, CTA revealed focal left ventricular myocardial contrast enhancement and parenchymal lung changes. Postmortem examination confirmed the presence of a large thrombus associated with arteriosclerosis and an intravascular sarcoma in the right pulmonary artery with metastases to the myocardium, lungs and brain.

  12. Adiabatically implementing quantum gates

    SciTech Connect

    Sun, Jie; Lu, Songfeng Liu, Fang

    2014-06-14

    We show that, through the approach of quantum adiabatic evolution, all of the usual quantum gates can be implemented efficiently, yielding running time of order O(1). This may be considered as a useful alternative to the standard quantum computing approach, which involves quantum gates transforming quantum states during the computing process.

  13. CCD gate definition process

    NASA Astrophysics Data System (ADS)

    Bluzer

    1986-02-01

    The present invention utilizes a double masking step in a CCD gate definition process to eliminate the re-entrant oxide by using a thin film layer other than photoresist to define the polysilicon gates used by defining the thin film layer with a double masking process before any of the polysilicon gate layer is etched. It is one object of the present invention, therefore, to provide an improved process for CCD gate definition. It is another object of the invention to provide an improved CCD gate definition process wherein a profiled oxide layer is produced over a polysilicon layer without re-entrant oxide regions. It is another object of the invention to provide an improved CCD gate definition process wherein a thin film layer is utilized to define the polysilicon gate layers. It is another object of the invention to provide an improved CCD gate definition process wherein the thin film layer is defined by a double masking process before any polysilicon layer is etched.

  14. Optical NAND gate

    DOEpatents

    Skogen, Erik J.; Raring, James; Tauke-Pedretti, Anna

    2011-08-09

    An optical NAND gate is formed from two pair of optical waveguide devices on a substrate, with each pair of the optical waveguide devices consisting of an electroabsorption modulator and a photodetector. One pair of the optical waveguide devices is electrically connected in parallel to operate as an optical AND gate; and the other pair of the optical waveguide devices is connected in series to operate as an optical NOT gate (i.e. an optical inverter). The optical NAND gate utilizes two digital optical inputs and a continuous light input to provide a NAND function output. The optical NAND gate can be formed from III-V compound semiconductor layers which are epitaxially deposited on a III-V compound semiconductor substrate, and operates at a wavelength in the range of 0.8-2.0 .mu.m.

  15. 18. DETAIL VIEW OF NONSUBMERSIBLE TAINTER GATE, SHOWING GATE AND ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    18. DETAIL VIEW OF NON-SUBMERSIBLE TAINTER GATE, SHOWING GATE AND GATE ARMS, GATE PIER AND DAM BRIDGE, LOOKING NORTHEAST - Upper Mississippi River 9-Foot Channel, Lock & Dam No. 8, On Mississippi River near Houston County, MN, Genoa, Vernon County, WI

  16. 17. DETAIL VIEW OF NONSUBMERSIBLE TAINTER GATE, SHOWING GATE AND ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    17. DETAIL VIEW OF NON-SUBMERSIBLE TAINTER GATE, SHOWING GATE AND GATE ARM, GATE PIER AND DAM BRIDGE, LOOKING SOUTHEAST - Upper Mississippi River 9-Foot Channel, Lock & Dam No. 8, On Mississippi River near Houston County, MN, Genoa, Vernon County, WI

  17. Optical NOR gate

    DOEpatents

    Skogen, Erik J.; Tauke-Pedretti, Anna

    2011-09-06

    An optical NOR gate is formed from two pair of optical waveguide devices on a substrate, with each pair of the optical waveguide devices consisting of an electroabsorption modulator electrically connected in series with a waveguide photodetector. The optical NOR gate utilizes two digital optical inputs and a continuous light input to provide a NOR function digital optical output. The optical NOR gate can be formed from III-V compound semiconductor layers which are epitaxially deposited on a III-V compound semiconductor substrate, and operates at a wavelength in the range of 0.8-2.0 .mu.m.

  18. Optical XOR gate

    SciTech Connect

    Vawter, G. Allen

    2013-11-12

    An optical XOR gate is formed as a photonic integrated circuit (PIC) from two sets of optical waveguide devices on a substrate, with each set of the optical waveguide devices including an electroabsorption modulator electrically connected in series with a waveguide photodetector. The optical XOR gate utilizes two digital optical inputs to generate an XOR function digital optical output. The optical XOR gate can be formed from III-V compound semiconductor layers which are epitaxially deposited on a III-V compound semiconductor substrate, and operates at a wavelength in the range of 0.8-2.0 .mu.m.

  19. SPECT myocardial perfusion imaging for the assessment of left ventricular mechanical dyssynchrony

    PubMed Central

    Chen, Ji; Garcia, Ernest V.; Bax, Jeroen J.; Iskandrian, Ami E.; Borges-Neto, Salvador; Soman, Prem

    2012-01-01

    Phase analysis of gated single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) is an evolving technique for measuring LV mechanical dyssynchrony. Since its inception in 2005, it has undergone considerable technical development and clinical evaluation. This article reviews the background, the technical and clinical characteristics, and evolving clinical applications of phase analysis of gated SPECT MPI in patients requiring cardiac resynchronization therapy or implantable cardioverter defibrillator therapy and in assessing LV diastolic dyssynchrony. PMID:21567281

  20. The human respiratory gate

    NASA Technical Reports Server (NTRS)

    Eckberg, Dwain L.

    2003-01-01

    Respiratory activity phasically alters membrane potentials of preganglionic vagal and sympathetic motoneurones and continuously modulates their responsiveness to stimulatory inputs. The most obvious manifestation of this 'respiratory gating' is respiratory sinus arrhythmia, the rhythmic fluctuations of electrocardiographic R-R intervals observed in healthy resting humans. Phasic autonomic motoneurone firing, reflecting the throughput of the system, depends importantly on the intensity of stimulatory inputs, such that when levels of stimulation are low (as with high arterial pressure and sympathetic activity, or low arterial pressure and vagal activity), respiratory fluctuations of sympathetic or vagal firing are also low. The respiratory gate has a finite capacity, and high levels of stimulation override the ability of respiration to gate autonomic responsiveness. Autonomic throughput also depends importantly on other factors, including especially, the frequency of breathing, the rate at which the gate opens and closes. Respiratory sinus arrhythmia is small at rapid, and large at slow breathing rates. The strong correlation between systolic pressure and R-R intervals at respiratory frequencies reflects the influence of respiration on these two measures, rather than arterial baroreflex physiology. A wide range of evidence suggests that respiratory activity gates the timing of autonomic motoneurone firing, but does not influence its tonic level. I propose that the most enduring significance of respiratory gating is its use as a precisely controlled experimental tool to tease out and better understand otherwise inaccessible human autonomic neurophysiological mechanisms.

  1. Advanced insulated gate bipolar transistor gate drive

    DOEpatents

    Short, James Evans; West, Shawn Michael; Fabean, Robert J.

    2009-08-04

    A gate drive for an insulated gate bipolar transistor (IGBT) includes a control and protection module coupled to a collector terminal of the IGBT, an optical communications module coupled to the control and protection module, a power supply module coupled to the control and protection module and an output power stage module with inputs coupled to the power supply module and the control and protection module, and outputs coupled to a gate terminal and an emitter terminal of the IGBT. The optical communications module is configured to send control signals to the control and protection module. The power supply module is configured to distribute inputted power to the control and protection module. The control and protection module outputs on/off, soft turn-off and/or soft turn-on signals to the output power stage module, which, in turn, supplies a current based on the signal(s) from the control and protection module for charging or discharging an input capacitance of the IGBT.

  2. Early-phase myocardial infarction: Evaluation by MR imaging

    SciTech Connect

    Tscholakoff, D.; Higgins, C.B.; McNamara, M.T.; Derugin, N.

    1986-06-01

    In vivo gated magnetic resonance (MR) imaging was performed in 12 dogs immediately after occlusion of the left anterior descending coronary artery and serially up to 5 hours and again between 4 and 14 days. This was done to evaluate the appearance of acute myocardial infarcts and to determine how soon after coronary artery occlusion MR imaging can demonstrate the site of acute myocardial ischemia. In nine dogs with postmortem evidence of myocardial infarction, regional increase of signal intensity of the myocardium was present by 3 hours after coronary occlusion and conformed to the site of myocardial infarct found at autopsy. The signal intensity on T2-weighted images of the infarcted on T2-weighted images of the infarcted myocardium was significantly greater than that of normal myocardium at 3, 4, and 5 hours after occlusion. The T2 (spin-spin) relaxation time was significantly prolonged in the region of myocardial infarct at 3, 4, and 5 hours post-occlusion compared with normal myocardium. Myocardial wall thinning and increased intracavitary flow signal were found in six dogs with comparable pre- and postocclusion images in late systole.

  3. The influence of number of counts in the myocardium in the determination of reproducible functional parameters in gated-SPECT studies simulated with GATE.

    PubMed

    Vieira, L; Costa, D C; Almeida, P

    2015-01-01

    Myocardial perfusion gated-single photon emission computed tomography (gated-SPECT) imaging is used for the combined evaluation of myocardial perfusion and left ventricular (LV) function. The aim of this study is to analyze the influence of counts/pixel and concomitantly the total counts in the myocardium for the calculation of myocardial functional parameters. Gated-SPECT studies were performed using a Monte Carlo GATE simulation package and the NCAT phantom. The simulations of these studies use the radiopharmaceutical (99m)Tc-labeled tracers (250, 350, 450 and 680 MBq) for standard patient types, effectively corresponding to the following activities of myocardium: 3, 4.2, 5.4-8.2 MBq. All studies were simulated using 15 and 30s/projection. The simulated data were reconstructed and processed by quantitative-gated-SPECT software, and the analysis of functional parameters in gated-SPECT images was done by using Bland-Altman test and Mann-Whitney-Wilcoxon test. In studies simulated using different times (15 and 30s/projection), it was noted that for the activities for full body: 250 and 350 MBq, there were statistically significant differences in parameters Motility and Thickness. For the left ventricular ejection fractio n (LVEF), end-systolic volume (ESV) it was only for 250 MBq, and 350 MBq in the end-diastolic volume (EDV), while the simulated studies with 450 and 680MBq showed no statistically significant differences for global functional parameters: LVEF, EDV and ESV. The number of counts/pixel and, concomitantly, the total counts per simulation do not significantly interfere with the determination of gated-SPECT functional parameters, when using the administered average activity of 450 MBq, corresponding to the 5.4 MBq of the myocardium, for standard patient types. Copyright © 2015 Elsevier España, S.L.U. and SEMNIM. All rights reserved.

  4. CFTR Gating I

    PubMed Central

    Bompadre, Silvia G.; Ai, Tomohiko; Cho, Jeong Han; Wang, Xiaohui; Sohma, Yoshiro; Li, Min; Hwang, Tzyh-Chang

    2005-01-01

    The CFTR chloride channel is activated by phosphorylation of serine residues in the regulatory (R) domain and then gated by ATP binding and hydrolysis at the nucleotide binding domains (NBDs). Studies of the ATP-dependent gating process in excised inside-out patches are very often hampered by channel rundown partly caused by membrane-associated phosphatases. Since the severed ΔR-CFTR, whose R domain is completely removed, can bypass the phosphorylation-dependent regulation, this mutant channel might be a useful tool to explore the gating mechanisms of CFTR. To this end, we investigated the regulation and gating of the ΔR-CFTR expressed in Chinese hamster ovary cells. In the cell-attached mode, basal ΔR-CFTR currents were always obtained in the absence of cAMP agonists. Application of cAMP agonists or PMA, a PKC activator, failed to affect the activity, indicating that the activity of ΔR-CFTR channels is indeed phosphorylation independent. Consistent with this conclusion, in excised inside-out patches, application of the catalytic subunit of PKA did not affect ATP-induced currents. Similarities of ATP-dependent gating between wild type and ΔR-CFTR make this phosphorylation-independent mutant a useful system to explore more extensively the gating mechanisms of CFTR. Using the ΔR-CFTR construct, we studied the inhibitory effect of ADP on CFTR gating. The Ki for ADP increases as the [ATP] is increased, suggesting a competitive mechanism of inhibition. Single channel kinetic analysis reveals a new closed state in the presence of ADP, consistent with a kinetic mechanism by which ADP binds at the same site as ATP for channel opening. Moreover, we found that the open time of the channel is shortened by as much as 54% in the presence of ADP. This unexpected result suggests another ADP binding site that modulates channel closing. PMID:15767295

  5. Acute myocardial infarction: estimation of at-risk and salvaged myocardium at myocardial perfusion SPECT 1 month after infarction.

    PubMed

    Romero-Farina, Guillermo; Aguadé-Bruix, Santiago; Candell-Riera, Jaume; Pizzi, M Nazarena; Pineda, Victor; Figueras, Jaume; Cuberas, Gemma; de León, Gustavo; Castell-Conesa, Joan; García-Dorado, David

    2013-11-01

    To estimate at-risk and salvaged myocardium by using gated single photon emission computed tomography (SPECT) myocardial perfusion imaging after acute myocardial infarction (AMI). The study was approved by the hospital's Ethical Committee on Clinical Trials (trial register number, PR(HG)36/2000), and all patients gave informed consent. Forty patients (mean age, 61.78 years; eight women) with a first AMI underwent two gated SPECT examinations--one before percutaneous coronary intervention (PCI) and one 4-5 weeks after PCI. Myocardium at risk was estimated by assessing the perfusion defect at the first gated SPECT examination, and salvaged myocardium was estimated by assessing the risk area minus necrosis at the second examination. Myocardium at risk was estimated by determining the discordance between the areas of left ventricular (LV) wall motion and perfusion at the second examination. Concordance between tests was analyzed by means of linear regression analysis, the Pearson correlation, the intraclass correlation coefficient, and Bland-Altman analysis. An improvement in perfusion, wall motion, wall thickening, and LV ejection fraction (P < .001) was observed at 1 month. At 1 month, the area with abnormal wall motion was greater than the area of altered perfusion (35.47 vs 23.1 cm(2); P = .007). The extent of myocardium at risk estimated from this discordance correlated well with myocardium at risk measured at the first gated SPECT examination and with salvaged myocardium between both studies (Pearson correlation: 0.78 and 0.6, respectively). Concordance for correct classification of patients with salvaged myocardium of 50% or greater was 83% (κ = 0.65). Myocardial perfusion gated SPECT performed 1 month after early PCI in a first AMI provides potentially useful information on at-risk and salvaged myocardium. http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.13122324/-/DC1. RSNA, 2013

  6. Radionuclide imaging of myocardial infarction using Tc-99m TBI

    SciTech Connect

    Holman, B.L.; Campbell, S.; Kirshenbaum, J.M.; Lister-James, J.; Jones, A.G.; Davison, A.; Antman, E.

    1985-05-01

    The cationic complex Tc-99m t-butylisonitrile (TBI) concentrates in the myocardial tissue of several animal species. Its myocardial distribution is proportional to blood flow both in zones of ischemia and in normal myocardium at rest. Planar, tomographic, and gated myocardial images have been obtained using Tc-99m TBI in the human. The authors investigated the potential application of Tc-99m TBI imaging to detect and localize myocardial infarction. Four subjects without clinical evidence of cardiovascular disease and five patients with ECG evidence of previous myocardial infarction were studied. Tc-99m TBI (10mCi) was injected intravenously with the patient in a resting state with planar imaging in the anterior, 30 and 70 degree LAO projections beginning one hr after injection. The distribution of the tracer was homogeneous throughout the left ventricular wall in the normal subjects. Regional perfusion defects were present in 4/5 of the patients with myocardial infarction. Location of the defects corresponded to the location of the infarct using ECG criteria (2 inferoposterior and 2 anterior). The patient in whom the Tc-99m TBI image appeared normal had sustained a subendocardial myocardial infarct which could not be localized by ECG; the other 4 pts had transmural infarcts. Anterior and 30 degree LAO images were of excellent quality in all cases; there was overlap of the liver on the inferior wall of the left ventricle on the 70 degree LAO views. The authors conclude that accurate perfusion imaging may be possible using Tc-99m TBI in patients with transmural myocardial infarction.

  7. Periodontitis and myocardial hypertrophy.

    PubMed

    Suzuki, Jun-Ichi; Sato, Hiroki; Kaneko, Makoto; Yoshida, Asuka; Aoyama, Norio; Akimoto, Shouta; Wakayama, Kouji; Kumagai, Hidetoshi; Ikeda, Yuichi; Akazawa, Hiroshi; Izumi, Yuichi; Isobe, Mitsuaki; Komuro, Issei

    2017-04-01

    There is a deep relationship between cardiovascular disease and periodontitis. It has been reported that myocardial hypertrophy may be affected by periodontitis in clinical settings. Although these clinical observations had some study limitations, they strongly suggest a direct association between severity of periodontitis and left ventricular hypertrophy. However, the detailed mechanisms between myocardial hypertrophy and periodontitis have not yet been elucidated. Recently, we demonstrated that periodontal bacteria infection is closely related to myocardial hypertrophy. In murine transverse aortic constriction models, a periodontal pathogen, Aggregatibacter actinomycetemcomitans markedly enhanced cardiac hypertrophy with matrix metalloproteinase-2 activation, while another pathogen Porphyromonas gingivalis (P.g.) did not accelerate these pathological changes. In the isoproterenol-induced myocardial hypertrophy model, P.g. induced myocardial hypertrophy through Toll-like receptor-2 signaling. From our results and other reports, regulation of chronic inflammation induced by periodontitis may have a key role in the treatment of myocardial hypertrophy. In this article, we review the pathophysiological mechanism between myocardial hypertrophy and periodontitis.

  8. A nanomechanical Fredkin gate.

    PubMed

    Wenzler, Josef-Stefan; Dunn, Tyler; Toffoli, Tommaso; Mohanty, Pritiraj

    2014-01-08

    Irreversible logic operations inevitably discard information, setting fundamental limitations on the flexibility and the efficiency of modern computation. To circumvent the limit imposed by the von Neumann-Landauer (VNL) principle, an important objective is the development of reversible logic gates, as proposed by Fredkin, Toffoli, Wilczek, Feynman, and others. Here, we present a novel nanomechanical logic architecture for implementing a Fredkin gate, a universal logic gate from which any reversible computation can be built. In addition to verifying the truth table, we demonstrate operation of the device as an AND, OR, NOT, and FANOUT gate. Excluding losses due to resonator dissipation and transduction, which will require significant improvement in order to minimize the overall energy cost, our device requires an energy of order 10(4) kT per logic operation, similar in magnitude to state-of-the-art transistor-based technologies. Ultimately, reversible nanomechanical logic gates could play a crucial role in developing highly efficient reversible computers, with implications for efficient error correction and quantum computing.

  9. 2. CANNON GATES. DETAIL OF NORTHWEST GATE STONE WALL TO ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    2. CANNON GATES. DETAIL OF NORTHWEST GATE STONE WALL TO LEFT IS A REMNANT OF THE ORIGINAL FACILITY BOUNDARY FENCE. IT IS CONSTRUCTED IN BLUE PUDDING STONE. - Picatinny Arsenal, State Route 15 near I-80, Dover, Morris County, NJ

  10. 7. DETAIL VIEW OF DAM, SHOWING ROLLER GATES, GATE PIERS, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    7. DETAIL VIEW OF DAM, SHOWING ROLLER GATES, GATE PIERS, HEADHOUSES AND DAM BRIDGE, LOOKING NORTHWEST, UPSTREAM - Upper Mississippi River 9-Foot Channel, Lock & Dam No. 9, Lynxville, Crawford County, WI

  11. Amplifying genetic logic gates.

    PubMed

    Bonnet, Jerome; Yin, Peter; Ortiz, Monica E; Subsoontorn, Pakpoom; Endy, Drew

    2013-05-03

    Organisms must process information encoded via developmental and environmental signals to survive and reproduce. Researchers have also engineered synthetic genetic logic to realize simpler, independent control of biological processes. We developed a three-terminal device architecture, termed the transcriptor, that uses bacteriophage serine integrases to control the flow of RNA polymerase along DNA. Integrase-mediated inversion or deletion of DNA encoding transcription terminators or a promoter modulates transcription rates. We realized permanent amplifying AND, NAND, OR, XOR, NOR, and XNOR gates actuated across common control signal ranges and sequential logic supporting autonomous cell-cell communication of DNA encoding distinct logic-gate states. The single-layer digital logic architecture developed here enables engineering of amplifying logic gates to control transcription rates within and across diverse organisms.

  12. Adiabatic gate teleportation.

    PubMed

    Bacon, Dave; Flammia, Steven T

    2009-09-18

    The difficulty in producing precisely timed and controlled quantum gates is a significant source of error in many physical implementations of quantum computers. Here we introduce a simple universal primitive, adiabatic gate teleportation, which is robust to timing errors and many control errors and maintains a constant energy gap throughout the computation above a degenerate ground state space. This construction allows for geometric robustness based upon the control of two independent qubit interactions. Further, our piecewise adiabatic evolution easily relates to the quantum circuit model, enabling the use of standard methods from fault-tolerance theory for establishing thresholds.

  13. Outlet side of gate, showing the Radial Gate, hoist mechanism ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Outlet side of gate, showing the Radial Gate, hoist mechanism and concrete walkway across the canal. The concrete baffle separating the afterbay and the cipoletti weir is in the foreground - Wellton-Mohawk Irrigation System, Radial Gate Check with Drop, Wellton Canal 9.9, West of Avenue 34 East & north of County Ninth Street, Wellton, Yuma County, AZ

  14. Exterior, looking northwest towards Main Gate, Gate House on left, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Exterior, looking northwest towards Main Gate, Gate House on left, Technical Equipment Building (Building 5760) in background to right - Beale Air Force Base, Perimeter Acquisition Vehicle Entry Phased-Array Warning System, Gate House, End of Spencer Paul Road, north of Warren Shingle Road (14th Street), Marysville, Yuba County, CA

  15. Exterior, looking southeast from within compound towards Main Gate, Gate ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Exterior, looking southeast from within compound towards Main Gate, Gate House center left - Beale Air Force Base, Perimeter Acquisition Vehicle Entry Phased-Array Warning System, Gate House, End of Spencer Paul Road, north of Warren Shingle Road (14th Street), Marysville, Yuba County, CA

  16. [Relationship between ventricular arrhythmias and myocardial fatty acid metabolism in patients with coronary heart disease: evaluation using iodine-123 beta-methyl-p-iodophenyl-pentadecanoic acid].

    PubMed

    Mori, H; Sakamoto, T; Ueda, Y; Yano, K

    1999-08-01

    The effect of metabolic abnormalities of myocardial fatty acids on ventricular arrhythmias was evaluated by myocardial imaging with iodine-123 beta-methyl-p-iodophenyl-pentadecanoic acid (BMIPP) in 27 patients with coronary heart disease. The disturbance of myocardial blood flow was also evaluated using thallium-201 (Tl). The patients were divided into 2 groups based on the character of the premature ventricular contractions: Group A: number of contractions > or = 120 per day and/or consecutive contractions (n = 9, mean age 63.7 yr), and Group B, number of contractions < 120 per day and no consecutive contractions (n = 18, mean age 64.2 yr). Left ventricular ejection fraction was measured by left ventriculography, and significant coronary artery stenosis was defined as stenosis of 75% or greater. Cardiac scintigraphy was performed using single photon emission computed tomography with BMIPP at rest in 27 patients and in the early phase (early Tl) and delayed phase of Tl (delayed Tl) in 20 patients. BMIPP and Tl uptakes were scored as 0: absent, 1: moderately reduced, 2: mildly reduced and 3: normal in 7 segments of the left ventricular wall and then the total scores were calculated in each patient. Ejection fraction significantly correlated with the scores of BMIPP, and early and delayed Tl(p < 0.001, respectively), although the ejection fraction in Group A was significantly less than in Group B (51.2 +/- 16.7% vs 68.2 +/- 14.4%, p < 0.02). The BMIPP scores in Group A were significantly less than those in Group B (14.2 +/- 4.3 vs 17.2 +/- 3.1, p < 0.05), but the early and delayed Tl scores in Group A were not significantly different compared with those in Group B. The BMIPP scores showed no significant differences between the patients with and without significant coronary artery stenosis, but the early and delayed Tl scores in the patients with stenosis were significantly less than those in patients without stenosis (early Tl: 19.8 +/- 2.6 vs 16.8 +/- 2.8, p < 0

  17. Comparison of single-photon emission computed tomographic (SPECT) myocardial perfusion imaging with thallium-201 and technetium-99m sestamibi in dogs.

    PubMed

    Leon, A R; Eisner, R L; Martin, S E; Schmarkey, L S; Aaron, A M; Boyers, A S; Burnham, K M; Oh, D J; Patterson, R E

    1992-12-01

    The purpose of the present study was to compare single-photon emission computed tomographic (SPECT) myocardial images of technetium-99m (Tc-99m) sestamibi and thallium-201 (Tl-201) isotopes in the same dog undergoing partial coronary occlusion during pharmacologic vasodilation. To date, no controlled study has been reported comparing SPECT Tc-99m sestamibi with SPECT Tl-201 imaging during stress with anatomic and physiologic standards. Mongrel dogs were anesthetized with chloralose and instrumented to record left anterior descending coronary blood flow and aortic pressure. Partial coronary occlusion with a hydraulic cuff reduced coronary vascular conductance, which is equal to the coronary blood flow normalized to aortic pressure during peak vasodilation with intravenous adenosine. Each dog received 5 mCi of Tl-201, then 30 mCi of Tc-99m sestamibi during partial coronary occlusion at peak vasodilation. Tomographic myocardial imaging was performed in a 180 degrees anterior arc scan for 33.5 min, first with Tl-201, and later, without moving the dog, for 33.5 min with Tc-99m sestamibi. Postmortem staining defined the region underperfused because of its dependence on the artery that was partially occluded. In seven dogs with moderate reduction in coronary blood flow, coronary vascular conductance decreased with partial coronary occlusion (47 +/- 12%) during Tl-201 imaging and (47 +/- 8%, p = NS) during Tc-99m sestamibi imaging. The underperfused region was 23.9 +/- 6.4% of total left ventricular mass. Counts in the defects were 39% higher (0.86 +/- 0.08 of normal counts) for Tc-99m sestamibi than for Tl-201 (0.64 +/- 0.09 of normal counts, p < 0.001), and the defect on SPECT Tc-99m sestamibi images occupied only a fraction (0.37 +/- 0.30) of the area of the defect on the Tl-201 images of the same dog. Bull's-eye displays constructed from the pathologic slices showed that the Tl-201 defect size was closer to the underperfused region of the left ventricular mass

  18. [Depression and myocardial infaction].

    PubMed

    Testuz, A

    2009-03-04

    Several works show an association between depression and the occurence of a first myocardial infarction. Depression after myocardial infarction seems to be a marker of poorer outcome, regardless of other risk factors or severity of the myocardial infarction. Dysautonomia and alteration of platelet activation are a few physiopathological changes shared by both affections, through which they might be related. Treatment of depression is not associated with better cardiovascular outcome, but selective serotonin reuptake inhibitors have been shown safe and efficient among patients with coronary heart disease. Cognitivo-comportemental approach and cardiovascular rehabilitation program after myocardial infarction also play a role in improving quality of life of the depressed patient with coronary heart disease.

  19. The four-gate transistor

    NASA Technical Reports Server (NTRS)

    Mojarradi, M. M.; Cristoveanu, S.; Allibert, F.; France, G.; Blalock, B.; Durfrene, B.

    2002-01-01

    The four-gate transistor or G4-FET combines MOSFET and JFET principles in a single SOI device. Experimental results reveal that each gate can modulate the drain current. Numerical simulations are presented to clarify the mechanisms of operation. The new device shows enhanced functionality, due to the combinatorial action of the four gates, and opens rather revolutionary applications.

  20. Stanford, Duke, Rice,... and Gates?

    ERIC Educational Resources Information Center

    Carey, Kevin

    2009-01-01

    This article presents an open letter to Bill Gates. In his letter, the author suggests that Bill Gates should build a brand-new university, a great 21st-century institution of higher learning. This university will be unlike anything the world has ever seen. He asks Bill Gates not to stop helping existing colleges create the higher-education system…

  1. The four-gate transistor

    NASA Technical Reports Server (NTRS)

    Mojarradi, M. M.; Cristoveanu, S.; Allibert, F.; France, G.; Blalock, B.; Durfrene, B.

    2002-01-01

    The four-gate transistor or G4-FET combines MOSFET and JFET principles in a single SOI device. Experimental results reveal that each gate can modulate the drain current. Numerical simulations are presented to clarify the mechanisms of operation. The new device shows enhanced functionality, due to the combinatorial action of the four gates, and opens rather revolutionary applications.

  2. Stanford, Duke, Rice,... and Gates?

    ERIC Educational Resources Information Center

    Carey, Kevin

    2009-01-01

    This article presents an open letter to Bill Gates. In his letter, the author suggests that Bill Gates should build a brand-new university, a great 21st-century institution of higher learning. This university will be unlike anything the world has ever seen. He asks Bill Gates not to stop helping existing colleges create the higher-education system…

  3. Nuclear cardiac imaging for the assessment of myocardial viability

    PubMed Central

    Slart, R.H.J.A.; Bax, J.J.; van der Wall, E.E.; van Veldhuisen, D.J.; Jager, P.L.; Dierckx, R.A.

    2005-01-01

    An important aspect of the diagnostic and prognostic work-up of patients with ischaemic cardiomyopathy is the assessment of myocardial viability. Patients with left ventricular dysfunction who have viable myocardium are the patients at highest risk because of the potential for ischaemia but at the same time benefit most from revascularisation. It is important to identify viable myocardium in these patients, and radionuclide myocardial scintigraphy is an excellent tool for this. Single-photon emission computed tomography perfusion scintigraphy (SPECT), whether using 201thallium, 99mTc-sestamibi, or 99mTc- tetrofosmin, in stress and/or rest protocols, has consistently been shown to be an effective modality for identifying myocardial viability and guiding appropriate management. Metabolic and perfusion imaging with positron emission tomography radiotracers frequently adds additional information and is a powerful tool for predicting which patients will have an improved outcome from revascularisation. New techniques in the nuclear cardiology field, such as attenuation corrected SPECT, dual isotope simultaneous acquisition (DISA) SPECT and gated FDG PET are promising and will further improve the detection of myocardial viability. Also the combination of multislice computed tomography scanners with PET opens possibilities of adding coronary calcium scoring and noninvasive coronary angiography to myocardial perfusion imaging and quantification. ImagesFigure 1Figure 2Figure 3 PMID:25696432

  4. Nanoparticle Based Logic Gates

    NASA Astrophysics Data System (ADS)

    Berven, Christopher; Wybourne, Martin; Longstreth, Lydia

    2003-05-01

    Ligand stabilized gold nanoparticles have novel properties that can be exploited for their use as possible building blocks for room-temperature single electron devices. With a core of 70 gold atoms or less (diameter <= 1.4 nm), the self-capacitance of these particles is a fraction of an atto-Farad. This small capacitance translates into an electrostatic charging energy well in excess of the thermal energy at room temperature. Single electron behavior has been demonstrated in one- and two-dimensional arrays of nanoparticles. In traditional single electron devices, the self-capacitance is negligible, whereas the self-capacitance in nanoparticle based devices can be the dominant capacitance. This means that the effect of charging a nanoparticle chain is highly localized which is in contrast to traditional single electron devices where the induced potential due to an excess electron on an island is felt by many neighboring islands. As a result, the current-voltage characteristics and plots of stable electron occupancy in the arrays have different behavior to that found in traditional devices. We show that this new regime of tunneling behavior can be exploited to create a novel family of single-electron logic gate devices. Using numerical simulation we have found that when a one-dimensional array of nanoparticles is gated in an electron-pump arrangement and properly biased, the behavior is that of an AND gate. The addition of an inverter circuit results in NAND gate behavior, the inverter providing the power necessary for the cascading of multiple NAND gates and the generation of arbitrary logic circuits.

  5. Myocardial Noncompaction Presenting With Myocardial Bridge

    PubMed Central

    Shen, Yuechun; Li, Xinchun; Lu, Dongfeng; Xiao, Aiyi; Li, Jun

    2015-01-01

    Abstract Myocardial noncompaction, namly isolated noncompaction of the left ventricular myocardium (NVM), is a rare congenital disease. It can be either seen in the absence of other cardiac anomalies, or associated with other congenital cardiac defects, mostly stenotic lesions of the left ventricular outflow tract. A myocardial bridge (MB) is thought being associated with coronary heart disease, such as coronary spasm, arrhythmia, and so on. The significance of MB in association with other congenital cardiac conditions is unknown. We report a novel case who was presented NVM and MB. A 34-year-old man complained of chest prickling-like pain and dizzy for 1 year. His blood pressure was 110/70 mm Hg. Echocardiograph revealed increased trabeculations below the level of papillary muscle of left ventricle (LV); deep intertrabecular recesses in the endocardial wall of LV particularly in apex free wall; and LV ejection fraction of 57%. A coronary computerized tomography scan showed that part, 38.9 cm, of left descending artery tunnel was surrounding by cardiac muscles rather than resting on top of the myocardium. The therapeutics interventions included lifestyle cares, agents of anti-ischemia and improvement myocardial cell metabolism. The patient was followed up for 2.6 years, and his general condition was stable. This case indicates that NVM can be developed with MB, and the complete diagnosis of NVM and MB should be made by different image studies. PMID:26356695

  6. Single-photon agents for tumor imaging: 201Tl, 99mTc-MIBI, and 99mTc-tetrofosmin.

    PubMed

    Fukumoto, Mitsutaka

    2004-04-01

    This review aims at fostering comprehension and knowledge not only for expert physicians who can skillfully handle various techniques for tumor imaging but also for young practitioners in the field of nuclear medicine. As image processing software and hardware become smaller, faster and better, SPECT will adapt and incorporate these advances. A principal advantage of SPECT over PET is the more widespread availability of the equipment and lower cost for the introduction of the system in community-based facilities. Moreover, SPECT has become less dependent on a limited number of acknowledged experts for its interpretation owing to a variety of handy computer tools for imaging analyses. The increasing use of PET in tumor imaging is not necessarily proportional to the decline of SPECT. General physicians' attention to SPECT technology would also increase more by evoking their interest in "tracer imaging."

  7. Thallium-201 imaging in a patient with mid-ventricular hypertrophic obstructive cardiomyopathy

    SciTech Connect

    Wakasugi, S.; Shibata, N.; Kobayashi, T.; Fudemoto, Y.; Hasegawa, Y.; Nakano, S.

    1988-10-01

    Findings specific to mid-ventricular hypertrophic obstructive cardiomyopathy were obtained in a patient by means of /sup 201/Tl planar myocardial scintigraphy. Namely, a myocardial band-like image dividing the left ventricle into two chambers was clearly shown. This was identified as hypertrophic muscle with sphincter-like muscular stenosis at the mid portion of the left ventricle.

  8. Exercise supplementation of dipyridamole for myocardial perfusion imaging

    SciTech Connect

    DePuey, E.G.

    1991-08-01

    The substitution of intravenous dipyridamole for symptom-limited treadmill exercise has provided a non-invasive means to diagnose coronary artery disease with 201Tl scintigraphy in patients unable to adequately exercise. Limitations of dipyridamole/thallium imaging are primarily due to suboptimal image quality secondary to hepatic tracer concentration and decreased test sensitivity in patients who are dipyridamole non-responders. Low-level treadmill exercise supplementation improves image quality, whereas handgrip has little, if any, benefit. The effect of low-level exercise in augmenting coronary blood flow is unknown and reports regarding the effect of handgrip are conflicting. The diagnostic benefit of these maneuvers in improving test sensitivity and decreasing the number of non-responders has not been documented. The combination of maximal, symptom-limited treadmill exercise and intravenous dipyridamole is a theoretically attractive option to improve overall test sensitivity, but the physiologic consequences and potential side effects should be more thoroughly investigated.

  9. Universal Superreplication of Unitary Gates

    NASA Astrophysics Data System (ADS)

    Chiribella, G.; Yang, Y.; Huang, C.

    2015-03-01

    Quantum states obey an asymptotic no-cloning theorem, stating that no deterministic machine can reliably replicate generic sequences of identically prepared pure states. In stark contrast, we show that generic sequences of unitary gates can be replicated deterministically at nearly quadratic rates, with an error vanishing on most inputs except for an exponentially small fraction. The result is not in contradiction with the no-cloning theorem, since the impossibility of deterministically transforming pure states into unitary gates prevents the application of the gate replication protocol to states. In addition to gate replication, we show that N parallel uses of a completely unknown unitary gate can be compressed into a single gate acting on O (log2N ) qubits, leading to an exponential reduction of the amount of quantum communication needed to implement the gate remotely.

  10. 3D perfusion mapping in the intact mouse heart after myocardial infarction using myocardial contrast echocardiography

    NASA Astrophysics Data System (ADS)

    Li, Yinbo; Yang, Zequan; French, Brent A.; Hossack, John A.

    2005-04-01

    An intact mouse model of surgically-induced myocardial infarction (MI) caused by permanent occlusion of the Left Anterior Descending (LAD) coronary artery was studied. Normal mice with no occlusion were also studied as controls. For each mouse, contrast enhanced ultrasound images of the heart were acquired in parallel cross-sections perpendicular to the sternum at millimeter increments. For accurate 3D reconstruction, ECG gating and a tri-axial adjustable micromanipulator were used for temporal and spatial registration. Ultrasound images at steady-state of blood refilling were color-coded in each slice to show relative perfusion. Myocardial perfusion defects and necrosis were also examined postmortem by staining with Phthalo blue and TTC red dyes. Good correlation (R>0.93) in perfused area size was observed between in vivo measurements and histological staining. A 3D multi-slice model and a 3D rendering of perfusion distribution were created and showed a promising match with postmortem results, lending further credence to its use as a more comprehensive and more reliable tool for in vivo assessment of myocardial perfusion than 2D tomographic analysis.

  11. Lidocaine Enhances Contractile Function of Ischemic Myocardial Regions in Mouse Model of Sustained Myocardial Ischemia

    PubMed Central

    Kania, Gabriela; Osto, Elena; Jakob, Philipp; Krasniqi, Nazmi; Beck-Schimmer, Beatrice; Blyszczuk, Przemyslaw; Eriksson, Urs

    2016-01-01

    Rationale Perioperative myocardial ischemia is common in high-risk patients. The use of interventional revascularisation or even thrombolysis is limited in this patient subset due to exceedingly high bleeding risks. Blockade of voltage-gated sodium channels (VGSC) with lidocaine had been suggested to reduce infarct size and cardiomyocyte cell death in ischemia/reperfusion models. However, the impact of lidocaine on cardiac function during sustained ischemia still remains unclear. Methods Sustained myocardial ischemia was induced by ligation of the left anterior descending artery in 12–16 weeks old male BALB/c mice. Subcutaneous lidocaine (30 mg/kg) was used to block VGSC. Cardiac function was quantified at baseline and at 72h by conventional and speckle-tracking based echocardiography to allow high-sensitivity in vivo phenotyping. Infarct size and cardiomyocyte cell death were assessed post mortem histologically and indirectly using troponin measurements. Results Ischemia strongly impaired both, global systolic and diastolic function, which were partially rescued in lidocaine treated in mice. No differences regarding infarct size and cardiomyocyte cell death were observed. Mechanistically, and as shown with speckle-tracking analysis, lidocaine specifically improves residual contractility in the ischemic but not in the remote, non-ischemic myocardium. Conclusion VGSC blockade with lidocaine rescues function of ischemic myocardium as a potential bridging to revascularisation in the setting of perioperative myocardial ischemia. PMID:27140425

  12. Quantitative myocardial perfusion SPECT.

    PubMed

    Tsui, B M; Frey, E C; LaCroix, K J; Lalush, D S; McCartney, W H; King, M A; Gullberg, G T

    1998-01-01

    In recent years, there has been much interest in the clinical application of attenuation compensation to myocardial perfusion single photon emission computed tomography (SPECT) with the promise that accurate quantitative images can be obtained to improve clinical diagnoses. The different attenuation compensation methods that are available create confusion and some misconceptions. Also, attenuation-compensated images reveal other image-degrading effects including collimator-detector blurring and scatter that are not apparent in uncompensated images. This article presents basic concepts of the major factors that degrade the quality and quantitative accuracy of myocardial perfusion SPECT images, and includes a discussion of the various image reconstruction and compensation methods and misconceptions and pitfalls in implementation. The differences between the various compensation methods and their performance are demonstrated. Particular emphasis is directed to an approach that promises to provide quantitative myocardial perfusion SPECT images by accurately compensating for the 3-dimensional (3-D) attenuation, collimator-detector response, and scatter effects. With advances in the computer hardware and optimized implementation techniques, quantitatively accurate and high-quality myocardial perfusion SPECT images can be obtained in clinically acceptable processing time. Examples from simulation, phantom, and patient studies are used to demonstrate the various aspects of the investigation. We conclude that quantitative myocardial perfusion SPECT, which holds great promise to improve clinical diagnosis, is an achievable goal in the near future.

  13. Noise Gating Solar Images

    NASA Astrophysics Data System (ADS)

    DeForest, Craig; Seaton, Daniel B.; Darnell, John A.

    2017-08-01

    I present and demonstrate a new, general purpose post-processing technique, "3D noise gating", that can reduce image noise by an order of magnitude or more without effective loss of spatial or temporal resolution in typical solar applications.Nearly all scientific images are, ultimately, limited by noise. Noise can be direct Poisson "shot noise" from photon counting effects, or introduced by other means such as detector read noise. Noise is typically represented as a random variable (perhaps with location- or image-dependent characteristics) that is sampled once per pixel or once per resolution element of an image sequence. Noise limits many aspects of image analysis, including photometry, spatiotemporal resolution, feature identification, morphology extraction, and background modeling and separation.Identifying and separating noise from image signal is difficult. The common practice of blurring in space and/or time works because most image "signal" is concentrated in the low Fourier components of an image, while noise is evenly distributed. Blurring in space and/or time attenuates the high spatial and temporal frequencies, reducing noise at the expense of also attenuating image detail. Noise-gating exploits the same property -- "coherence" -- that we use to identify features in images, to separate image features from noise.Processing image sequences through 3-D noise gating results in spectacular (more than 10x) improvements in signal-to-noise ratio, while not blurring bright, resolved features in either space or time. This improves most types of image analysis, including feature identification, time sequence extraction, absolute and relative photometry (including differential emission measure analysis), feature tracking, computer vision, correlation tracking, background modeling, cross-scale analysis, visual display/presentation, and image compression.I will introduce noise gating, describe the method, and show examples from several instruments (including SDO

  14. A quantum Fredkin gate

    PubMed Central

    Patel, Raj B.; Ho, Joseph; Ferreyrol, Franck; Ralph, Timothy C.; Pryde, Geoff J.

    2016-01-01

    Minimizing the resources required to build logic gates into useful processing circuits is key to realizing quantum computers. Although the salient features of a quantum computer have been shown in proof-of-principle experiments, difficulties in scaling quantum systems have made more complex operations intractable. This is exemplified in the classical Fredkin (controlled-SWAP) gate for which, despite theoretical proposals, no quantum analog has been realized. By adding control to the SWAP unitary, we use photonic qubit logic to demonstrate the first quantum Fredkin gate, which promises many applications in quantum information and measurement. We implement example algorithms and generate the highest-fidelity three-photon Greenberger-Horne-Zeilinger states to date. The technique we use allows one to add a control operation to a black-box unitary, something that is impossible in the standard circuit model. Our experiment represents the first use of this technique to control a two-qubit operation and paves the way for larger controlled circuits to be realized efficiently. PMID:27051868

  15. A quantum Fredkin gate.

    PubMed

    Patel, Raj B; Ho, Joseph; Ferreyrol, Franck; Ralph, Timothy C; Pryde, Geoff J

    2016-03-01

    Minimizing the resources required to build logic gates into useful processing circuits is key to realizing quantum computers. Although the salient features of a quantum computer have been shown in proof-of-principle experiments, difficulties in scaling quantum systems have made more complex operations intractable. This is exemplified in the classical Fredkin (controlled-SWAP) gate for which, despite theoretical proposals, no quantum analog has been realized. By adding control to the SWAP unitary, we use photonic qubit logic to demonstrate the first quantum Fredkin gate, which promises many applications in quantum information and measurement. We implement example algorithms and generate the highest-fidelity three-photon Greenberger-Horne-Zeilinger states to date. The technique we use allows one to add a control operation to a black-box unitary, something that is impossible in the standard circuit model. Our experiment represents the first use of this technique to control a two-qubit operation and paves the way for larger controlled circuits to be realized efficiently.

  16. Myocardial Lineage Development

    PubMed Central

    Evans, Sylvia M.; Yelon, Deborah; Conlon, Frank L.; Kirby, Margaret L.

    2010-01-01

    The myocardium of the heart is composed of multiple highly specialized myocardial lineages, including those of the ventricular and atrial myocardium, and the specialized conduction system. Specification and maturation of each of these lineages during heart development is a highly ordered, ongoing process involving multiple signaling pathways and their intersection with transcriptional regulatory networks. Here, we attempt to summarize and compare much of what we know about specification and maturation of myocardial lineages from studies in several different vertebrate model systems. To date, most research has focused on early specification, and while there is still more to learn, less is known about factors that promote subsequent maturation of myocardial lineages required to build the functioning adult heart. PMID:21148449

  17. ECG gated NMR-CT for cardiovascular diseases

    SciTech Connect

    Nishikawa, J.; Ohtake, T.; Machida, K.; Iio, M.; Yoshimoto, N.; Sugimoto, T.

    1985-05-01

    The authors have been applying ECG gated NMR-CT to mainly patients with myocardial infarction (MI), and hypertrophic cardiomyopathy (HCM). Thirteen patients with MI, 8 with HCM and 5 without any heart diseases were studied by ECG gated NMR imaging (spin-echo technique, TR: depends on patient heart rate, TE: 35 and 70 msec.) with 0.35 T superconducting magnet. On NMR images (MRI), the authors examined the wall thickness, wall motion and T/sub 2/ relaxation time in the area of diseased myocardium. The lesions of old MI were depicted as the area of thin wall and T/sub 2/ relaxation time of those lesions were similar to the area of non-infarcted myocardium. The lesions of recent MI (up to 3.5 months from the recent attack) were shown as the same wall thickness as the non-infarcted myocardium and the area of prolonged T/sub 2/ relaxation time compared with that of non-infarcted myocardium. MRI demonstrated diffusely thick myocardium in all patients with HCM. T/sub 2/ relaxation time of the areas of HCM was almost the same as that of normal myocardium, and it's difference among each ventricular wall in patients with HCM was not statistically significant. The authors conclude that ECG gated NMR-CT offers 3-D morphological information of the heart without any contrast material nor radioisotopes. ECG gated MRI provides the useful informations to diagnose MI, especially in the differential diagnosis between old and recent MI.

  18. Dual tracer autoradiographic study with thallium-201 and radioiodinated fatty acid in cardiomyopathic hamsters

    SciTech Connect

    Kurata, C.; Kobayashi, A.; Yamazaki, N.

    1989-01-01

    To investigate the usefulness of myocardial scintigraphy with radioiodinated 15-(p-iodophenyl)-3-R,S-methylpentadecanoic acid (BMIPP) in cardiomyopathy, quantitative dual tracer autoradiographic study with /sup 201/Tl and (/sup 125/I)BMIPP was performed in 27 cardiomyopathic Bio 14.6 Syrian hamsters and eight normal hamsters. Furthermore, 16 Bio 14.6 Syrian hamsters aged 21 days were divided into verapamil-treated (during 70 days) and control groups (respectively, n = 8), and autoradiography with /sup 201/Tl and (/sup 125/I)BMIPP was performed. Quantitative autoradiography demonstrated an uncoupling of /sup 201/Tl and (/sup 125/I)BMIPP distributions and a regional heterogeneity of (/sup 125/I)BMIPP distribution in cardiomyopathic hamsters aged more than 2 mo, while normal hamsters showed only mild heterogeneity of (/sup 125/I)BMIPP distribution without an uncoupling of tracers. Age-matched comparison between normal and cardiomyopathic hamsters (5-8 mo old) demonstrated that a difference between their (/sup 125/I)BMIPP distributions are more marked than that between their /sup 201/Tl distributions. Furthermore, (/sup 125/I)BMIPP visualized effects of verapamil on cardiomyopathy more distinctly than did /sup 201/Tl. In conclusion, myocardial imaging with (/sup 123/I)BMIPP could be useful for investigating cardiomyopathy and evaluating the efficacy of therapeutic intervention in patients with cardiomyopathy.

  19. 100-nm gate lithography for double-gate transistors

    NASA Astrophysics Data System (ADS)

    Krasnoperova, Azalia A.; Zhang, Ying; Babich, Inna V.; Treichler, John; Yoon, Jung H.; Guarini, Kathryn; Solomon, Paul M.

    2001-09-01

    The double gate field effect transistor (FET) is an exploratory device that promises certain performance advantages compared to traditional CMOS FETs. It can be scaled down further than the traditional devices because of the greater electrostatic control by the gates on the channel (about twice as short a channel length for the same gate oxide thickness), has steeper sub-threshold slope and about double the current for the same width. This paper presents lithographic results for double gate FET's developed at IBM's T. J. Watson Research Center. The device is built on bonded wafers with top and bottom gates self-aligned to each other. The channel is sandwiched between the top and bottom polysilicon gates and the gate length is defined using DUV lithography. An alternating phase shift mask was used to pattern gates with critical dimensions of 75 nm, 100 nm and 125 nm in photoresist. 50 nm gates in photoresist have also been patterned by 20% over-exposure of nominal 100 nm lines. No trim mask was needed because of a specific way the device was laid out. UV110 photoresist from Shipley on AR-3 antireflective layer were used. Process windows, developed and etched patterns are presented.

  20. Impact of gate geometry on ionic liquid gated ionotronic systems

    NASA Astrophysics Data System (ADS)

    Wong, A. T.; Noh, J. H.; Pudasaini, P. R.; Wolf, B.; Balke, N.; Herklotz, A.; Sharma, Y.; Haglund, A. V.; Dai, S.; Mandrus, D.; Rack, P. D.; Ward, T. Z.

    2017-04-01

    Ionic liquid electrolytes are gaining widespread application as a gate dielectric used to control ion transport in functional materials. This letter systematically examines the important influence that device geometry in standard "side gate" 3-terminal geometries plays in device performance of a well-known oxygen ion conductor. We show that the most influential component of device design is the ratio between the area of the gate electrode and the active channel, while the spacing between these components and their individual shapes has a negligible contribution. These findings provide much needed guidance in device design intended for ionotronic gating with ionic liquids.

  1. Myocardial diseases of animals.

    PubMed Central

    Van Vleet, J. F.; Ferrans, V. J.

    1986-01-01

    In this review we have attempted a comprehensive compilation of the cardiac morphologic changes that occur in spontaneous and experimental myocardial diseases of animals. Our coverage addresses diseases of mammals and birds and includes these diseases found in both domesticated and wild animals. A similar review of the myocardial diseases in this broad range of animal species has not been attempted previously. We have summarized and illustrated the gross, microscopic, and ultrastructural alterations for these myocardial diseases; and, whenever possible, we have reviewed their biochemical pathogenesis. We have arranged the myocardial diseases for presentation and discussion according to an etiologic classification with seven categories. These include a group of idiopathic or primary cardiomyopathies recognized in man (hypertrophic, dilated, and restrictive types) and a large group of secondary cardiomyopathies with known causes, such as inherited tendency; nutritional deficiency; toxicity; physical injury and shock; endocrine disorders, and myocarditides of viral, bacterial, and protozoal causation. Considerable overlap exists between each of the etiologic groups in the spectrum of pathologic alterations seen in the myocardium. These include various degenerative changes, myocyte necrosis, and inflammatory lesions. However, some diseases show rather characteristic myocardial alterations such as vacuolar degeneration in anthracycline cardiotoxicity, myofibrillar lysis in furazolidone cardiotoxicity, calcification in calcinosis of mice, glycogen accumulation in the glycogenoses, lipofuscinosis in cattle, fatty degeneration in erucic acid cardiotoxicity, myofiber disarray in hypertrophic cardiomyopathy, and lymphocytic inflammation with inclusion bodies in canine parvoviral myocarditis. The myocardial diseases represent the largest group in the spectrum of spontaneous cardiac diseases of animals. Pericardial and endocardial diseases and congential cardiac diseases are

  2. Multibit gates for quantum computing.

    PubMed

    Wang, X; Sørensen, A; Mølmer, K

    2001-04-23

    We present a general technique to implement products of many qubit operators communicating via a joint harmonic oscillator degree of freedom in a quantum computer. By conditional displacements and rotations we can implement Hamiltonians which are trigonometric functions of qubit operators. With such operators we can effectively implement higher order gates such as Toffoli gates and C(n)-NOT gates, and we show that the entire Grover search algorithm can be implemented in a direct way.

  3. Floating gate circuits in MOSIS

    NASA Astrophysics Data System (ADS)

    Mann, James R.

    1990-11-01

    The MOSIS foundry offers a two-poly CMOS process that can be used as a floating gate technology, albeit not with the same performance as commercial EEPROM foundries. This report characterizes the structures and programming techniques necessary to build floating gate structures and associated high-voltage addressing circuitry on the low-noise analog process available through MOSIS. Techniques that are used include Fowler-Nordheim tunneling, channel hot-electron injection, and avalanche injection. The dielectric materials between the floating gate and both the control gate and substrate are characterized. Unconventional lightly doped drain FET devices and additional circuit techniques for handling the high-voltage programming signals are presented.

  4. Compact gate valve

    DOEpatents

    Bobo, Gerald E.

    1977-01-01

    This invention relates to a double-disc gate valve which is compact, comparatively simple to construct, and capable of maintaining high closing pressures on the valve discs with low frictional forces. The valve casing includes axially aligned ports. Mounted in the casing is a sealed chamber which is pivotable transversely of the axis of the ports. The chamber contains the levers for moving the valve discs axially, and an actuator for the levers. When an external drive means pivots the chamber to a position where the discs are between the ports and axially aligned therewith, the actuator for the levers is energized to move the discs into sealing engagement with the ports.

  5. ONE SHAKE GATE FORMER

    DOEpatents

    Kalibjian, R.; Perez-Mendez, V.

    1957-08-20

    An improved circuit for forming square pulses having substantially short and precise durations is described. The gate forming circuit incorporates a secondary emission R. F. pentode adapted to receive input trigger pulses amd having a positive feedback loop comnected from the dynode to the control grid to maintain conduction in response to trigger pulses. A short circuited pulse delay line is employed to precisely control the conducting time of the tube and a circuit for squelching spurious oscillations is provided in the feedback loop.

  6. Free-breathing MOLLI: application to myocardial T(1) mapping.

    PubMed

    Tsai, Jyun-Ming; Huang, Teng-Yi; Tseng, Yu-Shen; Lin, Yi-Ru

    2012-12-01

    Of the myocardial T(1) mapping techniques, the modified Look-Locker inversion recovery (MOLLI) sequence is accurate and highly reproducible. The MOLLI sequence requires patients to hold their breath for 17 heartbeats during the scanning process to minimize respiratory motion-related artifacts. However, some patients are unable to hold their breath because of illness or limited breath-hold capacity. This study, therefore, aimed to develop a robust myocardial T(1) mapping method based on the MOLLI sequence for patients unable to perform voluntary breath-holds. This study presents a free-breathing MOLLI (FB-MOLLI) sequence and an optimized reconstruction method to allow myocardial T(1) mapping in vivo without breath-hold. Nine healthy volunteers participated in this study after providing institutionally approved consent. The FB-MOLLI sequence acquires 20 images within 29 heartbeats. The reconstruction program employs a two-step automatic image registration technique and an image selection method inspired by the self-gating cardiac imaging method. Results indicate that the proposed reconstruction method increases the accuracy and reproducibility of free-breathing T(1) measurements significantly (p < 0.001). The FB-MOLLI method provides a robust tool for clinical application in free-breathing myocardial T(1) mapping, and could greatly facilitate acquisition procedures during routine examinations.

  7. 16. Little Hell Gate Bridge with Big Hell Gate Bridge ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    16. Little Hell Gate Bridge with Big Hell Gate Bridge in background. Wards Island, New York Co., NY. Sec. 4207, MP 8.02. - Northeast Railroad Corridor, Amtrak Route between New Jersey/New York & New York/Connecticut State Lines, New York County, NY

  8. TRP channel gating physiology.

    PubMed

    Nieto-Posadas, Andrés; Jara-Oseguera, Andrés; Rosenbaum, Tamara

    2011-01-01

    Transient Receptor Potential (TRP) cation channels participate in several processes of vital importance in cell and organism physiology, and have been demonstrated to participate in the detection of sensory stimuli. The thermo TRP's reviewed: TRPV1 (vanilloid 1), TRPM8 (melastatin 8) and TRPA1 (ankyrin-like 1) are known to integrate different chemical and physical stimuli such as changes in temperature and sensing different irritant or pungent compounds. However, despite the physiological importance of these channels the mechanisms by which they detect incoming stimuli, how the sensing domains are coupled to channel gating and how these processes are connected to specific structural regions in the channel are not fully understood, but valuable information is available. Many sites involved in agonist detection have been characterized and gating models that describe many features of the channel's behavior have been put forward. In this review we will survey some of the key findings concerning the structural and molecular mechanisms of TRPV1, TRPA1 and TRPM8 activation.

  9. Perioperative Assessment of Myocardial Deformation

    PubMed Central

    Duncan, Andra E.; Alfirevic, Andrej; Sessler, Daniel I.; Popovic, Zoran B.; Thomas, James D.

    2014-01-01

    Evaluation of left ventricular performance improves risk assessment and guides anesthetic decisions. However, the most common echocardiographic measure of myocardial function, the left ventricular ejection fraction (LVEF), has important limitations. LVEF is limited by subjective interpretation which reduces accuracy and reproducibility, and LVEF assesses global function without characterizing regional myocardial abnormalities. An alternative objective echocardiographic measure of myocardial function is thus needed. Myocardial deformation analysis, which performs quantitative assessment of global and regional myocardial function, may be useful for perioperative care of surgical patients. Myocardial deformation analysis evaluates left ventricular mechanics by quantifying strain and strain rate. Strain describes percent change in myocardial length in the longitudinal (from base to apex) and circumferential (encircling the short-axis of the ventricle) direction and change in thickness in the radial direction. Segmental strain describes regional myocardial function. Strain is a negative number when the ventricle shortens longitudinally or circumferentially and is positive with radial thickening. Reference values for normal longitudinal strain from a recent meta-analysis using transthoracic echocardiography are (mean ± SD) −19.7 ± 0.4%, while radial and circumferential strain are 47.3 ± 1.9 and −23.3 ± 0.7%, respectively. The speed of myocardial deformation is also important and is characterized by strain rate. Longitudinal systolic strain rate in healthy subjects averages −1.10 ± 0.16 sec−1. Assessment of myocardial deformation requires consideration of both strain (change in deformation), which correlates with LVEF, and strain rate (speed of deformation), which correlates with rate of rise of left ventricular pressure (dP/dt). Myocardial deformation analysis also evaluates ventricular relaxation, twist, and untwist, providing new and noninvasive methods to

  10. Penn State DOE GATE Program

    SciTech Connect

    Anstrom, Joel

    2012-08-31

    The Graduate Automotive Technology Education (GATE) Program at The Pennsylvania State University (Penn State) was established in October 1998 pursuant to an award from the U.S. Department of Energy (U.S. DOE). The focus area of the Penn State GATE Program is advanced energy storage systems for electric and hybrid vehicles.

  11. Gates Learns to Think Big

    ERIC Educational Resources Information Center

    Robelen, Erik W.

    2006-01-01

    This article discusses how the philanthropy of Microsoft Corp software magnate co-chairs, Bill Gates and his wife Melinda, are reshaping the American high school nowadays. Gates and his wife have put the issue on the national agenda like never before, with a commitment of more than 1.3 billion US dollars this decade toward the foundation's agenda…

  12. Gates Learns to Think Big

    ERIC Educational Resources Information Center

    Robelen, Erik W.

    2006-01-01

    This article discusses how the philanthropy of Microsoft Corp software magnate co-chairs, Bill Gates and his wife Melinda, are reshaping the American high school nowadays. Gates and his wife have put the issue on the national agenda like never before, with a commitment of more than 1.3 billion US dollars this decade toward the foundation's agenda…

  13. On plant roots logical gates.

    PubMed

    Adamatzky, Andrew; Sirakoulis, Georgios Ch; Martínez, Genaro J; Baluška, Frantisek; Mancuso, Stefano

    Theoretical constructs of logical gates implemented with plant roots are morphological computing asynchronous devices. Values of Boolean variables are represented by plant roots. A presence of a plant root at a given site symbolises the logical True, an absence the logical False. Logical functions are calculated via interaction between roots. Two types of two-inputs-two-outputs gates are proposed: a gate 〈x, y〉→〈xy, x+y〉 where root apexes are guided by gravity and a gate 〈x,y〉→〈x¯y,x〉 where root apexes are guided by humidity. We propose a design of binary half-adder based on the gates. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. Protected gates for superconducting qubits

    NASA Astrophysics Data System (ADS)

    Brooks, Peter; Kitaev, Alexei; Preskill, John

    2013-05-01

    We analyze the accuracy of quantum phase gates acting on “0-π qubits” in superconducting circuits, where the gates are protected against thermal and Hamiltonian noise by continuous-variable quantum error-correcting codes. The gates are executed by turning on and off a tunable Josephson coupling between an LC oscillator and a qubit or pair of qubits; assuming perfect qubits, we show that the gate errors are exponentially small when the oscillator's impedance L/C is large compared to ℏ/4e2≈1kΩ. The protected gates are not computationally universal by themselves, but a scheme for universal fault-tolerant quantum computation can be constructed by combining them with unprotected noisy operations. We validate our analytic arguments with numerical simulations.

  15. Acute myocardial infarction.

    PubMed

    Boersma, Eric; Mercado, Nestor; Poldermans, Don; Gardien, Martin; Vos, Jeroen; Simoons, Maarten L

    2003-03-08

    Acute myocardial infarction is a common disease with serious consequences in mortality, morbidity, and cost to the society. Coronary atherosclerosis plays a pivotal part as the underlying substrate in many patients. In addition, a new definition of myocardial infarction has recently been introduced that has major implications from the epidemiological, societal, and patient points of view. The advent of coronary-care units and the results of randomised clinical trials on reperfusion therapy, lytic or percutaneous coronary intervention, and chronic medical treatment with various pharmacological agents have substantially changed the therapeutic approach, decreased in-hospital mortality, and improved the long-term outlook in survivors of the acute phase. New treatments will continue to emerge, but the greatest challenge will be to effectively implement preventive actions in all high-risk individuals and to expand delivery of acute treatment in a timely fashion for all eligible patients.

  16. Myocardial gene therapy

    NASA Astrophysics Data System (ADS)

    Isner, Jeffrey M.

    2002-01-01

    Gene therapy is proving likely to be a viable alternative to conventional therapies in coronary artery disease and heart failure. Phase 1 clinical trials indicate high levels of safety and clinical benefits with gene therapy using angiogenic growth factors in myocardial ischaemia. Although gene therapy for heart failure is still at the pre-clinical stage, experimental data indicate that therapeutic angiogenesis using short-term gene expression may elicit functional improvement in affected individuals.

  17. Myocardial Tagging With SSFP

    PubMed Central

    Herzka, Daniel A.; Guttman, Michael A.; McVeigh, Elliot R.

    2007-01-01

    This work presents the first implementation of myocardial tagging with refocused steady-state free precession (SSFP) and magnetization preparation. The combination of myocardial tagging (a noninvasive method for quantitative measurement of regional and global cardiac function) with the high tissue signal-to-noise ratio (SNR) obtained with SSFP is shown to yield improvements in terms of the myocardium–tag contrast-to-noise ratio (CNR) and tag persistence when compared to the current standard fast gradient-echo (FGRE) tagging protocol. Myocardium–tag CNR and tag persistence were studied using numerical simulations as well as phantom and human experiments. Both quantities were found to decrease with increasing imaging flip angle (α) due to an increased tag decay rate and a decrease in myocardial steady-state signal. However, higher α yielded better blood–myocardium contrast, indicating that optimal α is dependent on the application: higher α for better blood–myocardium boundary visualization, and lower α for better tag persistence. SSFP tagging provided the same myocardium–tag CNR as FGRE tagging when acquired at four times the bandwidth and better tag– and blood–myocardium CNRs than FGRE tagging when acquired at equal or twice the receiver bandwidth (RBW). The increased acquisition efficiency of SSFP allowed decreases in breath-hold duration, or increases in temporal resolution, as compared to FGRE. PMID:12541254

  18. Left ventricular energy model predicts adverse events in women with suspected myocardial ischemia: results from the NHLBI-sponsored women’s ischemia syndrome evaluation (WISE) study

    PubMed Central

    Weinberg, Nicole; Pohost, Gerald M.; Bairey Merz, C. Noel; Shaw, Leslee J.; Sopko, George; Fuisz, Anthon; Rogers, William J.; Walsh, Edward G.; Johnson, B. Delia; Sharaf, Barry L.; Pepine, Carl J.; Mankad, Sunil; Reis, Steven E.; Rayarao, Geetha; Vido, Diane A.; Bittner, Vera; Tauxe, Lindsey; Olson, Marian B.; Kelsey, Sheryl F.; Biederman, Robert WW

    2013-01-01

    Objectives To assess the prognostic value of a left ventricular energy-model in women with suspected myocardial ischemia. Background The prognostic value of internal energy utilization (IEU) of the left ventricle in women with suspected myocardial ischemia is unknown. Methods Women [n=227, mean age 59±12 years (range, 31-86 years)], with symptoms of myocardial ischemia, underwent myocardial perfusion imaging (MPI) assessment for regional perfusion defects along with measurement of ventricular volumes separately by gated Single Photon Emission Computed Tomography (SPECT) (n=207) and magnetic resonance imaging (MRI) (n=203). During follow-up (40±17 months), time to first major adverse cardiovascular event (MACE, death, myocardial infarction or hospitalization for congestive heart failure) was analyzed using MRI and gated SPECT variables. Results Adverse events occurred in 31 (14%). Multivariable Cox models were formed for each modality: IEU and wall thickness by MRI (Chi-squared 34, P<0.005) and IEU and systolic blood pressure by gated SEPCT (Chi-squared 34, P<0.005). The models remained predictive after adjustment for age, disease history and Framingham risk score. For each Cox model, patients were categorized as high-risk if the model hazard was positive and not high-risk otherwise. Kaplan-Meier analysis of time to MACE was performed for high-risk vs. not high-risk for MR (log rank 25.3, P<0.001) and gated SEPCT (log rank 18.2, P<0.001) models. Conclusions Among women with suspected myocardial ischemia a high internal energy utilization has higher prognostic value than either a low EF or the presence of a myocardial perfusion defect assessed using two independent modalities of MR or gated SPECT. PMID:24015377

  19. Impact of gate geometry on ionic liquid gated ionotronic systems

    DOE PAGES

    Wong, Anthony T.; Noh, Joo Hyon; Pudasaini, Pushpa Raj; ...

    2017-01-23

    Ionic liquid electrolytes are gaining widespread application as a gate dielectric used to control ion transport in functional materials. This letter systematically examines the important influence that device geometry in standard “side gate” 3-terminal geometries plays in device performance of a well-known oxygen ion conductor. We show that the most influential component of device design is the ratio between the area of the gate electrode and the active channel, while the spacing between these components and their individual shapes has a negligible contribution. Finally, these findings provide much needed guidance in device design intended for ionotronic gating with ionic liquids.

  20. Multifunctional MR monitoring of the healing process after myocardial infarction.

    PubMed

    Bönner, Florian; Jacoby, Christoph; Temme, Sebastian; Borg, Nadine; Ding, Zhaoping; Schrader, Jürgen; Flögel, Ulrich

    2014-01-01

    Healing of the myocardium after infarction comprises a variety of local adaptive processes which contribute to the functional outcome after the insult. Therefore, we aimed to establish a setting for concomitant assessment of regional alterations in contractile function, morphology, and immunological state to gain prognostic information on cardiac recovery after infarction. For this, mice were subjected to myocardial ischemia/reperfusion (I/R) and monitored for 28 days by cine MRI, T2 mapping, late gadolinium enhancement (LGE), and (19)F MRI. T2 values were calculated from gated multi-echo sequences. (19)F-loaded nanoparticles were injected intravenously for labelling circulating monocytes and making them detectable by (19)F MRI. In-house developed software was used for regional analysis of cine loops, T2 maps, LGE, and (19)F images to correlate local wall movement, tissue damage as well as monocyte recruitment over up to 200 sectors covering the left ventricle. This enabled us to evaluate simultaneously zonal cardiac necrosis, oedema, and inflammation patterns together with sectional fractional shortening (FS) and global myocardial function. Oedema, indicated by a rise in T2, showed a slightly better correlation with FS than LGE. Regional T2 values increased from 19 ms to above 30 ms after I/R. In the course of the healing process oedema resolved within 28 days, while myocardial function recovered. Infiltrating monocytes could be quantitatively tracked by (19)F MRI, as validated by flow cytometry. Furthermore, (19)F MRI proved to yield valuable insight on the outcome of myocardial infarction in a transgenic mouse model. In conclusion, our approach permits a comprehensive surveillance of key processes involved in myocardial healing providing independent and complementary information for individual prognosis.

  1. Perioperative myocardial infarction in patients undergoing myocardial revascularization surgery

    PubMed Central

    Pretto, Pericles; Martins, Gerez Fernandes; Biscaro, Andressa; Kruczan, Dany David; Jessen, Barbara

    2015-01-01

    Introduction Perioperative myocardial infarction adversely affects the prognosis of patients undergoing coronary artery bypass graft and its diagnosis was hampered by numerous difficulties, because the pathophysiology is different from the traditional instability atherosclerotic and the clinical difficulty to be characterized. Objective To identify the frequency of perioperative myocardial infarction and its outcome in patients undergoing coronary artery bypass graft. Methods Retrospective cohort study performed in a tertiary hospital specialized in cardiology, from May 01, 2011 to April 30, 2012, which included all records containing coronary artery bypass graft records. To confirm the diagnosis of perioperative myocardial infarction criteria, the Third Universal Definition of Myocardial Infarction was used. Results We analyzed 116 cases. Perioperative myocardial infarction was diagnosed in 28 patients (24.1%). Number of grafts and use and cardiopulmonary bypass time were associated with this diagnosis and the mean age was significantly higher in this group. The diagnostic criteria elevated troponin I, which was positive in 99.1% of cases regardless of diagnosis of perioperative myocardial infarction. No significant difference was found between length of hospital stay and intensive care unit in patients with and without this complication, however patients with perioperative myocardial infarction progressed with worse left ventricular function and more death cases. Conclusion The frequency of perioperative myocardial infarction found in this study was considered high and as a consequence the same observed average higher troponin I, more cases of worsening left ventricular function and death. PMID:25859867

  2. Commentary on WHO GATE Initiative.

    PubMed

    Cooper, Rory A

    2017-01-01

    Assistive technology is essential to people with spinal cord injuries (SCI) for living and participating in their communities. However, many people with SCI do not have access to adequate assistive technology and qualified services. The World Health Organization (WHO) is addressing this need through the Global Cooperation on Assistive Technology (GATE). The GATE initiative is focused on improving access to high-quality affordable AT world-wide. GATE working to meet the AT sector needs in response to the call by WHO to increase access to essential, high-quality, safe, effective and affordable medical devices, which is one of the six WHO leadership priorities.

  3. Superconducting gates with fluxon logics

    NASA Astrophysics Data System (ADS)

    Nacak, H.; Kusmartsev, F. V.

    2010-10-01

    We have developed several logic gates (OR, XOR, AND and NAND) made of superconducting Josephson junctions. The gates based of the flux cloning phenomenon and high speed of fluxons moving in Josephson junctions of different shapes. In a contrast with previous design the gates operates extremely fast since fluxons are moving with the speed close to the speed of light. We have demonstrated their operations and indicated several ways to made a more complicated logic elements which have at the same time a compact form.

  4. Robust Soldier Crab Ball Gate

    NASA Astrophysics Data System (ADS)

    Gunji, Yukio-Pegio; Nishiyama, Yuta; Adamatzky, Andrew

    2011-09-01

    Based on the field observation of soldier crabs, we previously proposed a model for a swarm of soldier crabs. Here, we describe the interaction of coherent swarms in the simulation model, which is implemented in a logical gate. Because a swarm is generated by inherent perturbation, a swarm can be generated and maintained under highly perturbed conditions. Thus, the model reveals a robust logical gate rather than stable one. In addition, we show that the logical gate of swarms is also implemented by real soldier crabs (Mictyris guinotae).

  5. Gated cardiac imaging using a continuously rotating CT scanner: clinical evaluation of 91 patients.

    PubMed

    Oyama, Y; Uji, T; Hirayama, T; Inada, Y; Ishikawa, T; Fujii, M

    1984-05-01

    To produce electrocardiographically (ECG)-gated computed tomographic (CT) images of the heart, a post-data-acquisition ECG correlation technique was used in which data for missing angular projections are derived from the original scan data to complete 360 angular projections. Improved image quality and clinical usefulness were demonstrated compared with routine nongated CT and two-dimensional echocardiography. Gated CT was better than nongated CT in 26 of 41 positive and three of five negative cases of suspected myocardial infarction, four of 10 positive and one of 12 negative cases of suspected left atrial mass, three of 10 cases with pericardial fluid collection, and three other cases. Compared with echocardiography, CT was of additional value in eight of 10 cases of myocardial infarction, five of nine positive and one of 10 negative cases of suspected left atrial mass, four of 10 positive and one of three negative cases of suspected pericardial fluid collection, and two other cases. The equipment required for CT gating is of low cost, but the examination time is lengthy and less conveniently performed than echocardiography. However, when echocardiography is indecisive or suspected to be falsely negative, gated CT imaging of the heart is recommended.

  6. Prognostic value of ECG-gated thallium-201 single-photon emission tomography in patients with coronary artery disease.

    PubMed

    Matsuo, Shinro; Matsumoto, Tetsuya; Nakae, Ichiro; Koh, Terue; Masuda, Daisuke; Takada, Masahiko; Murata, Kiyoshi; Horie, Minoru

    2004-10-01

    The phenomenon of reversible impairment in LV function has been well described and is known as myocardial stunning. Thallium-201 myocardial perfusion gated SPECT was used to evaluate myocardial stunning and its incremental prognostic value in patients with coronary artery disease. Fifty-six patients (aged 63+/-11 years) with coronary artery disease were included in this study. All subjects underwent exercise thallium scintigraphy. ECG-gated SPECT was obtained both at post-stress (10 minutes after the injection of 111 MBq of thallium at the time of peak exercise) and at rest (180 minutes). The left ventricular ejection fraction (LVEF) and end-systolic and end-diastolic volume (ESV, EDV) were determined by a quantitative gated SPECT (QGS) program. Follow-up was complete in all patients (mean 569 days). The magnitude of the depression of post-stress LVEF relative to the rest LVEF was correlated with the severity of ischemia (p < 0.05). The group with a median LVEF of more than 45% had a significantly higher event-free rate (p < 0.01). Assessment of post-stress left ventricular function by gated-SPECT provides incremental prognostic information and is useful in predicting cardiac events in patients with suspected or definite coronary artery disease.

  7. Reversible logic gates on Physarum Polycephalum

    SciTech Connect

    Schumann, Andrew

    2015-03-10

    In this paper, we consider possibilities how to implement asynchronous sequential logic gates and quantum-style reversible logic gates on Physarum polycephalum motions. We show that in asynchronous sequential logic gates we can erase information because of uncertainty in the direction of plasmodium propagation. Therefore quantum-style reversible logic gates are more preferable for designing logic circuits on Physarum polycephalum.

  8. 49 CFR 234.223 - Gate arm.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Gate arm. 234.223 Section 234.223 Transportation... Maintenance Standards § 234.223 Gate arm. Each gate arm, when in the downward position, shall extend across... clearly viewed by approaching highway users. Each gate arm shall start its downward motion not less...

  9. 49 CFR 234.223 - Gate arm.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 4 2014-10-01 2014-10-01 false Gate arm. 234.223 Section 234.223 Transportation... SYSTEMS Maintenance, Inspection, and Testing Maintenance Standards § 234.223 Gate arm. Each gate arm, when... maintained in a condition sufficient to be clearly viewed by approaching highway users. Each gate arm...

  10. 49 CFR 234.223 - Gate arm.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 4 2011-10-01 2011-10-01 false Gate arm. 234.223 Section 234.223 Transportation... Maintenance Standards § 234.223 Gate arm. Each gate arm, when in the downward position, shall extend across... clearly viewed by approaching highway users. Each gate arm shall start its downward motion not less...

  11. 49 CFR 234.223 - Gate arm.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 4 2012-10-01 2012-10-01 false Gate arm. 234.223 Section 234.223 Transportation... SYSTEMS Maintenance, Inspection, and Testing Maintenance Standards § 234.223 Gate arm. Each gate arm, when... maintained in a condition sufficient to be clearly viewed by approaching highway users. Each gate arm...

  12. Assessment of left ventricular diastolic function by gated single-photon emission tomography: comparison with Doppler echocardiography.

    PubMed

    Yamano, Tetsuhiro; Nakamura, Tomoki; Sakamoto, Kenzo; Hikosaka, Takato; Zen, Kan; Nakamura, Takeshi; Sawada, Takahisa; Azuma, Akihiro; Nishimura, Tsunehiko; Nakagawa, Masao

    2003-11-01

    Gated single-photon emission tomography (SPET) is not yet an established procedure for the evaluation of left ventricular (LV) diastolic function. This study examined diastolic function derived from gated SPET in comparison with an established diagnostic tool, Doppler echocardiography. We examined 37 consecutive patients with normal sinus rhythm who underwent gated technetium-99m tetrofosmin SPET. A gated SPET program was used with a temporal resolution of 32 frames per R-R interval. We obtained the Doppler transmitral flow velocity waveform immediately before gated SPET image acquisition. Patients who showed a ratio of peak early transmitral flow velocity to atrial flow velocity (E/A) of >1 or whose R-R intervals differed by >5% between Doppler echocardiography and gated SPET were excluded from this investigation. We compared diastolic indices and presumed corresponding intervals in diastole using the two methods. The peak filling rate (PFR) derived from gated SPET correlated with the Doppler peak velocity of the early transmitral flow (E) wave ( r=0.65) and deceleration of the E wave ( r=0.71). The time to PFR and percent atrial contribution to LV filling from gated SPET correlated excellently with the Doppler LV isovolumic relaxation time ( r=0.93) and the E/A ratio ( r=-0.85), respectively. There was a significant linear correlation in all the intervals from the R wave to the presumed corresponding diastolic points. The point of PFR in gated SPET and the peak of the E wave in Doppler echocardiography generally coincided. The onset of filling in gated SPET tended to be closer to the second heart sound than the start of the E wave in Doppler echocardiography. We conclude that gated SPET permits the assessment of not only myocardial perfusion and LV systolic function but also diastolic function, although there may be some errors in detection of the precise beginning of LV filling.

  13. Myocardial revascularisation after acute myocardial infarction.

    PubMed

    Bana, A; Yadava, O P; Ghadiok, R; Selot, N

    1999-05-15

    One hundred and twenty-three patients had coronary artery bypass grafting (CABG) within 30 days of acute myocardial infarction (AMI) from May 1992 to November 1997. Commonest infarct was anterior transmural (61.8%) and commonest indication of surgery was post-infarct persistent or recurrent angina (69.1%). Ten patients were operated within 48 h and 36 between 48 h to 2 weeks of having MI. Out of these, nine patients were having infarct extension and cardiogenic shock at the time of surgery. Pre-operatively fourteen patients were on inotropes of which six also had intra-aortic balloon pump (IABP) support. All patients had complete revascularisation with 3.8+/-1.2 distal anastomoses per patient. By multivariate analysis, we found that independent predictors of post-operative morbidity [inotropes >48 h, use of IABP, ventilation >24 h, ICU stay >5 days] and complications [re-exploration, arrhythmias, pulmonary complications, wound infection, cerebrovascular accident (CVA)] were left ventricular ejection fraction (LVEF) <30%, Q-wave MI, surgery <48 h after AMI, presence of pre-operative cardiogenic shock and age >60 years (P < or = 0.01). Mortality at 30 days was 3.3%. LVEF <30%, Q-wave MI, surgery <48 h after AMI, presence of pre-operative cardiogenic shock and age >60 years were found to be independent predictors of 30 days mortality (P < or = 0.01). Ninety patients were followed up for a mean duration of 33 months (1 to 65 months). There were three late deaths and five patients developed recurrence of angina. To conclude, CABG can be carried out with low risk following AMI in stable patients for post-infarct angina. Patients who undergo urgent or emergent surgery and who have pre-operative cardiogenic shock, IABP, poor left ventricular functions, age >60 years and Q-wave MI are at increased risk.

  14. Diurnal variations in myocardial metabolism

    USDA-ARS?s Scientific Manuscript database

    The heart is challenged by a plethora of extracellular stimuli over the course of a normal day, each of which distinctly influences myocardial contractile function. It is therefore not surprising that myocardial metabolism also oscillates in a time-of-day dependent manner. What is becoming increasin...

  15. The Gates, 1979-2005

    ERIC Educational Resources Information Center

    School Arts: The Art Education Magazine for Teachers, 2005

    2005-01-01

    One art critic called it pure Despite the mixed reviews of Christo and Jeanne-Claude's temporary art installation in New York's Central Park, the public reaction to The Gates was largely positive.The Gates consisted of 7,500 orange PVC frames straddling the park's walkways that varied in widths from 5 1/2 feet to 18 feet. Eight-foot-long ripstop…

  16. The Gates, 1979-2005

    ERIC Educational Resources Information Center

    School Arts: The Art Education Magazine for Teachers, 2005

    2005-01-01

    One art critic called it pure Despite the mixed reviews of Christo and Jeanne-Claude's temporary art installation in New York's Central Park, the public reaction to The Gates was largely positive.The Gates consisted of 7,500 orange PVC frames straddling the park's walkways that varied in widths from 5 1/2 feet to 18 feet. Eight-foot-long ripstop…

  17. Quantum gates with topological phases

    SciTech Connect

    Ionicioiu, Radu

    2003-09-01

    We investigate two models for performing topological quantum gates with the Aharonov-Bohm (AB) and Aharonov-Casher (AC) effects. Topological one- and two-qubit Abelian phases can be enacted with the AB effect using charge qubits, whereas the AC effect can be used to perform all single-qubit gates (Abelian and non-Abelian) for spin qubits. Possible experimental setups suitable for a solid-state implementation are briefly discussed.

  18. A molecular logic gate

    PubMed Central

    Kompa, K. L.; Levine, R. D.

    2001-01-01

    We propose a scheme for molecule-based information processing by combining well-studied spectroscopic techniques and recent results from chemical dynamics. Specifically it is discussed how optical transitions in single molecules can be used to rapidly perform classical (Boolean) logical operations. In the proposed way, a restricted number of states in a single molecule can act as a logical gate equivalent to at least two switches. It is argued that the four-level scheme can also be used to produce gain, because it allows an inversion, and not only a switching ability. The proposed scheme is quantum mechanical in that it takes advantage of the discrete nature of the energy levels but, we here discuss the temporal evolution, with the use of the populations only. On a longer time range we suggest that the same scheme could be extended to perform quantum logic, and a tentative suggestion, based on an available experiment, is discussed. We believe that the pumping can provide a partial proof of principle, although this and similar experiments were not interpreted thus far in our terms. PMID:11209046

  19. Logical gates in actin monomer.

    PubMed

    Adamatzky, Andrew

    2017-09-18

    We evaluate information processing capacity of a single actin molecule by calculating distributions of logical gates implemented by the molecule via propagating patterns of excitation. We represent a filamentous actin molecule as an excitable automaton network (F-actin automaton). where every atom updates its state depending on states of atoms its connected to with chemical bonds (hard neighbours) and atoms being in physical proximity to the atom (soft neighbours). A resting atom excites if a sum of its excited hard neighbours and a weighted sum of its soft neighbours belong to some specified interval. We demonstrate that F-actin automata implement OR, AND, XOR and AND-NOT gates via interacting patterns of excitation. Gate AND is the most common gate and gate XOR is the rarest. Using the architectures of gates discovered we implement one bit half-adder and controlled-not circuits in the F-actin automata. Speed and space values of the F-actin molecular computers are discussed.

  20. Latest design of gate valves

    SciTech Connect

    Kurzhofer, U.; Stolte, J.; Weyand, M.

    1996-12-01

    Babcock Sempell, one of the most important valve manufacturers in Europe, has delivered valves for the nuclear power industry since the beginning of the peaceful application of nuclear power in the 1960s. The latest innovation by Babcock Sempell is a gate valve that meets all recent technical requirements of the nuclear power technology. At the moment in the United States, Germany, Sweden, and many other countries, motor-operated gate and globe valves are judged very critically. Besides the absolute control of the so-called {open_quotes}trip failure,{close_quotes} the integrity of all valve parts submitted to operational forces must be maintained. In case of failure of the limit and torque switches, all valve designs have been tested with respect to the quality of guidance of the gate. The guidances (i.e., guides) shall avoid a tilting of the gate during the closing procedure. The gate valve newly designed by Babcock Sempell fulfills all these characteristic criteria. In addition, the valve has cobalt-free seat hardfacing, the suitability of which has been proven by friction tests as well as full-scale blowdown tests at the GAP of Siemens in Karlstein, West Germany. Babcock Sempell was to deliver more than 30 gate valves of this type for 5 Swedish nuclear power stations by autumn 1995. In the presentation, the author will report on the testing performed, qualifications, and sizing criteria which led to the new technical design.

  1. Changes in rest and exercise myocardial perfusion and left ventricular function 3 to 26 weeks after clinically uncomplicated acute myocardial infarction: effects of exercise training

    SciTech Connect

    Hung, J.; Gordon, E.P.; Houston, N.; Haskell, W.L.; Goris, M.L.; DeBusk, R.F.

    1984-11-01

    The effects of exercise training on exercise myocardial perfusion and left ventricular (LV) function in the first 6 months after clinically uncomplicated acute myocardial infarction (AMI) were assessed in 53 consecutive men aged 55 +/- 9 years. Symptom-limited treadmill exercise with thallium myocardial perfusion scintigraphy and symptom-limited upright bicycle ergometry with equilibrium gated radionuclide ventriculography were performed 3, 11 and 26 weeks after AMI by 23 men randomized to training and 30 randomized to no training. Peak cycle capacity increased in both groups between 3 and 26 weeks (p less than 0.01), but reached higher levels in trained than in untrained patients (803 +/- 149 vs 648 +/- 182 kg-m/min, p less than 0.01). Reversible thallium perfusion defects were significantly more frequent at 3 than at 26 weeks: 59% and 36% of patients, respectively (p less than 0.05), without significant inter-group differences. Values of LV ejection fraction at rest, submaximal and peak exercise did not change significantly in either group. The increase in functional capacity, i.e., peak treadmill or bicycle workload, that occurred 3 to 26 weeks after infarction was significantly correlated with the increase in peak exercise heart rate (p less than 0.001), but not with changes in myocardial perfusion or LV function determined by radionuclide techniques. Changes in myocardial perfusion or LV function do not appear to account for the improvement in peak functional capacity that occurs within the first 6 months after clinically uncomplicated AMI.

  2. Altered phosphate metabolism in myocardial infarction: P-31 MR spectroscopy

    SciTech Connect

    Bottomley, P.A.; Herfkens, R.J.; Smith, L.S.; Bashore, T.M.

    1987-12-01

    The high-energy myocardial phosphate metabolism of four patients with acute anterior myocardial infarction after coronary angioplasty and drug therapy was evaluated with cardiac-gated phosphorus magnetic resonance (MR) depth-resolved surface coil spectroscopy (DRESS) 5-9 days after the onset of symptoms. Significant reductions (about threefold) in the phosphocreatine (PCr) to inorganic phosphate (Pi) ratio and elevations in the Pi to adenosine triphosphate (ATP) ratio were observed in endocardially or transmurally derived MR spectra when compared with values from epicardially displaced spectra and values from seven healthy volunteers (P less than .05). High-energy phosphate metabolites and Pi ratios did not vary significantly during the cardiac cycle in healthy volunteers. However, contamination of Pi resonances by phosphomonoester components, including blood 2,3-diphosphoglycerate, precluded accurate spectral quantification of Pi and pH. The results indicate that localized P-31 MR spectroscopy may be used to directly assess cellular energy reserve in clinical myocardial infarction and to evaluate metabolic response to interventions.

  3. Myocardial and liver iron status using a fast T*2 quantitative MRI (T*2qMRI) technique.

    PubMed

    Maris, Thomas G; Papakonstantinou, Olympia; Chatzimanoli, Vasiliki; Papadakis, Alekos; Pagonidis, Konstantinos; Papanikolaou, Nickolas; Karantanas, Apostolos; Gourtsoyiannis, Nicholas

    2007-04-01

    This work demonstrates the use of a fast and precise methodology for evaluating myocardial and liver iron status in multitransfused thalassemic patients by means of a fast T(2) (*) quantitative MRI (T(2) (*)qMRI) technique. Myocardial and liver T(2) (*) values were calculated in 48 thalassemic patients and 21 normal subjects on a 1.5T MRI system using a breath-hold 2D single-slice multiecho gradient-echo (MEGRE) sequence (16 echoes, TR/TE1/TE16/FA = 160/2.7/37.65 ms/25 degrees ). No ECG gating was used. Myocardial T(2) (*), liver T(2) (*), and myocardial to muscle (CR/MS) and liver to muscle (LV/MS) T(2) (*) ratios were correlated with serum ferritin concentration (SFC) levels for all patients. Significant differences in myocardial and liver mean T(2) (*), CR/MS, and LV/MS T(2) (*) values between patients and normal subjects were found (P < 0.0005). Differences in paraspinous muscle mean T(2) (*) values between patients and normal subjects were not significant. Myocardial T(2) (*) and CR/MS T(2) (*) values were not correlated with SFC levels. Liver T(2) (*) and LV/MS T(2) (*) values were significantly correlated with SFC (r = 0.540, P < 0.0005). Myocardial T(2) (*) and CR/MS T(2) (*) values were not correlated with either liver T(2) (*) or LV/MS T(2) (*) values, respectively. We conclude that myocardial and liver iron deposition can be evaluated using the fast non-ECG-gated T(2) (*)qMRI technique.

  4. Quantum gate-set tomography

    NASA Astrophysics Data System (ADS)

    Blume-Kohout, Robin

    2014-03-01

    Quantum information technology is built on (1) physical qubits and (2) precise, accurate quantum logic gates that transform their states. Developing quantum logic gates requires good characterization - both in the development phase, where we need to identify a device's flaws so as to fix them, and in the production phase, where we need to make sure that the device works within specs and predict residual error rates and types. This task falls to quantum state and process tomography. But until recently, protocols for tomography relied on a pre-existing and perfectly calibrated reference frame comprising the measurements (and, for process tomography, input states) used to characterize the device. In practice, these measurements are neither independent nor perfectly known - they are usually implemented via exactly the same gates that we are trying to characterize! In the past year, several partial solutions to this self-consistency problem have been proposed. I will present a framework (gate set tomography, or GST) that addresses and resolves this problem, by self-consistently characterizing an entire set of quantum logic gates on a black-box quantum device. In particular, it contains an explicit closed-form protocol for linear-inversion gate set tomography (LGST), which is immune to both calibration error and technical pathologies like local maxima of the likelihood (which plagued earlier methods). GST also demonstrates significant (multiple orders of magnitude) improvements in efficiency over standard tomography by using data derived from long sequences of gates (much like randomized benchmarking). GST has now been applied to qubit devices in multiple technologies. I will present and discuss results of GST experiments in technologies including a single trapped-ion qubit and a silicon quantum dot qubit. Sandia National Laboratories is a multiprogram laboratory operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U

  5. Effect of reperfusion and hyperemia on the myocardial distribution of technetium-99m t-butylisonitrile

    SciTech Connect

    Holman, B.L.; Campbell, C.A.; Lister-James, J.; Jones, A.G.; Davison, A.; Kloner, R.A.

    1986-07-01

    Technetium-99m t-butylisonitrile ((/sup 99m/Tc)TBI) is a promising new radiotracer for myocardial imaging. Its myocardial uptake is sufficiently high in humans to permit planar, tomographic, and gated images of excellent technical quality. We studied the behavior of (/sup 99m/Tc)TBI in the dog at rest and under conditions of hyperemia and reperfusion in order to determine the relationship between (/sup 99m/Tc)TBI myocardial concentration and blood flow. After permanent occlusion of the left anterior descending artery, the correlation between the relative myocardial concentration of (/sup 99m/Tc)TBI and regional myocardial blood flow (RMBF) measured with radiolabeled microspheres was excellent. In a dog model of transient hyperemia, the concentration of (/sup 99m/Tc)TBI was directly related to blood flow but underestimated the degree of hyperemia. Technetium-99m TBI redistributed into transiently ischemic myocardium. The myocardial concentrations of (/sup 99m/Tc)TBI and thallium-201(/sup 201/TI) in transiently ischemic myocardium were similar at 10 and 30 min following reperfusion and were significantly higher than blood flow prior to reperfusion. When (/sup 99m/Tc)TBI was injected into the left anterior descending artery, the washout was slow, falling to 78% of initial activity at 120 min after injection. In conclusion, (/sup 99m/Tc)TBI reflects regional myocardial blood flow accurately in ischemic and normal resting myocardium and underestimates blood flow at high flows. The rate of myocardial redistribution after reperfusion is similar for (/sup 99m/Tc)TBI and /sup 201/TI.

  6. Single event gate rupture in thin gate oxides

    SciTech Connect

    Sexton, F.W.; Fleetwood, D.M.; Shaneyfelt, M.R.; Dodd, P.E.; Hash, G.L.

    1997-06-01

    As integrated circuit densities increase with each new technology generation, both the lateral and vertical dimensions shrink. Operating voltages, however, have not scaled as aggressively as feature size, with a resultant increase in the electric fields within advanced geometry devices. Oxide electric fields are in fact increasing to greater than 5 MV/cm as feature size approaches 0.1 {micro}m. This trend raises the concern that single event gate rupture (SEGR) may limit the scaling of advanced integrated circuits (ICs) for space applications. The dependence of single event gate rupture (SEGR) critical field on oxide thickness is examined for thin gate oxides. Critical field for SEGR increases with decreasing oxide thickness, consistent with an increasing intrinsic breakdown field.

  7. Dipyridamole thallium-201 scintigraphy as a preoperative screening test. A reexamination of its predictive potential. Study of Perioperative Ischemia Research Group

    SciTech Connect

    Mangano, D.T.; London, M.J.; Tubau, J.F.; Browner, W.S.; Hollenberg, M.; Krupski, W.; Layug, E.L.; Massie, B. )

    1991-08-01

    The authors examined the value of dipyridamole thallium-201 (201Tl) scintigraphy as a preoperative screening test for perioperative myocardial ischemia and infarction. They prospectively studied 60 patients undergoing elective vascular surgery. They performed 201Tl scintigraphy preoperatively and blinded all treating physicians to the results. Historical, clinical, laboratory, and physiological data were gathered throughout hospitalization. Myocardial ischemia was assessed during the intraoperative period using continuous 12-lead electrocardiography (ECG) and transesophageal echocardiography (TEE) and during the postoperative period using continuous two-lead ambulatory ECG. Adverse cardiac outcomes (cardiac death, myocardial infarction, unstable angina, severe ischemia, or congestive heart failure) were assessed daily throughout hospitalization. Twenty-two patients (37%) had defects that improved or reversed on delayed scintigrams (redistribution defects), 18 (30%) had persistent defects, and 20 (33%) had no defects on 201Tl scintigraphy. There was no association between redistribution defects and adverse cardiac outcomes: 54% (seven of 13) of adverse outcomes occurred in patients without redistribution defects, and the risk of an adverse outcome was not significantly increased in patients with redistribution defects. Consistent with these findings, there was also no association between redistribution defects and perioperative ischemia: 54% (19 of all 35) of perioperative ECG and TEE ischemic episodes and 58% (14 of 24) of severe ischemic episodes occurred in patients without redistribution defects. The sensitivity of 201Tl scintigraphy for perioperative ischemia and adverse outcomes ranged from 40% to 54%, specificity from 65% to 71%, positive predictive value from 27% to 47% and negative predictive value from 61% to 82%.

  8. Prospectively gated cardiac computed tomography.

    PubMed

    Moore, S C; Judy, P F; Garnic, J D; Kambic, G X; Bonk, F; Cochran, G; Margosian, P; McCroskey, W; Foote, F

    1983-01-01

    A fourth-generation scanner has been modified to perform prospectively gated cardiac computed tomography (CT). A computer program monitors the electrocardiogram (ECG) and predicts when to initiate the next scan in a gated series in order to acquire all projection data for a desired phase of the heart cycle. The system has been tested with dogs and has produced cross-sectional images of all phases of the cardiac cycle. Eight to ten scans per series were sufficient to obtain reproducible images of each transverse section in the end-diastolic and end-systolic phases. The radiation dose to the skin was approximately 1.4 cGy per scan. The prospectively gated system is more than twice as efficient as a retrospectively gated system in obtaining complete angular projection data for a 10% heart cycle window. A temporal smoothing technique to suppress reconstruction artifacts due to sorting inconsistent projection data was developed and evaluated. Image noise was reduced by averaging together any overlapping projection data. Prospectively gated cardiac CT has also been used to demonstrate that the error in attenuation measured with a single nongated CT scan through the heart can be as large as 50-60 CT numbers outside the heart in the lung field.

  9. Prevention of myocardial infarction.

    PubMed

    Adams, M R

    2002-12-01

    Despite the rapid advances that have been made in the treatment of coronary artery disease, myocardial infarction remains the major cause of death in the developed world and a growing problem for developing countries. To address this growing problem, a strategy aimed at prevention of events in high-risk individuals is required. This involves assessment of cardiovascular risk followed by risk reduction. At present there is no perfect technique available for risk prediction, although computed tomography and magnetic resonance imaging scanning, along with serum markers of inflammation, offer the greatest potential. The applicability of these techniques at present is also limited by cost and accessibility. Risk reduction is possible through lifestyle changes and drug therapy, and effective risk assessment is essential in selecting those most likely to benefit from these interventions.

  10. Detection of radiation cardiomyopathy by gated radionuclide angiography

    SciTech Connect

    Burns, R.J.; Bar-Shlomo, B.Z.; Druck, M.N.; Herman, J.G.; Gilbert, B.W.; Perrault, D.J.; McLaughlin, P.R.

    1983-02-01

    Twenty-one asymptomatic adults underwent rest and exercise gated radionuclide angiography seven to 20 years after having received mediastinal radiation (2,000 to 7,600 rads) for Hodgkin's disease. None of these patients received cytotoxic chemotherapy. Twelve patients (57 percent) had abnormal left (less than 53 percent at rest and/or greater than 5 percent decrease at peak exercise) and/or right (less than 27 percent at rest and/or greater than 5 percent decrease at peak exercise) ventricular ejection fractions. Previous reports have described myocardial fibrosis occurring late after therapeutic mediastinal radiation; however, the incidence of this occurrence based on clinical follow-up has been low. Rest and exercise radionuclide angiography is a sensitive method for assessing systolic ventricular function and reveals a high prevalence of cardiomyopathy that can be linked to previous radiotherapy.

  11. Positron emission tomography for the assessment of myocardial viability: an evidence-based analysis.

    PubMed

    2010-01-01

    myocardial viability. Intravenous contrast agents, which are high molecular weight inert gas microbubbles that act like red blood cells in the vascular space, can be used during echocardiography to assess myocardial viability. These agents allow for the assessment of myocardial blood flow (perfusion) and contractile function (as described above), as well as the simultaneous assessment of perfusion to make it possible to distinguish between stunned and hibernating myocardium. SPECT: SPECT can be performed using thallium-201 (Tl-201), a potassium analogue, or technetium-99 m labelled tracers. When Tl-201 is injected intravenously into a patient, it is taken up by the myocardial cells through regional perfusion, and Tl-201 is retained in the cell due to sodium/potassium ATPase pumps in the myocyte membrane. The stress-redistribution-reinjection protocol involves three sets of images. The first two image sets (taken immediately after stress and then three to four hours after stress) identify perfusion defects that may represent scar tissue or viable tissue that is severely hypoperfused. The third set of images is taken a few minutes after the re-injection of Tl-201 and after the second set of images is completed. These re-injection images identify viable tissue if the defects exhibit significant fill-in (> 10% increase in tracer uptake) on the re-injection images. The other common Tl-201 viability imaging protocol, rest-redistribution, involves SPECT imaging performed at rest five minutes after Tl-201 is injected and again three to four hours later. Viable tissue is identified if the delayed images exhibit significant fill-in of defects identified in the initial scans (> 10% increase in uptake) or if defects are fixed but the tracer activity is greater than 50%. There are two technetium-99 m tracers: sestamibi (MIBI) and tetrofosmin. The uptake and retention of these tracers is dependent on regional perfusion and the integrity of cellular membranes. Viability is assessed using

  12. Quantum gates by periodic driving

    PubMed Central

    Shi, Z. C.; Wang, W.; Yi, X. X.

    2016-01-01

    Topological quantum computation has been extensively studied in the past decades due to its robustness against decoherence. One way to realize the topological quantum computation is by adiabatic evolutions—it requires relatively long time to complete a gate, so the speed of quantum computation slows down. In this work, we present a method to realize single qubit quantum gates by periodic driving. Compared to adiabatic evolution, the single qubit gates can be realized at a fixed time much shorter than that by adiabatic evolution. The driving fields can be sinusoidal or square-well field. With the sinusoidal driving field, we derive an expression for the total operation time in the high-frequency limit, and an exact analytical expression for the evolution operator without any approximations is given for the square well driving. This study suggests that the period driving could provide us with a new direction in regulations of the operation time in topological quantum computation. PMID:26911900

  13. Ionic thermoelectric gating organic transistors

    NASA Astrophysics Data System (ADS)

    Zhao, Dan; Fabiano, Simone; Berggren, Magnus; Crispin, Xavier

    2017-01-01

    Temperature is one of the most important environmental stimuli to record and amplify. While traditional thermoelectric materials are attractive for temperature/heat flow sensing applications, their sensitivity is limited by their low Seebeck coefficient (~100 μV K-1). Here we take advantage of the large ionic thermoelectric Seebeck coefficient found in polymer electrolytes (~10,000 μV K-1) to introduce the concept of ionic thermoelectric gating a low-voltage organic transistor. The temperature sensing amplification of such ionic thermoelectric-gated devices is thousands of times superior to that of a single thermoelectric leg in traditional thermopiles. This suggests that ionic thermoelectric sensors offer a way to go beyond the limitations of traditional thermopiles and pyroelectric detectors. These findings pave the way for new infrared-gated electronic circuits with potential applications in photonics, thermography and electronic-skins.

  14. Electrostatic Gating of Ultrathin Films

    NASA Astrophysics Data System (ADS)

    Goldman, A. M.

    2014-07-01

    Electrostatic gating of ultrathin films can be used to modify electronic and magnetic properties of materials by effecting controlled alterations of carrier concentration while, in principle, not changing the level of disorder. As such, electrostatic gating can facilitate the development of novel devices and can serve as a means of exploring the fundamental properties of materials in a manner far simpler than is possible with the conventional approach of chemical doping. The entire phase diagram of a compound can be traversed by changing the gate voltage. In this review, we survey results involving conventional field effect devices as well as more recent progress, which has involved structures that rely on electrochemical configurations such as electric double-layer transistors. We emphasize progress involving thin films of oxide materials such as high-temperature superconductors, magnetic oxides, and oxides that undergo metal-insulator transitions.

  15. Ionic thermoelectric gating organic transistors

    PubMed Central

    Zhao, Dan; Fabiano, Simone; Berggren, Magnus; Crispin, Xavier

    2017-01-01

    Temperature is one of the most important environmental stimuli to record and amplify. While traditional thermoelectric materials are attractive for temperature/heat flow sensing applications, their sensitivity is limited by their low Seebeck coefficient (∼100 μV K−1). Here we take advantage of the large ionic thermoelectric Seebeck coefficient found in polymer electrolytes (∼10,000 μV K−1) to introduce the concept of ionic thermoelectric gating a low-voltage organic transistor. The temperature sensing amplification of such ionic thermoelectric-gated devices is thousands of times superior to that of a single thermoelectric leg in traditional thermopiles. This suggests that ionic thermoelectric sensors offer a way to go beyond the limitations of traditional thermopiles and pyroelectric detectors. These findings pave the way for new infrared-gated electronic circuits with potential applications in photonics, thermography and electronic-skins. PMID:28139738

  16. Death Due to Myocardial Bridging.

    PubMed

    Ural, M Numan; Eren, Filiz; Inanir, Nursel Türkmen; Eren, Bülent; Vojtisek, Tomas; Gürses, Murat Serdar

    2015-06-01

    Myocardial bridging is a congenital coronary pathology described as a segment of coronary artery which courses through the myocardial wall beneath the muscle bridge. Although the myocardial bridging prognosis is benign, have been also reported sudden death in medical literature. ¬A 30-year-old married woman was found dead at her home. After local prosecutors' investigation the death was declared as suspicious and forensic autopsy was obliged. The left anterior descending coronary artery was detected embedded deeply in the myocardium 2 cm from its coronary ostial origin. There were no other pathology to explain death. We analyzed sudden death case occurred because of myocardial bridging and the pathophysiological mechanisms in the light of medico-legal literature.

  17. Localizing a gate in CFTR

    PubMed Central

    Gao, Xiaolong; Hwang, Tzyh-Chang

    2015-01-01

    Experimental and computational studies have painted a picture of the chloride permeation pathway in cystic fibrosis transmembrane conductance regulator (CFTR) as a short narrow tunnel flanked by wider inner and outer vestibules. Although these studies also identified a number of transmembrane segments (TMs) as pore-lining, the exact location of CFTR’s gate(s) remains unknown. Here, using a channel-permeant probe, [Au(CN)2]−, we provide evidence that CFTR bears a gate that coincides with the predicted narrow section of the pore defined as residues 338–341 in TM6. Specifically, cysteines introduced cytoplasmic to the narrow region (i.e., positions 344 in TM6 and 1148 in TM12) can be modified by intracellular [Au(CN)2]− in both open and closed states, corroborating the conclusion that the internal vestibule does not harbor a gate. However, cysteines engineered to positions external to the presumed narrow region (e.g., 334, 335, and 337 in TM6) are all nonreactive toward cytoplasmic [Au(CN)2]− in the absence of ATP, whereas they can be better accessed by extracellular [Au(CN)2]− when the open probability is markedly reduced by introducing a second mutation, G1349D. As [Au(CN)2]− and chloride ions share the same permeation pathway, these results imply a gate is situated between amino acid residues 337 and 344 along TM6, encompassing the very segment that may also serve as the selectivity filter for CFTR. The unique position of a gate in the middle of the ion translocation pathway diverges from those seen in ATP-binding cassette (ABC) transporters and thus distinguishes CFTR from other members of the ABC transporter family. PMID:25675504

  18. Localizing a gate in CFTR.

    PubMed

    Gao, Xiaolong; Hwang, Tzyh-Chang

    2015-02-24

    Experimental and computational studies have painted a picture of the chloride permeation pathway in cystic fibrosis transmembrane conductance regulator (CFTR) as a short narrow tunnel flanked by wider inner and outer vestibules. Although these studies also identified a number of transmembrane segments (TMs) as pore-lining, the exact location of CFTR's gate(s) remains unknown. Here, using a channel-permeant probe, [Au(CN)2](-), we provide evidence that CFTR bears a gate that coincides with the predicted narrow section of the pore defined as residues 338-341 in TM6. Specifically, cysteines introduced cytoplasmic to the narrow region (i.e., positions 344 in TM6 and 1148 in TM12) can be modified by intracellular [Au(CN)2](-) in both open and closed states, corroborating the conclusion that the internal vestibule does not harbor a gate. However, cysteines engineered to positions external to the presumed narrow region (e.g., 334, 335, and 337 in TM6) are all nonreactive toward cytoplasmic [Au(CN)2](-) in the absence of ATP, whereas they can be better accessed by extracellular [Au(CN)2](-) when the open probability is markedly reduced by introducing a second mutation, G1349D. As [Au(CN)2](-) and chloride ions share the same permeation pathway, these results imply a gate is situated between amino acid residues 337 and 344 along TM6, encompassing the very segment that may also serve as the selectivity filter for CFTR. The unique position of a gate in the middle of the ion translocation pathway diverges from those seen in ATP-binding cassette (ABC) transporters and thus distinguishes CFTR from other members of the ABC transporter family.

  19. Reading Gate Positions with a Smartphone

    NASA Astrophysics Data System (ADS)

    van Overloop, Peter-Jules; Hut, Rolf

    2015-04-01

    Worldwide many flow gates are built in water networks in order to direct water to appropriate locations. Most of these gates are adjusted manually by field operators of water management organizations and it is often centrally not known what the new position of the gate is. This makes centralized management of the entire water network difficult. One of the reasons why the measurement of the gate position is usually not executed, is that for certain gates it is not easy to do such a reading. Tilting weirs or radial gates are examples where operators need special equipment (measuring rod and long level) to determine the position and it could even be a risky procedure. Another issue is that once the measurement is done, the value is jotted down in a notebook and later, at the office, entered in a computer system. So the entire monitoring procedure is not real-time and prone to human errors. A new way of monitoring gate positions is introduced. It consists of a level that is attached to the gate and an app with which a picture can be taken from the level. Using dedicated pattern recognition algorithms, the gate position can be read by using the angle of the level versus reference points on the gate, the radius of that gate and the absolute level of the joint around which the gate turn. The method uses gps-localization of the smartphone to store the gate position in the right location in the central database.

  20. HELLS GATE ROADLESS AREA, ARIZONA.

    USGS Publications Warehouse

    Conway, Clay M.; McColly, Robert A.

    1984-01-01

    Although no mineral-resource potential was identified in the Hells Gate Roadless Area during mineral surveys, the area is largely underlain by a regionally extensive Proterozoic granite-rhyolite complex which is tin-bearing. The geologic setting precludes the occurrence of fossil fuel resources and no other energy resources were identified. The potential for tin and associated metals in the Hells Gate Roadless Area and the region cannot be fully evaluated at this point. The granophyre and the upper part of the granite pluton along the northwestern margin of the area should be explored.

  1. Gating mechanisms of voltage-gated proton channels.

    PubMed

    Okamura, Yasushi; Fujiwara, Yuichiro; Sakata, Souhei

    2015-01-01

    Hv1 is a voltage-gated proton-selective channel that plays critical parts in host defense, sperm motility, and cancer progression. Hv1 contains a conserved voltage-sensor domain (VSD) that is shared by a large family of voltage-gated ion channels, but it lacks a pore domain. Voltage sensitivity and proton conductivity are conferred by a unitary VSD that consists of four transmembrane helices. The architecture of Hv1 differs from that of cation channels that form a pore in the center among multiple subunits (as in most cation channels) or homologous repeats (as in voltage-gated sodium and calcium channels). Hv1 forms a dimer in which a cytoplasmic coiled coil underpins the two protomers and forms a single, long helix that is contiguous with S4, the transmembrane voltage-sensing segment. The closed-state structure of Hv1 was recently solved using X-ray crystallography. In this article, we discuss the gating mechanism of Hv1 and focus on cooperativity within dimers and their sensitivity to metal ions.

  2. Magnetic resonance imaging (MRI) for the assessment of myocardial viability: an evidence-based analysis.

    PubMed

    2010-01-01

    diagnostic accuracy of echocardiographic assessment of myocardial viability. Intravenous contrast agents, which are high molecular weight inert gas microbubbles that act like red blood cells in the vascular space, can be used during echocardiography to assess myocardial viability. These agents allow for the assessment of myocardial blood flow (perfusion) and contractile function (as described above), as well as the simultaneous assessment of perfusion to make it possible to distinguish between stunned and hibernating myocardium. SPECT: SPECT can be performed using thallium-201 (Tl-201), a potassium analogue, or technetium-99 m labelled tracers. When Tl-201 is injected intravenously into a patient, it is taken up by the myocardial cells through regional perfusion, and Tl-201 is retained in the cell due to sodium/potassium ATPase pumps in the myocyte membrane. The stress-redistribution-reinjection protocol involves three sets of images. The first two image sets (taken immediately after stress and then three to four hours after stress) identify perfusion defects that may represent scar tissue or viable tissue that is severely hypoperfused. The third set of images is taken a few minutes after the re-injection of Tl-201 and after the second set of images is completed. These re-injection images identify viable tissue if the defects exhibit significant fill-in (> 10% increase in tracer uptake) on the re-injection images. The other common Tl-201 viability imaging protocol, rest-redistribution, involves SPECT imaging performed at rest five minutes after Tl-201 is injected and again three to four hours later. Viable tissue is identified if the delayed images exhibit significant fill-in of defects identified in the initial scans (> 10% increase in uptake) or if defects are fixed but the tracer activity is greater than 50%. There are two technetium-99 m tracers: sestamibi (MIBI) and tetrofosmin. The uptake and retention of these tracers is dependent on regional perfusion and the

  3. Radial gate evaluation: Olympus Dam, Colorado

    SciTech Connect

    1997-06-01

    The report presents a structural analysis of the radial gates of Olympus Dam in eastern Colorado. Five 20-foot wide by 17-foot high radial gates are used to control flow through the spillway at Olympus Dam. The spillway gates were designed in 1947. The gate arm assemblies consist of two separate wide flange beams, with a single brace between the arms. The arms pivot about a 4.0-inch diameter pin and bronze graphite-insert bushing. The pin is cantilevered from the pier anchor girder. The radial gates are supported by a pin bearing on a pier anchor birder bolted to the end of the concrete pier. The gates are operated by two-part wire rope 15,000-pound capacity hoise. Stoplog slots upstream of the radial gates are provided in the concrete piers. Selected drawings of the gates and hoists are located in appendix A.

  4. Chirality dependence of nanoscale ferromagnetic NOT gates

    NASA Astrophysics Data System (ADS)

    Lewis, E. R.; Petit, D.; O'Brien, L.; Zeng, H. T.; Read, D. E.; Cowburn, R. P.

    2011-03-01

    The behavior of a transverse domain wall (DW) interacting with a ferromagnetic NOT gate is studied with specific emphasis on the role of the DW chirality (sense of rotation of magnetization crossing the DW). We examine both the effect of the incoming DW chirality on the operation of the NOT gate and the effect of the gate on the DW chirality. We find that the chirality of the incoming DW does not affect the range of fields over which the NOT gate operates correctly. The effect of the NOT gate on the DW chirality depends on the chirality of the incoming DW: when the DW is incident on the NOT gate with the wide side of the DW on the inside of the V-shape formed by the gate, the chirality is conserved, but when the DW is incident on the gate with its wide side on the outside of the V-shape, the chirality may reverse.

  5. Wave Propagation of Myocardial Stretch: Correlation with Myocardial Stiffness

    PubMed Central

    Pislaru, Cristina; Pellikka, Patricia A.; Pislaru, Sorin V.

    2015-01-01

    The mechanism of flow propagation during diastole in the left ventricle (LV) has been well described. Little is known about the associated waves propagating along the heart wall s. These waves may have a mechanism similar to pulse wave propagation in arteries. The major goal of the study was to evaluate the effect of myocardial stiffness and preload on this wave transmission. Methods Longitudinal late diastolic deformation and wave speed (Vp) of myocardial stretch in the anterior LV wall were measured using sonomicrometry in sixteen pigs. Animals with normal and altered myocardial stiffness (acute myocardial infarction) were studied with and without preload alterations. Elastic modulus estimated from Vp (EVP; Moens-Korteweg equation) was compared to incremental elastic modulus obtained from exponential end -diastolic stress-strain relation (ESS). Myocardial distensibility and α-and β-coefficients of stress-strain relations were calculated. Results Vp was higher at reperfusion compared to baseline (2.6±1.3 m/s vs. 1.3±0.4 m/s; p=0.005) and best correlated with ESS (r 2=0.80, p<0.0001), β-coefficient (r2=0.78, p<0.0001), distensibility (r2=0.47, p=0.005), and wall thickness/diameter ratio (r2=0.42, p=0.009). Elastic moduli (EVP and ESS) were strongly correlated (r2=0.83, p<0.0001). Increasing preload increased Vp and EVP and decreased distensibility. At multivariate analysis, ESS, wall thickness, and end-diastolic and systolic LV pressures were independent predictors of Vp (r2model=0.83, p<0.0001). Conclusions The main determinants of wave propagation of longitudinal myocardial stretch were myocardial stiffness and LV geometry and pressure. This local wave speed could potentially be measured noninvasively by echocardiography. PMID:25193091

  6. Wave propagation of myocardial stretch: correlation with myocardial stiffness.

    PubMed

    Pislaru, Cristina; Pellikka, Patricia A; Pislaru, Sorin V

    2014-01-01

    The mechanism of flow propagation during diastole in the left ventricle (LV) has been well described. Little is known about the associated waves propagating along the heart walls. These waves may have a mechanism similar to pulse wave propagation in arteries. The major goal of the study was to evaluate the effect of myocardial stiffness and preload on this wave transmission. Longitudinal late diastolic deformation and wave speed (Vp) of myocardial stretch in the anterior LV wall were measured using sonomicrometry in 16 pigs. Animals with normal and altered myocardial stiffness (acute myocardial infarction) were studied with and without preload alterations. Elastic modulus estimated from Vp (E VP; Moens-Korteweg equation) was compared to incremental elastic modulus obtained from exponential end-diastolic stress-strain relation (E SS). Myocardial distensibility and α- and β-coefficients of stress-strain relations were calculated. Vp was higher at reperfusion compared to baseline (2.6 ± 1.3 vs. 1.3 ± 0.4 m/s; p = 0.005) and best correlated with E SS (r2 = 0.80, p < 0.0001), β-coefficient (r2 = 0.78, p < 0.0001), distensibility (r2 = 0.47, p = 0.005), and wall thickness/diameter ratio (r2 = 0.42, p = 0.009). Elastic moduli (E VP and E SS) were strongly correlated (r2 = 0.83, p < 0.0001). Increasing preload increased Vp and E VP and decreased distensibility. At multivariate analysis, E SS, wall thickness, and end-diastolic and systolic LV pressures were independent predictors of Vp (r2 model = 0.83, p < 0.0001). In conclusion, the main determinants of wave propagation of longitudinal myocardial stretch were myocardial stiffness and LV geometry and pressure. This local wave speed could potentially be measured noninvasively by echocardiography.

  7. Imaging of myocardial infarction using carbon nanotube micro-computed tomography and delayed contrast enhancement

    NASA Astrophysics Data System (ADS)

    Burk, Laurel M.; Wang, Kohan; Kang, Eunice; Rojas, Mauricio; Willis, Monte; Lee, Yueh Z.; Lu, Jianping; Zhou, Otto

    2011-03-01

    We demonstrate the application of our cardiac- and respiratory-gated carbon nanotube (CNT) micro-CT system by evaluating murine myocardial infarction models with a delayed contrast enhancement technique. Myocardial infarction was induced in 8 wild-type male mice. The ischemia reperfusion model was achieved by surgical occlusion of the LAD artery for 30 minutes followed by 24 hours of reperfusion. Free-breathing subjects were anesthetized with isoflurane during imaging. Respiratory and cardiac signals were monitored externally to gate the scan. Micro-CT data was obtained at 50kV, 3mA cathode current for 15ms per projection. All images were acquired during end exhalation at either 0msec or 55msec after the R-wave (diastole or systole, respectively). Following administration of Omnipaque 300mgI/mL at 0.1ml/5g, images were obtained at 0msec after the R-wave. Fenestra VC was then administered at a 0.1ml/5g dose, followed by images 0 and 55msec after the R-wave. Hearts were then harvested, sliced 1mm thick and stained with TTC. All animals survived surgery and imaging; all demonstrated obvious delayed contrast enhancement in the left ventricular wall in Omnipaque images. Fenestra VC revealed cardiac functional changes quantified by low ejection fractions. All subjects demonstrated areas of myocardial infarct in the LAD distribution on both TTC staining and micro-CT imaging. CNT enabled gated cardiac micro-CT imaging demonstrates the ability to consistently identify areas of myocardial infarct in mice, providing a powerful tool for the study of cardiovascular biology. Further work is ongoing to streamline the imaging protocol and perform more quantitative analysis of the images.

  8. [Fatty acid metabolism in patients with idiopathic dilated cardiomyopathy: characteristics and prognostic implications].

    PubMed

    Narita, M; Kurihara, T

    1995-05-01

    The characteristics of myocardial fatty acid metabolism in patients with idiopathic dilated cardiomyopathy (DCM) were investigated by myocardial imaging with beta-methyl-p-[123I]iodophenyl-pentadecanoic acid (BMIPP) in 16 patients with DCM, 8 patients with hypertensive heart failure (HHF), and 11 normal subjects. Rest myocardial imaging with BMIPP and 201Tl was performed on another day. The index of myocardial BMIPP uptake, or uptake ratio, was calculated from the percentage uptakes of BMIPP and 201Tl. The index of inhomogeneity of intramyocardial isotope distribution was calculated as the coefficient of variation of BMIPP and 201Tl. The uptake ratio was significantly lower in DCM and HHF patients than in normal subjects (p < 0.01). Uptake ratio correlated well with fractional shortening (r = 0.76, p < 0.01), and left ventricular ejection fraction (r = 0.58, p < 0.01). Although uptake ratio was not different between DCM and HHF patients, defects in BMIPP imaging appeared more frequently in DCM (69%) than in HHF (38%) patients. Furthermore, the extent of the defect in BMIPP imaging in DCM patients was larger than that in 201Tl imaging (p < 0.05), but in HHF patients the extent of the defects in both methods was similar. The coefficient of variation of BMIPP in DCM patients was greater than those in HHF patients and in normal subjects, but those of 201Tl were not different between the three groups. The coefficient of variation of BMIPP in DCM patients correlated well with serum norepinephrine level (r = 0.57, p < 0.01) and atrial natriuretic peptide (r = 0.77, p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

  9. Optimization of myocardial function.

    PubMed

    Alpert, N R; Mulieri, L A; Hasenfuss, G; Holubarsch, C

    1993-01-01

    Under normal conditions the cardiac output is designed to meet the metabolic needs of the organism. Thus, the demands imposed on the heart muscle can range from low values at rest to an order of magnitude greater values during exercise. The heart uses a number of strategies to meet the short- and long-term changes in demand. These strategies are of general biological interest and employ similar mechanisms to those responsible for the differences in muscle performance seen between muscle from various species and diverse muscle types within a given animal. This review deals with the heart's utilization of these strategies to meet a broad range of requirements. Tortoise (TM) and rat soleus (RS) muscles are slow, have high economy and develop low power. In contrast (FM) and rat extensor digitorum longus (REDL) are fast, have low economy and have a high power output. These differences are explainable in terms of the characteristics of the myosin head cross-bridge cycle (Cross-bridge tension-time integral: FM/FT = 0.024; REDL/RS = 0.16. Myosin ATPase activity: FM/TM = 15; RDEL/RS = 2.3) and excitation contraction coupling system (time to peak tension: FM/TM = 0.2; REDL/RS = 0.4). Heart muscle employs similar strategies (cross-bridge cycle; excitation contraction coupling) to meet short (catecholamine) and long (hypertrophy secondary to pressure overload or thyrotoxicosis) term changes in demand. In the presence of catecholamine power is increased while economy is decreased. This difference between control (C) and isoproterenol treated hearts (I) is explainable in terms of the contractile and excitation contraction coupling systems (Cross-bridge tension-time integral: I/C = 0.4. Tension independent heat: I/C = 2.0. Tension independent heat rate: I/C = 2.5). A persistent increase in the demand on the heart results in myocardial hypertrophy that is associated with intracellular reorganization. Hyperthyroidism (T) and pressure overload (PO) were used to produce myocardial

  10. Talking with Microsoft's Bill Gates.

    ERIC Educational Resources Information Center

    EDUCOM Review, 1994

    1994-01-01

    Presents the transcript of an interview with William Gates, chairman of Microsoft Corporation. Topics discussed include continued support from the information technology industry for higher education; experiences with recent college graduates in the industry; new technologies developing in the near future; alliances in the computer industry; and…

  11. Double-disc gate valve

    DOEpatents

    Wheatley, Seth J.

    1979-01-01

    This invention relates to an improvement in a conventional double-disc gate valve having a vertically movable gate assembly including a wedge, spreaders slidably engaged therewtih, a valve disc carried by the spreaders. When the gate assembly is lowered to a selected point in the valve casing, the valve discs are moved transversely outward to close inlet and outlet ports in the casing. The valve includes hold-down means for guiding the disc-and-spreader assemblies as they are moved transversely outward and inward. If such valves are operated at relatively high differential pressures, they sometimes jam during opening. Such jamming has been a problem for many years in gate valves used in gaseous diffusion plants for the separtion of uranium isotopes. The invention is based on the finding that the above-mentioned jamming results when the outlet disc tilts about its horizontal axis in a certain way during opening of the valve. In accordance with the invention, tilting of the outlet disc is maintained at a tolerable value by providing the disc with a rigid downwardly extending member and by providing the casing with a stop for limiting inward arcuate movement of the member to a preselected value during opening of the valve.

  12. Developing ICALL Tools Using GATE

    ERIC Educational Resources Information Center

    Wood, Peter

    2008-01-01

    This article discusses the use of the General Architecture for Text Engineering (GATE) as a tool for the development of ICALL and NLP applications. It outlines a paradigm shift in software development, which is mainly influenced by projects such as the Free Software Foundation. It looks at standards that have been proposed to facilitate the…

  13. Bill Gates eyes healthcare market.

    PubMed

    Dunbar, C

    1995-02-01

    The entrepreneurial spirit is still top in Bill Gates' mind as he look toward healthcare and other growth industries. Microsoft's CEO has not intention of going the way of other large technology companies that became obsolete before they could compete today.

  14. Developing ICALL Tools Using GATE

    ERIC Educational Resources Information Center

    Wood, Peter

    2008-01-01

    This article discusses the use of the General Architecture for Text Engineering (GATE) as a tool for the development of ICALL and NLP applications. It outlines a paradigm shift in software development, which is mainly influenced by projects such as the Free Software Foundation. It looks at standards that have been proposed to facilitate the…

  15. GATED PORES IN THE FERRITIN PROTEIN NANOCAGE

    PubMed Central

    Theil, Elizabeth C.; Liu, Xiaofeng S.; Tosha, Takehiko

    2008-01-01

    Synopsis and pictogram: Gated pores in the ferritin family of protein nanocages, illustrated in the pictogram, control transfer of ferrous iron into and out of the cages by regulating contact between hydrated ferric oxide mineral inside the protein cage, and reductants such as FMNH2 on the outside. The structural and functional homology between the gated ion channel proteins in inaccessible membranes and gated ferritin pores in the stable, water soluble nanoprotein, make studies of ferritin pores models for gated pores in many ion channel proteins. Properties of ferritin gated pores, which control rates of FMNH2 reduction of ferric iron in hydrated oxide minerals inside the protein nanocage, are discussed in terms of the conserved pore gate residues (arginine 72-apspartate 122 and leucine 110-leucine 134), of pore sensitivity to heat at temperatures 30 °C below that of the nanocage itself, and of pore sensitivity to physiological changes in urea (1–10 mM). Conditions which alter ferritin pore structure/function in solution, coupled with the high evolutionary conservation of the pore gates, suggest the presence of molecular regulators in vivo that recognize the pore gates and hold them either closed or open, depending on biological iron need. The apparent homology between ferrous ion transport through gated pores in the ferritin nanocage and ion transport through gated pores in ion channel proteins embedded in cell membranes, make studies of water soluble ferritin and the pore gating folding/unfolding a useful model for other gated pores. PMID:19262678

  16. Quantum Circuit Synthesis using a New Quantum Logic Gate Library of NCV Quantum Gates

    NASA Astrophysics Data System (ADS)

    Li, Zhiqiang; Chen, Sai; Song, Xiaoyu; Perkowski, Marek; Chen, Hanwu; Zhu, Wei

    2017-04-01

    Since Controlled-Square-Root-of-NOT (CV, CV‡) gates are not permutative quantum gates, many existing methods cannot effectively synthesize optimal 3-qubit circuits directly using the NOT, CNOT, Controlled-Square-Root-of-NOT quantum gate library (NCV), and the key of effective methods is the mapping of NCV gates to four-valued quantum gates. Firstly, we use NCV gates to create the new quantum logic gate library, which can be directly used to get the solutions with smaller quantum costs efficiently. Further, we present a novel generic method which quickly and directly constructs this new optimal quantum logic gate library using CNOT and Controlled-Square-Root-of-NOT gates. Finally, we present several encouraging experiments using these new permutative gates, and give a careful analysis of the method, which introduces a new idea to quantum circuit synthesis.

  17. Quantum Circuit Synthesis using a New Quantum Logic Gate Library of NCV Quantum Gates

    NASA Astrophysics Data System (ADS)

    Li, Zhiqiang; Chen, Sai; Song, Xiaoyu; Perkowski, Marek; Chen, Hanwu; Zhu, Wei

    2016-12-01

    Since Controlled-Square-Root-of-NOT (CV, CV‡) gates are not permutative quantum gates, many existing methods cannot effectively synthesize optimal 3-qubit circuits directly using the NOT, CNOT, Controlled-Square-Root-of-NOT quantum gate library (NCV), and the key of effective methods is the mapping of NCV gates to four-valued quantum gates. Firstly, we use NCV gates to create the new quantum logic gate library, which can be directly used to get the solutions with smaller quantum costs efficiently. Further, we present a novel generic method which quickly and directly constructs this new optimal quantum logic gate library using CNOT and Controlled-Square-Root-of-NOT gates. Finally, we present several encouraging experiments using these new permutative gates, and give a careful analysis of the method, which introduces a new idea to quantum circuit synthesis.

  18. Rat myocardial protein degradation.

    PubMed

    Steer, J H; Hopkins, B E

    1981-07-01

    1. Myocardial protein degradation rates were determined by following tyrosine release from rat isolated left hemi-atria in vitro. 2. After two 20 min preincubations the rate of tyrosine release from hemi-atria was constant for 4 h. 3. Skeletal muscle protein degradation was determined by following tyrosine release from rat isolated hemi-diaphragm (Fulks, Li & Goldberg, 1975). 4. Insulin (10(-7) M) inhibited tyrosine release from hemi-atria and hemi-diaphragm to a similar extent. A 48 h fast increased tyrosine release rate from hemi-diaphragm and decreased tyrosine release rate from hemi-atria. Hemi-diaphragm tyrosine release was inhibited by 15 mmol/l D-glucose but a variety of concentrations of D-glucose (0, 5, 15 mmol/l) had no effect on tyrosine release from hemi-atria. Five times the normal plasma levels of the branched-chain amino acids leucine, isoleucine and valine had no effect on tyrosine release from either hemi-atria or hemi-diaphragm.

  19. Myocardial complications of immunisations.

    PubMed

    Helle, E P; Koskenvuo, K; Heikkilä, J; Pikkarainen, J; Weckström, P

    1978-10-01

    Immunisation may induce myocardial complications. In this pilot study clinical, electrocardiographic, chemical and immunological findings have been studied during a six weeks' follow-up after routine immunisation (mumps, polio, tetanus, smallpox, diphtheria and type A meningococcal disease) among 234 Finnish conscripts at the beginning of their military service. Serial pattern of ECG changes suggestive of myocarditis was recorded in eight of the 234 conscripts one to two weeks after vaccination against smallpox and diphtheria. Changes were mainly minor ST segment elevations and T wave inversions and usually they disappeared in a few weeks. The ECG positives more often had a history of atopy, and their mean body temperatures and heart rates after the vaccinations were higher than among the other subjects (p less than 0.01). However, clinical myocarditis was never noted, nor were immunological or enzymological changes different among the ECG positives. Thus in 3% of the study population, evidence of postvaccinal myocarditis was noted, based on serial ECG patterns, but without any other evidence of cardiac disease.

  20. Myocardial mechanics in cardiomyopathies.

    PubMed

    Modesto, Karen; Sengupta, Partho P

    2014-01-01

    Cardiomyopathies are a heterogeneous group of diseases that can be phenotypically recognized by specific patterns of ventricular morphology and function. The authors summarize recent clinical observations that mechanistically link the multidirectional components of left ventricular (LV) deformation with morphological phenotypes of cardiomyopathies for offering key insights into the transmural heterogeneity of myocardial function. Subendocardial dysfunction predominantly alters LV longitudinal shortening, lengthening and suction performance and contributes to the phenotypic patterns of heart failure (HF) with preserved ejection fraction (EF) seen with hypertrophic and restrictive patterns of cardiomyopathy. On the other hand, a more progressive transmural disease results in reduction of LV circumferential and twist mechanics leading to the phenotypic pattern of dilated cardiomyopathy and the clinical syndrome of HF with reduced (EF). A proper characterization of LV transmural mechanics, energetics, and space-time distributions of pressure and shear stress may allow recognition of early functional changes that can forecast progression or reversal of LV remodeling. Furthermore, the interactions between LV muscle and fluid mechanics hold the promise for offering newer mechanistic insights and tracking impact of novel therapies.

  1. CAD of myocardial perfusion

    NASA Astrophysics Data System (ADS)

    Storm, Corstiaan J.; Slump, Cornelis H.

    2007-03-01

    Our purpose is in the automated evaluation of the physiological relevance of lesions in coronary angiograms. We aim to extract as much as possible quantitative information about the physiological condition of the heart from standard angiographic image sequences. Coronary angiography is still the gold standard for evaluating and diagnosing coronary abnormalities as it is able to locate precisely the coronary artery lesions. The dimensions of the stenosis can be assessed nowadays successfully with image processing based Quantitative Coronary Angiography (QCA) techniques. Our purpose is to assess the clinical relevance of the pertinent stenosis. We therefore analyze the myocardial perfusion as revealed in standard angiographic image sequences. In a Region-of-Interest (ROI) on the angiogram (without an overlaying major blood vessel) the contrast is measured as a function of time (the so-called time-density curve). The required hyperemic state of exercise is induced artificially by the injection of a vasodilator drug e.g. papaverine. In order to minimize motion artifacts we select based on the recorded ECG signal end-diastolic images in both a basal and a hyperemic run in the same projection to position the ROI. We present the development of the algorithms together with results of a small study of 20 patients which have been catheterized following the standard protocol.

  2. Optimization of side gate length and side gate voltage for sub-100-nm double-gate MOSFET

    NASA Astrophysics Data System (ADS)

    Kim, Jae-hong; Kim, Geun-ho; Ko, Suk-woong; Jung, Hak-kee

    2002-11-01

    In this paper, we have investigated double gate (DG) MOSFET structure, which has main gate (MG) and two side gates (SG). We know that optimum side gate voltage for each side gate length is about 2V in the main gate 50nm. Also, we know that optimum side gate length for each main gate length is 70nm above. DG MOSFET shows a small threshold voltage (Vth) roll-off. From the I-V characteristics, we obtained IDsat=510μA/μm at VMG=VDS=1.5V and VSG=3.0V for DG MOSFET with the main gate length of 50nm and the side gate length of 70nm. The subthreshold slope is 86mV/decade, transconductance is 111μA/V and DIBL (Drain Induced Barrier Lowering) is 51.3mV. Then, we have investigated the advantage of this structure for the application to multi-input NAND gate logic. Also, we have presented that TCAD simulator is suitable for device simulation.

  3. Effect of hypoxia on thallium kinetics in cultured chick myocardial cells

    SciTech Connect

    Friedman, B.J.; Beihn, R.; Friedman, J.P.

    1987-09-01

    To assess the effect of hypoxia on cellular thallium-201 (/sup 201/Tl) uptake and washout independent of coronary flow, we studied thallium kinetics during normoxia and hypoxia in cultured chick ventricular cells. Monolayers of contracting ventricular cells grown on coverslips were placed in a chamber and perfused to asymptote with media containing /sup 201/Tl. Perfusates were equilibrated with 5% CO/sub 2/-95% air or 5% CO/sub 2/-95% nitrogen for normoxia and hypoxia, respectively. Washout thallium kinetics were then observed during perfusion with unlabeled media. Twenty paired experiments were performed, randomly alternating the sequence of normoxia and hypoxia. Pharmacokinetics for thallium were determined by computer using standard formulae. Thallium uptake and washout were best described by assuming that intracellular thallium was contained within a single compartment. Cellular thallium uptake, as well as transfer rate constants for thallium uptake and for thallium washout during normoxia and hypoxia, were compared using paired t-tests. During normoxia and hypoxia, respectively, thallium uptake was 22 +/- 7% and 19 +/- 7% of asymptote (p less than 0.01); the compartmental rate constant for uptake by the cell was 0.16 +/- 0.07 min-1 and 0.15 +/- 0.06 min-1 (N.S.); and the transfer rate constant for washout from the cell was 0.26 +/- 0.06 min-1 and 0.23 +/- 0.05 min-1 (p less than 0.01). We conclude that there was a small (14%) decrease in thallium uptake during hypoxia. The rate of thallium uptake and washout was slightly less during hypoxia, although only the rate of washout was significantly less. These data show that cellular accumulation of thallium and the rate of washout of thallium were minimally decreased by hypoxia independent of blood flow.

  4. Myocardial perfusion imaging for detection of silent myocardial ischemia

    SciTech Connect

    Beller, G.A.

    1988-04-21

    Despite the widespread use of the exercise stress test in diagnosing asymptomatic myocardial ischemia, exercise radionuclide imaging remains useful for detecting silent ischemia in numerous patient populations, including those who are totally asymptomatic, those who have chronic stable angina, those who have recovered from an episode of unstable angina or an uncomplicated myocardial infarction, and those who have undergone angioplasty or received thrombolytic therapy. Studies show that thallium scintigraphy is more sensitive than exercise electrocardiography in detecting ischemia, i.e., in part, because perfusion defects occur more frequently than ST depression and before angina in the ischemic cascade. Thallium-201 scintigraphy can be performed to differentiate a true- from a false-positive exercise electrocardiographic test in patients with exercise-induced ST depression and no angina. The development of technetium-labeled isonitriles may improve the accuracy of myocardial perfusion imaging. 11 references.

  5. Environmental noise reduction for holonomic quantum gates

    SciTech Connect

    Parodi, Daniele; Zanghi, Nino; Sassetti, Maura; Solinas, Paolo

    2007-07-15

    We study the performance of holonomic quantum gates, driven by lasers, under the effect of a dissipative environment modeled as a thermal bath of oscillators. We show how to enhance the performance of the gates by a suitable choice of the loop in the manifold of the controllable parameters of the laser. For a simplified, albeit realistic model, we find the surprising result that for a long time evolution the performance of the gate (properly estimated in terms of average fidelity) increases. On the basis of this result, we compare holonomic gates with the so-called stimulated raman adiabatic passage (STIRAP) gates.

  6. RGB-NIR active gated imaging

    NASA Astrophysics Data System (ADS)

    Spooren, Nick; Geelen, Bert; Tack, Klaas; Lambrechts, Andy; Jayapala, Murali; Ginat, Ran; David, Yaara; Levi, Eyal; Grauer, Yoav

    2016-10-01

    This paper presents multispectral active gated imaging in relation to the transportation and security fields. Active gated imaging is based on a fast gated camera and pulsed illuminator, synchronized in the time domain to provide range based images. We have developed a multispectral pattern deposited on a gated CMOS Image Sensor (CIS) with a pulsed Near Infrared VCSEL module. This paper will cover the component-level description of the multispectral gated CIS including the camera and illuminator units. Furthermore, the design considerations and characterization results of the spectral filters are presented together with a newly developed image processing method.

  7. Attosecond Temporal Gating with Elliptically Polarized Light

    SciTech Connect

    Dudovich, N.; Smirnova, O.; Ivanov, M. Yu.; Villeneuve, D. M.; Corkum, P. B.; Levesque, J.; Zeidler, D.; Comtois, D.

    2006-12-22

    Temporal gating allows high accuracy time-resolved measurements of a broad range of ultrafast processes. By manipulating the interaction between an atom and an intense laser field, we extend gating into the nonlinear medium in which attosecond optical and electron pulses are generated. Our gate is an amplitude gate induced by ellipticity of the fundamental pulse. The gate modulates the spectrum of the high harmonic emission and we use the measured modulation to characterize the sub-laser-cycle dynamics of the recollision electron wave packet.

  8. MYOCARDIAL AKT: THE OMNIPRESENT NEXUS

    PubMed Central

    Sussman, Mark A.; Völkers, Mirko; Fischer, Kimberlee; Bailey, Brandi; Cottage, Christopher T.; Din, Shabana; Gude, Natalie; Avitabile, Daniele; Alvarez, Roberto; Sundararaman, Balaji; Quijada, Pearl; Mason, Matt; Konstandin, Mathias H.; Malhowski, Amy; Cheng, Zhaokang; Khan, Mohsin; McGregor, Michael

    2013-01-01

    One of the greatest examples of integrated signal transduction is revealed by examination of effects mediated by AKT kinase in myocardial biology. Positioned at the intersection of multiple afferent and efferent signals, AKT exemplifies a molecular sensing node that coordinates dynamic responses of the cell in literally every aspect of biological responses. The balanced and nuanced nature of homeostatic signaling is particularly essential within the myocardial context, where regulation of survival, energy production, contractility, and response to pathological stress all flow through the nexus of AKT activation or repression. Equally important, the loss of regulated AKT activity is primarily the cause or consequence of pathological conditions leading to remodeling of the heart and eventual decompensation. This review presents an overview compendium of the complex world of myocardial AKT biology gleaned from more than a decade of research. Summarization of the widespread influence that AKT exerts upon myocardial responses leaves no doubt that the participation of AKT in molecular signaling will need to be reckoned with as a seemingly omnipresent regulator of myocardial molecular biological responses. PMID:21742795

  9. Diurnal variations in myocardial metabolism.

    PubMed

    Bray, Molly S; Young, Martin E

    2008-07-15

    The heart is challenged by a plethora of extracellular stimuli over the course of a normal day, each of which distinctly influences myocardial contractile function. It is therefore not surprising that myocardial metabolism also oscillates in a time-of-day dependent manner. What is becoming increasingly apparent is that the heart exhibits diurnal variations in its intrinsic properties, including responsiveness to extracellular stimuli. This article summarizes our current knowledge regarding the mechanism(s) mediating diurnal variations in myocardial metabolism. Particular attention is focused towards the intramyocardial circadian clock, a cell autonomous molecular mechanism that appears to regulate myocardial metabolism both directly (e.g. triglyceride and glycogen metabolism) and indirectly (through modulation of the responsiveness of the myocardium to workload, insulin, and fatty acids). In doing so, the circadian clock within the cardiomyocyte allows the heart to anticipate environmental stimuli (such as changes in workload, feeding status) prior to their onset. This synchronization between the myocardium and its environment is enhanced by regular feeding schedules. Conversely, loss of synchronization may occur through disruption of the circadian clock and/or diurnal variations in neurohumoral factors (as observed during diabetes mellitus). Here, we discuss the possibility that loss of synchronization between the heart and its environment predisposes the heart to metabolic maladaptation and subsequent myocardial contractile dysfunction.

  10. Fast Gate: Subnanosecond Gate Detectors for Laser Radiography

    SciTech Connect

    Trebes, J.; Feit, M.; Hatchett, S.; Key, M.; Phillips, T.; Sefcik, J.; Snavely, R.; Weber, M.

    2000-02-25

    X-ray radiography is used as a principal diagnostic in a wide range of hydrodynamic tests relevant to the weapons program and also for basic materials and equation-of-state science studies. The quality of the x-ray radiograph can be significantly degraded by the scattering of x-rays within the object and by components of the test system itself. Elimination of these scattered x-rays from the recorded images can either substantially improve the image contrast and signal-to-noise or allow smaller, lower-cost x-ray sources to be used. The scattered x-rays could be minimized through the use of a much shorter-duration x-ray pulse and a fast, gated detector. The short duration x-ray pulse and the fast gated detector allow detection of only those x-rays which pass through the object being radiographed. X-rays which are the result of scattering have longer path lengths and take longer to reach the target. Most of these can be eliminated if the detector if gated off before they arrive at the detector. Until recently there were no sources of high energy x-rays (1-10 MeV) with short duration (sub 100 picosecond) pulses. Now the Petawatt Laser Facility (ref 1) at Lawrence Livermore National Laboratory has been able to produce 0.1 rads at 1 meter of MeV energy x-rays in 1-0 picoseconds. Efforts are underway to significantly increase this x-ray output. The combination of the existing short-duration, Petawatt-produced x-ray pulses and an x-ray detector with sub-100-ps gate times could eliminate most of the scattered x-rays from the radiograph image and allow highly improved radiography particularly for larger, high density test objects.

  11. Unifying Gate Synthesis and Magic State Distillation

    NASA Astrophysics Data System (ADS)

    Campbell, Earl T.; Howard, Mark

    2017-02-01

    The leading paradigm for performing a computation on quantum memories can be encapsulated as distill-then-synthesize. Initially, one performs several rounds of distillation to create high-fidelity magic states that provide one good T gate, an essential quantum logic gate. Subsequently, gate synthesis intersperses many T gates with Clifford gates to realize a desired circuit. We introduce a unified framework that implements one round of distillation and multiquibit gate synthesis in a single step. Typically, our method uses the same number of T gates as conventional synthesis but with the added benefit of quadratic error suppression. Because of this, one less round of magic state distillation needs to be performed, leading to significant resource savings.

  12. Quantum computing gates via optimal control

    NASA Astrophysics Data System (ADS)

    Atia, Yosi; Elias, Yuval; Mor, Tal; Weinstein, Yossi

    2014-10-01

    We demonstrate the use of optimal control to design two entropy-manipulating quantum gates which are more complex than the corresponding, commonly used, gates, such as CNOT and Toffoli (CCNOT): A two-qubit gate called polarization exchange (PE) and a three-qubit gate called polarization compression (COMP) were designed using GRAPE, an optimal control algorithm. Both gates were designed for a three-spin system. Our design provided efficient and robust nuclear magnetic resonance (NMR) radio frequency (RF) pulses for 13C2-trichloroethylene (TCE), our chosen three-spin system. We then experimentally applied these two quantum gates onto TCE at the NMR lab. Such design of these gates and others could be relevant for near-future applications of quantum computing devices.

  13. Morphological aspects of myocardial bridges.

    PubMed

    Lujinović, Almira; Kulenović, Amela; Kapur, Eldan; Gojak, Refet

    2013-11-01

    Although some myocardial bridges can be asymptomatic, their presence often causes coronary disease either through direct compression of the "tunnel" segment or through stimulation and accelerated development of atherosclerosis in the segment proximally to the myocardial bridge. The studied material contained 30 human hearts received from the Department of Anatomy. The hearts were preserved 3 to 5 days in 10% formalin solution. Thereafter, the fatty tissue was removed and arterial blood vessels prepared by careful dissection with special reference to the presence of the myocardial bridges. Length and thickness of the bridges were measured by the precise electronic caliper. The angle between the myocardial bridge fibre axis and other axis of the crossed blood vessel was measured by a goniometer. The presence of the bridges was confirmed in 53.33% of the researched material, most frequently (43.33%) above the anterior interventricular branch. The mean length of the bridges was 14.64 ± 9.03 mm and the mean thickness was 1.23 ± 1.32 mm. Myocardial bridge fibres pass over the descending blood vessel at the angle of 10-90 degrees. The results obtained on a limited sample suggest that the muscular index of myocardial bridge is the highest for bridges located on RIA, but that the difference is not significant in relation to bridges located on other branches. The results obtained suggest that bridges located on other branches, not only those on RIA, could have a great contractive power and, consequently, a great compressive force, which would be exerted on the wall of a crossed blood vessel.

  14. Morphological aspects of myocardial bridges

    PubMed Central

    Lujinović, Almira; Kulenović, Amela; Kapur, Eldan; Gojak, Refet

    2013-01-01

    Although some myocardial bridges can be asymptomatic, their presence often causes coronary disease either through direct compression of the “tunnel” segment or through stimulation and accelerated development of atherosclerosis in the segment proximally to the myocardial bridge. The studied material contained 30 human hearts received from the Department of Anatomy. The hearts were preserved 3 to 5 days in 10% formalin solution. Thereafter, the fatty tissue was removed and arterial blood vessels prepared by careful dissection with special reference to the presence of the myocardial bridges. Length and thickness of the bridges were measured by the precise electronic caliper. The angle between the myocardial bridge fibre axis and other axis of the crossed blood vessel was measured by a goniometer. The presence of the bridges was confirmed in 53.33% of the researched material, most frequently (43.33%) above the anterior interventricular branch. The mean length of the bridges was 14.64±9.03 mm and the mean thickness was 1.23±1.32 mm. Myocardial bridge fibres pass over the descending blood vessel at the angle of 10-90 degrees. The results obtained on a limited sample suggest that the muscular index of myocardial bridge is the highest for bridges located on RIA, but that the difference is not significant in relation to bridges located on other branches. The results obtained suggest that bridges located on other branches, not only those on RIA, could have a great contractive power and, consequently, a great compressive force, which would be exerted on the wall of a crossed blood vessel. PMID:24289755

  15. Microscale Digital Vacuum Electronic Gates

    NASA Technical Reports Server (NTRS)

    Manohara, Harish (Inventor); Mojarradi, Mohammed M. (Inventor)

    2014-01-01

    Systems and methods in accordance with embodiments of the invention implement microscale digital vacuum electronic gates. In one embodiment, a microscale digital vacuum electronic gate includes: a microscale field emitter that can emit electrons and that is a microscale cathode; and a microscale anode; where the microscale field emitter and the microscale anode are disposed within at least a partial vacuum; where the microscale field emitter and the microscale anode are separated by a gap; and where the potential difference between the microscale field emitter and the microscale anode is controllable such that the flow of electrons between the microscale field emitter and the microscale anode is thereby controllable; where when the microscale anode receives a flow of electrons, a first logic state is defined; and where when the microscale anode does not receive a flow of electrons, a second logic state is defined.

  16. Voltage-Gated Hydrophobic Nanopores

    SciTech Connect

    Lavrik, Nickolay V

    2011-01-01

    Hydrophobicity is a fundamental property that is responsible for numerous physical and biophysical aspects of molecular interactions in water. Peculiar behavior is expected for water in the vicinity of hydrophobic structures, such as nanopores. Indeed, hydrophobic nanopores can be found in two distinct states, dry and wet, even though the latter is thermodynamically unstable. Transitions between these two states are kinetically hindered in long pores but can be much faster in shorter pores. As it is demonstrated for the first time in this paper, these transitions can be induced by applying a voltage across a membrane with a single hydrophobic nanopore. Such voltage-induced gating in single nanopores can be realized in a reversible manner through electrowetting of inner walls of the nanopores. The resulting I-V curves of such artificial hydrophobic nanopores mimic biological voltage-gated channels.

  17. Cyclic networks of quantum gates

    NASA Astrophysics Data System (ADS)

    Cabauy, Peter

    In this thesis we first give an introduction to the basic aspects of quantum computation followed by an analysis of networks of quantum logic gates where the qubit lines are loops (cyclic). Thus far, investigations into cyclic networks of quantum logic gates have not been examined (as far as we know) by the quantum information community. In our investigations of cyclic quantum networks we have studied simple, one and two qubit systems. The analysis includes: classifying networks into groups, the dynamics of the qubits in a cyclic quantum network, and the perturbation effects of an external qubit acting on a cyclic quantum network. The analysis will be followed by a discussion on quantum algorithms and quantum information processing with cyclic quantum networks, a novel implementation of a cyclic network quantum memory and a discussion of quantum sensors via cyclic quantum networks.

  18. Paraganglioma causing a myocardial infarction

    PubMed Central

    DeMers, Gerard; Portouw, Steve

    2012-01-01

    Paragangliomas, extra-adrenal pheochromocytomas, are rare and classically associated with sustained or paroxysmal hypertension, headache, perspiration, palpitations, and anxiety. A 49-year-old male, parachute instructor, likely developed a hypertensive emergency when deploying his parachute leading to a myocardial infarction. A para-aortic tumor was incidentally discovered during the patient's emergency department work-up and was eventually surgically resected. He had no evidence of coronary disease during his evaluation. This case shows that a myocardial infarction may be the initial manifestation of these neuroendocrine tumors. Hypertensive emergency, much less elevated blood pressure may not be present at time of presentation. PMID:22787353

  19. Improved Flux-Gate Magnetometer

    NASA Technical Reports Server (NTRS)

    Garner, H. Douglas

    1987-01-01

    Simplified circuit drives heading indicator and senses magnetic field of Earth. Simple flux-gate magnetometer supplies digital readout of magnetic heading of vehicle, developed to drive heading indicator, or supply heading information to autopilot or to other navigational instruments. Important feature is core driven into saturation in one direction only by alternating drive voltage, which swings from zero to one polarity and back. Made in part of commercially available integrated circuits.

  20. Gated high speed optical detector

    NASA Technical Reports Server (NTRS)

    Green, S. I.; Carson, L. M.; Neal, G. W.

    1973-01-01

    The design, fabrication, and test of two gated, high speed optical detectors for use in high speed digital laser communication links are discussed. The optical detectors used a dynamic crossed field photomultiplier and electronics including dc bias and RF drive circuits, automatic remote synchronization circuits, automatic gain control circuits, and threshold detection circuits. The equipment is used to detect binary encoded signals from a mode locked neodynium laser.

  1. Voltage-gated Proton Channels

    PubMed Central

    DeCoursey, Thomas E.

    2014-01-01

    Voltage-gated proton channels, HV1, have vaulted from the realm of the esoteric into the forefront of a central question facing ion channel biophysicists, namely the mechanism by which voltage-dependent gating occurs. This transformation is the result of several factors. Identification of the gene in 2006 revealed that proton channels are homologues of the voltage-sensing domain of most other voltage-gated ion channels. Unique, or at least eccentric, properties of proton channels include dimeric architecture with dual conduction pathways, perfect proton selectivity, a single-channel conductance ~103 smaller than most ion channels, voltage-dependent gating that is strongly modulated by the pH gradient, ΔpH, and potent inhibition by Zn2+ (in many species) but an absence of other potent inhibitors. The recent identification of HV1 in three unicellular marine plankton species has dramatically expanded the phylogenetic family tree. Interest in proton channels in their own right has increased as important physiological roles have been identified in many cells. Proton channels trigger the bioluminescent flash of dinoflagellates, facilitate calcification by coccolithophores, regulate pH-dependent processes in eggs and sperm during fertilization, secrete acid to control the pH of airway fluids, facilitate histamine secretion by basophils, and play a signaling role in facilitating B-cell receptor mediated responses in B lymphocytes. The most elaborate and best-established functions occur in phagocytes, where proton channels optimize the activity of NADPH oxidase, an important producer of reactive oxygen species. Proton efflux mediated by HV1 balances the charge translocated across the membrane by electrons through NADPH oxidase, minimizes changes in cytoplasmic and phagosomal pH, limits osmotic swelling of the phagosome, and provides substrate H+ for the production of H2O2 and HOCl, reactive oxygen species crucial to killing pathogens. PMID:23798303

  2. Modes of glutamate receptor gating

    PubMed Central

    Popescu, Gabriela K

    2012-01-01

    Abstract The time course of excitatory synaptic currents, the major means of fast communication between neurons of the central nervous system, is encoded in the dynamic behaviour of post-synaptic glutamate-activated channels. First-pass attempts to explain the glutamate-elicited currents with mathematical models produced reaction mechanisms that included only the most basic functionally defined states: resting vs. liganded, closed vs. open, responsive vs. desensitized. In contrast, single-molecule observations afforded by the patch-clamp technique revealed an unanticipated kinetic multiplicity of transitions: from microseconds-lasting flickers to minutes-long modes. How these kinetically defined events impact the shape of the synaptic response, how they relate to rearrangements in receptor structure, and whether and how they are physiologically controlled represent currently active research directions. Modal gating, which refers to the slowest, least frequently observed ion-channel transitions, has been demonstrated for representatives of all ion channel families. However, reaction schemes have been largely confined to the short- and medium-range time scales. For glutamate receptors as well, modal gating has only recently come under rigorous scrutiny. This article reviews the evidence for modal gating of glutamate receptors and the still developing hypotheses about the mechanism(s) by which modal shifts occur and the ways in which they may impact the time course of synaptic transmission. PMID:22106181

  3. Thallium-201 myocardial scintigraphy in acute myocardial infarction and ischemia

    SciTech Connect

    Wackers, F.J.

    1982-04-01

    Thallium-201 scintigraphy provides a sensitive and reliable method of detecting acute myocardial infarction and ischemia when imaging is performed with understanding of the temporal characteristics and accuracy of the technique. The results of scintigraphy are related to the time interval between onset of symptoms and time of imaging. During the first 6 hr after chest pain almost all patients with acute myocardial infarction and approximately 50% of the patients with unstable angina will demonstrate /sup 201/TI pefusion defects. Delayed imaging at 2-4 hr will permit distinction between ischemia and infarction. In patients with acute myocardial infarction, the size of the perfusion defect accurately reflects the extent of the infarcted and/or jeopardized myocardium, which may be used for prognostic stratification. In view of the characteristics of /sup 201/TI scintigraphy, the most practical application of this technique is in patients in whom myocardial infarction has to be ruled out, and for early recognition of patients at high risk for complications.

  4. Myocardial Perfusion SPECT 2015 in Germany

    PubMed Central

    Burchert, Wolfgang; Schäfer, Wolfgang; Hacker, Marcus

    2016-01-01

    Summary Aim The working group Cardiovascular Nuclear Medicine of the German Society of Nuclear Medicine presents the results of the 7th survey of myocardial perfusion SPECT (MPS) of the reporting year 2015. Method 268 questionnaires (173 practices [PR], 67 hospitals [HO], 28 university hospitals [UH]) were evaluated. Results of the last survey from 2012 are set in squared brackets. Results MPS of 121 939 [105 941] patients were reported. 98 % [95 %] of all MPS were performed with Tc-99m radiopharmaceuticals and 2 % [5 %] with Tl-201. 78 % [79 %] of all patients were studied in PR, 14 % [15 %] in HO, and 8 % [6 %] in UH. A pharmacological stress test was performed in 43 % [39 %] (22 % [24 %] adenosine, 20 % [9 %] regadenoson, 1% [6 %] dipyridamole or dobutamine). Attenuation correction was applied in 25 % [2009: 10 %] of MPS. Gated SPECT was performed in 78 % [70 %] of all rest MPS, in 80 % [73 %] of all stress and in 76 % [67 %] of all stress and rest MPS. 53 % [33 %] of all nuclear medicine departments performed MPS scoring by default, whereas 24 % [41 %] did not apply any quantification. 31 % [26 %] of all departments noticed an increase in their counted MPS and 29 % [29 %] no changes. Data from 89 departments which participated in all surveys showed an increase in MPS count of 11.1 % (PR: 12.2 %, HO: 4.8 %, UH: 18.4 %). 70 % [60 %] of the MPS were requested by ambulatory care cardiologists. Conclusion The 2015 MPS survey reveals a high-grade adherence of routine MPS practice to current guidelines. The positive trend in MPS performance and number of MPS already observed in 2012 continues. Educational training remains necessary in the field of SPECT scoring. PMID:27909712

  5. Monolithic transistor gate energy recovery system

    NASA Technical Reports Server (NTRS)

    Rippel, Wally E. (Inventor)

    1989-01-01

    Energy is recovered from an insulated gate semiconductor switch, such as a MOSFET, that is otherwise lost in the gate capacitance by producing a notch in the gate control voltage for an interval B following an interval A after initial application of a gate control voltage pulse for turning the switch on, and a notch for an interval C following termination of the gate control voltage pulse followed by interval D during which the switch is turned on again, where each interval is a period .DELTA.T given by ##EQU1## L.sub.s is the inductance (discrete and/or parasitic) in series with the gate electrode of the insulated gate semiconductor switch, and C.sub.in is the capacitance of that switch between its gate and source electrodes. The interval .DELTA.T may be provided directly by timing in a pulse forming circuit for the gate control voltage applied, or adaptively by sensing the gate voltage v.sub.g and comparing it with fixed progressively higher voltages v.sub.1, v.sub.2 and v.sub.3, where v.sub.2 is intermediate v.sub.1 and v.sub.3 which correspond to the lower and upper levels of v.sub.g as the switch is turned off and on.

  6. Efficient Z gates for quantum computing

    NASA Astrophysics Data System (ADS)

    McKay, David C.; Wood, Christopher J.; Sheldon, Sarah; Chow, Jerry M.; Gambetta, Jay M.

    2017-08-01

    For superconducting qubits, microwave pulses drive rotations around the Bloch sphere. The phase of these drives can be used to generate zero-duration arbitrary virtual Z gates, which, combined with two Xπ /2 gates, can generate any SU(2) gate. Here we show how to best utilize these virtual Z gates to both improve algorithms and correct pulse errors. We perform randomized benchmarking using a Clifford set of Hadamard and Z gates and show that the error per Clifford is reduced versus a set consisting of standard finite-duration X and Y gates. Z gates can correct unitary rotation errors for weakly anharmonic qubits as an alternative to pulse-shaping techniques such as derivative removal by adiabatic gate (DRAG). We investigate leakage and show that a combination of DRAG pulse shaping to minimize leakage and Z gates to correct rotation errors realizes a 13.3 ns Xπ /2 gate characterized by low error [1.95 (3 ) ×10-4] and low leakage [3.1 (6 ) ×10-6] . Ultimately leakage is limited by the finite temperature of the qubit, but this limit is two orders of magnitude smaller than pulse errors due to decoherence.

  7. Gating of two pore domain potassium channels

    PubMed Central

    Mathie, Alistair; Al-Moubarak, Ehab; Veale, Emma L

    2010-01-01

    Two-pore-domain potassium (K2P) channels are responsible for background leak currents which regulate the membrane potential and excitability of many cell types. Their activity is modulated by a variety of chemical and physical stimuli which act to increase or decrease the open probability of individual K2P channels. Crystallographic data and homology modelling suggest that all K+ channels possess a highly conserved structure for ion selectivity and gating mechanisms. Like other K+ channels, K2P channels are thought to have two primary conserved gating mechanisms: an inactivation (or C-type) gate at the selectivity filter close to the extracellular side of the channel and an activation gate at the intracellular entrance to the channel involving key, identified, hinge glycine residues. Zinc and hydrogen ions regulate Drosophila KCNK0 and mammalian TASK channels, respectively, by interacting with the inactivation gate of these channels. In contrast, the voltage dependence of TASK3 channels is mediated through its activation gate. For KCNK0 it has been shown that the gates display positive cooperativity. It is of much interest to determine whether other K2P regulatory compounds interact with either the activation gate or the inactivation gate to alter channel activity or, indeed, whether additional regulatory gating pathways exist. PMID:20566661

  8. Gating of two pore domain potassium channels.

    PubMed

    Mathie, Alistair; Al-Moubarak, Ehab; Veale, Emma L

    2010-09-01

    Two-pore-domain potassium (K2P) channels are responsible for background leak currents which regulate the membrane potential and excitability of many cell types. Their activity is modulated by a variety of chemical and physical stimuli which act to increase or decrease the open probability of individual K2P channels. Crystallographic data and homology modelling suggest that all K(+) channels possess a highly conserved structure for ion selectivity and gating mechanisms. Like other K(+) channels, K2P channels are thought to have two primary conserved gating mechanisms: an inactivation (or C-type) gate at the selectivity filter close to the extracellular side of the channel and an activation gate at the intracellular entrance to the channel involving key, identified, hinge glycine residues. Zinc and hydrogen ions regulate Drosophila KCNK0 and mammalian TASK channels, respectively, by interacting with the inactivation gate of these channels. In contrast, the voltage dependence of TASK3 channels is mediated through its activation gate. For KCNK0 it has been shown that the gates display positive cooperativity. It is of much interest to determine whether other K2P regulatory compounds interact with either the activation gate or the inactivation gate to alter channel activity or, indeed, whether additional regulatory gating pathways exist.

  9. Investigation of myocardial stunning after cardiopulmonary resuscitation in pigs.

    PubMed

    Yang, Lin; Li, ChunSheng; Gao, ChunJin; Wang, Shuo; Ji, XianFei; Su, ZhiYu

    2011-04-01

    To investigate cardiac function and myocardial perfusion during 48 h after cardiopulmonary resuscitation (CPR), further to test myocardial stunning and seek indicators for long-term survival after CPR. After 4 min of untreated ventricular fibrillation, fifteen anesthetized pigs were studied at baseline and 2 h, 4 h, 24 h, and 48 h after restoration of spontaneous circulation (ROSC). Hemodynamic data, echocardiography and gated-single photon emission computed tomography myocardial perfusion images were carried out. Mean arterial pressure (MAP), coronary perfusion pressure (CPP) and cardiac troponin I (CTNI) showed significant differences between eventual survival animals and non-survival animals at 4 h after ROSC (109.2 ± 10.7 mmHg vs. 94.8 ± 12.3 mmHg, P=0.048; 100.8 ± 6.9 mmHg vs. 84.4±12.6 mmHg, P=0.011; 1.60 ± 0.13 ug/L vs. 1.75 ± 0.10 ug/L, P=0.046). Mitral valve early-to-late diastolic peak velocity ratio, mitral valve deceleration time recovered 24 h; ejection faction and the summed rest score recovered 48 h after ROSC. Cardiac systolic and early active relaxation dysfunctions were reversible within survival animals; cardiac stunning might be potentially adaptive and protective after CPR. The recovery of MAP, CPP, and CTNI could be the indicators for long-term survival after CPR. Copyright © 2011 The Editorial Board of Biomedical and Environmental Sciences. Published by Elsevier B.V. All rights reserved.

  10. Spousal Adjustment to Myocardial Infarction.

    ERIC Educational Resources Information Center

    Ziglar, Elisa J.

    This paper reviews the literature on the stresses and coping strategies of spouses of patients with myocardial infarction (MI). It attempts to identify specific problem areas of adjustment for the spouse and to explore the effects of spousal adjustment on patient recovery. Chapter one provides an overview of the importance in examining the…

  11. Myocardial revascularization in Jehovah Witnesses.

    PubMed

    Seifert, P E; Auer, J E; Hohensee, P

    1989-04-01

    The refusal of certain patients to accept blood transfusions need not be a deterrent to surgery. We report on nine Jehovah's Witnesses who over a one-year period underwent myocardial revascularization without significant blood loss or decrease in hematocrit values.

  12. Imaging techniques for myocardial inflammation

    SciTech Connect

    O'Connell, J.B.; Henkin, R.E.; Robinson, J.A.

    1986-03-01

    Dilated cardiomyopathy (DC) represents a heterogeneous group of disorders which results in morbidity and mortality in young individuals. Recent evidence suggests that a subset of these patients have histologic evidence of myocarditis which is potentially treatable with immunosuppression. The identification of myocardial inflammation may therefore lead to development of therapeutic regimens designed to treat the cause rather than the effect of the myocardial disease. Ultimately, this may result in improvement in the abysmal prognosis of DC. The currently accepted technique for identification of active myocardial inflammation is endomyocardial biopsy. This technique is not perfect, however, since pathologic standards for the diagnosis of myocarditis have not been established. Furthermore, focal inflammation may give rise to sampling error. The inflammation-avid radioisotope gallium-67 citrate has been used as an adjunct to biopsy improving the yield of myocarditis from 7 percent to 36 percent. Serial imaging correlates well to biopsy results. Future studies are designed to study the applicability of lymphocyte labelling techniques to myocardial inflammatory disease.

  13. Severe Hypokalemia Masquerading Myocardial Ischemia

    PubMed Central

    Petrov, Daniel Bogdanov; Sardovski, Svetlozar Ivanov; Milanova, Maria Hristova

    2012-01-01

    An advanced degree of body potassium deficit may produce striking changes in the electrocardiogram (ECG). These changes can result in incidental findings on the 12-lead ECG or precipitate potentially life-threatening dysrhythmias. Although usually readily recognized, at times these abnormalities may be confused with myocardial ischemia. The object was to report a case of severe hypokalemia mimicking myocardial ischemia. A 33-year-old, previously healthy man, presented to the Emergency Department (ED) with a progressive weakness and chest discomfort. The electrocardiogram showed a marked ST-segment depression in leads II, III, aVF, V1-V6. The initial diagnosis was non ST-elevation myocardial infarction. Echocardiography was normal and troponin levels were within normal limits. A more detailed history revealed that the patient had an episode of acute gastroenteritis with diarrhea and vomiting. Serum chemistries were notable for a potassium concentration of 1,8 mmol per liter. With aggressive electrolyte correction, the ECG abnormalities reverted as potassium levels normalized. Hypokalemia induced ST-segment depression may simulate myocardial ischemia. The differential diagnosis might be difficult, especially in the cases when ST changes are accompanied with chest discomfort.

  14. Hafnium zirconate gate dielectric for advanced gate stack applications

    NASA Astrophysics Data System (ADS)

    Hegde, R. I.; Triyoso, D. H.; Samavedam, S. B.; White, B. E.

    2007-04-01

    We report on the development of a hafnium zirconate (HfZrO4) alloy gate dielectric for advanced gate stack applications. The HfZrO4 and hafnium dioxide (HfO2) films were formed by atomic layer deposition using metal halides and heavy water as precursors. The HfZrO4 material properties were examined and compared with those of HfO2 by a wide variety of analytical methods. The dielectric properties, device performance, and reliability of HfZrO4 were investigated by fabricating HfZrO4/tantalum carbide (TaxCy) metal-oxide-semiconductor field effect transistor. The HfZrO4 dielectric film has smaller band gap, smaller and more uniform grains, less charge traps, and more uniform film quality than HfO2. The HfZrO4 dielectric films exhibited good thermal stability with silicon. Compared to HfO2, the HfZrO4 gate dielectric showed lower capacitance equivalent thickness value, higher transconductance, less charge trapping, higher drive current, lower threshold voltage (Vt), reduced capacitance-voltage (C-V ) hysteresis, lower interface state density, superior wafer level thickness uniformity, and longer positive bias temperature instability lifetime. Incorporation of zirconium dioxide (ZrO2) into HfO2 enhances the dielectric constant (k ) of the resulting HfZrO4 which is associated with structural phase transformation from mainly monoclinic to tetragonal. The tetragonal phase increases the k value of HfZrO4 dielectric to a large value as predicted. The improved device characteristics are attributed to less oxygen vacancy in the fine grained microstructure of HfZrO4 films.

  15. Reversible logic gate using adiabatic superconducting devices

    PubMed Central

    Takeuchi, N.; Yamanashi, Y.; Yoshikawa, N.

    2014-01-01

    Reversible computing has been studied since Rolf Landauer advanced the argument that has come to be known as Landauer's principle. This principle states that there is no minimum energy dissipation for logic operations in reversible computing, because it is not accompanied by reductions in information entropy. However, until now, no practical reversible logic gates have been demonstrated. One of the problems is that reversible logic gates must be built by using extremely energy-efficient logic devices. Another difficulty is that reversible logic gates must be both logically and physically reversible. Here we propose the first practical reversible logic gate using adiabatic superconducting devices and experimentally demonstrate the logical and physical reversibility of the gate. Additionally, we estimate the energy dissipation of the gate, and discuss the minimum energy dissipation required for reversible logic operations. It is expected that the results of this study will enable reversible computing to move from the theoretical stage into practical usage. PMID:25220698

  16. Reversible logic gate using adiabatic superconducting devices

    NASA Astrophysics Data System (ADS)

    Takeuchi, N.; Yamanashi, Y.; Yoshikawa, N.

    2014-09-01

    Reversible computing has been studied since Rolf Landauer advanced the argument that has come to be known as Landauer's principle. This principle states that there is no minimum energy dissipation for logic operations in reversible computing, because it is not accompanied by reductions in information entropy. However, until now, no practical reversible logic gates have been demonstrated. One of the problems is that reversible logic gates must be built by using extremely energy-efficient logic devices. Another difficulty is that reversible logic gates must be both logically and physically reversible. Here we propose the first practical reversible logic gate using adiabatic superconducting devices and experimentally demonstrate the logical and physical reversibility of the gate. Additionally, we estimate the energy dissipation of the gate, and discuss the minimum energy dissipation required for reversible logic operations. It is expected that the results of this study will enable reversible computing to move from the theoretical stage into practical usage.

  17. Reversible logic gate using adiabatic superconducting devices.

    PubMed

    Takeuchi, N; Yamanashi, Y; Yoshikawa, N

    2014-09-15

    Reversible computing has been studied since Rolf Landauer advanced the argument that has come to be known as Landauer's principle. This principle states that there is no minimum energy dissipation for logic operations in reversible computing, because it is not accompanied by reductions in information entropy. However, until now, no practical reversible logic gates have been demonstrated. One of the problems is that reversible logic gates must be built by using extremely energy-efficient logic devices. Another difficulty is that reversible logic gates must be both logically and physically reversible. Here we propose the first practical reversible logic gate using adiabatic superconducting devices and experimentally demonstrate the logical and physical reversibility of the gate. Additionally, we estimate the energy dissipation of the gate, and discuss the minimum energy dissipation required for reversible logic operations. It is expected that the results of this study will enable reversible computing to move from the theoretical stage into practical usage.

  18. A bistable electromagnetically actuated rotary gate microvalve

    NASA Astrophysics Data System (ADS)

    Luharuka, Rajesh; Hesketh, Peter J.

    2008-03-01

    Two types of rotary gate microvalves are developed for flow modulation in microfluidic systems. These microvalves have been tested for an open flow rate of up to 100 sccm and operate under a differential pressure of 6 psig with flow modulation of up to 100. The microvalve consists of a suspended gate that rotates in the plane of the chip to regulate flow through the orifice. The gate is suspended by a novel fully compliant in-plane rotary bistable micromechanism (IPRBM) that advantageously constrains the gate in all degrees of freedom except for in-plane rotational motion. Multiple inlet/outlet orifices provide flexibility of operating the microvalve in three different flow configurations. The rotary gate microvalve is switched with an external electromagnetic actuator. The suspended gate is made of a soft magnetic material and its electromagnetic actuation is based on the operating principle of a variable-reluctance stepper motor.

  19. Experimental superposition of orders of quantum gates

    PubMed Central

    Procopio, Lorenzo M.; Moqanaki, Amir; Araújo, Mateus; Costa, Fabio; Alonso Calafell, Irati; Dowd, Emma G.; Hamel, Deny R.; Rozema, Lee A.; Brukner, Časlav; Walther, Philip

    2015-01-01

    Quantum computers achieve a speed-up by placing quantum bits (qubits) in superpositions of different states. However, it has recently been appreciated that quantum mechanics also allows one to ‘superimpose different operations'. Furthermore, it has been shown that using a qubit to coherently control the gate order allows one to accomplish a task—determining if two gates commute or anti-commute—with fewer gate uses than any known quantum algorithm. Here we experimentally demonstrate this advantage, in a photonic context, using a second qubit to control the order in which two gates are applied to a first qubit. We create the required superposition of gate orders by using additional degrees of freedom of the photons encoding our qubits. The new resource we exploit can be interpreted as a superposition of causal orders, and could allow quantum algorithms to be implemented with an efficiency unlikely to be achieved on a fixed-gate-order quantum computer. PMID:26250107

  20. Experimental superposition of orders of quantum gates.

    PubMed

    Procopio, Lorenzo M; Moqanaki, Amir; Araújo, Mateus; Costa, Fabio; Alonso Calafell, Irati; Dowd, Emma G; Hamel, Deny R; Rozema, Lee A; Brukner, Časlav; Walther, Philip

    2015-08-07

    Quantum computers achieve a speed-up by placing quantum bits (qubits) in superpositions of different states. However, it has recently been appreciated that quantum mechanics also allows one to 'superimpose different operations'. Furthermore, it has been shown that using a qubit to coherently control the gate order allows one to accomplish a task--determining if two gates commute or anti-commute--with fewer gate uses than any known quantum algorithm. Here we experimentally demonstrate this advantage, in a photonic context, using a second qubit to control the order in which two gates are applied to a first qubit. We create the required superposition of gate orders by using additional degrees of freedom of the photons encoding our qubits. The new resource we exploit can be interpreted as a superposition of causal orders, and could allow quantum algorithms to be implemented with an efficiency unlikely to be achieved on a fixed-gate-order quantum computer.

  1. Contact gating at GHz frequency in graphene

    PubMed Central

    Wilmart, Q.; Inhofer, A.; Boukhicha, M.; Yang, W.; Rosticher, M.; Morfin, P.; Garroum, N.; Fève, G.; Berroir, J.-M.; Plaçais, B.

    2016-01-01

    The paradigm of graphene transistors is based on the gate modulation of the channel carrier density by means of a local channel gate. This standard architecture is subject to the scaling limit of the channel length and further restrictions due to access and contact resistances impeding the device performance. We propose a novel design, overcoming these issues by implementing additional local gates underneath the contact region which allow a full control of the Klein barrier taking place at the contact edge. In particular, our work demonstrates the GHz operation of transistors driven by independent contact gates. We benchmark the standard channel and novel contact gating and report for the later dynamical transconductance levels at the state of the art. Our finding may find applications in electronics and optoelectronics whenever there is need to control independently the Fermi level and the electrostatic potential of electronic sources or to get rid of cumbersome local channel gates. PMID:26879709

  2. System and Method for Scan Range Gating

    NASA Technical Reports Server (NTRS)

    Zuk, David M. (Inventor); Lindemann, Scott (Inventor)

    2017-01-01

    A system for scanning light to define a range gated signal includes a pulsed coherent light source that directs light into the atmosphere, a light gathering instrument that receives the light modified by atmospheric backscatter and transfers the light onto an image plane, a scanner that scans collimated light from the image plane to form a range gated signal from the light modified by atmospheric backscatter, a control circuit that coordinates timing of a scan rate of the scanner and a pulse rate of the pulsed coherent light source so that the range gated signal is formed according to a desired range gate, an optical device onto which an image of the range gated signal is scanned, and an interferometer to which the image of the range gated signal is directed by the optical device. The interferometer is configured to modify the image according to a desired analysis.

  3. Cognitive mechanisms associated with auditory sensory gating.

    PubMed

    Jones, L A; Hills, P J; Dick, K M; Jones, S P; Bright, P

    2016-02-01

    Sensory gating is a neurophysiological measure of inhibition that is characterised by a reduction in the P50 event-related potential to a repeated identical stimulus. The objective of this work was to determine the cognitive mechanisms that relate to the neurological phenomenon of auditory sensory gating. Sixty participants underwent a battery of 10 cognitive tasks, including qualitatively different measures of attentional inhibition, working memory, and fluid intelligence. Participants additionally completed a paired-stimulus paradigm as a measure of auditory sensory gating. A correlational analysis revealed that several tasks correlated significantly with sensory gating. However once fluid intelligence and working memory were accounted for, only a measure of latent inhibition and accuracy scores on the continuous performance task showed significant sensitivity to sensory gating. We conclude that sensory gating reflects the identification of goal-irrelevant information at the encoding (input) stage and the subsequent ability to selectively attend to goal-relevant information based on that previous identification.

  4. Contact gating at GHz frequency in graphene.

    PubMed

    Wilmart, Q; Inhofer, A; Boukhicha, M; Yang, W; Rosticher, M; Morfin, P; Garroum, N; Fève, G; Berroir, J-M; Plaçais, B

    2016-02-16

    The paradigm of graphene transistors is based on the gate modulation of the channel carrier density by means of a local channel gate. This standard architecture is subject to the scaling limit of the channel length and further restrictions due to access and contact resistances impeding the device performance. We propose a novel design, overcoming these issues by implementing additional local gates underneath the contact region which allow a full control of the Klein barrier taking place at the contact edge. In particular, our work demonstrates the GHz operation of transistors driven by independent contact gates. We benchmark the standard channel and novel contact gating and report for the later dynamical transconductance levels at the state of the art. Our finding may find applications in electronics and optoelectronics whenever there is need to control independently the Fermi level and the electrostatic potential of electronic sources or to get rid of cumbersome local channel gates.

  5. Cognitive mechanisms associated with auditory sensory gating

    PubMed Central

    Jones, L.A.; Hills, P.J.; Dick, K.M.; Jones, S.P.; Bright, P.

    2016-01-01

    Sensory gating is a neurophysiological measure of inhibition that is characterised by a reduction in the P50 event-related potential to a repeated identical stimulus. The objective of this work was to determine the cognitive mechanisms that relate to the neurological phenomenon of auditory sensory gating. Sixty participants underwent a battery of 10 cognitive tasks, including qualitatively different measures of attentional inhibition, working memory, and fluid intelligence. Participants additionally completed a paired-stimulus paradigm as a measure of auditory sensory gating. A correlational analysis revealed that several tasks correlated significantly with sensory gating. However once fluid intelligence and working memory were accounted for, only a measure of latent inhibition and accuracy scores on the continuous performance task showed significant sensitivity to sensory gating. We conclude that sensory gating reflects the identification of goal-irrelevant information at the encoding (input) stage and the subsequent ability to selectively attend to goal-relevant information based on that previous identification. PMID:26716891

  6. Myocardial protection in heart surgery.

    PubMed

    Mentzer, Robert M

    2011-01-01

    One of the unmet clinical needs in heart surgery is the prevention of myocardial stunning and necrosis that occurs as a result of ischemia-reperfusion. Myocardial stunning, a frequent consequence after heart surgery, is characterized by a requirement for postoperative inotropic support despite a technically satisfactory heart operation. In high-risk patients with marginal cardiac reserve, stunning is a major cause of prolonged critical care and may be associated with as much as a 5-fold increase in mortality. In contrast, the frequency of myocardial necrosis (myocardial infarction [MI]) after cardiac surgery is less appreciated and its consequences are much more subtle. The consequences may not be apparent for months to years. While we now have a much better understanding of the molecular mechanisms underlying myocardial stunning and MI, we still have no effective way to prevent these complications, nor a consistently effective means to engage the well-studied endogenous mechanisms of cardioprotection. The failure to develop clinically effective interventions is multifactorial and can be attributed to reliance on findings obtained from subcellular and cellular studies, to drawing conclusions from preclinical large animal studies that have been conducted in a disease-free state, and to accepting less than robust surrogate markers of injury in phase II clinical trials. These factors also explain the disappointing failure to identify effective adjuvant therapy in the setting of percutaneous coronary revascularization for acute MI (AMI) and reperfusion injury. These issues have contributed to the disappointing outcomes of large and costly phase III trials, resulting in a lack of enthusiasm on the part of the pharmaceutical industry to engage in further drug development for this indication. The purpose of this review is to (1) define the scope of the clinical problem; (2) summarize the outcomes of selected phases II and III clinical trials; and (3) identify the gap that

  7. Myocardial disarray. A critical review.

    PubMed Central

    Becker, A E; Caruso, G

    1982-01-01

    Myocardial disarray or disorganisation is at present a contentious topic, not least because its value as a clinical marker for hypertrophic cardiomyopathy has changed considerably over the years. Initially observed as one of the features of asymmetric septal hypertrophy, disarray has since been promoted as its pathognomonic histological feature, regarded by some observers as the morphological manifestation of a genetically transmitted myocardial defect. Recently, however, it has become evident that myocardial disarray is not limited to hypertrophic cardiomyopathy, but is encountered in hearts with both congenital and acquired conditions, and is also observed in normal hearts. The specificity of disarray for hypertrophic cardiomyopathy is thus seriously questioned. Latterly, it has been suggested that disarray, judged from through-and-through sections of the ventricular midseptum is a highly specific and sensitive marker of hypertrophic cardiomyopathy when considered in quantitative rather than qualitative fashion. The present study sets out to answer the question whether disarray could be the histological expression of the normal but intricate fibre architecture of the heart, a consideration also initiated by debatable definitions of normality and abnormality of myocardial histology. Gross fibre dissections in five normal hearts showed that many sites occurred in which disarray was a natural phenomenon. In five more hearts it was found that the plane of section of a tissue block might profoundly influence the histology. In fact, tissue cubicles sampled from different faces showed a change in histology in the vast majority. Thus the diagnostic significance of myocardial disarray as a marker of hypertrophic cardiomyopathy in the clinical setting almost vanishes; a change in orientation of a tissue section may actually turn "normality" into "disarray". Images PMID:7044398

  8. Positron Emission Tomography for the Assessment of Myocardial Viability

    PubMed Central

    2010-01-01

    , harmonic imaging, and power doppler imaging may help to improve the diagnostic accuracy of echocardiographic assessment of myocardial viability. Stress Echocardiography with Contrast Intravenous contrast agents, which are high molecular weight inert gas microbubbles that act like red blood cells in the vascular space, can be used during echocardiography to assess myocardial viability. These agents allow for the assessment of myocardial blood flow (perfusion) and contractile function (as described above), as well as the simultaneous assessment of perfusion to make it possible to distinguish between stunned and hibernating myocardium. SPECT SPECT can be performed using thallium-201 (Tl-201), a potassium analogue, or technetium-99 m labelled tracers. When Tl-201 is injected intravenously into a patient, it is taken up by the myocardial cells through regional perfusion, and Tl-201 is retained in the cell due to sodium/potassium ATPase pumps in the myocyte membrane. The stress-redistribution-reinjection protocol involves three sets of images. The first two image sets (taken immediately after stress and then three to four hours after stress) identify perfusion defects that may represent scar tissue or viable tissue that is severely hypoperfused. The third set of images is taken a few minutes after the re-injection of Tl-201 and after the second set of images is completed. These re-injection images identify viable tissue if the defects exhibit significant fill-in (> 10% increase in tracer uptake) on the re-injection images. The other common Tl-201 viability imaging protocol, rest-redistribution, involves SPECT imaging performed at rest five minutes after Tl-201 is injected and again three to four hours later. Viable tissue is identified if the delayed images exhibit significant fill-in of defects identified in the initial scans (> 10% increase in uptake) or if defects are fixed but the tracer activity is greater than 50%. There are two technetium-99 m tracers: sestamibi (MIBI

  9. Criteria for universality of quantum gates

    NASA Astrophysics Data System (ADS)

    Sawicki, Adam; Karnas, Katarzyna

    2017-06-01

    We consider the problem of deciding if a set of quantum one-qudit gates S ={U1,...,Un} is universal. We provide the compact-form criteria leading to a simple algorithm that allows deciding the universality of any given set of gates in a finite number of steps. Moreover, for a nonuniversal S our criteria indicate what types of gates can be added to S to turn it into a universal set.

  10. Floating gate transistors as biosensors (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Frisbie, C. Daniel

    2016-11-01

    Electrolyte gated transistors (EGTs) are a sub-class of thin film transistors that are extremely promising for biological sensing applications. These devices employ a solid electrolyte as the gate insulator; the very large capacitance of the electrolyte results in low voltage operation and high transconductance or gain. This talk will describe the fabrication of floating gate EGTs and their use as ricin sensors. The critical performance metrics for EGTs compared with other types of TFTs will also be reviewed.

  11. Comparison of radionuclide and enzymatic estimate of infarct size in patients with acute myocardial infarction

    SciTech Connect

    Hirsowitz, G.S.; Lakier, J.B.; Marks, D.S.; Lee, T.G.; Goldberg, A.D.; Goldstein, S.

    1983-06-01

    A comparison was made of the estimated size of the myocardial infarction occurring in 26 patients with a first infarction using creatine kinase (CK) enzyme release between radionuclide gated blood pool measurement of total and regional ventricular function and thallium-201 scintigraphic measurement of myocardial perfusion defects. Creatine kinase estimates of infarct size (enzymatic infarct size) correlated closely with the percent of abnormal contracting regions, left ventricular ejection fraction and thallium-201 estimates of percent of abnormal perfusion area (r . 0.78, 0.69 and 0.74, respectively, p less than 0.01). A close correlation also existed between percent abnormal perfusion area and percent of abnormal contracting regions (r . 0.81, p less than 0.01) and left ventricular ejection fraction (r . 0.69, p less than 0.01). Enzymatic infarct size was larger in anterior (116 +/- 37 CK-g-Eq) than inferior (52 +/- 29 CK-g-Eq) myocardial infarction (p less than 0.01) and was associated with significantly more left ventricular functional impairment as determined by left ventricular ejection fraction (33 +/- 7 versus 60 +/- 10%) (p less than 0.01) and percent abnormal perfusion area (58 +/- 14 versus 13 +/- 12) (p less than 0.01). No significant correlation was observed between enzymatic infarct size and right ventricular ejection fraction. These different methods of estimating infarct size correlated closely with each other in these patients with a first uncomplicated myocardial infarction.

  12. The Effectiveness of Non-ECG-Gated Contrast-Enhanced Computed Tomography for the Diagnosis of Non-ST Segment Elevation Acute Coronary Syndrome.

    PubMed

    Watanabe, Tomomi; Furuse, Yoshiyuki; Ohta, Yasutoshi; Kato, Masahiko; Ogawa, Toshihide; Yamamoto, Kazuhiro

    2016-09-28

    Non-ST segment elevation acute coronary syndrome (NSTE-ACS) can be difficult to diagnose accurately, especially in the hyper-acute phase. Non-ECG-gated contrast-enhanced computed tomography (non-ECG-gated CE-CT) has been used in many institutions for screening acute chest pain. Although early defects (EDs) observed in non-ECG-gated CE-CT have been reported as a sign of acute myocardial ischemia, the precise diagnostic value of this sign for acute coronary syndrome has not been fully elucidated. We investigated the usefulness of non-ECG-gated CE-CT for the diagnosis of NSTE-ACS. We retrospectively reviewed 556 patients who were hospitalized for acute-onset chest pain and who underwent emergent coronary angiography. Non-ECG-gated CE-CT was performed in 23 of these patients. Two readers independently analyzed CT images using a 5-point scale. Of the 23 patients, 13 were diagnosed with NSTE-ACS. The remaining 10 patients were diagnosed with other conditions. The sensitivity, specificity, positive predictive value, and negative predictive value, respectively, of EDs on non-ECG-gated CE-CT to detect NSTE-ACS were 84.6%, 90%, 91.7%, and 81.8%. The identification of EDs was consistent between the two readers. Non-ECG-gated CE-CT may be useful not only to triage patients with chest pain by ruling out other conditions, but also to accurately diagnose NSTE-ACS.

  13. Gate engineered performance of single molecular transistor

    NASA Astrophysics Data System (ADS)

    Ray, S. J.

    2016-05-01

    The operation, performance and electrostatics of multigated Single Molecular Transistor (SMT) devices are investigated using first-principles based density functional theory calculations for planar (pentacene) and non-planar (sucrose) molecules as islands. It has been found that the incorporation of larger numbers of gates allows enhanced electrostatic control in the SMT operation which has been quantified from the energy calculations and estimation of the gate capacitances. The effect of multiple gates is more dominant for a non-planar molecule than a planar molecule within an SMT which indicates the usefulness of such multi-gate architectures for future nanoelectronic devices.

  14. Realization of quantum gates by Lyapunov control

    NASA Astrophysics Data System (ADS)

    Hou, S. C.; Wang, L. C.; Yi, X. X.

    2014-02-01

    We propose a Lyapunov control design to achieve specific (or a family of) unitary time-evolution operators, i.e., quantum gates in the Schrödinger picture by tracking control. Two examples are presented. In the first, we illustrate how to realize the Hadamard gate in a single-qubit system, while in the second, the controlled-NOT (CNOT) gate is implemented in two-qubit systems with the Ising and Heisenberg interactions. Furthermore, we demonstrate that the control can drive the time-evolution operator into the local equivalence class of the CNOT gate and the operator keeps in this class forever with the existence of Ising coupling.

  15. Four Great Gates: Dilemmas, Directions and Distractions in Educational Research

    ERIC Educational Resources Information Center

    Delamont, Sara

    2005-01-01

    In James Elroy Flecker's poem "The Gates of Damascus", the poet imagines four exits from the safe comfortable city to the outside world. Each gate takes the traveller into a different set of temptations and dangers. The Aleppo Gate leads to trade and commerce, the Mecca Gate is for faith and pilgrimage, the Lebanon Gate is for exploration and the…

  16. Gating, enhanced gating, and beyond: information utilization strategies for motion management, applied to preclinical PET

    PubMed Central

    2013-01-01

    Background Respiratory gating and gate optimization strategies present solutions for overcoming image degradation caused by respiratory motion in PET and traditionally utilize hardware systems and/or employ complex processing algorithms. In this work, we aimed to advance recently emerging data-driven gating methods and introduce a new strategy for optimizing the four-dimensional data based on information contained in that data. These algorithms are combined to form an automated motion correction workflow. Methods Software-based gating methods were applied to a nonspecific population of 84 small-animal rat PET scans to create respiratory gated images. The gated PET images were then optimized using an algorithm we introduce as ‘gating+’ to reduce noise and optimize signal; the technique was also tested using simulations. Gating+ is based on a principle of only using gated information if and where it adds a net benefit, as evaluated in temporal frequency space. Motion-corrected images were assessed quantitatively and qualitatively. Results Of the small-animal PET scans, 71% exhibited quantifiable motion after software gating. The mean liver displacement was 3.25 mm for gated and 3.04 mm for gating+ images. The (relative) mean percent standard deviations measured in background ROIs were 1.53, 1.05, and 1.00 for the gated, gating+, and ungated values, respectively. Simulations confirmed that gating+ image voxels had a higher probability of being accurate relative to the corresponding ungated values under varying noise and motion scenarios. Additionally, we found motion mapping and phase decoupling models that readily extend from gating+ processing. Conclusions Raw PET data contain information about motion that is not currently utilized. In our work, we showed that through automated processing of standard (ungated) PET acquisitions, (motion-) information-rich images can be constructed with minimal risk of noise introduction. Such methods have the potential for

  17. Picosecond Optoelectronic AND-GATE

    DTIC Science & Technology

    1994-08-01

    SOTA. The bias, gate. and 13 ground probes make contact to their respective bond pads. Fig. 12 Temporal response of the SOTA. 14 Fig. 13 Sheet resistance for...post-annealed, lattice matched LT-GaAs, LT- 18 In0.35GaO. 65 As, LT-In0.53Ga0 .4 7As. The sheet resistance for polycrystalline LT-In0 .35Ga0...65As is also shown. The minimum acceptable values for sheet resistance for detector areas of 50x50 ptm 2 and 8x8 4tm 2 are shown and correspond to a dark

  18. Voltage-Gated Calcium Channels

    NASA Astrophysics Data System (ADS)

    Zamponi, Gerald Werner

    Voltage Gated Calcium Channels is the first comprehensive book in the calcium channel field, encompassing over thirty years of progress towards our understanding of calcium channel structure, function, regulation, physiology, pharmacology, and genetics. This book balances contributions from many of the leading authorities in the calcium channel field with fresh perspectives from risings stars in the area, taking into account the most recent literature and concepts. This is the only all-encompassing calcium channel book currently available, and is an essential resource for academic researchers at all levels in the areas neuroscience, biophysics, and cardiovascular sciences, as well as to researchers in the drug discovery area.

  19. Ribose facilitates thallium-201 redistribution in patients with coronary artery disease

    SciTech Connect

    Perlmutter, N.S.; Wilson, R.A.; Angello, D.A.; Palac, R.T.; Lin, J.; Brown, B.G. )

    1991-02-01

    To investigate whether i.v. infusion of ribose, an adenine nucleotide precursor, postischemia facilitates thallium-201 (201Tl) redistribution and improves identification of ischemic myocardium in patients with coronary artery disease (CAD), 17 patients underwent two exercise 201Tl stress tests, performed 1-2 wk apart. After immediate postexercise planar imaging, patients received either i.v. ribose (3.3 mg/kg/min x 30 min) or saline as a control. Additional imaging was performed 1 and 4 hr postexercise. Reversible defects were identified by count-profile analysis. Significantly more (nearly twice as many) reversible 201Tl defects were identified on the post-ribose images compared to the post-saline (control) images at both 1 and 4 hr postexercise (p less than 0.001). Quantitative analyses of the coronary arteriogram was available in 13 patients and confirmed that the additional reversible defects were in myocardial regions supplied by stenosed arteries. We conclude that ribose appears to facilitate 201Tl redistribution in patients with CAD and enhances identification of ischemic myocardium.

  20. Abnormal thallium 201 scintigraphy during low-dose vasopressin infusions

    SciTech Connect

    Davison, R.; Kaplan, K.; Bines, A.; Spies, S.; Reed, M.T.; Lesch, M.

    1986-12-01

    Thallium 201 (/sup 201/Tl) myocardial scans were obtained in 16 patients just prior to the discontinuation of a vasopressin infusion (.1 to .2 units/min) administered for the treatment of upper gastrointestinal bleeding. Repeat scintigraphy was performed two to three hours after the vasopressin was stopped. Eleven of the 16 patients (69 percent) demonstrated areas of decreased myocardial /sup 201/Tl uptake that resolved after the infusion was stopped. Heart rate-blood pressure product was significantly lower at the time of the second scan. Autopsies were secured in three of 11 scan-positive patients: one had severe coronary artery obstruction, one nonsignificant disease, and another had normal coronary arteries. Vasopressin, even at low doses, can induce abnormalities in myocardial perfusion that are probably mediated by a direct effect on the coronary circulation. They are usually not detectable by routine monitoring techniques and conceivably form the basis for the cardiovascular morbidity associated with the use of this agent.

  1. Stimuli-responsive smart gating membranes.

    PubMed

    Liu, Zhuang; Wang, Wei; Xie, Rui; Ju, Xiao-Jie; Chu, Liang-Yin

    2016-02-07

    Membranes are playing paramount roles in the sustainable development of myriad fields such as energy, environmental and resource management, and human health. However, the unalterable pore size and surface properties of traditional porous membranes restrict their efficient applications. The performances of traditional membranes will be weakened upon unavoidable membrane fouling, and they cannot be applied to cases where self-regulated permeability and selectivity are required. Inspired by natural cell membranes with stimuli-responsive channels, artificial stimuli-responsive smart gating membranes are developed by chemically/physically incorporating stimuli-responsive materials as functional gates into traditional porous membranes, to provide advanced functions and enhanced performances for breaking the bottlenecks of traditional membrane technologies. Smart gating membranes, integrating the advantages of traditional porous membrane substrates and smart functional gates, can self-regulate their permeability and selectivity via the flexible adjustment of pore sizes and surface properties based on the "open/close" switch of the smart gates in response to environmental stimuli. This tutorial review summarizes the recent developments in stimuli-responsive smart gating membranes, including the design strategies and the fabrication strategies that are based on the introduction of the stimuli-responsive gates after or during membrane formation, and the positively and negatively responsive gating models of versatile stimuli-responsive smart gating membranes, as well as the advanced applications of smart gating membranes for regulating substance concentration in reactors, controlling the release rate of drugs, separating active molecules based on size or affinity, and the self-cleaning of membrane surfaces. With self-regulated membrane performances, smart gating membranes show great power for use in global sustainable development.

  2. Hydrophobic Gating in Ion Channels

    PubMed Central

    Aryal, Prafulla; Sansom, Mark S.P.; Tucker, Stephen J.

    2016-01-01

    Biological ion channels are nanoscale transmembrane pores. When water and ions are enclosed within the narrow confines of a sub-nanometer hydrophobic pore, they exhibit behavior not evident from macroscopic descriptions. At this nanoscopic level, the unfavorable interaction between the lining of a hydrophobic pore and water may lead to liquid-vapor oscillations. The resultant transient vapor state is ‘dewetted’ i.e. effectively devoid of water molecules within all, or part of the pore, thus leading to an energetic barrier to ion conduction. This process, termed ‘hydrophobic gating’, was first observed in molecular dynamics simulations of model nanopores, where the principles underlying hydrophobic gating (i.e. changes in diameter, polarity, or transmembrane voltage) have now been extensively validated. Computational, structural and functional studies now indicate that biological ion channels may also exploit hydrophobic gating to regulate ion flow within their pores. Here we review the evidence for this process, and propose that this unusual behavior of water represents an increasingly important element in understanding the relationship between ion channel structure and function. PMID:25106689

  3. 23. DETAIL VIEW OF SUBMERSIBLE TAINTER GATE, SHOWING TRUNNION PIN, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    23. DETAIL VIEW OF SUBMERSIBLE TAINTER GATE, SHOWING TRUNNION PIN, GATE ARM AND GATE GAUGE, LOOKING SOUTHEAST - Upper Mississippi River 9-Foot Channel, Lock & Dam No. 10, Guttenberg, Clayton County, IA

  4. 17. DETAIL VIEW OF TAINTER GATE, SHOWING SUBMERSIBLE (LEFT) AND ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    17. DETAIL VIEW OF TAINTER GATE, SHOWING SUBMERSIBLE (LEFT) AND NONSUBMERSIBLE (RIGHT) GATES, PIERS AND DAM BRIDGE, WITH ROLLER GATE HEADHOUSE IN BACKGROUND, LOOKING NORTHEAST - Upper Mississippi River 9-Foot Channel, Lock & Dam No. 10, Guttenberg, Clayton County, IA

  5. 2. DETAIL OF CONTROL GATE ADJACENT TO LIFT LOCK NO. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    2. DETAIL OF CONTROL GATE ADJACENT TO LIFT LOCK NO. 7; THIS CONTROL GATE IS A 1980s RECONSTRUCTION. - Illinois & Michigan Canal, Lift Lock No. 7 & Control Gate, East side of DuPage River, Channahon, Will County, IL

  6. 17. DETAIL VIEW OF ROLLER GATE (IN RAISED POSITION), SHOWING ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    17. DETAIL VIEW OF ROLLER GATE (IN RAISED POSITION), SHOWING GATE FLANGES, GATE HEATER (LEFT FOREGROUND), ROLLER TRACK, CHAIN AND BRIDGE GIRDER, LOOKING EAST - Upper Mississippi River 9-Foot Channel Project, Lock & Dam No. 3, Red Wing, Goodhue County, MN

  7. Nanosecond gating properties of proximity focused microchannel plate image intensifiers

    NASA Astrophysics Data System (ADS)

    King, N. S. P.; King, N. S. P.; Yates, G. J.; Jaramillo, S. A.; Noel, B. W.; Detch, J. L., Jr.; Ogle, J. W.

    The optical gating properties of Multichannel plate image intensifiers were characterized. Emphasis was placed on parameters relevant to gating speed and correlations between the applied electrical and resultant optical gates.

  8. Terahertz amplification in RTD-gated HEMTs with a grating-gate wave coupling topology

    NASA Astrophysics Data System (ADS)

    Condori Quispe, Hugo O.; Encomendero-Risco, Jimy J.; Xing, Huili Grace; Sensale-Rodriguez, Berardi

    2016-08-01

    We theoretically analyze the operation of a terahertz amplifier consisting of a resonant-tunneling-diode gated high-electron-mobility transistor (RTD-gated HEMT) in a grating-gate topology. In these devices, the key element enabling substantial power gain is the efficient coupling of terahertz waves into and out of plasmons in the RTD-gated HEMT channel, i.e., the gain medium, via the grating-gate itself, part of the active device, rather than by an external antenna structure as discussed in previous works, therefore potentially enabling terahertz amplification with associated power gains >40 dB.

  9. A gate drive circuit for gate-turn-off (GTO) devices in series stack.

    SciTech Connect

    Despe, O.

    1999-04-13

    A gate-turn-off (GTO) switch is under development at the Advanced Photon Source as a replacement for a thyratron switch in high power pulsed application. The high voltage in the application requires multiple GTOs connected in series. One component that is critical to the success of GTO operation is the gate drive circuit. The gate drive circuit has to provide fast high-current pulses to the GTO gate for fast turn-on and turn-off. It also has to be able to operate while floating at high voltage. This paper describes a gate drive circuit that meets these requirements.

  10. Terahertz amplification in RTD-gated HEMTs with a grating-gate wave coupling topology

    SciTech Connect

    Condori Quispe, Hugo O.; Sensale-Rodriguez, Berardi; Encomendero-Risco, Jimy J.; Xing, Huili Grace

    2016-08-08

    We theoretically analyze the operation of a terahertz amplifier consisting of a resonant-tunneling-diode gated high-electron-mobility transistor (RTD-gated HEMT) in a grating-gate topology. In these devices, the key element enabling substantial power gain is the efficient coupling of terahertz waves into and out of plasmons in the RTD-gated HEMT channel, i.e., the gain medium, via the grating-gate itself, part of the active device, rather than by an external antenna structure as discussed in previous works, therefore potentially enabling terahertz amplification with associated power gains >40 dB.

  11. Normal limits for left ventricular ejection fraction and volumes determined by gated single photon emission computed tomography--a comparison between two quantification methods.

    PubMed

    Lomsky, Milan; Johansson, Lena; Gjertsson, Peter; Björk, Jonas; Edenbrandt, Lars

    2008-05-01

    To compare gender-related normal limits for left ventricular (LV) ejection fraction (EF), end-diastolic and end-systolic volumes (EDV and ESV), obtained using two myocardial perfusion-gated single photon emission computed tomography (SPECT) quantification methods. A total of 185 patients were retrospectively selected from a consecutive series of patients examined for coronary artery disease (CAD) or for management of known CAD. Patients were included in the study group if they had normal or probably normal results with stress and rest perfusion imaging and if the combined interpretation of perfusion studies and gated rest studies showed no signs or suspicion of myocardial infarction. The gated SPECT studies were performed using a 2-day stress/gated rest Tc-99m sestamibi protocol. All patient studies were processed using CAFU and quantitative-gated SPECT (QGS), the two software packages for quantification of gated SPECT images. The lower normal limits for EF were higher for CAFU compared with QGS for both women (59% versus 53%) and men (54% versus 47%). The upper normal limits for EDV were also higher for CAFU compared with QGS for both women (133 versus 107 ml) and men (182 versus 161 ml). The differences between the software packages were small for ESV (women 44 versus 44 ml; men 69 versus 74 ml). Gender-specific normal limits need to be applied for LV EF and volumes determined by gated SPECT. Separate criteria for abnormal LV EF and EDV need to be used for women and men depending on the software package used.

  12. Combined rest redistribution thallium-201 SPECT and low-dose dobutamine contractility assessment in a simple and practical new viability protocol.

    PubMed

    Heiba, Sherif I; Yee, Gennie; Abdel-Dayem, Hussein M; Youssef, Irini; Coppola, John

    2009-02-01

    Rest-redistribution (RR) thallium-201 (Tl-201) imaging is commonly used for myocardial viability evaluation. Contractile reserve (CR) assessment with low-dose dobutamine (LDD) is another method that highly predicts functional recovery following revascularization. In this study, we investigate the feasibility of a new protocol that provides combined Tl-201 uptake, resting and CR functional regional myocardial information in a single examination. A total of 41 patients underwent RR-gated-SPECT Tl-201 myocardial perfusion imaging. The LDD infusion was maintained during delayed imaging. Segmental Tl-201 uptake was classified into normal, fixed decrease (mild to absent) and reversible, and sub-classified by wall motion (WM)/thickening (WT) changes between early resting and delayed LDD gated images into normal, fixed or improved dysfunctional (CR present) segments. Out of 820 examined segments, 33 showed no appreciable Tl-201 uptake to evaluate WM/WT. In a dysfunctional myocardium, CR was significantly higher (P < 0.001) in reversible and fixed than in normal Tl-201 segments. The CR in dysfunctional segments with fixed decrease Tl-201 uptake was significantly higher (P < 0.05) in mild and moderate than in severe fixed defects. Both fixed Tl-201 defects and lack of CR were observed more (P < 0.05) in akinetic/dyskinetic than in hypokinetic segments. Simultaneous assessment of myocardial viability by RR Tl-201 uptake, resting and CR functional regional information is feasible and can be easily attained using this new protocol. Moreover, this protocol requires no additional time or radioactivity when compared with the usual RR Tl-201 protocol. Validation of this protocol with patients' revascularization data is needed.

  13. [Premonitory sign of myocardial rupture].

    PubMed

    Lauten, A; Dittrich, P

    1975-10-01

    It is reported on 14 cases in which a rupture of the myocardium occurred following a myocardial infarction. The moment of the appearance as well as anamnestic and clinical peculiarities are examined. As the only usable symptom of the rupture the symptomatology of the electromechanic dissociation must be taken into consideration. Finally it is referred to the on principle possible operative consequences of the rupture of the myocardium (oversewing or infarctetomy).

  14. Myocardial structure and matrix metalloproteinases.

    PubMed

    Aggeli, C; Pietri, P; Felekos, I; Rautopoulos, L; Toutouzas, K; Tsiamis, E; Stefanadis, C

    2012-01-01

    Metalloproteinases (MMPs) are enzymes which enhance proteolysis of extracellular matrix proteins. The pathophysiologic and prognostic role of MMPs has been demonstrated in numerous studies. The present review covers a wide a range of topics with regards to MMPs structural and functional properties, as well as their role in myocardial remodeling in several cardiovascular diseases. Moreover, the clinical and therapeutic implications from their assessment are highlighted.

  15. Tachyarrhythmias in acute myocardial infarction.

    PubMed

    McLean, K H; Bett, J N; Saltups, A

    1975-02-01

    In 1505 patients with acute myocardial infarction (MI) serious ventricular arrhythmias were commoner in those with transmural ECG changes, and were associated with an increase in mortality and in the incidence of left ventricular failure (LVF) as well as higher peak serum lactic dehydrogenase (LDH) levels. Atrial fibrillation (AF) occurred more often in older patients and in those with LVF and clinical evidence of pericarditis.

  16. Functional tests for myocardial ischemia

    SciTech Connect

    Levinson, J.R.; Guiney, T.E.; Boucher, C.A. )

    1991-01-01

    Functional tests for myocardial ischemia are numerous. Most depend upon a combination of either exercise or pharmacologic intervention with analysis of the electrocardiogram, of regional perfusion with radionuclide imaging, or of regional wall motion with radionuclide imaging or echocardiography. While each test has unique features, especially at the research level, they are generally quite similar in clinical practice, so the clinician is advised to concentrate on one or two in which local expertise is high.22 references.

  17. Protected gates for topological quantum field theories

    NASA Astrophysics Data System (ADS)

    Beverland, Michael E.; Buerschaper, Oliver; Koenig, Robert; Pastawski, Fernando; Preskill, John; Sijher, Sumit

    2016-02-01

    We study restrictions on locality-preserving unitary logical gates for topological quantum codes in two spatial dimensions. A locality-preserving operation is one which maps local operators to local operators — for example, a constant-depth quantum circuit of geometrically local gates, or evolution for a constant time governed by a geometrically local bounded-strength Hamiltonian. Locality-preserving logical gates of topological codes are intrinsically fault tolerant because spatially localized errors remain localized, and hence sufficiently dilute errors remain correctable. By invoking general properties of two-dimensional topological field theories, we find that the locality-preserving logical gates are severely limited for codes which admit non-abelian anyons, in particular, there are no locality-preserving logical gates on the torus or the sphere with M punctures if the braiding of anyons is computationally universal. Furthermore, for Ising anyons on the M-punctured sphere, locality-preserving gates must be elements of the logical Pauli group. We derive these results by relating logical gates of a topological code to automorphisms of the Verlinde algebra of the corresponding anyon model, and by requiring the logical gates to be compatible with basis changes in the logical Hilbert space arising from local F-moves and the mapping class group.

  18. Channel gating pore: a new therapeutic target.

    PubMed

    Kornilov, Polina; Peretz, Asher; Attali, Bernard

    2013-09-01

    Each subunit of voltage-gated cation channels comprises a voltage-sensing domain and a pore region. In a paper recently published in Cell Research, Li et al. showed that the gating charge pathway of the voltage sensor of the KCNQ2 K+ channel can accommodate small opener molecules and offer a new target to treat hyperexcitability disorders.

  19. Quantum logic gates for superconducting resonator qudits

    SciTech Connect

    Strauch, Frederick W.

    2011-11-15

    We study quantum information processing using superpositions of Fock states in superconducting resonators as quantum d-level systems (qudits). A universal set of single and coupled logic gates is theoretically proposed for resonators coupled by superconducting circuits of Josephson junctions. These gates use experimentally demonstrated interactions and provide an attractive route to quantum information processing using harmonic oscillator modes.

  20. Using Gates to Enhance Your Paddling Program.

    ERIC Educational Resources Information Center

    Kauffman, Robert B.; Mason, David W.

    1995-01-01

    Describes methods for constructing gates and slalom courses to teach paddling skills to young campers. Describes how the English Gate system, a standardized course, can be used both for instruction and to test camper's paddling skills. Recommends the use of a three-level award system (novice, intermediate, and expert) to recognize camper…

  1. Reconstruction of dynamic gated cardiac SPECT

    SciTech Connect

    Jin Mingwu; Yang Yongyi; King, Michael A.

    2006-11-15

    In this paper we propose an image reconstruction procedure which aims to unify gated single photon emission computed tomography (SPECT) and dynamic SPECT into a single method. We divide the cardiac cycle into a number of gate intervals as in gated SPECT, but treat the tracer distribution for each gate as a time-varying signal. By using both dynamic and motion-compensated temporal regularization, our reconstruction procedure will produce an image sequence that shows both cardiac motion and time-varying tracer distribution simultaneously. To demonstrate the proposed reconstruction method, we simulated gated cardiac perfusion imaging using the gated mathematical cardiac-torso (gMCAT) phantom with Tc99m-Teboroxime as the imaging agent. Our results show that the proposed method can produce more accurate reconstruction of gated dynamic images than independent reconstruction of individual gate frames with spatial smoothness alone. In particular, our results show that the former could improve the contrast to noise ratio of a simulated perfusion defect by as much as 100% when compared to the latter.

  2. Protected gates for topological quantum field theories

    SciTech Connect

    Beverland, Michael E.; Pastawski, Fernando; Preskill, John; Buerschaper, Oliver; Koenig, Robert; Sijher, Sumit

    2016-02-15

    We study restrictions on locality-preserving unitary logical gates for topological quantum codes in two spatial dimensions. A locality-preserving operation is one which maps local operators to local operators — for example, a constant-depth quantum circuit of geometrically local gates, or evolution for a constant time governed by a geometrically local bounded-strength Hamiltonian. Locality-preserving logical gates of topological codes are intrinsically fault tolerant because spatially localized errors remain localized, and hence sufficiently dilute errors remain correctable. By invoking general properties of two-dimensional topological field theories, we find that the locality-preserving logical gates are severely limited for codes which admit non-abelian anyons, in particular, there are no locality-preserving logical gates on the torus or the sphere with M punctures if the braiding of anyons is computationally universal. Furthermore, for Ising anyons on the M-punctured sphere, locality-preserving gates must be elements of the logical Pauli group. We derive these results by relating logical gates of a topological code to automorphisms of the Verlinde algebra of the corresponding anyon model, and by requiring the logical gates to be compatible with basis changes in the logical Hilbert space arising from local F-moves and the mapping class group.

  3. Retaining latch for a water pit gate

    DOEpatents

    Beale, A.R.

    1997-11-18

    A retaining latch is described for use in a hazardous materials storage or handling facility to adjustably retain a water pit gate in a gate frame. A retaining latch is provided comprising a latch plate which is rotatably mounted to each end of the top of the gate and a recessed opening, formed in the gate frame, for engaging an edge of the latch plate. The latch plate is circular in profile with one side cut away or flat, such that the latch plate is D-shaped. The remaining circular edge of the latch plate comprises steps of successively reduced thickness. The stepped edge of the latch plate fits inside a recessed opening formed in the gate frame. As the latch plate is rotated, alternate steps of the latch plate are engaged by the recessed opening. When the latch plate is rotated such that the flat portion of the latch plate faces the recessed opening in the gate frame, there is no connection between the opening and the latch plate and the gate is unlatched from the gate frame. 4 figs.

  4. Retaining latch for a water pit gate

    SciTech Connect

    Beale, A.R.

    1997-11-18

    A retaining latch is described for use in a hazardous materials storage or handling facility to adjustably retain a water pit gate in a gate frame. A retaining latch is provided comprising a latch plate which is rotatably mounted to each end of the top of the gate and a recessed opening, formed in the gate frame, for engaging an edge of the latch plate. The latch plate is circular in profile with one side cut away or flat, such that the latch plate is D-shaped. The remaining circular edge of the latch plate comprises steps of successively reduced thickness. The stepped edge of the latch plate fits inside a recessed opening formed in the gate frame. As the latch plate is rotated, alternate steps of the latch plate are engaged by the recessed opening. When the latch plate is rotated such that the flat portion of the latch plate faces the recessed opening in the gate frame, there is no connection between the opening and the latch plate and the gate is unlatched from the gate frame. 4 figs.

  5. Retaining latch for a water pit gate

    SciTech Connect

    Beale, A.R.

    1996-12-31

    The present invention relates to retaining devices which are used to latch two elements or parts together and, more particularly, to gate latches for use in locking a gate to a wall bracket in a water pit utilized to store or handle hazardous materials. A retaining latch is provided comprising a latch plate which is rotatably mounted to each end of the top of the gate and a recessed opening, formed in the gate frame, for engaging an edge of the latch plate. The latch plate is circular in profile with one side cut away or flat, such that the latch plate is D-shaped. The remaining circular edge of the latch plate comprises steps of successively reduced thickness. The stepped edge of the latch plate fits inside a recessed opening formed in the gate frame. As the latch plate is rotated, alternate steps of the latch plate are engaged by the recessed opening. When the latch plate is rotated such that the flat portion of the latch plate faces the recessed opening in the gate frame, there is no connection between the opening and the latch plate and the gate is unlatched from the gate frame.

  6. Retaining latch for a water pit gate

    SciTech Connect

    Beale, Arden R.

    1997-01-01

    A retaining latch for use in a hazardous materials storage or handling facility to adjustably retain a water pit gate in a gate frame. A retaining latch is provided comprising a latch plate which is rotatably mounted to each end of the top of the gate and a recessed opening, formed in the gate frame, for engaging an edge of the latch plate. The latch plate is circular in profile with one side cut away or flat, such that the latch plate is D-shaped. The remaining circular edge of the latch plate comprises steps of successively reduced thickness. The stepped edge of the latch plate fits inside a recessed opening formed in the gate frame. As the latch plate is rotated, alternate steps of the latch plate are engaged by the recessed opening. When the latch plate is rotated such that the flat portion of the latch plate faces the recessed opening in the gate frame, there is no connection between the opening and the latch plate and the gate is unlatched from the gate frame.

  7. Automatically closing swing gate closure assembly

    DOEpatents

    Chang, Shih-Chih; Schuck, William J.; Gilmore, Richard F.

    1988-01-01

    A swing gate closure assembly for nuclear reactor tipoff assembly wherein the swing gate is cammed open by a fuel element or spacer but is reliably closed at a desired closing rate primarily by hydraulic forces in the absence of a fuel charge.

  8. A pilot study on diagnosis of coronary artery disease using computed tomography first-pass myocardial perfusion imaging at rest

    PubMed Central

    Wang, Qi; Qin, Jing; Gai, Lu-yue; Chen, Yun-dai; Dong, Wei; Guan, Zhi-wei; Wang, Zhi-guo; Sun, Zhi-jun; Tian, Jia-he

    2011-01-01

    Background: Although computed tomography coronary angiography (CTCA) can identify coronary stenosis, little data exists on the ability of multislice computed tomography (MSCT) to detect myocardial perfusion defects at rest. Methods: In 33 patients with diagnosed or suspected coronary artery disease (CAD), CTCA using retrospective electrocardiography (ECG) gating at rest and invasive coronary angiography (ICA) was performed. The 2D myocardial images were reconstructed in diastolic and systolic phases using the same raw data for CTCA. CT values of the myocardium were used as an estimate of myocardial enhancement, which were shown by color mapping. Myocardial ischemia was defined as a pattern of transient endocardial hypo-enhancement at systole and normal enhancement at diastole. The results of ICA were taken as the reference standard. Results: When a diameter reduction of more than 50% in ICA was used as diagnostic criteria of CAD, the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of CT first-pass myocardial perfusion imaging (MPI) at rest were 0.85, 0.67, 0.92, and 0.50 per patient, respectively, and 0.58, 0.93, 0.85, and 0.76 per vessel, respectively. Conclusions: CT first-pass MPI at rest could detect CAD patients, which could become a practical and convenient way to detect ischemia, consequently offering the ability for MSCT to act as a “one stop shop” for the diagnosis of CAD. PMID:21634042

  9. [Psychiatric disorders following myocardial infarction].

    PubMed

    Meincke, Ulrich; Hoff, Paul

    2006-05-15

    The number of patients who survive acute myocardial infarction has increased during recent decades. In addition, demographic development results in a rising incidence of cardiovascular diseases. Based on these facts, also the significance of psychiatric disorders is growing that may occur after myocardial infarction, such as depression, posttraumatic stress and anxiety disorders. Physicians are faced with the challenge to identify these clinical entities, that show a syndromal overlap with somatic complaints after myocardial infarction. After differentiation prompt start of adequate psychiatric-psychotherapeutic interventions is of relevance, not only regarding the patient's quality of life, but also in terms of cardiovascular prognosis. Indeed, depressive and anxiety disorders are known to be associated with a poor compliance as for rehabilitation and secondary prevention of cardiovascular disorders. Moreover, some studies suggest depression to be an independent risk factor of coronary heart disease. Consequently, early recognition and treatment, most often primarily in the hands of internists and cardiologists, are of enormous importance for the course and prognosis of the psychiatric disorder but also of cardiovascular disease.

  10. Myocardial Infarction in the Elderly

    PubMed Central

    Carro, Amelia; Kaski, Juan Carlos

    2011-01-01

    Advances in pharmacological treatment and effective early myocardial revascularization have –in recent years- led to improved clinical outcomes in patients with acute myocardial infarction (AMI). However, it has been suggested that compared to younger subjects, elderly AMI patients are less likely to receive evidence-based treatment, including myocardial revascularization therapy. Several reasons have been postulated to explain this trend, including uncertainty regarding the true benefits of the interventions commonly used in this setting as well as increased risk mainly associated with comorbidities. The diagnosis, management, and post-hospitalization care of elderly patients presenting with an acute coronary syndrome pose many difficulties at present. A complex interplay of variables such as comorbidities, functional and socioeconomic status, side effects associated with multiple drug administration, and individual biologic variability, all contribute to creating a complex clinical scenario. In this complex setting, clinicians are often required to extrapolate evidence-based results obtained in cardiovascular trials from which older patients are often, implicitly or explicitly, excluded. This article reviews current recommendations regarding management of AMI in the elderly. PMID:22396870

  11. Terahertz plasmon amplification in RTD-gated HEMTs with a grating-gate

    NASA Astrophysics Data System (ADS)

    Condori Quispe, Hugo O.; Encomendero, Jimy; Xing, Huili Grace; Sensale Rodriguez, Berardi

    2016-09-01

    We analyze amplification of terahertz plasmons in a grating-gate semiconductor hetero-structure. The device consists of a resonant-tunneling-diode gated high-electron-mobility transistor (RTD-gated HEMT), i.e. a HEMT structure with a double-barrier gate stack enabling resonant tunneling from gate to channel. In these devices, the key element enabling substantial power gain is the coupling of terahertz waves into and out of plasmons in the RTD-gated HEMT channel, i.e. the gain medium, via the grating-gate itself, part of the active device, rather than by an external antenna structure as in previous works, enabling amplification with associated power gain >> 30 dB at room temperature.

  12. Dual-Gate p-GaN Gate High Electron Mobility Transistors for Steep Subthreshold Slope.

    PubMed

    Bae, Jong-Ho; Lee, Jong-Ho

    2016-05-01

    A steep subthreshold slope characteristic is achieved through p-GaN gate HEMT with dual-gate structure. Obtained subthreshold slope is less than 120 μV/dec. Based on the measured and simulated data obtained from single-gate device, breakdown of parasitic floating-base bipolar transistor and floating gate charged with holes are responsible to increase abruptly in drain current. In the dual-gate device, on-current degrades with high temperature but subthreshold slope is not changed. To observe the switching speed of dual-gate device and transient response of drain current are measured. According to the transient responses of drain current, switching speed of the dual-gate device is about 10(-5) sec.

  13. Gating of Permanent Molds for ALuminum Casting

    SciTech Connect

    David Schwam; John F. Wallace; Tom Engle; Qingming Chang

    2004-03-30

    This report summarizes a two-year project, DE-FC07-01ID13983 that concerns the gating of aluminum castings in permanent molds. The main goal of the project is to improve the quality of aluminum castings produced in permanent molds. The approach taken was determine how the vertical type gating systems used for permanent mold castings can be designed to fill the mold cavity with a minimum of damage to the quality of the resulting casting. It is evident that somewhat different systems are preferred for different shapes and sizes of aluminum castings. The main problems caused by improper gating are entrained aluminum oxide films and entrapped gas. The project highlights the characteristic features of gating systems used in permanent mold aluminum foundries and recommends gating procedures designed to avoid common defects. The study also provides direct evidence on the filling pattern and heat flow behavior in permanent mold castings.

  14. Logic gates based on ion transistors.

    PubMed

    Tybrandt, Klas; Forchheimer, Robert; Berggren, Magnus

    2012-05-29

    Precise control over processing, transport and delivery of ionic and molecular signals is of great importance in numerous fields of life sciences. Integrated circuits based on ion transistors would be one approach to route and dispense complex chemical signal patterns to achieve such control. To date several types of ion transistors have been reported; however, only individual devices have so far been presented and most of them are not functional at physiological salt concentrations. Here we report integrated chemical logic gates based on ion bipolar junction transistors. Inverters and NAND gates of both npn type and complementary type are demonstrated. We find that complementary ion gates have higher gain and lower power consumption, as compared with the single transistor-type gates, which imitates the advantages of complementary logics found in conventional electronics. Ion inverters and NAND gates lay the groundwork for further development of solid-state chemical delivery circuits.

  15. Glare suppression by coherence gated negation

    PubMed Central

    Zhou, Edward Haojiang; Shibukawa, Atsushi; Brake, Joshua; Ruan, Haowen; Yang, Changhuei

    2016-01-01

    Imaging of a weak target hidden behind a scattering medium can be significantly confounded by glare. We report a method, termed coherence gated negation (CGN), that uses destructive optical interference to suppress glare and allow improved imaging of a weak target. As a demonstration, we show that by permuting through a set range of amplitude and phase values for a reference beam interfering with the optical field from the glare and target reflection, we can suppress glare by an order of magnitude, even when the optical wavefront is highly disordered. This strategy significantly departs from conventional coherence gating methods in that CGN actively “gates out” the unwanted optical contributions while conventional methods “gate in” the target optical signal. We further show that the CGN method can outperform conventional coherence gating image quality in certain scenarios by more effectively rejecting unwanted optical contributions. PMID:28713849

  16. Myocardialization of the cardiac outflow tract

    NASA Technical Reports Server (NTRS)

    van den Hoff, M. J.; Moorman, A. F.; Ruijter, J. M.; Lamers, W. H.; Bennington, R. W.; Markwald, R. R.; Wessels, A.

    1999-01-01

    During development, the single-circuited cardiac tube transforms into a double-circuited four-chambered heart by a complex process of remodeling, differential growth, and septation. In this process the endocardial cushion tissues of the atrioventricular junction and outflow tract (OFT) play a crucial role as they contribute to the mesenchymal components of the developing septa and valves in the developing heart. After fusion, the endocardial ridges in the proximal portion of the OFT initially form a mesenchymal outlet septum. In the adult heart, however, this outlet septum is basically a muscular structure. Hence, the mesenchyme of the proximal outlet septum has to be replaced by cardiomyocytes. We have dubbed this process "myocardialization." Our immunohistochemical analysis of staged chicken hearts demonstrates that myocardialization takes place by ingrowth of existing myocardium into the mesenchymal outlet septum. Compared to other events in cardiac septation, it is a relatively late process, being initialized around stage H/H28 and being basically completed around stage H/H38. To unravel the molecular mechanisms that are responsible for the induction and regulation of myocardialization, an in vitro culture system in which myocardialization could be mimicked and manipulated was developed. Using this in vitro myocardialization assay it was observed that under the standard culture conditions (i) whole OFT explants from stage H/H20 and younger did not spontaneously myocardialize the collagen matrix, (ii) explants from stage H/H21 and older spontaneously formed extensive myocardial networks, (iii) the myocardium of the OFT could be induced to myocardialize and was therefore "myocardialization-competent" at all stages tested (H/H16-30), (iv) myocardialization was induced by factors produced by, most likely, the nonmyocardial component of the outflow tract, (v) at none of the embryonic stages analyzed was ventricular myocardium myocardialization-competent, and finally

  17. Characteristics of gated treatment using an optical surface imaging and gating system on an Elekta linac.

    PubMed

    Freislederer, Philipp; Reiner, Michael; Hoischen, Winfried; Quanz, Anton; Heinz, Christian; Walter, Franziska; Belka, Claus; Soehn, Matthias

    2015-03-19

    Knowing the technical characteristics of gated radiotherapy equipment is crucial for ensuring precise and accurate treatment when using techniques such as Deep-Inspiration Breath-Hold and gating under free breathing. With one of the first installations of the novel surface imaging system Catalyst™ (C-RAD AB, Sweden) in connection with an Elekta Synergy linear accelerator (Elekta AB, Sweden) via the Elekta Response Interface, characteristics like dose delivery accuracy and time delay were investigated prior to clinical implementation of gated treatments in our institution. In this study a moving phantom was used to simulate respiratory motion which was registered by the Catalyst™ system. The gating level was set manually. Within this gating window a trigger signal is automatically sent to the linac initiating treatment delivery. Dose measurements of gated linac treatment beams with different gating levels were recorded with a static 2D-Diode Array (MapCheck2, Sun Nuclear Co., USA) and compared to ungated reference measurements for different field sizes. In addition, the time delay of gated treatment beams was measured using radiographic film. The difference in dose delivery between gated and ungated treatment decreases with the size of the chosen gating level. For clinically relevant gating levels of about 30%, the differences in dose delivery accuracy remain below 1%. In comparison with other system configurations in literature, the beam-on time delay shows a large deviation of 851 ms ± 100 ms. When performing gated treatment, especially for free-breathing gating, factors as time delay and dose delivery have to be evaluated regularly in terms of a quality assurance process. Once these parameters are known they can be accounted and compensated for, e.g. by adjusting the pre-selected gating level or the internal target volume margins and by using prediction algorithms for breathing curves. The usage of prediction algorithms becomes inevitable with the high

  18. Imaging of myocardial perfusion with magnetic resonance.

    PubMed

    Barkhausen, Jörg; Hunold, Peter; Jochims, Markus; Debatin, Jörg F

    2004-06-01

    Coronary artery disease (CAD) is currently the leading cause of death in developed nations. Reflecting the complexity of cardiac function and morphology, noninvasive diagnosis of CAD represents a major challenge for medical imaging. Although coronary artery stenoses can be depicted with magnetic resonance (MR) and computed tomography (CT) techniques, its functional or hemodynamic impact frequently remains elusive. Therefore, there is growing interest in other, target organ-specific parameters such as myocardial function at stress and first-pass myocardial perfusion imaging to assess myocardial blood flow. This review explores the pathophysiologic background, recent technical developments, and current clinical status of first-pass MR imaging (MRI) of myocardial perfusion.

  19. Myocardial bridges: Overview of diagnosis and management.

    PubMed

    Rogers, Ian S; Tremmel, Jennifer A; Schnittger, Ingela

    2017-09-01

    A myocardial bridge is a segment of a coronary artery that travels into the myocardium instead of the normal epicardial course. Although it is general perception that myocardial bridges are normal variants, patients with myocardial bridges can present with symptoms, such as exertional chest pain, that cannot be explained by a secondary etiology. Such patients may benefit from individualized medical/surgical therapy. This article describes the prevalence, clinical presentation, classification, evaluation, and management of children and adults with symptomatic myocardial bridges. © 2017 The Authors Congenital Heart Disease published by Wiley Periodicals, Inc.

  20. [Vectorcardiographic diagnosis of the myocardial inactivatable zone].

    PubMed

    de Micheli, A; Medrano, G A

    1989-01-01

    Clinical importance of the vectorcardiographic exploration (distant and spatial) of the myocardial electrical phenomenon is emphasized. This technique constitutes a useful integration of electrocardiographic exploration (near and analytical). The more characteristic morphological and chronological changes due to an inactivatable area are discussed in the light of ventricular myocardial depolarization. Some typical vectorcardiographic features corresponding to the presence of a myocardial inactivatable zone are presented. The utility of the complementary elements which vectorcardiography can bring to electrocardiography is emphasized. Both of these procedures integrate a rational exploration of electrical activity of the myocardium, the solid base of prognostic and therapeutic decisions in cases of myocardial infarction.

  1. Arrhythmias in Post-Myocardial Infarction Patients

    ClinicalTrials.gov

    2017-07-24

    Myocardial Infarction; Coronary Artery Disease; Arrythmia; ECG Electrical Alternans; Atrioventricular Block; Atrial Fibrillation; Atrial Flutter; Ventricular Tachycardia; Ventricular Fibrillation; Ventricular Arrythmia

  2. Myocardial perfusion scintigraphy: the evidence

    PubMed Central

    Anagnostopoulos, C.; Cerqueira, M.; Ell, P. J.; Flint, E. J.; Harbinson, M.; Kelion, A. D.; Al-Mohammad, A.; Prvulovich, E. M.; Shaw, L. J.; Tweddel, A. C.

    2003-01-01

    This review summarises the evidence for the role of myocardial perfusion scintigraphy (MPS) in patients with known or suspected coronary artery disease. It is the product of a consensus conference organised by the British Cardiac Society, the British Nuclear Cardiology Society and the British Nuclear Medicine Society and is endorsed by the Royal College of Physicians of London and the Royal College of Radiologists. It was used to inform the UK National Institute of Clinical Excellence in their appraisal of MPS in patients with chest pain and myocardial infarction. MPS is a well-established, non-invasive imaging technique with a large body of evidence to support its effectiveness in the diagnosis and management of angina and myocardial infarction. It is more accurate than the exercise ECG in detecting myocardial ischaemia and it is the single most powerful technique for predicting future coronary events. The high diagnostic accuracy of MPS allows reliable risk stratification and guides the selection of patients for further interventions, such as revascularisation. This in turn allows more appropriate utilisation of resources, with the potential for both improved clinical outcomes and greater cost-effectiveness. Evidence from modelling and observational studies supports the enhanced cost-effectiveness associated with MPS use. In patients presenting with stable or acute chest pain, strategies of investigation involving MPS are more cost-effective than those not using the technique. MPS also has particular advantages over alternative techniques in the management of a number of patient subgroups, including women, the elderly and those with diabetes, and its use will have a favourable impact on cost-effectiveness in these groups. MPS is already an integral part of many clinical guidelines for the investigation and management of angina and myocardial infarction. However, the technique is underutilised in the UK, as judged by the inappropriately long waiting times and by

  3. Gate Controlled Spin Precession Effect

    NASA Astrophysics Data System (ADS)

    Naser Zainuddin, Abu; Siddiqui, Lutfe; Hong, Seokmin; Datta, Supriyo

    2010-03-01

    A two-dimensional (2D) non-local lateral spin-transport model is developed based on the non-equilibrium Green's function (NEGF) formalism for ballistic carriers in mode space approach. The effect of gate controlled Rashba spin-orbit (RSO) interaction in modulating the non-local spin voltage has been explicitly taken into account. We found a quantitative agreement with the recent observation on non-local controlled spin-precession by Koo et. al [1]. The phase shift observed in the voltage according to the analytical equation used in [1] is found to be the consequence of both multichannel effect and the effect of injecting and detecting ferromagnetic contact length. In such structures we predict that a short length contact as well as an etched out channel can improve the non-local voltage significantly. [1] H. C. Koo et. al. Science, 325, 1515 (2009).

  4. Locking apparatus for gate valves

    DOEpatents

    Fabyan, J.; Williams, C.W.

    A locking apparatus for fluid operated valves having a piston connected to the valve actuator which moves in response to applied pressure within a cylinder housing having a cylinder head, a catch block is secured to the piston, and the cylinder head incorporates a catch pin. Pressure applied to the cylinder to open the valve moves the piston adjacent to the cylinder head where the catch pin automatically engages the catch block preventing further movement of the piston or premature closure of the valve. Application of pressure to the cylinder to close the valve, retracts the catch pin, allowing the valve to close. Included are one or more selector valves, for selecting pressure application to other apparatus depending on the gate valve position, open or closed, protecting such apparatus from damage due to premature closing caused by pressure loss or operational error.

  5. Locking apparatus for gate valves

    DOEpatents

    Fabyan, Joseph; Williams, Carl W.

    1988-01-01

    A locking apparatus for fluid operated valves having a piston connected to the valve actuator which moves in response to applied pressure within a cylinder housing having a cylinder head, a catch block is secured to the piston, and the cylinder head incorporates a catch pin. Pressure applied to the cylinder to open the valve moves the piston adjacent to the cylinder head where the catch pin automatically engages the catch block preventing futher movement of the piston or premature closure of the valve. Application of pressure to the cylinder to close the valve, retracts the catch pin, allowing the valve to close. Included are one or more selector valves, for selecting pressure application to other apparatus depending on the gate valve position, open or closed, protecting such apparatus from damage due to premature closing caused by pressure loss or operational error.

  6. Voltage-gated sodium channels

    PubMed Central

    Abdelsayed, Mena; Sokolov, Stanislav

    2013-01-01

    Epilepsy is a brain disorder characterized by seizures and convulsions. The basis of epilepsy is an increase in neuronal excitability that, in some cases, may be caused by functional defects in neuronal voltage gated sodium channels, Nav1.1 and Nav1.2. The effects of antiepileptic drugs (AEDs) as effective therapies for epilepsy have been characterized by extensive research. Most of the classic AEDs targeting Nav share a common mechanism of action by stabilizing the channel’s fast-inactivated state. In contrast, novel AEDs, such as lacosamide, stabilize the slow-inactivated state in neuronal Nav1.1 and Nav1.7 isoforms. This paper reviews the different mechanisms by which this stabilization occurs to determine new methods for treatment. PMID:23531742

  7. Mechanosensitive gating of Kv channels.

    PubMed

    Morris, Catherine E; Prikryl, Emil A; Joós, Béla

    2015-01-01

    K-selective voltage-gated channels (Kv) are multi-conformation bilayer-embedded proteins whose mechanosensitive (MS) Popen(V) implies that at least one conformational transition requires the restructuring of the channel-bilayer interface. Unlike Morris and colleagues, who attributed MS-Kv responses to a cooperative V-dependent closed-closed expansion↔compaction transition near the open state, Mackinnon and colleagues invoke expansion during a V-independent closed↔open transition. With increasing membrane tension, they suggest, the closed↔open equilibrium constant, L, can increase >100-fold, thereby taking steady-state Popen from 0→1; "exquisite sensitivity to small…mechanical perturbations", they state, makes a Kv "as much a mechanosensitive…as…a voltage-dependent channel". Devised to explain successive gK(V) curves in excised patches where tension spontaneously increased until lysis, their L-based model falters in part because of an overlooked IK feature; with recovery from slow inactivation factored in, their g(V) datasets are fully explained by the earlier model (a MS V-dependent closed-closed transition, invariant L≥4). An L-based MS-Kv predicts neither known Kv time courses nor the distinctive MS responses of Kv-ILT. It predicts Kv densities (hence gating charge per V-sensor) several-fold different from established values. If opening depended on elevated tension (L-based model), standard gK(V) operation would be compromised by animal cells' membrane flaccidity. A MS V-dependent transition is, by contrast, unproblematic on all counts. Since these issues bear directly on recent findings that mechanically-modulated Kv channels subtly tune pain-related excitability in peripheral mechanoreceptor neurons we undertook excitability modeling (evoked action potentials). Kvs with MS V-dependent closed-closed transitions produce nuanced mechanically-modulated excitability whereas an L-based MS-Kv yields extreme, possibly excessive (physiologically

  8. Design and rationale for the Myocardial Stem Cell Administration After Acute Myocardial Infarction (MYSTAR) Study: a multicenter, prospective, randomized, single-blind trial comparing early and late intracoronary or combined (percutaneous intramyocardial and intracoronary) administration of nonselected autologous bone marrow cells to patients after acute myocardial infarction.

    PubMed

    Nyolczas, Noémi; Gyöngyösi, Mariann; Beran, Gilbert; Dettke, Markus; Graf, Senta; Sochor, Heinz; Christ, Günther; Edes, István; Balogh, László; Krause, Korff T; Jaquet, Kai; Kuck, Karl-Heinz; Benedek, Imre; Hintea, Theodora; Kiss, Róbert; Préda, István; Kotevski, Vladimir; Pejkov, Hristo; Dudek, Darius; Heba, Grzegorz; Sylven, Christer; Charwat, Silvia; Jacob, Ronaldo; Maurer, Gerald; Lang, Irene; Glogar, Dietmar

    2007-02-01

    Previous data suggest that bone marrow-derived stem cells (BM-SCs) decrease the infarct size and beneficially affect the postinfarction remodeling. The Myocardial Stem Cell Administration After Acute Myocardial Infarction Study is a multicenter, prospective, randomized, single-blind clinical trial designed to compare the early and late intracoronary or combined (percutaneous intramyocardial and intracoronary) administration of BM-SCs to patients after acute myocardial infarction (AMI) with reopened infarct-related artery. The primary end points are the changes in resting myocardial perfusion defect size and left ventricular ejection fraction (gated single photon emission computed tomography [SPECT] scintigraphy) 3 months after BM-SCs therapy. The secondary end points relate to evaluation of (1) the safety and feasibility of the application modes, (2) the changes in left ventricular wall motion score index (transthoracic echocardiography), (3) myocardial voltage and segmental wall motion (NOGA mapping), (4) left ventricular end-diastolic and end-systolic volumes (contrast ventriculography), and (5) the clinical symptoms (Canadian Cardiovascular Society [CCS] anina score and New York Heart Association [NYHA] functional class) at follow-up. Three hundred sixty patients are randomly assigned into 1 of 4 groups: group A, early treatment (21-42 days after AMI) with intracoronary injection; group B, early treatment with combined application; group C, late treatment (3 months after AMI) with intracoronary delivery; and group D, late treatment with combined administration of BM-SCs. Besides the BM-SCs therapy, the standardized treatment of AMI is applied in all patients. The Myocardial Stem Cell Administration After Acute Myocardial Infarction Trial is the first randomized trial to investigate the effects of the combined (intramyocardial and intracoronary) and the intracoronary mode of delivery of BM-SCs therapy in the early and late periods after AMI.

  9. Serial myocardial perfusion imaging: defining a significant change and targeting management decisions.

    PubMed

    Iskandrian, Ami E; Hage, Fadi G; Shaw,