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1. Effect of color coding and subtraction on the accuracy of contrast echocardiography

Author

Pasquet, A, Greenberg, N, Brunken, R, Thomas, J. D, and Marwick, T. H

Subjects
Life Sciences (General)
Abstract

BACKGROUND: Contrast echocardiography may be used to assess myocardial perfusion. However, gray scale assessment of myocardial contrast echocardiography (MCE) is difficult because of variations in regional backscatter intensity, difficulties in distinguishing varying shades of gray, and artifacts or attenuation. We sought to determine whether the assessment of rest myocardial perfusion by MCE could be improved with subtraction and color coding. METHODS AND RESULTS: MCE was performed in 31 patients with previous myocardial infarction with a 2nd generation agent (NC100100, Nycomed AS), using harmonic triggered or continuous imaging and gain settings were kept constant throughout the study. Digitized images were post processed by subtraction of baseline from contrast data and colorized to reflect the intensity of myocardial contrast. Gray scale MCE alone, MCE images combined with baseline and subtracted colorized images were scored independently using a 16 segment model. The presence and severity of myocardial contrast abnormalities were compared with perfusion defined by rest MIBI-SPECT. Segments that were not visualized by continuous (17%) or triggered imaging (14%) after color processing were excluded from further analysis. The specificity of gray scale MCE alone (56%) or MCE combined with baseline 2D (47%) was significantly enhanced by subtraction and color coding (76%, p<0.001) of triggered images. The accuracy of the gray scale approaches (respectively 52% and 47%) was increased to 70% (p<0.001). Similarly, for continuous images, the specificity of gray scale MCE with and without baseline comparison was 23% and 42% respectively, compared with 60% after post processing (p<0.001). The accuracy of colorized images (59%) was also significantly greater than gray scale MCE (43% and 29%, p<0.001). The sensitivity of MCE for both acquisitions was not altered by subtraction. CONCLUSION: Post-processing with subtraction and color coding significantly improves the accuracy and specificity of MCE for detection of perfusion defects.

Published
1999
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4. Cognitive load measurement

Author

Brunken, R, Seufert, T, Paas, Fred, Plass, J., Moreno, R., Brunken, R., and Department of Psychology, Education and Child Studies

Published
2010

5. Verbesserte Anpassungsfähigkeit des Änderungsmanagements durch komplementäre Selbstorganisation

Author

Brunken, R., Krause, F.-L., and Publica

Subjects
Änderungsmanagement, Führungskraft, Organisationsentwicklung, Geschäftsprozeß, Prozessverantwortlicher, Selbstorganisation, Änderungsmanagementverantwortlicher, Virtuelle Produktentstehung
Abstract

In der vorliegenden Arbeit wird dargelegt, dass innerbetriebliche Prozesse bei komplexen Aufgabenstellungen durch die Anwendung von Selbstorganisationskonzepten schneller und zielgerichteter angepasst werden können. Eine verbesserte Anpassungsfähigkeit wiederum führt zu verbesserten Wettbewerbsfähigkeiten von Unternehmen, da die Aufbau- und Ablauforganisation und der Technologieeinsatz schneller den geänderten Anforderungen angepasst werden können. Es werden Empfehlungen für Interventionen in die Organisation von Prozessgestaltungen und Technologiefestlegungen beschrieben und es wird ein Konzept für die Verbreitung von neuen Prozessen und Technologieanwendungen dargelegt. Als Beispiel dient das Änderungsmanagement für technische Änderungen an komplexen Produkten.

Published
2002

6. Patient management after noninvasive cardiac imaging results from SPARC (Study of myocardial perfusion and coronary anatomy imaging roles in coronary artery disease).

Author

Hachamovitch, R., Nutter, B., Hlatky, M.A., Shaw, L.J., Ridner, M.L., Dorbala, S., Beanlands, R.S., Chow, B.J., Branscomb, E., Chareonthaitawee, P., Weigold, W.G., Voros, S., Abbara, S., Yasuda, T., Jacobs, J.E., Lesser, J., Berman, D.S., Thomson, L.E., Raman, S., Heller, G.V., Schussheim, A., Brunken, R., Williams, K.A., Farkas, S., Delbeke, D., Schoepf, U.J., Reichek, N., Rabinowitz, S., Sigman, S.R., Patterson, R., Corn, C.R., White, R., Kazerooni, E., Corbett, J., Bokhari, S., Machac, J., Guarneri, E., Borges-Neto, S., Millstine, J.W., Caldwell, J., Arrighi, J., Hoffmann, U., Budoff, M., Lima, J., Johnson, J.R., Johnson, B., Gaber, M., Williams, J.A., Foster, C., Hainer, J., Carli, M.F. Di, Hachamovitch, R., Nutter, B., Hlatky, M.A., Shaw, L.J., Ridner, M.L., Dorbala, S., Beanlands, R.S., Chow, B.J., Branscomb, E., Chareonthaitawee, P., Weigold, W.G., Voros, S., Abbara, S., Yasuda, T., Jacobs, J.E., Lesser, J., Berman, D.S., Thomson, L.E., Raman, S., Heller, G.V., Schussheim, A., Brunken, R., Williams, K.A., Farkas, S., Delbeke, D., Schoepf, U.J., Reichek, N., Rabinowitz, S., Sigman, S.R., Patterson, R., Corn, C.R., White, R., Kazerooni, E., Corbett, J., Bokhari, S., Machac, J., Guarneri, E., Borges-Neto, S., Millstine, J.W., Caldwell, J., Arrighi, J., Hoffmann, U., Budoff, M., Lima, J., Johnson, J.R., Johnson, B., Gaber, M., Williams, J.A., Foster, C., Hainer, J., and Carli, M.F. Di

Abstract

Item does not contain fulltext, OBJECTIVES: This study examined short-term cardiac catheterization rates and medication changes after cardiac imaging. BACKGROUND: Noninvasive cardiac imaging is widely used in coronary artery disease, but its effects on subsequent patient management are unclear. METHODS: We assessed the 90-day post-test rates of catheterization and medication changes in a prospective registry of 1,703 patients without a documented history of coronary artery disease and an intermediate to high likelihood of coronary artery disease undergoing cardiac single-photon emission computed tomography, positron emission tomography, or 64-slice coronary computed tomography angiography. RESULTS: Baseline medication use was relatively infrequent. At 90 days, 9.6% of patients underwent catheterization. The rates of catheterization and medication changes increased in proportion to test abnormality findings. Among patients with the most severe test result findings, 38% to 61% were not referred to catheterization, 20% to 30% were not receiving aspirin, 35% to 44% were not receiving a beta-blocker, and 20% to 25% were not receiving a lipid-lowering agent at 90 days after the index test. Risk-adjusted analyses revealed that compared with stress single-photon emission computed tomography or positron emission tomography, changes in aspirin and lipid-lowering agent use was greater after computed tomography angiography, as was the 90-day catheterization referral rate in the setting of normal/nonobstructive and mildly abnormal test results. CONCLUSIONS: Overall, noninvasive testing had only a modest impact on clinical management of patients referred for clinical testing. Although post-imaging use of cardiac catheterization and medical therapy increased in proportion to the degree of abnormality findings, the frequency of catheterization and medication change suggests possible undertreatment of higher risk patients. Patients were more likely to undergo cardiac catheterization after computed tomography angio

Published
2012

7. Schema acquisition and sources of cognitive load

Author

Plass, J., Moreno, R, Brunken, R, Kalyuga, Slava, Education, Faculty of Arts & Social Sciences, UNSW, Plass, J., Moreno, R, Brunken, R, and Kalyuga, Slava, Education, Faculty of Arts & Social Sciences, UNSW

Published
2010

8. Cognitive load theory: Recent theoretical advances

Author

Plass, J., Moreno, R, Brunken, R, Sweller, John, Education, Faculty of Arts & Social Sciences, UNSW, Plass, J., Moreno, R, Brunken, R, and Sweller, John, Education, Faculty of Arts & Social Sciences, UNSW

Published
2010

9. Individual differences and cognitive load theory

Author

Plass, J., Moreno, R, Brunken, R, Kalyuga, Slava, Education, Faculty of Arts & Social Sciences, UNSW, Plass, J., Moreno, R, Brunken, R, and Kalyuga, Slava, Education, Faculty of Arts & Social Sciences, UNSW

Published
2010

23. Evaluation of the effect of glucose ingestion and kinetic model configurations of FDG in the normal liver

Author

Choi, Y, Hawkins, R, Huang, S, Brunken, R, Hoh, C, Messa, M, Nitzsche, E, Phelps, M, Schelbert, H, Hawkins, RA, Huang, SC, Brunken, RC, Hoh, CK, Nitzsche, EU, Phelps, ME, Schelbert, HR, MESSA, MARIA CRISTINA, Choi, Y, Hawkins, R, Huang, S, Brunken, R, Hoh, C, Messa, M, Nitzsche, E, Phelps, M, Schelbert, H, Hawkins, RA, Huang, SC, Brunken, RC, Hoh, CK, Nitzsche, EU, Phelps, ME, Schelbert, HR, and MESSA, MARIA CRISTINA

Abstract

The liver plays an important role in glucose homeostasis. PET studies with 2-[F-18]fluoro-2-deoxy-D-glucose (FDG) of the liver (e.g., in neoplasms) require an understanding of the effects of dietary conditions on hepatic FDG uptake. METHODS: Twenty studies were performed on 10 normal volunteers (ages 24 +/- 4) after fasting 4 to 19 hr and again after oral consumption of 100 g of dextrose to investigate tracer kinetic model configurations of FDG in the normal liver and to evaluate the impact of oral glucose on liver in normal subjects. Dynamic PET images were acquired for about 1 hr using a Siemens/CTI 931 tomograph. RESULTS: A three-compartment model with an input function delay time parameter was the statistically preferred model configuration. The model estimated transport rate constant from plasma to liver, K1, increased significantly (p < 0.05) from 0.864 +/- 0.136 ml/min/g in fasting studies to 1.058 +/- 0.269 ml/min/g in postglucose studies. Glucose loading also significantly increased (p < 0.01) the rate constant for FDG phosphorylation, k3, from 0.005 +/- 0.003 min-1 in fasting studies to 0.013 +/- 0.007 min-1 in postglucose administration and, consequently, significantly increased both the phosphorylation fraction (k3/(k2 + k3)) and the influx constant (K1k3/(k2 + k3)). No significant differences in the liver-to-plasma transport rate constant, k2, dephosphorylation constant, k4, or distribution volume of FDG (K1/(k2 + k3)) were observed. CONCLUSION: Dynamic FDG-PET studies can be used to evaluate kinetics of liver glucose metabolism. The results indicate that dietary conditions have a significant effect on hepatic FDG kinetics. Because of the higher net FDG uptake by normal liver after glucose loading, fasting conditions are preferred for FDG liver tumor studies to increase the tumor-to-background contrast.

Published
1994

36. Beneficial effect of residual anterograde flow on tissue viability as assessed by positron emission tomography in patients with myocardial infarction.

Author

SCHWAIGER, M., BRUNKEN, R. C., KRIVOKAPICH, J., CHILD, J. S., TILLISCH, J. H., PHELPS, M. E., and SCHELBERT, H. R.

Abstract

With the advent of therapeutic interventions to restore blood flow in patients with acute infarction, early identification of salvageable myocardium has gained clinical importance. It was the purpose of this study to define regional blood flow and glucose metabolism in patients with acute myocardial infarction as assessed by positron emission tomography (PET) and to correlate these findings with coronary anatomy. In 15 patients blood flow as determined by N-13 ammonia was reduced in 37 left ventricular segments. In 20 segments there was a similar decrease in FDG uptake, consistent with tissue necrosis. In contrast, 17 segments with reduced blood flow revealed maintained FDG uptake suggesting residual viability in the electrocardiographically defined ‘infarct segment’. PET viability and necrosis was significantly associated with presence or absence of anterograde flow in the infarct artery. Evaluation of regional wall motion did not distinguish segments with PET criteria for viability from segments with necrosis. Thus, in patients without thrombolytic therapy during evolving myocardial infarction, spontaneous reperfusion appears to be beneficial for tissue survival. PET offers the unique possibility to assess tissue viability early after the ischaemic injury where evaluation of wall motion fails to identify salvageable myocardium. [ABSTRACT FROM PUBLISHER]

Published
1987
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37. Relation of myocardial perfusion at rest and during pharmacologic stress to the PET patterns of tissue viability in patients with severe left ventricular dysfunction.

Author

Di Carli, M F, Asgarzadie, F, Schelbert, H R, Brunken, R C, Rokhsar, S, and Maddahi, J

Subjects
CORONARY heart disease complications, HEART ventricle diseases, AMMONIA, COMPARATIVE studies, CORONARY circulation, DEOXY sugars, HEART, CARDIAC contraction, LEFT heart ventricle, RESEARCH methodology, MEDICAL cooperation, MYOCARDIUM, RADIOISOTOPES, RADIOPHARMACEUTICALS, RESEARCH, POSITRON emission tomography, VASODILATORS, EVALUATION research, PHENOMENOLOGICAL biology, DIPYRIDAMOLE, PHARMACODYNAMICS
Abstract

Background: Stress perfusion imaging can assess effectively the amount of jeopardized myocardium, but its use for identifying underperfused but viable myocardium has yielded variable results. We evaluated the relation between measurements of myocardial perfusion at rest and during pharmacologic stress and the patterns of tissue viability as determined by positron emission tomographic (PET) imaging.Methods and Results: We studied 33 patients with coronary artery disease and left ventricular (LV) dysfunction (LV ejection fraction, 30%+/-8%). PET imaging was used to evaluate regional myocardial perfusion at rest and during pharmacologic stress with [13N]-ammonia as a flow tracer, and to delineate patterns of tissue viability (i.e., perfusion-metabolism mismatch or match) using [18F]-deoxyglucose (FDG). We analyzed 429 myocardial regions, of which 229 were dysfunctional at rest. Of these, 30 had normal perfusion and 199 were hypoperfused. A severe resting defect (deficit >40% below normal) predicted lack of significant tissue viability; 31 of 35 regions (89%) had a PET match pattern denoting transmural fibrosis. Although regions with mild or moderate resting defects (deficit <40% below normal) showed evidence of metabolic activity, perfusion measurements alone failed to identify regions with PET mismatch (reflecting hibernating myocardium). Reversible stress defects were observed with slightly higher frequency in regions with a PET mismatch (10 of 37) than in those with a PET match (36 of 162) pattern of viability. A reversible stress defect was a specific (78%) marker, but was a relatively insensitive marker (27%) of viable myocardium as defined by the PET mismatch pattern.Conclusions: In patients with LV dysfunction, the severity of regional contractile abnormalities correlates with the severity of flow deficit at rest. Severe reductions in resting blood flow in these dysfunctional regions identify predominantly nonviable myocardium that is unlikely to have improved function after revascularization. Although dysfunctional myocardium with mild to moderate flow reductions contains variable amounts of viable tissue (as assessed by FDG uptake), flow measurements alone do not distinguish between regions with PET mismatch (potentially reversible dysfunction) and PET match (irreversible dysfunction). The presence of an irreversible defect on stress imaging is a relatively specific (78%) marker of PET match, whereas a reversible stress defect is a rather insensitive (27%) marker of viability, as defined by the PET mismatch pattern. [ABSTRACT FROM AUTHOR]

Published
1998

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