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  • 1
    Keywords: evaluation ; Germany ; imaging ; QUANTIFICATION ; SYSTEM ; SYSTEMS ; VOLUME ; NEW-YORK ; ACCURACY ; SURGERY ; validation ; FLOW ; magnetic resonance ; MAGNETIC-RESONANCE ; magnetic resonance imaging ; VECTORS ; VECTOR ; SURFACE ; RECONSTRUCTION ; COLOR DOPPLER ; LACKING ; VOLUMES ; AORTIC REGURGITATION ; CARDIOVASCULAR-SYSTEM ; CONTROL-VOLUME METHOD ; INTEGRATION ; MITRAL REGURGITATION ; QUANTITATIVE ASSESSMENT ; resonance imaging ; respiratory system ; STANDARD ; VALVULAR REGURGITATION ; VELOCITY
    Abstract: Background. Three-dimensional assessment of regurgitant jet volume is the prerequisite for stratifying valve insufficiency. However, systematic comparison of three-dimensional methods is lacking. Therefore, we evaluated magnetic resonance imaging and three-dimensional echocardiography experimentally. Methods. An insufficiency chamber (22 x 18.5 x 27 cm; ostia 10, 16, and 20 mm; regurgitant volumes 2.3 to 25 mL) within experimental circulation (BioMedicus pump, tubes, pulsatile flow 0.2 to 1.9 L/min) was used for three-dimensional echocardiography (HP Sonos 2500) and magnetic resonance imaging (Siemens Magnetom Vision). Doppler flowmeter served as a gold standard. Segmentation used thresholding and surface integration of velocity vectors. jet volume was evaluated qualitatively by polynom fitting. Results. jet volume calculated by magnetic resonance (r = 0.99, p 〈 0.0001) and by echocardiography (r = 0.99, p 〈 0.0001) correlated identically to the gold standard. jet volume derived from imaging correlated with each other by r = 0.98 (p 〈 0.0001). Polynom fits indicated a more paraboloid shape of magnetic resonance jet volume. Conclusions. Experimentally, three-dimensional echocardiography and magnetic resonance imaging possess identical accuracy for determining regurgitant jet volume. Magnetic resonance imaging seems to provide qualitatively better image data for three-dimensional reconstruction. (C) 2004 by The Society of Thoracic Surgeons
    Type of Publication: Journal article published
    PubMed ID: 15223411
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  • 2
    Keywords: CANCER ; tumor ; carcinoma ; Germany ; LUNG ; PERFUSION ; THERAPY ; CT ; DENSITY ; LUNG-CANCER ; NEW-YORK ; TUMORS ; PATIENT ; CONTRAST ; INJECTION ; treatment ; DIFFERENCE ; REGION ; REGIONS ; LOCALIZATION ; PARAMETERS ; tomography ; CARCINOMAS ; COMPUTED-TOMOGRAPHY ; PET ; lung neoplasms ; PULMONARY ; DYNAMIC CT ; X-ray computed
    Abstract: Advanced bronchial carcinomas by means of perfusion and peak enhancement using dynamic contrast-enhanced multislice CT are characterized. Twenty-four patients with advanced bronchial carcinoma were examined. During breathhold, after injection of a contrast-medium (CM), 25 scans were performed (I scan/s) at a fixed table position. Density-time curves were evaluated from regions of interest of the whole tumor and high- and low-enhancing tumor areas. Perfusion and peak enhancement were calculated using the maximum-slope method of Miles and compared with size, localization (central or peripheral) and histology. Perfusion of large tumors (〉50 cm(3)) averaged over both the whole tumor (P=0.001) and the highest enhancing area (P=0.003) was significantly lower than that of smaller ones. Independent of size, central carcinomas had a significantly (P=0.04) lower perfusion (mean 27.9 ml/min/100 g) than peripheral ones (mean 66.5 ml/min/100 9). In contrast, peak enhancement of central and peripheral carcinomas was not significantly different. Between non-small-cell lung cancers and small-cell lung cancers, no significant differences were observed in both parameters. In seven tumors, density increase after CM administration started earlier than in the aorta, indicating considerable blood supply from pulmonary vessels. Tumor perfusion was dependent on tumor size and localization, but not on histology. Furthermore, perfusion CT disclosed blood supply from both pulmonary and/or bronchial vessels in some tumors
    Type of Publication: Journal article published
    PubMed ID: 15029450
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  • 3
    Keywords: ADOLESCENTS, AGE, analysis, ANGIOGRAPHY, Aorta, CHILDREN, comparison, compliance, CONGENITAL HEART-D
    Abstract: Purpose: To compare the aortic compliance of the normal-sized aorta of adolescents with Marfan syndrome and healthy controls using MR measurements of the aortic distensibility and pulse wave velocity. Materials and Methods: Fourteen patients (median age: 15 (9-21] years) and 11 healthy subjects (23 [12-32] years) were examined at 1.5 T. The MR protocol included 2D steady-state free precession (SSFP)-CINE MRI of the aortic distensibility and PC-MRI of the pulse wave velocity. All measurements were positioned perpendicular to the descending,aorta at the level of the diaphragm for assessing the changes in the aortic cross-sectional areas and additionally above and below this plane for assessing the pulse wave velocity. In addition contrast-enhanced 3D-MR angiography was performed in adolescents with Marfan syndrome to exclude morphologic changes and to prove normal-sized aorta. Results: Compared with control subjects, adolescents with Marfan syndrome had significantly decreased distensibility and significantly increased pulse wave velocity (chi(2)-test, p = 0.0002) using an age-related non-linear regression analysis. The related aortic compliance was significantly decreased (chi(2)-test, p = 0.0002). There was a good correlation between the two methods (r = 0.86). A low intraobserver variability was found for both methods (〈= 2 %). Conclusions: MRI allows detecting abnormal elastic aortic wall properties already in the normal-sized aorta of adolescents with Marfan syndrome. Monitoring of these properties could be relevant for evaluating disease onset and progression. MRI has the potential value of compliance measurements for the follow-up and to guide therapy indications
    Type of Publication: Journal article published
    PubMed ID: 17638174
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  • 4
    ISSN: 1432-2102
    Keywords: Schlüsselwörter ; Spiral-CT ; Herz ; Retrospektives Gating ; Zeitauflösung ; Key words ; Spiral CT ; Heart imaging ; Retrospective gating ; Temporal resolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary Purpose: Spiral CT of the heart using the established ways of ECG synchronization is hampered by the relatively long acquisition times of 250 to 500 ms. This only allows to acquire diastolic images in patients with moderate heart rates. In this work, algorithms for time-optimized retrospective cardiac gating are presented, and their potential to improve temporal resolution is investigated. Material and methods: These algorithms use data from multiple gantry rotations for image reconstruction, which is possible for multi-scans at fixed slice positions as well as for overlapping spiral scans. Temporal resolution was quantified using computer simulations and compared to experimental data from pigs. Results: Using a conventional sub-second CT scanner, considerably higher temporal resolutions are possible with spiral scanning. A temporal resolution of 170 ms already provides systolic images with little motion artifacts. Higher temporal resolutions of up to 70 ms are demonstrated for multi-scans, which allows to depict ventricle wall movement over the complete cardiac cycle. Discussion: The method of time-optimized retrospective cardiac gating broadens the spectrum of conventional spiral-CT for cardiac imaging. It can be directly transferred to multi-slice scanners. Here it can be used clinically because of reduced scan time. Potential applications are the determination of functional cardiac parameters like ejection fraction and the detection of disorders of ventricle wall movement.
    Notes: Zusammenfassung Zielsetzung: Die Spiral-CT des Herzens ist mit bisherigen Verfahren zur EKG-Synchronisation nur eingeschränkt möglich. Die Aufnahmezeit von ca. 250 bis 500 ms ermöglicht nur diastolische Aufnahmen bei Patienten mit moderater Herzfrequenz. In dieser Arbeit wurden Algorithmen zum zeitoptimierten retrospektiven EKG-Gating entwickelt und untersucht, wie höhere Zeitauflösungen erreicht werden können. Material und Methode: Das Prinzip der Algorithmen ist es, Daten von mehreren Gantry-Umläufen für die Bildrekonstruktion heranzuziehen. Dies ist sowohl in einzelnen Schichten als auch bei Spiralscans mit überlappenden Aufnahmeschichten möglich. Die Zeitauflösung wurde durch Computersimulationen für verschiedene Aufnahmeparameter bestimmt und mit Experimenten an Schweinen verglichen. Ergebnisse: Es zeigt sich, dass mit einem Standard-Subsekunden-CT-Scanner mit überlappenden Spiralen deutlich höhere Zeitauflösungen möglich sind, bereits 170 ms ermöglichen eine Darstellung der Systole mit nur minimalen Bewegungsartefakten. An einzelnen Schichten wurden Zeitauflösungen von bis zu 70 ms demonstriert, womit die Herzwandbewegung über den kompletten Herzzyklus dargestellt werden kann. Diskussion: Die Methode des zeitoptimierten retrospektiven EKG-Gating erweitert die Einsatzmöglichkeiten herkömmlicher Spiral-CTs für die Bildgebung des Herzens. Sie lässt sich direkt auf Multizeilen-CTs übertragen, wo sie wegen der Reduktion der Untersuchungszeit klinisch eingesetzt werden kann. Mögliche Anwendungen sind die Bestimmung von funktionellen Herzparametern wie Ejektionsfraktion und die Detektion von Wandbewegungsstörungen.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1435-2451
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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