Kowallick, Johannes Tammo

[["dc.bibliographiccitation.firstpage","1066"],["dc.bibliographiccitation.issue","10"],["dc.bibliographiccitation.journal","Clinical Radiology"],["dc.bibliographiccitation.lastpage","1071"],["dc.bibliographiccitation.volume","69"],["dc.contributor.author","Fasshauer, Martin"],["dc.contributor.author","Joseph, Arun A."],["dc.contributor.author","Kowallick, Johannes Tammo"],["dc.contributor.author","Unterberg-Buchwald, Christine"],["dc.contributor.author","Merboldt, Klaus-Dietmar"],["dc.contributor.author","Voit, Dirk"],["dc.contributor.author","Steinmetz, M."],["dc.contributor.author","Staab, Wieland"],["dc.contributor.author","Schaetz, S."],["dc.contributor.author","Zhang, S."],["dc.contributor.author","Frahm, Jens"],["dc.contributor.author","Lotz, Joachim"],["dc.contributor.author","Sohns, J. M."],["dc.date.accessioned","2018-11-07T09:34:30Z"],["dc.date.available","2018-11-07T09:34:30Z"],["dc.date.issued","2014"],["dc.description.abstract","AIM: To evaluate the potential of real-time phase-contrast flow magnetic resonance imaging (MRI) at 40 ms resolution for the simultaneous determination of blood flow in the ascending aorta (AA) and superior vena cava (SVC) in response to reduced intrathoracic pressure (Mueller manoeuvre). MATERIALS AND METHODS: Through-plane flow was assessed in 20 healthy young subjects using real-time phase-contrast MRI based on highly undersampled radial fast low-angle shot (FLASH) with image reconstruction by regularized non-linear inversion. Haemodynamic alterations (three repetitions per subject = 60 events) were evaluated during normal breathing (10 s), inhalation with nearly closed epiglottis (10 s), and recovery (20 s). RESULTS: Relative to normal breathing and despite interindividual differences, reduced intrathoracic pressure by at least 30 mmHg significantly decreased the initial peak mean velocity (averaged across the lumen) in the AA by -24 +/- 9% and increased the velocity in the SVC by +28 +/- 25% (p < 0.0001, n = 23 successful events). Respective changes in flow volume per heartbeat were -25 +/- 9% in the AA and +49 +/- 44% in the SVC (p < 0.0001, n = 23). Flow parameters returned to baseline during sustained pressure reduction, while the heart rate was elevated by 10% (p < 0.0001) after the start (n = 24) and end (n = 17) of the manoeuvre. CONCLUSIONS: Real-time flow MRI during low intrathoracic pressure non-invasively revealed quantitative haemodynamic adjustments in both the AA and SVC. (C) 2014 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved."],["dc.description.sponsorship","DFG [LO 1773/1]"],["dc.identifier.doi","10.1016/j.crad.2014.06.004"],["dc.identifier.isi","000342881800013"],["dc.identifier.pmid","25060931"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/32184"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","W B Saunders Co Ltd"],["dc.relation.issn","1365-229X"],["dc.relation.issn","0009-9260"],["dc.title","Real-time phase-contrast flow MRI of haemodynamic changes in the ascending aorta and superior vena cava during Mueller manoeuvre"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","206"],["dc.bibliographiccitation.issue","1"],["dc.bibliographiccitation.journal","Journal of magnetic resonance imaging : JMRI"],["dc.bibliographiccitation.lastpage","213"],["dc.bibliographiccitation.volume","40"],["dc.contributor.author","Joseph, Arun"],["dc.contributor.author","Kowallick, Johannes T."],["dc.contributor.author","Merboldt, Klaus-Dietmar"],["dc.contributor.author","Voit, Dirk"],["dc.contributor.author","Schaetz, Sebastian"],["dc.contributor.author","Zhang, Shuo"],["dc.contributor.author","Sohns, Jan M."],["dc.contributor.author","Lotz, Joachim"],["dc.contributor.author","Frahm, Jens"],["dc.date.accessioned","2019-07-09T11:41:30Z"],["dc.date.available","2019-07-09T11:41:30Z"],["dc.date.issued","2014-07-01"],["dc.description.abstract","PURPOSE: To evaluate a novel real-time phase-contrast magnetic resonance imaging (MRI) technique for the assessment of through-plane flow in the ascending aorta. MATERIALS AND METHODS: Real-time MRI was based on a radial fast low-angle shot (FLASH) sequence with about 30-fold undersampling and image reconstruction by regularized nonlinear inversion. Phase-contrast maps were obtained from two (interleaved or sequential) acquisitions with and without a bipolar velocity-encoding gradient. Blood flow in the ascending aorta was studied in 10 healthy volunteers at 3 T by both real-time MRI (15 sec during free breathing) and electrocardiogram (ECG)-synchronized cine MRI (with and without breath holding). Flow velocities and stroke volumes were evaluated using standard postprocessing software. RESULTS: The total acquisition time for a pair of phase-contrast images was 40.0 msec (TR/TE = 2.86/1.93 msec, 10° flip angle, 7 spokes per image) for a nominal in-plane resolution of 1.3 mm and a section thickness of 6 mm. Quantitative evaluations of spatially averaged flow velocities and stroke volumes were comparable for real-time and cine methods when real-time MRI data were averaged across heartbeats. For individual heartbeats real-time phase-contrast MRI resulted in higher peak velocities for values above 120 cm s(-1). CONCLUSION: Real-time phase-contrast MRI of blood flow in the human aorta yields functional parameters for individual heartbeats. When averaged across heartbeats real-time flow velocities and stroke volumes are comparable to values obtained by conventional cine MRI."],["dc.identifier.doi","10.1002/jmri.24328"],["dc.identifier.fs","605197"],["dc.identifier.pmid","24123295"],["dc.identifier.purl","https://resolver.sub.uni-goettingen.de/purl?gs-1/12139"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/58445"],["dc.language.iso","en"],["dc.notes.intern","Merged from goescholar"],["dc.relation.issn","1522-2586"],["dc.rights","CC BY-NC 4.0"],["dc.rights.uri","https://creativecommons.org/licenses/by-nc/4.0"],["dc.subject.mesh","Adult"],["dc.subject.mesh","Algorithms"],["dc.subject.mesh","Aorta"],["dc.subject.mesh","Blood Flow Velocity"],["dc.subject.mesh","Computer Systems"],["dc.subject.mesh","Humans"],["dc.subject.mesh","Image Enhancement"],["dc.subject.mesh","Image Interpretation, Computer-Assisted"],["dc.subject.mesh","Magnetic Resonance Angiography"],["dc.subject.mesh","Magnetic Resonance Imaging, Cine"],["dc.subject.mesh","Male"],["dc.subject.mesh","Reproducibility of Results"],["dc.subject.mesh","Rheology"],["dc.subject.mesh","Sensitivity and Specificity"],["dc.subject.mesh","Young Adult"],["dc.title","Real-time flow MRI of the aorta at a resolution of 40 msec."],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.version","published_version"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.artnumber","20140401"],["dc.bibliographiccitation.issue","1042"],["dc.bibliographiccitation.journal","British Journal of Radiology"],["dc.bibliographiccitation.volume","87"],["dc.contributor.author","Kowallick, Johannes Tammo"],["dc.contributor.author","Joseph, Arun A."],["dc.contributor.author","Unterberg-Buchwald, Christine"],["dc.contributor.author","Fasshauer, Martin"],["dc.contributor.author","van Wijk, K."],["dc.contributor.author","Merboldt, Klaus-Dietmar"],["dc.contributor.author","Voit, Dirk"],["dc.contributor.author","Frahm, Jens"],["dc.contributor.author","Lotz, Joachim"],["dc.contributor.author","Sohns, J. M."],["dc.date.accessioned","2018-11-07T09:34:40Z"],["dc.date.available","2018-11-07T09:34:40Z"],["dc.date.issued","2014"],["dc.description.abstract","Objective: Real-time phase-contrast flow MRI at high spatiotemporal resolution was applied to simultaneously evaluate haemodynamic functions in the ascending aorta (AA) and superior vena cava (SVC) during elevated intrathoracic pressure (Valsalva manoeuvre). Methods: Real-time phase-contrast flow MRI at 3 T was based on highly undersampled radial gradient-echo acquisitions and phase-sensitive image reconstructions by regularized non-linear inversion. Dynamic alterations of flow parameters were obtained for 19 subjects at 40-ms temporal resolution, 1.33-mm in-plane resolution and 6-mm section thickness. Real-time measurements were performed during normal breathing (10 s), increased intrathoracic pressure (10 s) and recovery (20 s). Results: Real-time measurements were technically successful in all volunteers. During the Valsalva manoeuvre (late strain) and relative to values during normal breathing, the mean peak flow velocity and flow volume decreased significantly in both vessels (p < 0.001) followed by a return to normal parameters within the first 10 s of recovery in the AA. By contrast, flow in the SVC presented with a brief (1-2 heartbeats) but strong overshoot of both the peak velocity and blood volume immediately after pressure release followed by rapid normalization. Conclusion: Real-time phase-contrast flow MRI may assess cardiac haemodynamics non-invasively, in multiple vessels, across the entire luminal area and at high temporal and spatial resolution. Advances in knowledge: Future clinical applications of this technique promise new insights into haemodynamic alterations associated with pre-clinical congestive heart failure or diastolic dysfunction, especially in cases where echocardiography is technically compromised."],["dc.description.sponsorship","DFG [LO 1773/1-1]"],["dc.identifier.doi","10.1259/bjr.20140401"],["dc.identifier.isi","000342620300018"],["dc.identifier.pmid","25074791"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/32222"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","British Inst Radiology"],["dc.relation.issn","1748-880X"],["dc.relation.issn","0007-1285"],["dc.title","Real-time phase-contrast flow MRI of the ascending aorta and superior vena cava as a function of intrathoracic pressure (Valsalva manoeuvre)"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.issue","S1"],["dc.bibliographiccitation.journal","Journal of Cardiovascular Magnetic Resonance"],["dc.bibliographiccitation.volume","15"],["dc.contributor.author","Sohns, Jan Martin"],["dc.contributor.author","Unterberg-Buchwald, Christina"],["dc.contributor.author","Kowallick, Johannes Tammo"],["dc.contributor.author","Steinmetz, Michael"],["dc.contributor.author","Schulte, Christina"],["dc.contributor.author","Staab, Wieland"],["dc.contributor.author","Joseph, Arun A."],["dc.contributor.author","Merboldt, Klaus-Dietmar"],["dc.contributor.author","Voit, Dirk"],["dc.contributor.author","Zhang, Shuo"],["dc.contributor.author","Uecker, Martin"],["dc.contributor.author","Frahm, Jens"],["dc.contributor.author","Lotz, Joachim"],["dc.date.accessioned","2020-05-13T13:46:13Z"],["dc.date.available","2020-05-13T13:46:13Z"],["dc.date.issued","2013"],["dc.description.abstract","Background A high resolution real-time phase-contrast MRI flow technique was used to measure flow dynamics in the ascending aorta as well as superior vena cava. MRI technique based on undersampled radial fast low-angle shot acquisitions with phase-sensitive image reconstructions by regularized nonlinear inversion. Normal flow values as well as flow measurements during physiologic stress tests like Valsalva (increased intrathoracic pressure) and Mueller (decreased intrathoracic pressure, reverse of Valsalva maneuver) were obtained in healthy volunteers. Methods Blood flow was measured in the ascending aorta and superior vena cava using a single scan plane perpendicular to the ascending aorta at the level of the right pulmonary artery. In-plane resolution of 1.8 mm, section thickness of 6 mm at a real-time resolution of 48 ms was achieved by TR 3.44 ms; TE 2.76 ms; flip angle, 10 degrees and seven radial spokes per image. Scans were done in a clinical 3T scanner. ECG was co-registered for documentation only. Realtime scans were done for 20 seconds in normal measurements, 30 seconds for physiologic and stress maneuvers - 10 seconds normal breathing, 10 seconds applied stress, 10 seconds recovery time. Image analysis was done using a specifically modified prototype software Qflow by Medis, NL. Results Realtime measurements were successful in all cases. We observed a decrease of blood-flow during Valsalva and Mueller maneuver in the ascending aorta. At the beginning of the maneuver, the blood flow increased under both increased and reduced intrathoracic pressure, followed by a continuous period of nearly 20 sec of decreased flow. A reactive hyperdynamic flow response was detected after restarting regular breathing. Conclusions High resolution real-time MRI flow measurements are able to resolve detailed physiological blood flow changes during Vasalva and Mueller maneuvers with high reliability. The results are in consistence with published echocardiography studies on Valsalva and Mueller maneuvers. Free breathing and patient's movement did not disturb the scan and image quality with this new technique. This technique might provide new insights into pathophysiologic changes associated for example with preclinical congestive heart failure."],["dc.identifier.doi","10.1186/1532-429X-15-S1-E17"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/65378"],["dc.language.iso","en"],["dc.relation.issn","1532-429X"],["dc.title","Real-time cardiac phase contrast MRI blood flow including Valsalva and Mueller maneuver. Initial experiences"],["dc.type","journal_article"],["dc.type.internalPublication","unknown"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.issue","S1"],["dc.bibliographiccitation.journal","Journal of Cardiovascular Magnetic Resonance"],["dc.bibliographiccitation.volume","15"],["dc.contributor.author","Lotz, Joachim"],["dc.contributor.author","Sohns, Jan Martin"],["dc.contributor.author","Steinmetz, Michael"],["dc.contributor.author","Kowallick, Johannes Tammo"],["dc.contributor.author","Schulte, Christina"],["dc.contributor.author","Staab, Wieland"],["dc.contributor.author","Joseph, Arun A."],["dc.contributor.author","Merboldt, Klaus-Dietmar"],["dc.contributor.author","Voit, Dirk"],["dc.contributor.author","Zhang, Shuo"],["dc.contributor.author","Uecker, Martin"],["dc.contributor.author","Unterberg-Buchwald, Christina"],["dc.contributor.author","Hasenfuss, Gerd"],["dc.contributor.author","Frahm, Jens"],["dc.date.accessioned","2020-05-13T13:46:20Z"],["dc.date.available","2020-05-13T13:46:20Z"],["dc.date.issued","2013"],["dc.description.abstract","Background A new MRI technology for real-time MRI at high temporal and high spatial resolution was applied to CMR. First clinical applications cover dynamic imaging of wall motion and volume changes during cardiac arrhythmias as well as quantitative flow measurements under physiologic stress maneuvers. Methods A recently introduced real-time MRI method based on undersampled radial FLASH sequences with image reconstruction by regularized nonlinear inversion was applied to CMR. Anatomical imaging in real time was performed at 34 ms temporal resolution (30 fps) using 1.5 mm in-plane resolution and 6 mm slice thickness. Real-time quantitative flow measurements employed two acquisitions at 20 ms resolution, yielding a temporal resolution of 40 ms (25 fps) at 1.3 mm in-plane resolution and 6 mm slice thickness. Healthy volunteers as well as patients with arrhythmia were examined in a clinical 3T MR scanner. The image series were analyzed using a modified standard software capable of dealing with 100 to 900 images per slice position. The ECG signal was co-registered for documentation and ease of image analysis. Results The new high-resolution real-time MRI technique was used to analyze the beat-to-beat variability of patients with arrhythmia and to define ejection fractions in normal and arrhythmic episodes. Quantitative flow measurements were obtained in all major intrathoracic vessels during free breathing. Specific measurements during increased (Valsalva maneouver) and reduced intrathoracic pressure (Mueller maneouver) were obtained in healthy volunteers to document cardiovascular response to physiologic stressors. Regional wall motion, ventricular volumes, myocardial mass and ejection fraction were derived including standard deviations based on temporal variability of the heart cycle. Suitable software strategies for the analysis of the large datasets are indispensible to bring real-time CMR into clinical routine. Conclusions Real-time CMR with high temporal and high spatial resolution emerges as a promising tool for future clinical studies."],["dc.identifier.doi","10.1186/1532-429X-15-S1-E99"],["dc.identifier.purl","https://resolver.sub.uni-goettingen.de/purl?gs-1/8915"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/65379"],["dc.language.iso","en"],["dc.notes.intern","Merged from goescholar"],["dc.relation.issn","1532-429X"],["dc.rights","Goescholar"],["dc.rights.uri","https://goescholar.uni-goettingen.de/licenses"],["dc.title","High resolution real-time CMR of function and flow: initial clinical results"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.version","published_version"],["dspace.entity.type","Publication"]]