Frahm, Jens

[["dc.bibliographiccitation.artnumber","10"],["dc.bibliographiccitation.issue","1"],["dc.bibliographiccitation.journal","Fluids and Barriers of the CNS"],["dc.bibliographiccitation.volume","16"],["dc.contributor.author","Aktas, Gökmen"],["dc.contributor.author","Kollmeier, Jost M."],["dc.contributor.author","Joseph, Arun A."],["dc.contributor.author","Merboldt, Klaus-Dietmar"],["dc.contributor.author","Ludwig, Hans-Christoph"],["dc.contributor.author","Gärtner, Jutta"],["dc.contributor.author","Frahm, Jens"],["dc.contributor.author","Dreha-Kulaczewski, Steffi"],["dc.date.accessioned","2019-07-09T11:50:48Z"],["dc.date.available","2019-07-09T11:50:48Z"],["dc.date.issued","2019"],["dc.description.abstract","Background Respiration-induced pressure changes represent a powerful driving force of CSF dynamics as previously demonstrated using flow-sensitive real-time magnetic resonance imaging (MRI). The purpose of the present study was to elucidate the sensitivity of CSF flow along the spinal canal to forced thoracic versus abdominal respiration. Methods Eighteen subjects without known illness were studied using real-time phase-contrast flow MRI at 3 T in the aqueduct and along the spinal canal at levels C3, Th1, Th8 and L3. Subjects performed a protocol of forced breathing comprising four cycles of 2.5 s inspiration and 2.5 s expiration. Results The quantitative results for spinal CSF flow rates and volumes confirm previous findings of an upward movement during forced inspiration and reversed downward flow during subsequent exhalation—for both breathing types. However, the effects were more pronounced for abdominal than for thoracic breathing, in particular at spinal levels Th8 and L3. In general, CSF net flow volumes were very similar for both breathing conditions pointing upwards in all locations. Conclusions Spinal CSF dynamics are sensitive to varying respiratory performances. The different CSF flow volumes in response to deep thoracic versus abdominal breathing reflect instantaneous adjustments of intrathoracic and intraabdominal pressure, respectively. Real-time MRI access to CSF flow in response to defined respiration patterns will be of clinical importance for patients with disturbed CSF circulation like hydrocephalus, pseudotumor cerebri and others."],["dc.identifier.doi","10.1186/s12987-019-0130-0"],["dc.identifier.pmid","30947716"],["dc.identifier.purl","https://resolver.sub.uni-goettingen.de/purl?gs-1/16002"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/59832"],["dc.language.iso","en"],["dc.notes.intern","Merged from goescholar"],["dc.rights","CC BY 4.0"],["dc.rights.uri","https://creativecommons.org/licenses/by/4.0"],["dc.title","Spinal CSF flow in response to forced thoracic and abdominal respiration"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.version","published_version"],["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","39"],["dc.bibliographiccitation.journal","Journal of Cardiovascular Magnetic Resonance"],["dc.bibliographiccitation.volume","12"],["dc.contributor.author","Zhang, Shuo"],["dc.contributor.author","Uecker, Martin"],["dc.contributor.author","Voit, Dirk"],["dc.contributor.author","Merboldt, Klaus-Dietmar"],["dc.contributor.author","Frahm, Jens"],["dc.date.accessioned","2017-09-07T11:45:20Z"],["dc.date.available","2017-09-07T11:45:20Z"],["dc.date.issued","2010"],["dc.description.abstract","Background: Functional assessments of the heart by dynamic cardiovascular magnetic resonance (CMR) commonly rely on (i) electrocardiographic (ECG) gating yielding pseudo real-time cine representations, (ii) balanced gradient-echo sequences referred to as steady-state free precession (SSFP), and (iii) breath holding or respiratory gating. Problems may therefore be due to the need for a robust ECG signal, the occurrence of arrhythmia and beat to beat variations, technical instabilities (e.g., SSFP \"banding\" artefacts), and limited patient compliance and comfort. Here we describe a new approach providing true real-time CMR with image acquisition times as short as 20 to 30 ms or rates of 30 to 50 frames per second. Methods: The approach relies on a previously developed real-time MR method, which combines a strongly undersampled radial FLASH CMR sequence with image reconstruction by regularized nonlinear inversion. While iterative reconstructions are currently performed offline due to limited computer speed, online monitoring during scanning is accomplished using gridding reconstructions with a sliding window at the same frame rate but with lower image quality. Results: Scans of healthy young subjects were performed at 3 T without ECG gating and during free breathing. The resulting images yield T1 contrast (depending on flip angle) with an opposed-phase or in-phase condition for water and fat signals (depending on echo time). They completely avoid (i) susceptibility-induced artefacts due to the very short echo times, (ii) radiofrequency power limitations due to excitations with flip angles of 10 degrees or less, and ( iii) the risk of peripheral nerve stimulation due to the use of normal gradient switching modes. For a section thickness of 8 mm, real-time images offer a spatial resolution and total acquisition time of 1.5 mm at 30 ms and 2.0 mm at 22 ms, respectively. Conclusions: Though awaiting thorough clinical evaluation, this work describes a robust and flexible acquisition and reconstruction technique for real-time CMR at the ultimate limit of this technology."],["dc.identifier.doi","10.1186/1532-429X-12-39"],["dc.identifier.gro","3142887"],["dc.identifier.isi","000282340700001"],["dc.identifier.pmid","20615228"],["dc.identifier.purl","https://resolver.sub.uni-goettingen.de/purl?gs-1/5669"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/340"],["dc.notes.intern","WoS Import 2017-03-10"],["dc.notes.intern","Merged from goescholar"],["dc.notes.status","final"],["dc.notes.submitter","PUB_WoS_Import"],["dc.publisher","Biomed Central Ltd"],["dc.relation.issn","1097-6647"],["dc.rights","CC BY 2.0"],["dc.rights.uri","https://creativecommons.org/licenses/by/2.0"],["dc.title","Real-time cardiovascular magnetic resonance at high temporal resolution: radial FLASH with nonlinear inverse reconstruction"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.subtype","original"],["dc.type.version","published_version"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.issue","1"],["dc.bibliographiccitation.journal","Scientific Reports"],["dc.bibliographiccitation.volume","8"],["dc.contributor.author","Dreha-Kulaczewski, Steffi"],["dc.contributor.author","Konopka, Mareen"],["dc.contributor.author","Joseph, Arun A"],["dc.contributor.author","Kollmeier, Jost"],["dc.contributor.author","Merboldt, Klaus-Dietmar"],["dc.contributor.author","Ludwig, Hans-Christoph"],["dc.contributor.author","Gärtner, Jutta"],["dc.contributor.author","Frahm, Jens"],["dc.date.accessioned","2020-12-10T18:10:09Z"],["dc.date.available","2020-12-10T18:10:09Z"],["dc.date.issued","2018"],["dc.identifier.doi","10.1038/s41598-018-23908-z"],["dc.identifier.eissn","2045-2322"],["dc.identifier.purl","https://resolver.sub.uni-goettingen.de/purl?gs-1/15427"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/73869"],["dc.language.iso","en"],["dc.notes.intern","DOI Import GROB-354"],["dc.notes.intern","Merged from goescholar"],["dc.rights","CC BY 4.0"],["dc.rights.uri","https://creativecommons.org/licenses/by/4.0"],["dc.title","Respiration and the watershed of spinal CSF flow in humans"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.version","published_version"],["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"]]