Frahm, Jens

[["dc.bibliographiccitation.firstpage","730"],["dc.bibliographiccitation.issue","2"],["dc.bibliographiccitation.journal","Magnetic Resonance in Medicine"],["dc.bibliographiccitation.lastpage","740"],["dc.bibliographiccitation.volume","79"],["dc.contributor.author","Wang, Xiaoqing"],["dc.contributor.author","Roeloffs, Volkert"],["dc.contributor.author","Klosowski, Jakob"],["dc.contributor.author","Tan, Zhengguo"],["dc.contributor.author","Voit, Dirk"],["dc.contributor.author","Uecker, Martin"],["dc.contributor.author","Frahm, Jens"],["dc.date.accessioned","2018-01-17T13:53:19Z"],["dc.date.accessioned","2020-05-13T11:04:28Z"],["dc.date.available","2018-01-17T13:53:19Z"],["dc.date.available","2020-05-13T11:04:28Z"],["dc.date.issued","2018"],["dc.description.abstract","To develop a model-based reconstruction technique for single-shot T1 mapping with high spatial resolution, accuracy, and precision using an inversion-recovery (IR) fast low-angle shot (FLASH) acquisition with radial encoding."],["dc.identifier.doi","10.1002/mrm.26726"],["dc.identifier.pmid","28603934"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/11736"],["dc.language.iso","en"],["dc.notes.status","final"],["dc.relation.doi","10.1002/mrm.26726"],["dc.relation.issn","1522-2594"],["dc.title","Model-based T1 mapping with sparsity constraints using single-shot inversion-recovery radial FLASH"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.journal","Japanese Journal of Radiology"],["dc.contributor.author","Biggemann, Lorenz"],["dc.contributor.author","Uhlig, Johannes"],["dc.contributor.author","Gliem, Nina"],["dc.contributor.author","Al-Bourini, Omar"],["dc.contributor.author","Wedi, Edris"],["dc.contributor.author","Ellenrieder, Volker"],["dc.contributor.author","Ghadimi, Michael"],["dc.contributor.author","Uecker, Martin"],["dc.contributor.author","Frahm, Jens"],["dc.contributor.author","Lotz, Joachim"],["dc.contributor.author","Streit, Ulrike"],["dc.date.accessioned","2022-01-11T14:05:34Z"],["dc.date.available","2022-01-11T14:05:34Z"],["dc.date.issued","2021"],["dc.description.abstract","Abstract Purpose To assess the esophagogastric junction (EGJ) on real-time MRI and compare imaging parameters to EGJ morphology on high-resolution manometry (HRM). Methods A total of 105 of 117 eligible patients who underwent real-time MRI and high-resolution manometry for GERD-like symptoms between 2015 and 2018 at a single center were retrospectively evaluated (male n  = 57; female n  = 48; mean age 52.5 ± 15.4 years). Real-time MRI was performed at a median investigation time of 15 min (1 frame/40 ms). On HRM, EGJ morphology was assessed according to the Chicago classification of esophageal motility disorders. Real-time MRI was performed at 3 T using highly undersampled radial fast low-angle shot acquisitions with NLINV image reconstruction. A 10 mL pineapple juice bolus served as oral contrast agent at supine position. Real-time MRI films of the EGJ were acquired during swallowing events and during Valsalva maneuver. Anatomic and functional MRI parameters were compared to EGJ morphology on HRM. Results On HRM, n  = 42 patients presented with EGJ type I (40.0%), n  = 33 with EGJ type II (31.4%), and n  = 30 with EGJ type III (28.6%). On real-time MRI, hiatal hernia was more common in patients with EGJ type III (66.7%) than in patients with EGJ type I (26.2%) and EGJ type II (30.3%; p  < 0.001). Sliding hiatal hernia was more frequent in patients with EGJ type II (33.3%) than in patients with EGJ type III (16.7%) and EGJ type I (7.1%; p  = 0.017). The mean esophagus–fundus angle of patients was 85 ± 31° at rest and increased to 101 ± 36° during Valsalva maneuver. Conclusion Real-time MRI is a non-invasive imaging method for assessment of the esophagogastric junction. Real-time MRI can visualize dynamic changes of the EGJ during swallowing events."],["dc.identifier.doi","10.1007/s11604-021-01210-9"],["dc.identifier.pii","1210"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/97695"],["dc.language.iso","en"],["dc.notes.intern","DOI-Import GROB-507"],["dc.relation.eissn","1867-108X"],["dc.relation.issn","1867-1071"],["dc.relation.orgunit","Universitätsmedizin Göttingen"],["dc.relation.orgunit","Institut für Diagnostische und Interventionelle Neuroradiologie"],["dc.relation.orgunit","Max-Planck-Institut für biophysikalische Chemie"],["dc.title","Assessment of esophagogastric junction morphology by dynamic real-time MRI: comparison of imaging features to high-resolution manometry"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.subtype","original_ja"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.artnumber","3527269"],["dc.bibliographiccitation.firstpage","1"],["dc.bibliographiccitation.journal","Computational and Mathematical Methods in Medicine"],["dc.bibliographiccitation.lastpage","11"],["dc.bibliographiccitation.volume","2017"],["dc.contributor.author","Schaetz, Sebastian"],["dc.contributor.author","Voit, Dirk"],["dc.contributor.author","Frahm, Jens"],["dc.contributor.author","Uecker, Martin"],["dc.date.accessioned","2019-07-09T11:45:03Z"],["dc.date.accessioned","2020-05-13T11:05:04Z"],["dc.date.available","2019-07-09T11:45:03Z"],["dc.date.available","2020-05-13T11:05:04Z"],["dc.date.issued","2017"],["dc.description.abstract","To develop generic optimization strategies for image reconstruction using graphical processing units (GPUs) in magnetic resonance imaging (MRI) and to exemplarily report on our experience with a highly accelerated implementation of the nonlinear inversion (NLINV) algorithm for dynamic MRI with high frame rates."],["dc.identifier.doi","10.1155/2017/3527269"],["dc.identifier.pmid","29463984"],["dc.identifier.purl","https://resolver.sub.uni-goettingen.de/purl?gs-1/15017"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/59150"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/65303"],["dc.language.iso","en"],["dc.notes.intern","Merged from goescholar"],["dc.relation.eissn","1748-6718"],["dc.relation.issn","1748-670X"],["dc.rights","Goescholar"],["dc.rights.uri","https://goescholar.uni-goettingen.de/licenses"],["dc.subject.ddc","610"],["dc.title","Accelerated Computing in Magnetic Resonance Imaging: Real-Time Imaging Using Nonlinear Inverse Reconstruction"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.version","published_version"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.issue","S 01"],["dc.bibliographiccitation.journal","RöFo"],["dc.bibliographiccitation.volume","185"],["dc.contributor.author","Sohns, Jan Martin"],["dc.contributor.author","Kowallick, Johannes Tammo"],["dc.contributor.author","Unterberg-Buchwald, Susan C."],["dc.contributor.author","Staab, Wieland"],["dc.contributor.author","Baur, Joseph A."],["dc.contributor.author","Merboldt, K. D."],["dc.contributor.author","Uecker, Martin"],["dc.contributor.author","Voit, D."],["dc.contributor.author","Zhang, S."],["dc.contributor.author","Frahm, Jens"],["dc.contributor.author","Lotz, Joachim"],["dc.date.accessioned","2020-05-13T13:45:52Z"],["dc.date.available","2020-05-13T13:45:52Z"],["dc.date.issued","2013"],["dc.description.abstract","Ziele: Hochaufgelöste Echtzeit-Phasenkontrast-MRT-Flussmessungen wurden u.a. in der Aorta ascendens angewendet. Die MRT-Technik basiert auf einer stark unterabgetasteten radialen FLASH-Sequenz und anschließender Bildrekonstruktion mit nicht-linearer Inversion. Normale Flussmessungen und Flusswerte wurden während physiologischer Stresstests wie dem Valsalva- (erhöhter intrathorakaler Druck) und Müllermaneuver (erniedrigter intrathorakaler Druck) bei gesunden Probanden durchgeführt. Methode: Der Blutfluss wurde in den großen thorakalen Gefäßen gemessen, In-plane 1.2 mm, Schichtdicke 6 mm und realer Echtzeitauflösung von 40 ms. Die TR betrug 3.44 ms, TE 2.76 ms. Alle Scans wurden in einem 3T MRT durchgeführt. Das EKG-Signal wurde zur besseren Zuordnung der Herzphasen mit aufgezeichnet. Die Echtzeitmessungen wurden in Ruhe sowie 10 s Valsalva und 10 s Müllermanöver durchgeführt. Die Bildanalyse erfolgte in einer modifizierten Standardsoftware QFlow, Medis, Leiden NL. Ergebnis: Echtzeitflussmessungen konnten erfolgreich bei allen Probanden (n = 10) durchgeführt werden. Wir beobachteten unter Stressbedingungen einen Abfall des Blutflusses, der Maximalgeschwindigkeit und der kardialen Auswurfleistung sowie eine Herzfrequenzzunahme unter Valsalva- und Müllermaneuver in der Aorta ascendens. Zu Beginn der Stressmaneuver stieg der Blutfluss und die Auswurfleitung initial an unter erhöhten und reduzierten intrathorakalen Druckverhältnissen, gefolgt von einer kontinuierlichen 10 s dauernden Abnahme. Anschließend folgte wieder eine Normalisierung nach Stressbeendigung. Schlussfolgerung: Hoch aufgelöste Echtzeit-MRT-Flussmessungen sind sehr gut dafür geeignet um physiologische Blutflussveränderungen während dem Valsalva- und Müllermaneuver bei Stressbedingungen darzustellen. Die Ergebnisse stimmen mit Beobachtungen aus der Echokardiografie überein. Mit dieser neuen Echtzeit-Flusstechnik gibt es neue Möglichkeiten um pathologische Veränderungen am Herzen darzustellen wie bei angeborenen Herzfehlern oder Kardiomyopathien."],["dc.identifier.doi","10.1055/s-0033-1346232"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/65375"],["dc.language.iso","de"],["dc.relation.eissn","1438-9010"],["dc.relation.issn","1438-9029"],["dc.title","Echtzeit-Cardio-MRT-Phasenkontrast-Flussmessungen mit dem Valsalva- und Müllermaneuver als Stresstest"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dspace.entity.type","Publication"]]

[["dc.contributor.author","Frahm, Jens"],["dc.contributor.author","Uecker, Martin"],["dc.contributor.author","Zhang, Shuo"],["dc.date.accessioned","2020-05-13T13:46:06Z"],["dc.date.available","2020-05-13T13:46:06Z"],["dc.date.issued","2013"],["dc.description.abstract","A method for reconstructing a sequence of magnetic resonance (MR) images of an object under investigation, includes the steps of (a) providing a series of sets of image raw data including an image content of the MR images to be reconstructed, the image raw data being collected with the use of at least one radiofrequency receiver coil of a magnetic resonance imaging (MRI) device, wherein each set of image raw data includes a plurality of data samples being generated with a gradient-echo sequence, in particular a FLASH sequence, that spatially encodes an MRI signal received with the at least one radiofrequency receiver coil using a non-Cartesian k-space trajectory, each set of image raw data includes a set of homogeneously distributed lines in k-space with equivalent spatial frequency content, the lines of each set of image raw data cross the center of k-space and cover a continuous range of spatial frequencies, and the positions of the lines of each set of image raw data differ in successive sets of image raw data, and (b) subjecting the sets of image raw data to a regularized nonlinear inverse reconstruction process to provide the sequence of MR images, wherein each of the MR images is created by a simultaneous estimation of a sensitivity of the at least one receiver coil and the image content and in dependency on a difference between a current estimation of the sensitivity of the at least one receiver coil and the image content and a preceding estimation of the sensitivity of the at least one receiver coil and the image content."],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/65377"],["dc.language.iso","en"],["dc.title","Method and device for reconstructing a sequence of magnetic resonance images"],["dc.type","patent"],["dc.type.internalPublication","yes"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","4691"],["dc.bibliographiccitation.issue","9"],["dc.bibliographiccitation.journal","European Radiology"],["dc.bibliographiccitation.lastpage","4698"],["dc.bibliographiccitation.volume","29"],["dc.contributor.author","Hosseini, Ali Seif Amir"],["dc.contributor.author","Uhlig, Johannes"],["dc.contributor.author","Streit, Ulrike"],["dc.contributor.author","Voit, Dirk"],["dc.contributor.author","Uhlig, Annemarie"],["dc.contributor.author","Ellenrieder, Volker"],["dc.contributor.author","Ghadimi, Michael B."],["dc.contributor.author","Sprenger, Thilo"],["dc.contributor.author","Beham, Alexander Wilhelm"],["dc.contributor.author","Uecker, Martin"],["dc.contributor.author","Frahm, Jens"],["dc.contributor.author","Lotz, Joachim"],["dc.contributor.author","Biggemann, Lorenz"],["dc.date.accessioned","2020-05-13T13:45:02Z"],["dc.date.available","2020-05-13T13:45:02Z"],["dc.date.issued","2019"],["dc.description.abstract","Purpose To assess the diagnostic potential of dynamic real-time MRI for fundoplication failure in patients with persistent or recurrent GERD-like (gastroesophageal reflux disease) complaints. Material and methods Twenty-two consecutive patients (male n = 11; female n = 11; median age 59 years) with recurrent or persistent GERD-like symptom after fundoplication were enrolled between 2015 and 2017. Median duration of GERD-like symptoms was 21 months. Real-time MRI (3 Tesla) was performed at 40 ms temporal resolution using undersampled radial fast low-angle shot acquisitions with nonlinear inverse image reconstruction. MRI movies dynamically visualized bolus transit of pineapple juice through the gastroesophageal junction, position of the fundoplication wrap and recurring hernia or reflux during Valsalva maneuver. MRI results were compared to endoscopic findings. Results Real-time MRI was successfully completed in all patients without adverse events (average examination time 15 min). Morphological correlates for GERD-like symptoms were evident in 20 patients (90.1%) with gastric reflux in 19 cases. Nine patients (40.1%) had wrap disruption and recurrent gastric hernia. Wrap migration or telescoping hernia was detected in nine patients (40.1%). One patient presented with continued reflux despite intact fundoplication wrap. Esophageal dysmotility with delayed bolus passage was observed in one case. On endoscopy, gastric hernia or wrap disruption was diagnosed in seven cases, and esophagitis or Barret’s metaplasia in nine cases."],["dc.identifier.doi","10.1007/s00330-019-06025-x"],["dc.identifier.pmid","30805702"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/65369"],["dc.language.iso","en"],["dc.relation.eissn","1432-1084"],["dc.relation.issn","0938-7994"],["dc.title","Real-time MRI for the dynamic assessment of fundoplication failure in patients with gastroesophageal reflux disease"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.artnumber","108856"],["dc.bibliographiccitation.journal","European Journal of Radiology"],["dc.bibliographiccitation.volume","125"],["dc.contributor.author","Hosseini, Ali Seif Amir"],["dc.contributor.author","Uhlig, Johannes"],["dc.contributor.author","Streit, Ulrike"],["dc.contributor.author","Gliem, Nina"],["dc.contributor.author","Wedi, Edris"],["dc.contributor.author","Ellenrieder, Volker"],["dc.contributor.author","Ghadimi, Michael B."],["dc.contributor.author","Ahmed, Saheeb"],["dc.contributor.author","Uecker, Martin"],["dc.contributor.author","Frahm, Jens"],["dc.contributor.author","Lotz, Joachim"],["dc.contributor.author","Biggemann, Lorenz"],["dc.date.accessioned","2020-05-13T13:44:06Z"],["dc.date.available","2020-05-13T13:44:06Z"],["dc.date.issued","2020-04"],["dc.description.abstract","Purpose To evaluate the diagnostic potential of real-time MRI for dynamic assessment of gastroesophageal reflux in patients with GERD (gastroesophageal reflux disease)-like symptoms compared to pH-metry and impedance. Methods Patients who underwent real-time MRI and pH-metry between 2015–2018 were included in this retrospective study. Real-time MRI at 3 T was achieved by undersampled radial FLASH acquisitions with iterative image reconstruction by NLINV. Real-time MRI visualized transit of pineapple juice through the gastroesophageal junction and during Valsalva maneuver. MRI results were compared to 24 h pH-metry to assess acidic reflux (following Lyon Consensus guidelines) and to impedance to assess non-acidic reflux. A standard 2 × 2 table was chosen to calculate diagnostic performance. Results 91/93 eligible patients fulfilled inclusion criteria (male n = 49; female n = 42; median age 55 y). All MRI studies were successfully completed without adverse events at a mean examination time of 15 min. On real-time MRI, reflux was evident in 60 patients (66 %). pH-metry revealed reflux in 41 patients (45 %), and impedance in 54 patients (59 %). Compared to pH-metry and impedance, real-time MRI sensitivity was 0.78 (95 % CI: 0.66-0.87), specificity 0.67 (95 % CI: 0.45-0.84) and PPV 0.87 (95 % CI: 0.75-0.94). Conclusion Real-time MRI is an imaging method for assessment of gastroesophageal reflux in patients with GERD-like symptoms. Considering its high positive predictive value, real-time MRI can accurately identify patients in which further invasive testing with pH-metry and impedance might be considered."],["dc.identifier.doi","10.1016/j.ejrad.2020.108856"],["dc.identifier.pmid","32062571"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/65362"],["dc.language.iso","en"],["dc.relation.eissn","1872-7727"],["dc.relation.issn","0720-048X"],["dc.title","Real-time MRI for dynamic assessment of gastroesophageal reflux disease: Comparison to pH-metry and impedance"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.subtype","original_ja"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","1759"],["dc.bibliographiccitation.issue","11"],["dc.bibliographiccitation.journal","IEEE Transactions on Medical Imaging"],["dc.bibliographiccitation.lastpage","1769"],["dc.bibliographiccitation.volume","28"],["dc.contributor.author","Block, Kai Tobias"],["dc.contributor.author","Uecker, Martin"],["dc.contributor.author","Frahm, Jens"],["dc.date.accessioned","2017-09-07T11:46:46Z"],["dc.date.available","2017-09-07T11:46:46Z"],["dc.date.issued","2009"],["dc.description.abstract","In radial fast spin-echo magnetic resonance imaging (MRI), a set of overlapping spokes with an inconsistent T2 weighting is acquired, which results in an averaged image contrast when employing conventional image reconstruction techniques. This work demonstrates that the problem may be overcome with the use of a dedicated reconstruction method that further allows for T2 quantification by extracting the embedded relaxation information. Thus, the proposed reconstruction method directly yields a spin-density and relaxivity map from only a single radial data set. The method is based on an inverse formulation of the problem and involves a modeling of the received MRI signal. Because the solution is found by numerical optimization, the approach exploits all data acquired. Further, it handles multicoil data and optionally allows for the incorporation of additional prior knowledge. Simulations and experimental results for a phantom and human brain in vivo demonstrate that the method yields spin-density and relaxivity maps that are neither affected by the typical artifacts from TE mixing, nor by streaking artifacts from the incomplete k-space coverage at individual echo times."],["dc.identifier.doi","10.1109/TMI.2009.2023119"],["dc.identifier.gro","3143029"],["dc.identifier.isi","000271437600011"],["dc.identifier.pmid","19502124"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/498"],["dc.notes.intern","WoS Import 2017-03-10"],["dc.notes.status","final"],["dc.notes.submitter","PUB_WoS_Import"],["dc.publisher","Ieee-inst Electrical Electronics Engineers Inc"],["dc.relation.issn","0278-0062"],["dc.title","Model-Based Iterative Reconstruction for Radial Fast Spin-Echo MRI"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.subtype","original"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.artnumber","2560964"],["dc.bibliographiccitation.journal","Computational and Mathematical Methods in Medicine"],["dc.bibliographiccitation.lastpage","8"],["dc.bibliographiccitation.volume","2018"],["dc.contributor.author","Wang, Xiaoqing"],["dc.contributor.author","Voit, Dirk"],["dc.contributor.author","Roeloffs, Volkert"],["dc.contributor.author","Uecker, Martin"],["dc.contributor.author","Frahm, Jens"],["dc.date.accessioned","2020-05-13T11:04:56Z"],["dc.date.available","2020-05-13T11:04:56Z"],["dc.date.issued","2018"],["dc.description.abstract","To develop a high-speed multislice T1 mapping method based on a single-shot inversion-recovery (IR) radial FLASH acquisition and a regularized model-based reconstruction."],["dc.identifier.doi","10.1155/2018/2560964"],["dc.identifier.pmid","30186361"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/65302"],["dc.language.iso","en"],["dc.relation.eissn","1748-6718"],["dc.relation.issn","1748-670X"],["dc.title","Fast Interleaved Multislice T1 Mapping: Model-Based Reconstruction of Single-Shot Inversion-Recovery Radial FLASH"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","461"],["dc.bibliographiccitation.issue","4"],["dc.bibliographiccitation.journal","Imaging in Medicine"],["dc.bibliographiccitation.lastpage","476"],["dc.bibliographiccitation.volume","4"],["dc.contributor.author","Uecker, Martin"],["dc.contributor.author","Zhang, Shuo"],["dc.contributor.author","Voit, Dirk"],["dc.contributor.author","Merboldt, Klaus-Dietmar"],["dc.contributor.author","Frahm, Jens"],["dc.date.accessioned","2017-09-07T11:54:24Z"],["dc.date.available","2017-09-07T11:54:24Z"],["dc.date.issued","2012"],["dc.identifier.doi","10.2217/iim.12.32"],["dc.identifier.gro","3145161"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/2866"],["dc.notes.intern","Crossref Import"],["dc.notes.status","public"],["dc.publisher","Future Medicine Ltd"],["dc.relation.issn","1755-5191"],["dc.relation.issn","1755-5205"],["dc.title","Real-time MRI: recent advances using radial FLASH"],["dc.type","journal_article"],["dc.type.internalPublication","unknown"],["dc.type.peerReviewed","no"],["dspace.entity.type","Publication"]]