Kallenberg, Kai

[["dc.bibliographiccitation.firstpage","217"],["dc.bibliographiccitation.issue","2"],["dc.bibliographiccitation.journal","Journal of Neuro-Oncology"],["dc.bibliographiccitation.lastpage","222"],["dc.bibliographiccitation.volume","112"],["dc.contributor.author","Kallenberg, Kai"],["dc.contributor.author","Goldmann, Torben"],["dc.contributor.author","Menke, Jan"],["dc.contributor.author","Strik, Herwig Matthias"],["dc.contributor.author","Bock, Hans-Christoph"],["dc.contributor.author","Stockhammer, Florian"],["dc.contributor.author","Buhk, Jan-Hendrik"],["dc.contributor.author","Frahm, Jens"],["dc.contributor.author","Dechent, Peter"],["dc.contributor.author","Knauth, Michael"],["dc.date.accessioned","2018-11-07T09:26:42Z"],["dc.date.available","2018-11-07T09:26:42Z"],["dc.date.issued","2013"],["dc.description.abstract","The most frequent primary brain tumors, anaplastic astrocytomas (AA) and glioblastomas (GBM): tend to invasion of the surrounding brain. Histopathological studies found malignant cells in macroscopically unsuspicious brain parenchyma remote from the primary tumor, even affecting the contralateral hemisphere. In early stages, diffuse interneural infiltration with changes of the apparent diffusion coefficient (ADC) and fractional anisotropy (FA) is suspected. The purpose of this study was to investigate the value of DTI as a possible instrument of depicting evidence of tumor invasion into the corpus callosum (CC). Preoperatively, 31 patients with high-grade brain tumors (8 AA and 23 GBM) were examined by MRI at 3 T, applying a high-resolution diffusion tensor imaging (DTI) sequence. ADC- and FA-values were analyzed in the tumor-associated area of the CC as identified by fiber tracking, and were compared to matched healthy controls. In (MR-)morphologically normal appearing CC the ADC values were elevated in the tumor patients (n = 22; 0.978 x 10(-3) mmA(2)/s) compared to matched controls (0.917 x 10(-3) mmA(2)/s, p < 0.05), and the corresponding relative FA was reduced (rFA: 88 %, p < 0.01). The effect was pronounced in case of affection of the CC visible on MRI (n = 9; 0.978 x 10(-3) mmA(2)/s, p < 0.05; rFA: 72 %, p < 0.01). Changes in diffusivity and anisotropy in the CC can be interpreted as an indicator of tumor spread into the contralateral hemisphere not visible on conventional MRI."],["dc.description.sponsorship","Volkswagen Stiftung [ZN1635, ZN 2193]"],["dc.identifier.doi","10.1007/s11060-013-1049-y"],["dc.identifier.isi","000316755000009"],["dc.identifier.pmid","23344787"],["dc.identifier.purl","https://resolver.sub.uni-goettingen.de/purl?gs-1/10366"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/30361"],["dc.notes.intern","Merged from goescholar"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Springer"],["dc.relation.issn","0167-594X"],["dc.rights","Goescholar"],["dc.rights.uri","https://goescholar.uni-goettingen.de/licenses"],["dc.title","Glioma infiltration of the corpus callosum: early signs detected by DTI"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dc.type.version","published_version"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","805"],["dc.bibliographiccitation.issue","3"],["dc.bibliographiccitation.journal","Radiology"],["dc.bibliographiccitation.lastpage","812"],["dc.bibliographiccitation.volume","253"],["dc.contributor.author","Kallenberg, Kai"],["dc.contributor.author","Bock, Hans-Christoph"],["dc.contributor.author","Helms, Gunther"],["dc.contributor.author","Jung, Klaus"],["dc.contributor.author","Wrede, Arne"],["dc.contributor.author","Buhk, Jan-Hendrik"],["dc.contributor.author","Giese, Alf"],["dc.contributor.author","Frahm, Jens"],["dc.contributor.author","Strik, Herwig"],["dc.contributor.author","Dechent, Peter"],["dc.contributor.author","Knauth, Michael"],["dc.date.accessioned","2018-11-07T11:21:46Z"],["dc.date.available","2018-11-07T11:21:46Z"],["dc.date.issued","2009"],["dc.description.abstract","Purpose: To use localized in vivo proton magnetic resonance (MR) spectroscopy of the contralateral hemisphere in patients with glioblastoma multiforme (GBM) to detect alterations in cerebral metabolites as potential markers of infiltrating GBM cells. Materials and Methods: The study was approved by the ethics committee, and written informed consent was obtained. Twenty-two patients with newly diagnosed and untreated GBM underwent in vivo single-voxel short echo time proton MR spectroscopy with a 3-T MR imaging system. Absolute metabolite concentrations in the hemisphere contralateral to the tumor were compared with data from five patients with low-grade gliomas (LGGs) and from a group of 14 age-matched control subjects by using analysis of variance and subsequent t tests or corresponding nonparametric tests. Results: In the contralateral hemisphere, MR spectroscopy revealed increased concentrations of myo-inositol and glutamine. Mean myo-inositol levels were significantly increased in patients with GBM (3.6 mmol/L +/- 0.8 [standard deviation]) relative to levels in control subjects (3.1 mmol/L +/- 0.6; P = .03) and tended to be higher relative to levels in patients with LGG (2.7 mmol/L +/- 0.8; P = .09). Mean glutamine concentrations in patients with GBM (3.4 mmol/L +/- 0.9) differed significantly from those in control subjects (2.7 mmol/L +/- 0.7; P < .01); mean concentrations in patients with GBM differed from those in patients with LGG (2.4 mmol/L +/- 0.5; P < .01). There were no significant differences between data in patients with LGG and in control subjects. Conclusion: Increased concentrations of myo-inositol and glutamine in the contralateral normal-appearing white matter of GBM patients are consistent with mild astrocytosis and suggest the detectability of early neoplastic infiltration by using proton MR spectroscopy in vivo. (C) RSNA, 2009"],["dc.identifier.doi","10.1148/radiol.2533071654"],["dc.identifier.isi","000272247300028"],["dc.identifier.pmid","19789222"],["dc.identifier.purl","https://resolver.sub.uni-goettingen.de/purl?gs-1/6268"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/55854"],["dc.notes.intern","Merged from goescholar"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Radiological Soc North America"],["dc.relation.issn","0033-8419"],["dc.rights","Goescholar"],["dc.rights.uri","https://goescholar.uni-goettingen.de/licenses"],["dc.title","Untreated Glioblastoma Multiforme: Increased Myo-inositol and Glutamine Levels in the Contralateral Cerebral Hemisphere at Proton MR Spectroscopy"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","855"],["dc.bibliographiccitation.issue","10"],["dc.bibliographiccitation.journal","Neuroradiology"],["dc.bibliographiccitation.lastpage","861"],["dc.bibliographiccitation.volume","50"],["dc.contributor.author","Buhk, Jan-Hendrik"],["dc.contributor.author","Kallenberg, Kai"],["dc.contributor.author","Mohr, Alexander"],["dc.contributor.author","Dechent, Peter"],["dc.contributor.author","Knauth, Michael"],["dc.date.accessioned","2018-11-07T11:10:45Z"],["dc.date.available","2018-11-07T11:10:45Z"],["dc.date.issued","2008"],["dc.description.abstract","Introduction Long-term follow-up after coil embolization of intracranial aneurysms is mandatory to monitor coil compacting and aneurysm recurrence. Most centers perform one digital subtraction angiography (DSA) on follow-up continuing with time-of-flight magnetic resonance angiography (TOF-MRA). This study explores the diagnostic value of TOF-MRA at 1.5 T versus 3 T compared to DSA. Materials and methods In 18 patients with 20 aneurysms treated with coil embolization, TOF-MRA at 1.5 and 3 T were performed the day before follow-up DSA, the latter serving as reference. Optimized diagnostic protocols were applied (1.5 T: 0.78 x 0.55 x 0.8 mm, voxel size; acquisition time (TA), 6.37 min; 3 T: 0.56 x 0.45 x 0.65 mm, voxel size; TA, 3.12 min). Three independent neuroradiologists experienced in neuroendovascular therapy rated the occlusion rate (\"complete occlusion\" vs. \"residual neck\" vs. \"residual aneurysm\") and compared the two methods subjectively. Weighted kappa statistics were calculated to assess the level of interobserver agreement. Results Compared to DSA, TOF-MRA was more sensitive in detecting neck remnants, with a slight advantage at 3 T. Regarding artifact load, there are advantages at 1.5 T. Ratings of the occlusion rate correlated highly between all observers (r > 0.85, p < 0.001, respectively). Interobserver agreement was high in all cases (kappa(w) approximate to 0.8, respectively). Conclusion TOF-MRA is a reliable tool for follow-up imaging of cerebral aneurysms after endovascular treatment. Our study shows no advantage of TOF-MRA at 3 T over 1.5 T, when comparable measurement protocols are applied. TOF-MRA at 1.5 T therefore provides appropriate information regarding a therapeutic decision."],["dc.identifier.doi","10.1007/s00234-008-0413-7"],["dc.identifier.isi","000259576300005"],["dc.identifier.pmid","18523761"],["dc.identifier.purl","https://resolver.sub.uni-goettingen.de/purl?goescholar/3105"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/53277"],["dc.notes.intern","Merged from goescholar"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Springer"],["dc.relation.issn","0028-3940"],["dc.rights","Goescholar"],["dc.rights.uri","https://goescholar.uni-goettingen.de/licenses"],["dc.title","No advantage of time-of-flight magnetic resonance angiography at 3 Tesla compared to 1.5 Tesla in the follow-up after endovascular treatment of cerebral aneurysms"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dc.type.version","published_version"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","430"],["dc.bibliographiccitation.issue","2"],["dc.bibliographiccitation.journal","European Radiology"],["dc.bibliographiccitation.lastpage","436"],["dc.bibliographiccitation.volume","19"],["dc.contributor.author","Buhk, Jan-Hendrik"],["dc.contributor.author","Kallenberg, Kai"],["dc.contributor.author","Mohr, Alexander"],["dc.contributor.author","Dechent, Peter"],["dc.contributor.author","Knauth, Michael"],["dc.date.accessioned","2018-11-07T08:33:01Z"],["dc.date.available","2018-11-07T08:33:01Z"],["dc.date.issued","2009"],["dc.description.abstract","Following coil embolization of intracranial aneurysms, many centers perform at least one digital subtraction angiography (DSA) continuing with time-of-flight magnetic resonance angiography (TOF-MRA). Angiographic computed tomography (ACT) provides high-resolution data from a rotational acquisition of a c-arm-mounted flat panel detector. This study evaluates possible advantages of applying ACT in aneurysm follow-up. In 22 patients DSA examinations with a rotational acquisition were performed. Rotational data were processed into an isotropic high-resolution volume. TOF-MRA was performed the day before DSA. Three experienced neuroradiologists performed a rating of the occlusion rate and a subjective method comparison. Weighted kappa statistics were calculated to assess the level of interobserver agreement. Compared to DSA, the diagnostic value of ACT as well as of TOF-MRA was rated to be inferior, although the sensitivity of detecting residual necks was higher with both techniques. Compared to TOF-MRA, ACT achieves favorable ratings only in aneurysms after stent-remodeling. Interobserver agreement was high for all techniques. Ratings of the occlusion rate correlated highly between all observers (r > 0.85, p < 0.001, respectively). In selected patients ACT can add valuable diagnostic information to DSA. TOF-MRA remains a highly sensitive method for aneurysm follow-up."],["dc.identifier.doi","10.1007/s00330-008-1171-y"],["dc.identifier.isi","000262579000020"],["dc.identifier.pmid","18810455"],["dc.identifier.purl","https://resolver.sub.uni-goettingen.de/purl?goescholar/3502"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/17474"],["dc.notes.intern","Merged from goescholar"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Springer"],["dc.relation.issn","0938-7994"],["dc.rights","Goescholar"],["dc.rights.uri","https://goescholar.uni-goettingen.de/licenses"],["dc.title","Evaluation of angiographic computed tomography in the follow-up after endovascular treatment of cerebral aneurysms-a comparative study with DSA and TOF-MRA"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dc.type.version","published_version"],["dspace.entity.type","Publication"]]