Mohr, Alexander

[["dc.bibliographiccitation.firstpage","226"],["dc.bibliographiccitation.issue","3"],["dc.bibliographiccitation.journal","Folia Neuropathologica"],["dc.bibliographiccitation.lastpage","233"],["dc.bibliographiccitation.volume","52"],["dc.contributor.author","Kallenberg, Kai"],["dc.contributor.author","Goldmann, Torben"],["dc.contributor.author","Menke, Jan"],["dc.contributor.author","Strik, Herwig"],["dc.contributor.author","Bock, Hans-Christoph"],["dc.contributor.author","Mohr, Alexander"],["dc.contributor.author","Buhk, Jan-Hendrik"],["dc.contributor.author","Frahm, Jens"],["dc.contributor.author","Dechent, Peter"],["dc.contributor.author","Knauth, Michael"],["dc.date.accessioned","2018-11-07T09:45:46Z"],["dc.date.available","2018-11-07T09:45:46Z"],["dc.date.issued","2014"],["dc.description.abstract","Introduction: Malignant brain tumors tend to migration and invasion of surrounding brain tissue. Histopathological studies reported malignant cells in macroscopically unsuspicious parenchyma (normal appearing white matter - NAWM) remote from the tumor localization. In early stages, diffuse interneural infiltration with changes of the apparent diffusion coefficient (ADC) and fractional anisotropy (FA) is hypothesized. Material and methods: Patients' ADC and FA values from NAWM of the hemisphere contralateral to a malignant glioma were compared to age- and sex-matched normal controls. Results: Apparent diffusion coefficient levels of the entire contra lateral hemisphere revealed a significant increase and a decrease of FA levels. An even more pronounced ADC increase was found in a region mirroring the glioma location. Conclusions: In patients with previously untreated anaplastic astrocytoma or glioblastoma, an increase of the ADC and a reduction of FA were found in the brain parenchyma of the hemisphere contralateral to the tumor localization. In the absence of visible MRI abnormalities, this may be an early indicator of microstructural changes of the NAWM attributed to malignant brain tumor."],["dc.description.sponsorship","Volkswagen Stiftung [ZN1635, ZN 2193]"],["dc.identifier.doi","10.5114/fn.2014.45563"],["dc.identifier.isi","000342712000002"],["dc.identifier.pmid","25310733"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/34702"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.relation.issn","1509-572X"],["dc.relation.issn","1641-4640"],["dc.title","Abnormalities in the normal appearing white matter of the cerebral hemisphere contralateral to a malignant brain tumor detected by diffusion tensor imaging"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","99"],["dc.bibliographiccitation.issue","1"],["dc.bibliographiccitation.journal","Journal of Cerebral Blood Flow & Metabolism"],["dc.bibliographiccitation.lastpage","111"],["dc.bibliographiccitation.volume","26"],["dc.contributor.author","Bailey, Damian Miles"],["dc.contributor.author","Roukens, R."],["dc.contributor.author","Knauth, Michael"],["dc.contributor.author","Kallenberg, Kai"],["dc.contributor.author","Christ, S."],["dc.contributor.author","Mohr, A."],["dc.contributor.author","Genius, J."],["dc.contributor.author","Storch-Hagenlocher, B."],["dc.contributor.author","Meisel, F."],["dc.contributor.author","McEneny, J."],["dc.contributor.author","Young, I. S."],["dc.contributor.author","Steiner, Tamara"],["dc.contributor.author","Hess, Katharina"],["dc.contributor.author","Bartsch, P."],["dc.date.accessioned","2018-11-07T10:36:06Z"],["dc.date.available","2018-11-07T10:36:06Z"],["dc.date.issued","2006"],["dc.description.abstract","The present study combined molecular and neuroimaging techniques to examine if free radical-mediated damage to barrier function in hypoxia would result in extracellular edema, raise intracranial pressure (ICP) and account for the neurological symptoms typical of high-altitude headache (HAH) also known as acute mountain sickness (AMS). Twenty-two subjects were randomly exposed for 18 h to 12% (hypoxia) and 21% oxygen (O-2 (normoxia)) for collection of venous blood (0 h, 8 h, 15 h, 18 h) and CSF (18 h) after lumbar puncture (LP). Electron paramagnetic resonance (EPR) spectroscopy identified a clear increase in the blood and CSF concentration of O-2 and carbon-centered free radicals (P < 0.05 versus normoxia) subsequently identified as lipid-derived alkoxyl (LO center dot) and alkyl (LC center dot) species. Magnetic resonance imaging (MRI) demonstrated a mild increase in brain volume (7.0 +/- 4.8 mL or 0.6% +/- 0.4%, P < 0.05 versus normoxia) that resolved within 6 h of normoxic recovery. However, there was no detectable evidence for gross barrier dysfunction, elevated lumbar pressures, T-2 prolongation or associated neuronal and astroglial damage. Clinical AMS was diagnosed in 50% of subjects during the hypoxic trial and corresponding headache scores were markedly elevated (P < 0.05 versus non-AMS). A greater increase in brain volume was observed, though this was slight, independent of oxidative stress, barrier dysfunction, raised lumbar pressure, vascular damage and measurable evidence of cerebral edema and only apparent in the most severe of cases. These findings suggest that free-radical-mediated vasogenic edema is not an important pathophysiological event that contributes to the mild brain swelling observed in HAH."],["dc.identifier.doi","10.1038/sj.jcbfm.9600169"],["dc.identifier.isi","000235975500010"],["dc.identifier.pmid","15959459"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/45246"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Nature Publishing Group"],["dc.relation.issn","0271-678X"],["dc.title","Free radical-mediated damage to barrier function is not associated with altered brain morphology in high-altitude headache"],["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","400"],["dc.bibliographiccitation.issue","5"],["dc.bibliographiccitation.journal","Journal of Neurological Surgery Part A-Central European Neurosurgery"],["dc.bibliographiccitation.lastpage","405"],["dc.bibliographiccitation.volume","77"],["dc.contributor.author","Behme, Daniel"],["dc.contributor.author","Malinova, Vesna"],["dc.contributor.author","Kallenberg, Kai"],["dc.contributor.author","Knauth, Michael"],["dc.contributor.author","Mohr, A."],["dc.date.accessioned","2018-11-07T10:08:54Z"],["dc.date.available","2018-11-07T10:08:54Z"],["dc.date.issued","2016"],["dc.description.abstract","Background and Purpose Coil embolization of ruptured and unruptured aneurysms has emerged as a widely accepted alternative to clipping. Unfortunately, coil-embolized aneurysms need a long-term imaging follow-up to confirm the stability of the occlusion status. We investigated whether contrast-enhanced time-of-flight (ToF) magnetic resonance angiography (MRA) (gadolinium [Gdi-ToF) provides any diagnostic benefit over conventional ToF MRA (nonenhanced [NE]-ToF) in this context. Material and Methods From October 2013 to January 2015, all patients who were regularly scheduled for their follow-up after coil embolization were examined with GdToF and NE-ToF angiography. The general visibility of the occlusion result was compared between the two MRAs as well as with the last digital subtraction angiography (DSA) available. Subgroups of interest (follow-up after stent-assisted coil embolization, cases with already known aneurysm remnants) were also analyzed. Results A total of 70 patients (44 female) harboring 74 treated aneurysms were examined. The reproducibility of the DSA result in terms of therapeutic relevance was 100%. In 10 of 74 cases (14%), the aneurysm status was more difficult to judge in the NE-ToF images (p = 0.02), and the visualization of small vessels was significantly better in the Gd-ToF (p = 0.003). NE-ToF did not fail to show any aneurysm remnants but were more difficult to depict in 35% of the cases (p = 0.09). Regarding the aneurysms that were coiled with stent assistance, there was no significant difference in terms of the visualization (p = 0.1). Conclusion Gd-ToF angiography is in general not superior to NE-ToF for the follow-up of coil-embolized aneurysms."],["dc.identifier.doi","10.1055/s-0036-1582014"],["dc.identifier.isi","000388993200005"],["dc.identifier.pmid","27168318"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/39563"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Thieme Medical Publ Inc"],["dc.relation.issn","2193-6323"],["dc.relation.issn","2193-6315"],["dc.title","Unenhanced Time-of-Flight MR Angiography versus Gadolinium-Enhanced Time-of-Flight MR Angiography in the Follow-Up of Coil-Embolized Aneurysms"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","1064"],["dc.bibliographiccitation.issue","5"],["dc.bibliographiccitation.journal","Journal of Cerebral Blood Flow & Metabolism"],["dc.bibliographiccitation.lastpage","1071"],["dc.bibliographiccitation.volume","27"],["dc.contributor.author","Kallenberg, Kai"],["dc.contributor.author","Bailey, Damian Miles"],["dc.contributor.author","Christ, Stefan"],["dc.contributor.author","Mohr, Alexander"],["dc.contributor.author","Roukens, Robin"],["dc.contributor.author","Menold, Elmar"],["dc.contributor.author","Steiner, Thorsten"],["dc.contributor.author","Baertsch, Peter D."],["dc.contributor.author","Knauth, Michael"],["dc.date.accessioned","2018-11-07T11:02:46Z"],["dc.date.available","2018-11-07T11:02:46Z"],["dc.date.issued","2007"],["dc.description.abstract","The present study applied T-2- and diffusion-weighted magnetic resonance imaging to examine if mild cerebral edema and subsequent brain swelling are implicated in the pathophysiology of acute mountain sickness (AMS). Twenty-two subjects were examined in normoxia ( 21% O-2), after 16 hours passive exposure to normobaric hypoxia (12% O-2) corresponding to a simulated altitude of 4,500m and after 6 hours recovery in normoxia. Clinical AMS was diagnosed in 50% of subjects during hypoxia and corresponding headache scores were markedly elevated (P < 0.05 versus non-AMS). Hypoxia was associated with a mild increase in brain volume (+ 7.0 +/- 4.8 ml, P < 0.05 versus preexposure baseline) that resolved during normoxic recovery. Hypoxia was also associated with an increased T-2 relaxation time ( T(2)rt) and a general trend toward an increased apparent diffusion coefficient (ADC). During the normoxic recovery, brain volume and T(2)rt recovered to pre-exposure baseline values, whereas a more marked reduction in ADC in the splenium of the corpus callosum ( SCC) was observed ( P < 0.05). While changes in brain volume and T(2)rt were not selectively different in AMS, ADC values were consistently lower (P < 0.05 versus non-AMS) and associated with the severity of neurologic symptoms. Acute mountain sickness was also characterized by an increased brain to intracranial volume ratio ( P < 0.05 versus non-AMS). These findings indicate that mild extracellular vasogenic edema contributes to the generalized brain swelling observed at high altitude, independent of AMS. In contrast, intracellular cytotoxic edema combined with an anatomic predisposition to a `tight- fit' brain may prove of pathophysiologic significance, although the increase in brain volume in hypoxia was only about 0.5% of total brain volume."],["dc.identifier.doi","10.1038/sj.jcbfm.9600404"],["dc.identifier.isi","000245999300017"],["dc.identifier.pmid","17024110"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/51461"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Nature Publishing Group"],["dc.relation.issn","0271-678X"],["dc.title","Magnetic resonance imaging evidence of cytotoxic cerebral edema in acute mountain sickness"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["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"]]

[["dc.bibliographiccitation.firstpage","1164"],["dc.bibliographiccitation.issue","6"],["dc.bibliographiccitation.journal","American Journal of Neuroradiology"],["dc.bibliographiccitation.lastpage","1167"],["dc.bibliographiccitation.volume","34"],["dc.contributor.author","Focke, Niels K."],["dc.contributor.author","Kallenberg, Kai"],["dc.contributor.author","Mohr, A."],["dc.contributor.author","Djukic, M."],["dc.contributor.author","Nau, R."],["dc.contributor.author","Schmidt, H."],["dc.date.accessioned","2018-11-07T09:23:46Z"],["dc.date.available","2018-11-07T09:23:46Z"],["dc.date.issued","2013"],["dc.description.abstract","BACKGROUND AND PURPOSE: The structural basis of cognitive sequelae after bacterial meningitis in humans is still poorly understood. In animal models and human autopsy cases, neuronal apoptosis of the hippocampal formation in particular seems to play an important role. Here, we aimed to analyze if BM entails MR imaging structural consequences in humans in vivo. MATERIALS AND METHODS: We applied voxel-based morphometry in a cohort of BM survivors with normal conventional MR imaging after resolution of the acute inflammation to assess morphologic differences. RESULTS: We found clear gray matter volume loss in the limbic system including the hippocampal formation, thalamus, and cingulate gyri bilaterally as well as in the temporal lobe. These results were corroborated by an alternative atlas-based method. CONCLUSIONS: Even in patients with normal routine MR imaging results, clear-cut gray matter atrophy with a mesial temporal/limbic pattern was evident. The anatomic distribution is compatible with the neuropsychological deficit commonly observed in patients after BM. The similarity of the observed atrophy may point to causal link between BM and mesial temporal epilepsy."],["dc.description.sponsorship","DFG"],["dc.identifier.doi","10.3174/ajnr.A3351"],["dc.identifier.isi","000329847700015"],["dc.identifier.pmid","23194831"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/29659"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Amer Soc Neuroradiology"],["dc.relation.issn","1936-959X"],["dc.relation.issn","0195-6108"],["dc.title","Distributed, Limbic Gray Matter Atrophy in Patients after Bacterial Meningitis"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]