Publications by authors named "Theo Demerath"

8 Publications

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Stereotactic cysto-ventricular catheters in craniopharyngiomas: an effective minimally invasive method to improve visual impairment and achieve long-term cyst volume reduction.

Neurosurg Rev 2021 Mar 5. Epub 2021 Mar 5.

Department of Stereotactic and Functional Neurosurgery, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Breisacher Str. 64, D-79106, Freiburg, Germany.

Craniopharyngiomas are typically located in the sellar region and frequently contain space-occupying cysts. They usually cause visual impairment and endocrine disorders. Due to the high potential morbidity associated with radical resection, several less invasive surgical approaches have been developed. This study investigated stereotactic-guided implantation of cysto-ventricular catheters (CVC) as a new method to reduce and control cystic components. Twelve patients with cystic craniopharyngiomas were treated with CVC in our hospital between 04/2013 and 05/2017. The clinical and radiological data were retrospectively analysed to evaluate safety aspects as well as ophthalmological and endocrine symptoms. The long-term development of tumour and cyst volumes was assessed by volumetry. The median age of our patients was 69.0 years and the median follow-up period was 41.0 months. Volumetric analyses demonstrated a mean reduction of cyst volume of 64.2% after CVC implantation. At last follow-up assessment, there was a mean reduction of cyst volume of 92.0% and total tumour volume of 85.8% after completion of radiotherapy. Visual acuity improved in 90% of affected patients, and visual field defects improved in 70% of affected patients. No patient showed ophthalmological deterioration after surgery, and endocrine disorders remained stable. Stereotactic implantation of CVC proved to be a safe minimally invasive method for the long-term reduction of cystic components with improved ophthalmological symptoms. The consequential decrease of total tumour volumes optimised conditions for adjuvant radiotherapy. Given the low surgical morbidity and the effective drainage of tumour cysts, this technique should be considered for the treatment of selected cystic craniopharyngiomas.
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http://dx.doi.org/10.1007/s10143-021-01510-8DOI Listing
March 2021

Dural Arteriovenous Fistula Formation Secondary to Cerebral Venous Thrombosis: Longitudinal Magnetic Resonance Imaging Assessment Using 4D-Combo-MR-Venography.

Thromb Haemost 2021 Mar 3. Epub 2021 Mar 3.

Department of Neuroradiology, Medical Center-University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany.

Background And Purpose:  Dural arteriovenous fistulae (DAVFs) can develop secondary to cerebral venous thrombosis (CVT). The incidence of DAVF has not yet been investigated prospectively.

Methods:  Between July 2012 and January 2018, combined static and dynamic 4D MR venography (4D-combo-MRV) was performed in 24 consecutive patients at diagnosis of CVT and after 6 months. 3 Tesla magnetic resonance imaging with time of flight and contrast-enhanced magnetization-prepared rapid acquisition with gradient echo were performed at baseline to evaluate the extent of thrombosis and affected vessel segments. Baseline and follow-up 4D-combo-MRV were assessed for signs of DAVF. Interrater reliability of DAVF detection and the extent of recanalization were analyzed with kappa statistics.

Results:  DAVFs were detected in 4/30 CVT patients (13.3%, 95% confidence interval [CI] 3.3-26.7). Two of 24 patients (8.3%, 95% CI: 0-20.8) had coincidental DAVF with CVT on admission. At follow-up, de novo formation of DAVF following CVT was seen in 2/24 patients (8.3%, 95% CI: 0-20.8). Both de novo DAVFs were low grade and benign fistulae (Cognard type 1, 2a), which had developed at previously thrombosed segments. Endovascular treatment was required in two high degree lesions (Cognard 2a + b) detected at baseline and in one de novo DAVF (Cognard 1) because of debilitating headache and tinnitus. Thrombus load, vessel recanalization, and frequency of cerebral lesions (hemorrhage, ischemia) were not associated with DAVF occurrence.

Conclusion:  This exploratory study showed that de novo DAVF formation occurs more frequently than previously described. Although de novo DAVFs were benign, 75% of all detected DAVFs required endovascular treatment. Therefore, screening for DAVF by dynamic MRV, such as 4D-combo-MRV, seems worthwhile in CVT patients.
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http://dx.doi.org/10.1055/s-0041-1723991DOI Listing
March 2021

Apples and oranges.

Epilepsia 2021 01 25;62(1):279-280. Epub 2020 Nov 25.

Department of Neuroradiology, Faculty of Medicine, Medical Center - University of Freiburg, University of Freiburg, Breisgau, Germany.

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http://dx.doi.org/10.1111/epi.16770DOI Listing
January 2021

High-resolution compressed-sensing time-of-flight MRA in a case of acute ICA/MCA dissection.

Neuroradiology 2020 Jun 20;62(6):753-756. Epub 2020 Mar 20.

Department of Radiology and Nuclear Medicine, University Hospital Basel, Petersgraben 4, CH-4031, Basel, Switzerland.

Purpose: Acute, isolated intracranial dissection (ICD) represents a rare and challenging cause of acute stroke. DSA is considered to be the gold standard imaging modality in patients with ICD. The role of novel, high-resolution (HR) compressed-sensing (CS) time-of-flight (TOF) MRA techniques in ICDs is unclear.

Methods: A 22-year-old male patient with an isolated right ICA/MCA intracranial dissection underwent "conventional" 3-T TOF MRA, HR CS TOF MRA and also DSA including digital rotational angiography.

Results: Unlike the "conventional" TOF MRA, HR CS TOF MRA provided comparable image quality to rotational angiography and a dissection membrane was clearly visible in both techniques.

Conclusion: In this single case study, we demonstrated the feasibility of a novel HR CS TOF in a case of an acute isolated intracranial ICA/MCA dissection, which needs to be validated in a larger case series.
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http://dx.doi.org/10.1007/s00234-020-02395-yDOI Listing
June 2020

Integrative Diffusion-Weighted Imaging and Radiogenomic Network Analysis of Glioblastoma multiforme.

Sci Rep 2017 03 7;7:43523. Epub 2017 Mar 7.

Department of Neuroradiology, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Germany.

In the past, changes of the Apparent Diffusion Coefficient in glioblastoma multiforme have been shown to be related to specific genes and described as being associated with survival. The purpose of this study was to investigate diffusion imaging parameters in combination with genome-wide expression data in order to obtain a comprehensive characterisation of the transcriptomic changes indicated by diffusion imaging parameters. Diffusion-weighted imaging, molecular and clinical data were collected prospectively in 21 patients. Before surgery, MRI diffusion metrics such as axial (AD), radial (RD), mean diffusivity (MD) and fractional anisotropy (FA) were assessed from the contrast enhancing tumour regions. Intraoperatively, tissue was sampled from the same areas using neuronavigation. Transcriptional data of the tissue samples was analysed by Weighted Gene Co-Expression Network Analysis (WGCNA) thus classifying genes into modules based on their network-based affiliations. Subsequent Gene Set Enrichment Analysis (GSEA) identified biological functions or pathways of the expression modules. Network analysis showed a strong association between FA and epithelial-to-mesenchymal-transition (EMT) pathway activation. Also, patients with high FA had a worse clinical outcome. MD correlated with neural function related genes and patients with high MD values had longer overall survival. In conclusion, FA and MD are associated with distinct molecular patterns and opposed clinical outcomes.
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http://dx.doi.org/10.1038/srep43523DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5339871PMC
March 2017

Mesoscopic imaging of glioblastomas: Are diffusion, perfusion and spectroscopic measures influenced by the radiogenetic phenotype?

Neuroradiol J 2017 Feb 19;30(1):36-47. Epub 2016 Nov 19.

1 Department of Neuroradiology, Medical Centre-University of Freiburg, Germany.

The purpose of this study was to identify markers from perfusion, diffusion, and chemical shift imaging in glioblastomas (GBMs) and to correlate them with genetically determined and previously published patterns of structural magnetic resonance (MR) imaging. Twenty-six patients (mean age 60 years, 13 female) with GBM were investigated. Imaging consisted of native and contrast-enhanced 3D data, perfusion, diffusion, and spectroscopic imaging. In the presence of minor necrosis, cerebral blood volume (CBV) was higher (median ± SD, 2.23% ± 0.93) than in pronounced necrosis (1.02% ± 0.71), p = 0.0003. CBV adjacent to peritumoral fluid-attenuated inversion recovery (FLAIR) hyperintensity was lower in edema (1.72% ± 0.31) than in infiltration (1.91% ± 0.35), p = 0.039. Axial diffusivity adjacent to peritumoral FLAIR hyperintensity was lower in severe mass effect (1.08*10 mm/s ± 0.08) than in mild mass effect (1.14*10 mm/s ± 0.06), p = 0.048. Myo-inositol was positively correlated with a marker for mitosis (Ki-67) in contrast-enhancing tumor, r = 0.5, p = 0.0002. Changed CBV and axial diffusivity, even outside FLAIR hyperintensity, in adjacent normal-appearing matter can be discussed as to be related to angiogenesis pathways and to activated proliferation genes. The correlation between myo-inositol and Ki-67 might be attributed to its binding to cell surface receptors regulating tumorous proliferation of astrocytic cells.
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http://dx.doi.org/10.1177/1971400916678225DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5564334PMC
February 2017

Molecular differences between cerebral blood volume and vessel size in glioblastoma multiforme.

Oncotarget 2017 Feb;8(7):11083-11093

Department of Neuroradiology, Medical Center University of Freiburg, Freiburg, Germany.

The purpose of this study was to investigate the molecular background of cerebral blood volume (CBV) and vessel size (VS) of capillaries in glioblastoma multiforme (GBM). Both parameters are derived from extended perfusion MR imaging.A prospective case study including 21 patients (median age 66 years, 10 females) was performed. Before operation, CBV and VS of contrast enhancing tumor were assessed. Tissue was sampled from the assessed areas under neuronavigation control. After RNA extraction, transcriptional data was analyzed by Weighted Gene Co-Expression Network Analysis (WGCNA) and split into modules based on its network affiliations. Gene Set Enrichment Analysis (GSEA) identified biological functions or pathways of the genetic modules. These were applied on 484 GBM samples of the TCGA database.Ten modules were highly correlated to CBV and VS. One module was exclusively associated to VS and highly correlated to hypoxia, another one exclusively to CBV showing strong enrichments in the Epithelial Growth Factor (EGF) pathway and Epithelial-to-Mesenchymal-Transition (EMT). Moreover, patients with increased CBV and VS predominantly showed a mesenchymal gene-expression, a finding that could be corroborated by TCGA data.In conclusion, CBV and VS mirror different genetic pathways and reflect certain molecular subclasses of GBM.
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http://dx.doi.org/10.18632/oncotarget.11522DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5355248PMC
February 2017

Natriuretic peptides buffer renin-dependent hypertension.

Am J Physiol Renal Physiol 2014 Jun 9;306(12):F1489-98. Epub 2014 Apr 9.

Institute of Physiology, University of Regensburg, Regensburg, Germany

The renin-angiotensin-aldosterone system and cardiac natriuretic peptides [atrial natriuretic peptide (ANP) and B-type natriuretic peptide (BNP)] are opposing control mechanisms for arterial blood pressure. Accordingly, an inverse relationship between plasma renin concentration (PRC) and ANP exists in most circumstances. However, PRC and ANP levels are both elevated in renovascular hypertension. Because ANP can directly suppress renin release, we used ANP knockout (ANP(-/-)) mice to investigate whether high ANP levels attenuate the increase in PRC in response to renal hypoperfusion, thus buffering renovascular hypertension. ANP(-/-) mice were hypertensive and had reduced PRC compared with that in wild-type ANP(+/+) mice under control conditions. Unilateral renal artery stenosis (2-kidney, 1-clip) for 1 wk induced similar increases in blood pressure and PRC in both genotypes. Unexpectedly, plasma BNP concentrations in ANP(-/-) mice significantly increased in response to two-kidney, one-clip treatment, potentially compensating for the lack of ANP. In fact, in mice lacking guanylyl cyclase A (GC-A(-/-) mice), which is the common receptor for both ANP and BNP, renovascular hypertension was markedly augmented compared with that in wild-type GC-A(+/+) mice. However, the higher blood pressure in GC-A(-/-) mice was not caused by disinhibition of the renin system because PRC and renal renin synthesis were significantly lower in GC-A(-/-) mice than in GC-A(+/+) mice. Thus, natriuretic peptides buffer renal vascular hypertension via renin-independent effects, such as vasorelaxation. The latter possibility is supported by experiments in isolated perfused mouse kidneys, in which physiological concentrations of ANP and BNP elicited renal vasodilatation and attenuated renal vasoconstriction in response to angiotensin II.
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http://dx.doi.org/10.1152/ajprenal.00668.2013DOI Listing
June 2014