Ropinski T.,University of Munster |
Doring C.,European Institute for Molecular Imaging |
Rezk-Salama C.,Mediadesign University of Applied Social Sciences
IEEE Computer Graphics and Applications | Year: 2010
Advanced illumination models can support depth perception. However, for volume rendering, gradient-based shading models are still the standard. This is because the computation of more advanced lighting effects is expensive and thus strongly affects rendering performance. Nevertheless, interactive frame rates are important for both the interactive design of visual representations and the exploration process. An interactive volumetric lighting model simulates scattering and shadowing to generate high-quality images. Compared to gradient-based shading, this model achieves superior image quality and higher frame rates. To evaluate this model, a user study had participants perform depth perception tasks. The study's results indicate that this model can significantly improve depth perception, compared to conventional gradient-based volume shading. Additionally, because this model isn't based on a gradient computation, it's less sensitive to noise and therefore applicable to imaging modalities suffering from a low signal-to-noise ratio, such as magnetic resonance imaging or 3D ultrasound. © 2006 IEEE.
Euskirchen P.,University of Bergen |
Euskirchen P.,Max Planck Institute for Neurological Research |
Skaftnesmo K.-O.,University of Bergen |
Huszthy P.C.,University of Bergen |
And 5 more authors.
Experimental Cell Research | Year: 2011
The cell fate determinant NUMB orchestrates asymmetric cell division in flies and mammals and has lately been suggested to have a tumor suppressor function in breast and lung cancer. Here, we studied NUMB in the context of malignant gliomas. We used ectopic expression of NUMB in order to inhibit proliferation and induce differentiation in glioma cells by alteration of Notch, Hedgehog and p53 signaling. We found that NUMB is consistently expressed in glioma biopsies with predominance of NUMB2/4 isoforms as determined by isoform-specific real-time PCR and Western blotting. Upon lentiviral overexpression, in vitro proliferation rate and the grade of differentiation as assessed by morphology and expression of neural and glial markers remained unchanged. Orthotopic xenografts of NUMB-transduced human U87 glioma cells could be established in nude rats without impairing engraftment or causing significant changes in morphology based on magnetic resonance imaging (MRI). The previously reported alteration of Hedgehog and p53 signaling by NUMB could not be recapitulated in glioma cells. We thus show that in experimental gliomas, NUMB overexpression most likely does not exert a tumor suppressor function such as seen in epithelial cancers. © 2011 Elsevier Inc.
Hoerr V.,University Hospital Muenster |
Nagelmann N.,University Hospital Muenster |
Nauerth A.,Bruker |
Kuhlmann M.T.,European Institute for Molecular Imaging |
And 2 more authors.
Journal of Cardiovascular Magnetic Resonance | Year: 2013
Background: To overcome flow and electrocardiogram-trigger artifacts in cardiovascular magnetic resonance (CMR), we have implemented a cardiac and respiratory self-gated cine ultra-short echo time (UTE) sequence. We have assessed its performance in healthy mice by comparing the results with those obtained with a self-gated cine fast low angle shot (FLASH) sequence and with echocardiography. Methods. 2D self-gated cine UTE (TE/TR = 314 μs/6.2 ms, resolution: 129 × 129 μm, scan time per slice: 5 min 5 sec) and self-gated cine FLASH (TE/TR = 3 ms/6.2 ms, resolution: 129 × 129 μm, scan time per slice: 4 min 49 sec) images were acquired at 9.4 T. Volume of the left and right ventricular (LV, RV) myocardium as well as the end-diastolic and -systolic volume was segmented manually in MR images and myocardial mass, stroke volume (SV), ejection fraction (EF) and cardiac output (CO) were determined. Statistical differences were analyzed by using Student t test and Bland-Altman analyses. Results: Self-gated cine UTE provided high quality images with high contrast-to-noise ratio (CNR) also for the RV myocardium (CNR§ssub§ blood-myocardium§esub§ = 25.5 ± 7.8). Compared to cine FLASH, susceptibility, motion, and flow artifacts were considerably reduced due to the short TE of 314 μs. The aortic valve was clearly discernible over the entire cardiac cycle. Myocardial mass, SV, EF and CO determined by self-gated UTE were identical to the values measured with self-gated FLASH and showed good agreement to the results obtained by echocardiography. Conclusions: Self-gated UTE allows for robust measurement of cardiac parameters of diagnostic interest. Image quality is superior to self-gated FLASH, rendering the method a powerful alternative for the assessment of cardiac function at high magnetic fields. © 2013 Hoerr et al.; licensee BioMed Central Ltd.
Hesselmann V.,University of Munster |
Niederstadt T.,University of Munster |
Dziewas R.,University of Munster |
Ritter M.,University of Munster |
And 7 more authors.
American Journal of Neuroradiology | Year: 2012
BACKGROUND AND PURPOSE: Our research focuses on interventional neuroradiology (stroke treatment including imaging methods) and general neuroimaging with an emphasis on functional MR imaging. Our aim was to determine the efficacy of revascularization (TIMI) of middle cerebral and/or carotid artery occlusion by means of mechanical recanalization techniques and to evaluate the impact of collateralization, mismatch in perfusion CT, time to revascularization, grade of revascularization on tissue, and clinical outcome in patients with acute ischemic stroke. MATERIALS AND METHODS: Thirty-one patients with MCA and/or ICA occlusion were included. Ischemic stroke was diagnosed by NECT, CTA, and volume PCT for grading collateralization and mismatch. Time to recanalization was measured from the onset of stroke to the time point of DSA-proved mechanical recanalization. Tissue outcome was calculated by segmentation of infarct size between pre- and postinterventional CT and percentage mismatch lost. Clinical outcome was determined by the mRS. RESULTS: Twenty-one of 31 patients (61.8%) presented with MCA and 10/31 patients (38.2%), with distal ICA occlusions. Sufficient recanalization (TIMI 2 and 3) was achieved in 23/31 (75%). Clinical evaluation revealed an mRS score of ≤2 in 25.5%. Age (r = 0.439, P = .038) and TIMI (r = 0.544, P = .002) showed the strongest correlation with clinical outcome. Time to recanalization, TIMI score, and mismatch were associated with a good tissue outcome in ANOVA. CONCLUSIONS: Favorable outcome after mechanical recanalization of acute MCA and ICA occlusion depends on time to and grade of recanalization, mismatch, and collateralization. These results indicate that multimodal stroke imaging is helpful to guide therapy decisions and to indicate patients amenable for mechanical recanalization.
Bunk E.C.,Stem Cell Biology and Regeneration Group |
Stelzer S.,Stem Cell Biology and Regeneration Group |
Hermann S.,European Institute for Molecular Imaging |
Schafers M.,European Institute for Molecular Imaging |
And 2 more authors.
Aging Cell | Year: 2011
Adult neurogenesis within the subgranular zone (SGZ) of the hippocampal dentate gyrus and the subventricular zone (SVZ) of the lateral ventricle (LV) has been most intensely studied within the brains of rodents such as mice and rats. However, little is known about the cell types and processes involved in adult neurogenesis within primates such as the common marmoset (Callithrix jacchus). Moreover, substantial differences seem to exist between the neurogenic niche of the LV between rodents and humans. Here, we set out to use immunohistochemical and autogradiographic analysis to characterize the anatomy of the neurogenic niches and the expression of cell type-specific markers in those niches in the adult common marmoset brain. Moreover, we demonstrate significant differences in the activity of neurogenesis in the adult marmoset brain compared to the adult mouse brain. Finally, we provide evidence for ongoing proliferation of neuroblasts within both the SGZ and SVZ of the adult brain and further show that the age-dependent decline of neurogenesis in the hippocampus is associated with a decrease in neuroblast cells. © 2010 The Authors. Aging Cell © 2010 Blackwell Publishing Ltd/Anatomical Society of Great Britain and Ireland.