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33 results on '"Nimsky, Christopher"'

1. Development and pilot validation of laser path anchor (LPA): A novel tool for augmented reality surgical navigation

Author

Qi Ziyu, Zhang Jiashu, Chen Xiaolei, Nimsky Christopher, and Bopp Miriam H. A.

Subjects
augmented reality, navigation, surgery, laser, Medicine
Abstract

Augmented reality navigation (ARN) enhances localization and operation by overlaying virtual guides onto realworld surgical fields. The study introduces a laser path anchor (LPA), a novel tool for ARN in surgery aimed at mitigating depth perception challenges. The LPA anchors the virtual planned path onto the physical laser beam, ensuring accurate puncture from any perspective. The tool consists of a rack, a primary laser emitter, an indicating laser emitter, and an AR marker with intrinsic and extrinsic properties validated through calibration and testing. Intrinsic validation involved measuring the parallelism between the indicating and primary laser using Cartesian graph screens. Extrinsic validation assessed the alignment and shortest distance between the virtual path and primary lasers. Results showed an angle deviation of 0.08° between the indicating and primary laser and 1.44° ± 0.47° between the virtual path and primary lasers, with a shortest distance of 7.60 mm ± 2.50 mm. The usability test demonstrated the LPA’s effectiveness in guiding needle insertions without altering the perspective or distracting the surgeon. Despite some limitations, the LPA enhances the user’s perception of linear objects and eliminates the need for perspective adjustments during puncture, warranting further development.

Published
2024
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2. Intraoperative navigated ultrasound in posterior fossa surgery

Author

Bopp Miriam, Saß Benjamin, Pojskic Mirza, Grote Alexander, and Nimsky Christopher

Subjects
navigation, intraoperative ultrasound, posterior fossa surgery, image-guided surgery, Medicine
Abstract

High navigation accuracy is a prerequisite for tailored and safe tumor resections. However, in posterior fossa surgery, especially in the semi-sitting position, navigation is often considered to be non-useful due to limited accuracy caused by gravitational effects and brain-shift. To enable navigation in these surgical approaches intraoperative evaluation of accuracy and navigation update strategies are required. Navigated intraoperative ultrasound (iUS) might serve as valuable tool to quantify navigation accuracy and even update navigation to gain higher accuracy. Data of 23 patients (28 lesions) undergoing navigation supported surgery in the posterior fossa with application of navigated iUS including acquisition of a 3D iUS data set were evaluated retrospectively based on intraoperative ratings on accuracy and tumor segmentation based on preoperative magnetic resonance imaging (MRI) and iUS data. In nine cases (eleven lesions) navigation was rated “insufficient” leading to a navigation update by manually outlining the tumor volumes within the iUS data set, whereas in all other cases navigation accuracy was rated “sufficient” with no need for further updates. Tumor volume was comparable between MRIand iUS-based segmentation. IUS was successfully applied in navigation-supported surgery in the posterior fossa in the semisitting position enabling continuous navigation-support throughout surgery by evaluation of navigation accuracy and navigation updates, supporting safe maximum tumor resection.

Published
2024
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3. Targeting Aggressive Pituitary Adenomas at the Molecular Level—A Review

Author

Voellger, Benjamin, Zhang, Zhuo, Benzel, Julia, Wang, Junwen, Lei, Ting, Nimsky, Christopher, and Bartsch, Jörg-Walter

Subjects
invasiveness, proliferation, adjuvant treatment, molecular biology, Medicine, Review, pituitary adenomas, hormone secretion
Abstract

Pituitary adenomas (PAs) are mostly benign endocrine tumors that can be treated by resection or medication. However, up to 10% of PAs show an aggressive behavior with invasion of adjacent tissue, rapid proliferation, or recurrence. Here, we provide an overview of target structures in aggressive PAs and summarize current clinical trials including, but not limited to, PAs. Mainly, drug targets in PAs are based on general features of tumor cells such as immune checkpoints, so that programmed cell death 1 (ligand 1) (PD-1/PD-L1) targeting may bear potential to cure aggressive PAs. In addition, epidermal growth factor receptor (EGFR), mammalian target of rapamycin (mTOR), vascular endothelial growth factor (VEGF), fibroblast growth factor (FGF) and their downstream pathways are triggered in PAs, thereby modulating tumor cell proliferation, migration and/or tumor angiogenesis. Temozolomide (TMZ) can be an effective treatment of aggressive PAs. Combination of TMZ with 5-Fluorouracil (5-FU) or with radiotherapy could strengthen the therapeutic effects as compared to TMZ alone. Dopamine agonists (DAs) are the first line treatment for prolactinomas. Dopamine receptors are also expressed in other subtypes of PAs which renders Das potentially suitable to treat other subtypes of PAs. Furthermore, targeting the invasive behavior of PAs could improve therapy. In this regard, human matrix metalloproteinase (MMP) family members and estrogens receptors (ERs) are highly expressed in aggressive PAs, and numerous studies demonstrated the role of these proteins to modulate invasiveness of PAs. This leaves a number of treatment options for aggressive PAs as reviewed here.

Published
2022

4. Der Einfluss von navigiertem intraoperativen 3D-Ultraschall auf die Gliomchirurgie

Author

Saß, Benjamin, Pojskic, Mirza, Zivkovic, Darko, Nimsky, Christopher, and Bopp, Miriam

Subjects
ddc: 610, 610 Medical sciences, Medicine
Abstract

Objective: Neuronavigation is widely used in neurosurgical procedures, providing a low target registration error depending on the type of registration. However, surgical progress is associated with a decrease in accuracy caused by brain shift. This issue can be addressed by intraoperative live imaging.[for full text, please go to the a.m. URL], 72. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie (DGNC), Joint Meeting mit der Polnischen Gesellschaft für Neurochirurgie

Published
2021
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5. Die vergleichende Transkriptom-Analyse von temozolomid-resistenten GBM-Stammzellen und GBM-Rezidiven offenbart Carbonic Anhydrase 2 (CA-2) als vorrangigen Resistenz-Faktor

Author

Bartsch, Jörg-Walter, Zhao, Kai, Hannen, Ricarda, Carl, Barbara, Pagenstecher, Axel, and Nimsky, Christopher

Subjects
ddc: 610, 610 Medical sciences, Medicine
Abstract

Objective: About 95 % of GBM patients show tumor relapse leaving them with limited therapeutic options as recurrent tumors are often resistant to temozolomide (TMZ). GBM-like stem cells (GSCs) are considered to be the major obstacle in therapy resistance, so that characterization of their response[for full text, please go to the a.m. URL], 71. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie (DGNC), 9. Joint Meeting mit der Japanischen Gesellschaft für Neurochirurgie

Published
2020

6. Die Inhibition des Discoidin-Rezeptors DDR1 verbessert die Effektivität der adjuvanten Therapie in Glioblastomen

Author

Vehlow, Anne, Klapproth, Erik, Hannen, Ricarda, Temme, Achim, Nimsky, Christopher, Cordes, Nils, and Bartsch, Jörg-Walter

Subjects
endocrine system, ddc: 610, fungi, 610 Medical sciences, Medicine
Abstract

Objective: A major obstacle to adjuvant GBM therapy using radiatio and temozolomide (TMZ) is the formation of drug- and radiation-resistant GBM stem cells (GSCs). Interestingly, GSCs utilize collagen signalling to regulate TMZ resistance. In order to understand this process in detail, a study was initiated[for full text, please go to the a.m. URL], 71. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie (DGNC), 9. Joint Meeting mit der Japanischen Gesellschaft für Neurochirurgie

Published
2020

7. The impact of position-orientation adaptive smoothing in diffusion weighted imaging—From diffusion metrics to fiber tractography

Author

Yang, Jia, Carl, Barbara, Nimsky, Christopher, and Bopp, Miriam H. A.

Subjects
Central Nervous System, Adult, Computer and Information Sciences, Imaging Techniques, Science, Brain Morphometry, Materials Science, Material Properties, Pyramidal Tracts, Neuroimaging, Research and Analysis Methods, Nervous System, Diagnostic Radiology, Diagnostic Medicine, Medicine and Health Sciences, Image Processing, Computer-Assisted, Humans, Orientation, Spatial, Observer Variation, Brain Mapping, Diffusion Weighted Imaging, Radiology and Imaging, Physics, Biology and Life Sciences, Brain, Reproducibility of Results, Research Assessment, Condensed Matter Physics, Magnetic Resonance Imaging, Reproducibility, Healthy Volunteers, Diffusion Tensor Imaging, Data Acquisition, Diffusion Magnetic Resonance Imaging, Physical Sciences, Medicine, Anisotropy, Anatomy, Tractography, Research Article, Neuroscience
Abstract

In contrast to commonly used approaches to improve data quality in diffusion weighted imaging, position-orientation adaptive smoothing (POAS) provides an edge-preserving post-processing approach. This study aims to investigate its potential and effects on image quality, diffusion metrics, and fiber tractography of the corticospinal tract in relation to non-post-processed and averaged data. 22 healthy volunteers were included in this study. For each volunteer five clinically applicable diffusion weighted imaging data sets were acquired and post-processed by standard averaging and POAS. POAS post-processing led to significantly higher signal-to-noise-ratios (p < 0.001), lower fractional anisotropy across the whole brain (p < 0.05) and reduced intra-subject variability of diffusion weighted imaging signal intensity and fractional anisotropy (p < 0.001, p = 0.006). Fiber tractography of the corticospinal tract resulted in significantly (p = 0.027, p = 0.014) larger tract volumes while fiber density was the lowest. Similarity across tractography results was highest for POAS post-processed data (p < 0.001). POAS post-processing enhances image quality, decreases the intra-subject variability of signal intensity and fractional anisotropy, increases fiber tract volume of the corticospinal tract, and leads to higher reproducibility of tractography results. Thus, POAS post-processing supports a reliable and more accurate fiber tractography of the corticospinal tract, being mandatory for the clinical use.

Published
2020

8. Die Mikroumgebung im Glioblastom verwendet den ADAM8 Metalloprotease-Osteopontin Signalweg, um die Tumor-Angiogenese zu regulieren

Author

Bartsch, Jörg-Walter, Li, Yu, Schlomann, Uwe, Pagenstecher, Axel, and Nimsky, Christopher

Subjects
ddc: 610, 610 Medical sciences, Medicine
Abstract

Objective: In the tumor microenvironment, ADAMs proteinases are important mediators of cell-cell communication between tumor cells and tumor-associated macrophages/microglia. One such proteinase, ADAM8, is highly expressed in glioblastomas and associated with a poor prognosis for GBM patients. [for full text, please go to the a.m. URL], 70. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie (DGNC), Joint Meeting mit der Skandinavischen Gesellschaft für Neurochirurgie

Published
2019

9. Einfluss von Denoising diffusiongewichteter Bilddaten auf Diffusions-Tensor Parameter

Author

Yang, Jia, Bopp, Miriam, Carl, Barbara, and Nimsky, Christopher

Subjects
ddc: 610, 610 Medical sciences, Medicine
Abstract

Objective: Diffusion weighted imaging (DWI) based fiber tractography (FT) plays an important role in pre-surgical planning. However, DWI suffers from artifacts during acquisition and low spatial signal-to-noise-ratio (SNR), which might affect diffusion metrics. Up to now, different denoising algorithms[for full text, please go to the a.m. URL], 70. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie (DGNC), Joint Meeting mit der Skandinavischen Gesellschaft für Neurochirurgie

Published
2019

10. Einfluss von Denoising diffusionsgewichteter Bilddaten auf die Faserbahndarstellung der Pyramidenbahn

Author

Yang, Jia, Bopp, Miriam, Carl, Barbara, and Nimsky, Christopher

Subjects
ddc: 610, 610 Medical sciences, Medicine
Abstract

Objective: Diffusion weighted imaging (DWI) is the basis of fiber tractography (FT) playing an important role in pre-surgical planning. However, DWI suffers from various artifacts during data acquisition and low spatial signal-to-noise-ratio (SNR), which can lead to erroneous results in FT. Various [for full text, please go to the a.m. URL], 70. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie (DGNC), Joint Meeting mit der Skandinavischen Gesellschaft für Neurochirurgie

Published
2019
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11. MicroRNAs 130a and 720 as prognostic biomarkers in patients with glioblastoma

Author

Benescu, Andreea-Cristina, Hannen, Ricarda, Nimsky, Christopher, Meier , Lara, Carl, Barbara, and Bartsch, Jörg-Walter

Subjects
ddc: 610, 610 Medical sciences, Medicine
Abstract

Objective: Detection of GBM recurrence is mainly based on Magnetic-Resonance-Imaging (MRI), however at a late stage, when recurrent tumors are already manifested. Thus there is a desperate need for novel methods to detect recurrent GBMs at earlier stages. In this context "liquid biopsies" [for full text, please go to the a.m. URL], 69. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie (DGNC), Joint Meeting mit der Mexikanischen und Kolumbianischen Gesellschaft für Neurochirurgie

Published
2018

12. Localization and reliable activation of language areas in a novel passive listening paradigm: A test-retest fMRI study

Author

Seefried, Sabine, Bopp, Miriam, Kessler, Roman, Herholz, Peer, Carl, Barbara, and Nimsky, Christopher

Subjects
ddc: 610, 610 Medical sciences, Medicine
Abstract

Objective: Accurate and reliable localization of brain regions associated with language processing is important to improve planning prior to neurosurgical interventions and to reduce the risk of postoperative neurological deficits. This is especially important for patients who suffer from a tumor in[for full text, please go to the a.m. URL], 69. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie (DGNC), Joint Meeting mit der Mexikanischen und Kolumbianischen Gesellschaft für Neurochirurgie

Published
2018

13. AIRO iCT based registration vs. fiducial based registration - an approach to lower radiation exposure

Author

Bopp, Miriam, Carl, Barbara, and Nimsky, Christopher

Subjects
ddc: 610, 610 Medical sciences, Medicine
Abstract

Objective: Mapping image space and physical space in neuronavigation is most commonly performed using fiducial based imaging approaches based on MR or CT imaging, whereas CT images show superior registration accuracy due to image distortion within the MR images. As CT imaging is associated with radiation[for full text, please go to the a.m. URL], 69. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie (DGNC), Joint Meeting mit der Mexikanischen und Kolumbianischen Gesellschaft für Neurochirurgie

Published
2018
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14. The role of calpains in Glioblastoma

Author

Hannen, Ricarda, Chen, Chia-yi, Bartsch, Jörg-Walter, Nimsky, Christopher, and Schilling, Oliver

Subjects
ddc: 610, 610 Medical sciences, Medicine
Abstract

Objective: The massive infiltration of tumor cells into the surrounding brain tissue and the development of resistance mechanisms towards adjuvant radio- and chemotherapy are two main aspects that need to be overcome, for a successful treatment of Glioblastoma (GBM). In both these processes, calcium-dependent[for full text, please go to the a.m. URL], 69. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie (DGNC), Joint Meeting mit der Mexikanischen und Kolumbianischen Gesellschaft für Neurochirurgie

Published
2018

15. Towards systematic screening of gene signatures mediating resistance to radio- and chemotherapy in GBM

Author

Hauswald, Maria, Hannen, Ricarda, Carl, Barbara, Nimsky, Christopher, Acker, Till, Garvalov, Boyan, and Bartsch, Jörg-Walter

Subjects
ddc: 610, 610 Medical sciences, Medicine, nervous system diseases
Abstract

Objective: Glioblastoma multiforme (GBM) is characterized by high rates of relapse (~90 %) after surgery despite patients receiving radio- and chemotherapy. The main reason for relapse is the survival of glioblastoma stem cells (GSCs) which is characterized by increased expression of specific[for full text, please go to the a.m. URL], 68. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie (DGNC), 7. Joint Meeting mit der Society of British Neurological Surgeons (SBNS)

Published
2017
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16. The metalloprotease ADAM8 mediates brain metastasis formation by regulating transendothelial migration

Author

Conrad, Catharina, Götte, Malena, Schlomann, Uwe, Carl, Barbara, Nimsky, Christopher, and Bartsch, Jörg-Walter

Subjects
ddc: 610, 610 Medical sciences, Medicine
Abstract

Objective: Brain metastases outnumber primary neoplasms ten-fold, and are associated with a poor prognosis. Patients with metastatic, triple negative breast cancers are at high risk (25-46%) of developing brain metastases at some point in the course of their disease. Recently we demonstrated that[for full text, please go to the a.m. URL], 68. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie (DGNC), 7. Joint Meeting mit der Society of British Neurological Surgeons (SBNS)

Published
2017

17. Impact of Susceptibility Artifact Correction on Fiber Tractography of the Corticospinal Tracts

Author

Bopp, Miriam, Knopf, Jan-Raphael, Carl, Barbara, and Nimsky, Christopher

Subjects
ddc: 610, 610 Medical sciences, Medicine
Abstract

Objective: Diffusion Tensor Imaging (DTI) and DTI-based fiber tractography (DTI-FT) has become a routine tool in multimodality neuronavigation to outline major white matter tracts non-invasively. The spatial extent of white matter tracts is commonly underestimated, leading to larger safety margins and[for full text, please go to the a.m. URL], 68. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie (DGNC), 7. Joint Meeting mit der Society of British Neurological Surgeons (SBNS)

Published
2017

18. Mapping the language network using passive fMRI

Author

Bauer, Miriam H. A., Herholz, Peer, Pojskic, Mirza, Carl, Barbara, and Nimsky, Christopher

Subjects
language mapping, ddc: 610, glioma, fMRI, 610 Medical sciences, Medicine
Abstract

Objective: To preoperatively localize and intraoperatively visualize components of the language network, such as Broca’s and Wernicke’s area, typically functional MRI (fMRI) is performed using word generation tasks or semantic decision tasks. These active fMRI tasks are heavily dependent[for full text, please go to the a.m. URL], 67. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie (DGNC), 1. Joint Meeting mit der Koreanischen Gesellschaft für Neurochirurgie (KNS)

Published
2016

19. Long-term outcome of total (TR) versus near total (NTR) resected supratentorial low-grade gliomas using functional neuronavigation and intraoperative 1.5 T MR imaging

Author

Merkel, Andreas, Weiser, Melanie, Stadlbauer, Andreas, Nimsky, Christopher, Ganslandt, Oliver, Buchfelder, Michael, and Rössler, Karl

Subjects
intraoperative MR imaging, neuronavigation, ddc: 610, 610 Medical sciences, Medicine, low grade gliomas
Abstract

Objective: Maximized surgical resection has become an important treatment strategy in the modern management of supratentorial lobar low-grade gliomas of the adult. To investigate the difference in prognosis of total versus near total or subtotal resected tumors mostly infiltrating eloquent brain tissue,[for full text, please go to the a.m. URL], 66. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie (DGNC)

Published
2015

20. The metalloprotease-disintegrin ADAM8 mediates brain metastasis of breast cancer cells

Author

Conrad, Catharina, Schlomann, Uwe, Nimsky, Christopher, Preston, Jane, Kamm, Roger, and Bartsch, Jörg W.

Subjects
ddc: 610, Metalloproteases, 610 Medical sciences, Medicine, Metastases, Blood Brain Barrier
Abstract

Objective: Brain metastases outnumber primary neoplasms ten-fold, and are associated with a poor prognosis. Patients with metastatic, triple negative breast cancers are at high risk (25-46%) of developing brain metastases at some point in the course of their disease. Recently we demonstrated that[for full text, please go to the a.m. URL], 66. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie (DGNC)

Published
2015

21. Metalloproteases as mediators of therapy resistance in glioblastoma

Author

Eibach, Michael, Bartsch, Jörg W., Schlomann, Uwe, Conrad, Catharina, Carl, Barbara, and Nimsky, Christopher

Subjects
Protease inhibition, ddc: 610, 610 Medical sciences, Medicine, Adjuvant therapy, GBM
Abstract

Objective: GBM adjuvant therapy using radiotherapy and/or Temozolomide (TMZ) remains inefficient due to resistance mechanisms. One possible mechanism of this observed resistance is due to proteolytic shedding of cell surface proteins. For shedding events, MMP and ADAM metalloproteases (MPs) are[for full text, please go to the a.m. URL], 66. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie (DGNC)

Published
2015

22. Expression of invasion related-proteins in pituitary adenomas

Author

Voellger, Benjamin, Wang, Junwen, Carl, Barbara, Bartsch, Jörg-Walter, and Nimsky, Christopher

Subjects
carbohydrates (lipids), ddc: 610, invasiveness, proteases, pituitary adenomas, 610 Medical sciences, Medicine
Abstract

Objective: To assess the relation of gene expression levels of matrix metalloproteinases (MMPs) and "A Disintegrin and Metalloprotease Domain" (ADAM) proteins with invasiveness in human pituitary adenomas, as such proteins are known to be related with invasiveness in other tumor entities. [for full text, please go to the a.m. URL], 66. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie (DGNC)

Published
2015

23. Non-fluorescence confocal laserendomicroscopy as an intraoperative tool for tumor classification and resection control

Author

Carl, Barbara, Schodrowski, Johanna, and Nimsky, Christopher

Subjects
tumor, nervous system, ddc: 610, confocal laserendomicroscopy, 610 Medical sciences, Medicine, frozen section
Abstract

Objective: To establish an intraoperative technique to differentiate tumor from healthy tissue we used confocal laserendomicroscopy (CLEM) without fluorescence in tumor patients. In addition confocal laserendomicroscopy was performed in murine cerebrum and cerebellum to show typical architecture [for full text, please go to the a.m. URL], 65. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie (DGNC)

Published
2014

24. The metalloprotease ADAM8 contributes to temozolomide chemoresistance and enhanced invasiveness of human glioblastoma cells

Author

Eibach, Michael, Dong, Fangyong, Bartsch, Jörg W., Schlomann, Uwe, Conrad, Catharina, Schieber, Susanne, Strik, Herwig, Carl, Barbara, and Nimsky, Christopher

Subjects
metalloprotease inhibitor, ddc: 610, TMZ chemoresistance, Akt signalling, 610 Medical sciences, Medicine
Abstract

Objective: Despite multimodal therapy, GBM chemotherapy with Temozolomide (TMZ) remains inefficient due to chemoresistance. One possible mechanism of this observed resistance is due to proteolytic shedding of cell surface proteins. MMP and ADAM metalloproteases (MPs) are responsible for these cleavage[for full text, please go to the a.m. URL], 65. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie (DGNC)

Published
2014

25. Optic radiation fiber tractography in glioma patients based on high angular resolution diffusion imaging with compressed sensing compared with diffusion tensor imaging

Author

Kuhnt, Daniela, Bauer, Miriam, Freitag, Dennik, and Nimsky, Christopher

Subjects
ddc: 610, Fiber Tractography, diffusion MR images, Glioma, 610 Medical sciences, Medicine
Abstract

Objective: Fiber tractography integrated in the navigation system has shown to contribute to low postoperative morbidity in glioma surgery. Up to now, in the clinical routine it is mostly based on diffusion tensor imaging (DTI). However, there are known drawbacks in the resolution of crossing-, kissing-,[for full text, please go to the a.m. URL], 64. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie (DGNC)

Published
2013

26. Intraoperative MRI in transsphenoidal reoperations for nonfunctioning pituitary adenomas

Author

Berkmann, Sven, Schlaffer, Sven, Nimsky, Christopher, Fahlbusch, Rudolf, and Buchfelder, Michael

Subjects
ddc: 610, reoperation, 610 Medical sciences, Medicine, pituitary, intraoperative MRI
Abstract

Objective: This retrospective study evaluates the impact of intraoperative MRI (iMRI) on the extent of transsphenoidal revision surgery in patients presenting with recurrent or persisting non-functioning pituitary adenomas. Method: Between 2002 and 2012, 109 patients were re-operated at our institution[for full text, please go to the a.m. URL], 64. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie (DGNC)

Published
2013
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27. Towards graph-based reconstruction of the corticospinal tract

Author

Breininger, Katharina, Bauer, Miriam H. A., Kuhnt, Daniela, Freisleben, Bernd, and Nimsky, Christopher

Subjects
Corticospinal Tract, Fiber Tracking, ddc: 610, DTI, 610 Medical sciences, Medicine
Abstract

Objective: Diffusion Tensor Imaging (DTI) and fiber tractography are popular and routinely used techniques to reconstruct and visualize major white matter tracts in the human brain in-vivo. During neurosurgical procedures, reliable and precise information about the spatial location, its course and spatial[for full text, please go to the a.m. URL], 64. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie (DGNC)

Published
2013

28. Nanoscaled liposomes increase homogeneity in contrast enhanced ultrasound imaging

Author

Becker, Andreas, Marxer, Elena, Brüßler, Jana, Bakowsky, Udo, and Nimsky, Christopher

Subjects
ddc: 610, 610 Medical sciences, Medicine
Abstract

Objective: In neurosurgery ultrasound (US) contrast enhanced imaging is used in brain perfusion measurement or in the diagnosis of vasospasm after subarachnoidal hemorrhage. Texture and homogeneity of contrast enhanced US is a crucial criteria of image quality in brightness mode e.g. in cerebral tumor[for full text, please go to the a.m. URL], 61. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie (DGNC) im Rahmen der Neurowoche 2010

Published
2010

29. Quantification of WHO grade IV-glioma removal by intraoperative high-field magnetic resonance imaging

Author

Kuhnt, Daniela, Ganslandt, Oliver, Becker, Andreas, Buchfelder, Michael, and Nimsky, Christopher

Subjects
ddc: 610, 610 Medical sciences, Medicine
Abstract

Objective: To investigate the contribution of high-field intraoperative magnetic resonance imaging (iMRI) and navigation with integrated functional image data on the amount of resected tumor volume in glioblastoma-surgery. Methods: We investigated 135 patients with supratentorial glioblastoma multiforme[for full text, please go to the a.m. URL], 61. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie (DGNC) im Rahmen der Neurowoche 2010

Published
2010
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30. Optic Radiation Fiber Tractography in Glioma Patients Based on High Angular Resolution Diffusion Imaging with Compressed Sensing Compared with Diffusion Tensor Imaging - Initial Experience.

Author

Kuhnt, Daniela, Bauer, Miriam H. A., Sommer, Jens, Merhof, Dorit, and Nimsky, Christopher

Subjects
GLIOMAS, DIAGNOSTIC imaging, COMPRESSED sensing, COMPARATIVE studies, DIFFUSION tensor imaging, NEUROPHYSIOLOGY, PATIENTS
Abstract

Objective: Up to now, fiber tractography in the clinical routine is mostly based on diffusion tensor imaging (DTI). However, there are known drawbacks in the resolution of crossing or kissing fibers and in the vicinity of a tumor or edema. These restrictions can be overcome by tractography based on High Angular Resolution Diffusion Imaging (HARDI) which in turn requires larger numbers of gradients resulting in longer acquisition times. Using compressed sensing (CS) techniques, HARDI signals can be obtained by using less non-collinear diffusion gradients, thus enabling the use of HARDI-based fiber tractography in the clinical routine. Methods: Eight patients with gliomas in the temporal lobe, in proximity to the optic radiation (OR), underwent 3T MRI including a diffusion-weighted dataset with 30 gradient directions. Fiber tractography of the OR using a deterministic streamline algorithm based on DTI was compared to tractography based on reconstructed diffusion signals using HARDI+CS. Results: HARDI+CS based tractography displayed the OR more conclusively compared to the DTI-based results in all eight cases. In particular, the potential of HARDI+CS-based tractography was observed for cases of high grade gliomas with significant peritumoral edema, larger tumor size or closer proximity of tumor and reconstructed fiber tract. Conclusions: Overcoming the problem of long acquisition times, HARDI+CS seems to be a promising basis for fiber tractography of the OR in regions of disturbed diffusion, areas of high interest in glioma surgery. [ABSTRACT FROM AUTHOR]

Published
2013
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31. Reconstruction of White Matter Tracts via Repeated Deterministic Streamline Tracking – Initial Experience

Author

Bauer, Miriam H. A., Kuhnt, Daniela, Barbieri, Sebastiano, Klein, Jan, Becker, Andreas, Freisleben, Bernd, Hahn, Horst K., and Nimsky, Christopher

Subjects
DIFFUSION tensor imaging, IMAGE reconstruction, BRAIN imaging, NEUROSURGERY, OPERATIVE surgery, POSTOPERATIVE pain, DATA analysis
Abstract

Diffusion Tensor Imaging (DTI) and fiber tractography are established methods to reconstruct major white matter tracts in the human brain in-vivo. Particularly in the context of neurosurgical procedures, reliable information about the course of fiber bundles is important to minimize postoperative deficits while maximizing the tumor resection volume. Since routinely used deterministic streamline tractography approaches often underestimate the spatial extent of white matter tracts, a novel approach to improve fiber segmentation is presented here, considering clinical time constraints. Therefore, fiber tracking visualization is enhanced with statistical information from multiple tracking applications to determine uncertainty in reconstruction based on clinical DTI data. After initial deterministic fiber tracking and centerline calculation, new seed regions are generated along the result’s midline. Tracking is applied to all new seed regions afterwards, varying in number and applied offset. The number of fibers passing each voxel is computed to model different levels of fiber bundle membership. Experimental results using an artificial data set of an anatomical software phantom are presented, using the Dice Similarity Coefficient (DSC) as a measure of segmentation quality. Different parameter combinations were classified to be superior to others providing significantly improved results with DSCs of 81.02%±4.12%, 81.32%±4.22% and 80.99%±3.81% for different levels of added noise in comparison to the deterministic fiber tracking procedure using the two-ROI approach with average DSCs of 65.08%±5.31%, 64.73%±6.02% and 65.91%±6.42%. Whole brain tractography based on the seed volume generated by the calculated seeds delivers average DSCs of 67.12%±0.86%, 75.10%±0.28% and 72.91%±0.15%, original whole brain tractography delivers DSCs of 67.16%, 75.03% and 75.54%, using initial ROIs as combined include regions, which is clearly improved by the repeated fiber tractography method. [ABSTRACT FROM AUTHOR]

Published
2013
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32. Pituitary Adenoma Volumetry with 3D Slicer

Author

Egger, Jan, Kapur, Tina, Nimsky, Christopher, and Kikinis, Ron

Subjects
Biology, Endocrine System, Endocrine Physiology, Pituitary, Computer Science, Algorithms, Computing Methods, Medicine, Oncology, Endocrine Tumors, Pituitaryadenomas, Radiology, Anatomy, Physiology, Cancers, Neoplasms
Abstract

In this study, we present pituitary adenoma volumetry using the free and open source medical image computing platform for biomedical research: (3D) Slicer. Volumetric changes in cerebral pathologies like pituitary adenomas are a critical factor in treatment decisions by physicians and in general the volume is acquired manually. Therefore, manual slice-by-slice segmentations in magnetic resonance imaging (MRI) data, which have been obtained at regular intervals, are performed. In contrast to this manual time consuming slice-by-slice segmentation process Slicer is an alternative which can be significantly faster and less user intensive. In this contribution, we compare pure manual segmentations of ten pituitary adenomas with semi-automatic segmentations under Slicer. Thus, physicians drew the boundaries completely manually on a slice-by-slice basis and performed a Slicer-enhanced segmentation using the competitive region-growing based module of Slicer named GrowCut. Results showed that the time and user effort required for GrowCut-based segmentations were on average about thirty percent less than the pure manual segmentations. Furthermore, we calculated the Dice Similarity Coefficient (DSC) between the manual and the Slicer-based segmentations to proof that the two are comparable yielding an average DSC of 81.97±3.39%.

Published
2012
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33. Square-Cut: A Segmentation Algorithm on the Basis of a Rectangle Shape

Author

Dukatz, Thomas, Kolodziej, Malgorzata, Zukić, Dženan, Freisleben, Bernd, Nimsky, Christopher, Egger, Jan, and Kapur, Tina

Subjects
biology, anatomy and physiology, musculoskeletal system, computer science, algorithms, computer applications, computing methods, mathematics, medicine, radiology, diagnostic radiology, surgery
Abstract

We present a rectangle-based segmentation algorithm that sets up a graph and performs a graph cut to separate an object from the background. However, graph-based algorithms distribute the graph's nodes uniformly and equidistantly on the image. Then, a smoothness term is added to force the cut to prefer a particular shape. This strategy does not allow the cut to prefer a certain structure, especially when areas of the object are indistinguishable from the background. We solve this problem by referring to a rectangle shape of the object when sampling the graph nodes, i.e., the nodes are distributed non-uniformly and non-equidistantly on the image. This strategy can be useful, when areas of the object are indistinguishable from the background. For evaluation, we focus on vertebrae images from Magnetic Resonance Imaging (MRI) datasets to support the time consuming manual slice-by-slice segmentation performed by physicians. The ground truth of the vertebrae boundaries were manually extracted by two clinical experts (neurological surgeons) with several years of experience in spine surgery and afterwards compared with the automatic segmentation results of the proposed scheme yielding an average Dice Similarity Coefficient (DSC) of 90.97±2.2%.

Published
2012
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