10 results on '"Sebastian Bickelhaupt"'
Search Results
2. Sodium and quantitative hydrogen parameter changes in muscle tissue after eccentric exercise and in delayed‐onset muscle soreness assessed with magnetic resonance imaging
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Svenja A. Höger, Lena V. Gast, Benjamin Marty, Thilo Hotfiel, Sebastian Bickelhaupt, Michael Uder, Rafael Heiss, and Armin M. Nagel
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Molecular Medicine ,Radiology, Nuclear Medicine and imaging ,Spectroscopy - Abstract
The objective of the current study was to assess sodium (
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- 2022
3. A novel normalization for amide proton transfer CEST MRI to correct for fat signal–induced artifacts: application to human breast cancer imaging
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Sarah Schott, Lisa Loi, Ferdinand Zimmermann, Moritz Zaiss, Andreas Korzowski, Patrick Schuenke, Sebastian Bickelhaupt, Johannes Breitling, Jan Eric Meissner, Steffen Goerke, Peter Bachert, Mark E. Ladd, Daniel Paech, and Heinz-Peter Schlemmer
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Adult ,Cest mri ,Normal Distribution ,Normalization (image processing) ,Amide proton ,Breast Neoplasms ,Cancer imaging ,In Vitro Techniques ,Body Mass Index ,030218 nuclear medicine & medical imaging ,03 medical and health sciences ,0302 clinical medicine ,Nuclear magnetic resonance ,Image Processing, Computer-Assisted ,Humans ,Sunflower Oil ,Phase relation ,Radiology, Nuclear Medicine and imaging ,In patient ,Physics ,Temperature ,Hydrogen-Ion Concentration ,Middle Aged ,Magnetic Resonance Imaging ,Healthy Volunteers ,Adipose Tissue ,Relaxation effect ,Female ,Artifacts ,Human breast ,Algorithms ,030217 neurology & neurosurgery - Abstract
Purpose: The application of amide proton transfer (APT) CEST MRI for diagnosis of breast cancer is of emerging interest. However, APT imaging in the human breast is affected by the ubiquitous fat signal preventing a straightforward application of existing acquisition protocols. Although the spectral region of the APT signal does not coincide with fat resonances, the fat signal leads to an incorrect normalization of the Z‐spectrum, and therefore to distorted APT effects. In this study, we propose a novel normalization for APT‐CEST MRI that corrects for fat signal–induced artifacts in the postprocessing without the need for application of fat saturation schemes or water–fat separation approaches. Methods The novel normalization uses the residual signal at the spectral position of the direct water saturation to estimate the fat contribution. A comprehensive theoretical description of the normalization for an arbitrary phase relation of the water and fat signal is provided. Functionality and applicability of the proposed normalization was demonstrated by in vitro and in vivo experiments. Results In vitro, an underestimation of the conventional APT contrast of approximately −1.2% per 1% fat fraction was observed. The novel normalization yielded an APT contrast independent of the fat contribution, which was also independent of the water‐fat phase relation. This allowed APT imaging in patients with mamma carcinoma corrected for fat signal contribution, field inhomogeneities, spillover dilution, and water relaxation effects. Conclusion The proposed normalization increases the specificity of APT imaging in tissues with varying fat content and represents a time‐efficient and specific absorption rate–efficient alternative to fat saturation and water–fat separation approaches.
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- 2019
4. Abbreviated MRI Protocols in Breast Cancer Diagnostics
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Heinz-Peter Schlemmer, Franziska Koenig, Katerina Deike-Hofmann, Constantin Dreher, Sebastian Bickelhaupt, Stefan Delorme, and Daniel Paech
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Protocol (science) ,medicine.medical_specialty ,medicine.diagnostic_test ,business.industry ,Early detection ,Evidence-based medicine ,Clinical routine ,medicine.disease ,030218 nuclear medicine & medical imaging ,Imaging modalities ,03 medical and health sciences ,0302 clinical medicine ,Breast cancer ,Medicine ,Breast MRI ,Radiology, Nuclear Medicine and imaging ,Medical physics ,Stage (cooking) ,business - Abstract
Oncologic imaging focused on the detection of breast cancer is of increasing importance, with over 1.7 million new cases detected each year worldwide. MRI of the breast has been described to be one of the most sensitive imaging modalities in breast cancer detection; however, clinical use is limited due to high costs. In the past, the objective and clinical routine of oncologic imaging was to provide one extended imaging protocol covering all potential needs and clinical implications regardless of the specific clinical indication or question. Future protocols might be more focused according to a "keep it short and simple" approach, with a reduction of patient magnet time and a limited number of images to review. Rather than replacing conventional full-diagnostic breast MRI protocols, these approaches aim at introducing a new thinking in oncologic imaging using a diversification of available imaging approaches targeted to the dedicated clinical needs of the individual patient. Here we review current approaches on using abbreviated protocols that aim to increase the clinical availability and use of breast MRI for improved early detection of breast cancer. Level of Evidence: 2 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2019;49:647-658.
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- 2018
5. Chemical exchange saturation transfer (CEST) signal intensity at 7T MRI of WHO IV° gliomas is dependent on the anatomic location
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Andreas Unterberg, Martin Bendszus, Patrick Schuenke, Constantin Dreher, Moritz Zaiss, Felix Sahm, Johanna Oberhollenzer, Johannes Windschuh, Daniel Paech, Jan Eric Meissner, Alexander Radbruch, Heinz Peter Schlemmer, Peter Bachert, Sebastian Regnery, Wolfgang Wick, Mark E. Ladd, and Sebastian Bickelhaupt
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education.field_of_study ,medicine.diagnostic_test ,Receiver operating characteristic ,business.industry ,Population ,Brain tumor ,Magnetic resonance imaging ,medicine.disease ,Lateralization of brain function ,030218 nuclear medicine & medical imaging ,03 medical and health sciences ,Exact test ,0302 clinical medicine ,Nuclear magnetic resonance ,Neuroimaging ,Glioma ,medicine ,Radiology, Nuclear Medicine and imaging ,business ,education - Abstract
Background Chemical exchange saturation transfer (CEST) is a novel MRI technique applied to brain tumor patients. Purpose To investigate the anatomic location dependence of CEST MRI obtained at 7T and histopathological/molecular parameters in WHO IV° glioma patients. Study type Analytic prospective study. Population Twenty-one patients with newly diagnosed WHO IV° gliomas were studied prior to surgery; 11 healthy volunteers were investigated. Field strength/sequence Conventional MRI (contrast-enhanced, T2 w and diffusion-weighted imaging) at 3T and T2 w and CEST MRI at 7T was performed for patients and both patients and volunteers. Assessment Mean CEST signal intensities (nuclear-Overhauser-enhancement [NOE], amide-proton-transfer [APT], downfield NOE-suppressed APT [dns-APT]), ADC values, and histopathological/molecular parameters were evaluated with regard to hemisphere location and contact with the subventricular zone. CEST signal intensities of cerebral tissue of healthy volunteers were evaluated with regard to hemisphere discrimination. Statistical tests Spearman correlation, Mann-Whitney U-test, Wilcoxon signed-rank-test, Fisher's exact test, and area under the receiver operating curve. Results Maximum APT and dns-APT signal intensities were significantly different in right vs. left hemisphere gliomas (P = 0.037 and P = 0.007), but not in right vs. left hemisphere cerebral tissue of healthy subjects (P = 0.062-0.859). Mean ADC values were significantly decreased in right vs. left hemisphere gliomas (P = 0.044). Mean NOE signal intensity did not differ significantly between gliomas of either hemisphere (P = 0.820), but in case of subventricular zone contact (P = 0.047). A significant correlation was observed between APT and dns-APT and ADC signal intensities (rs = -0.627, P = 0.004 and rs = -0.534, P = 0.019), but not between NOE and ADC (rs = -0.341, P = 0.154). Histopathological/molecular parameters were not significantly different concerning the tumor location (P = 0.104-1.000, P = 0.286-0.696). Data conclusion APT, dns-APT, and ADC were inversely correlated and depended on the gliomas' hemisphere location. NOE showed significant dependence on subventricular zone contact. Location dependency of APT- and NOE-mediated CEST effects should be considered in clinical investigations of CEST MRI. Level of evidence 2 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2019;49:777-785.
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- 2018
6. Prediction of malignancy by a radiomic signature from contrast agent-free diffusion MRI in suspicious breast lesions found on screening mammography
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Franziska Steudle, Heinz Peter Schlemmer, Frederik Bernd Laun, David Bonekamp, Manuel Wiesenfarth, Michael Götz, Klaus H. Maier-Hein, Heidi Daniel, Wolfgang Lederer, Daniel Paech, Philipp Kickingereder, Nils Gählert, Sebastian Bickelhaupt, and Diana Tichy
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medicine.medical_specialty ,medicine.diagnostic_test ,Receiver operating characteristic ,business.industry ,Magnetic resonance imaging ,Malignancy ,medicine.disease ,030218 nuclear medicine & medical imaging ,03 medical and health sciences ,Breast cancer screening ,0302 clinical medicine ,030220 oncology & carcinogenesis ,medicine ,Mammography ,Breast MRI ,Effective diffusion coefficient ,Radiology, Nuclear Medicine and imaging ,Radiology ,Stage (cooking) ,business - Abstract
Purpose To assess radiomics as a tool to determine how well lesions found suspicious on breast cancer screening X-ray mammography can be categorized into malignant and benign with unenhanced magnetic resonance (MR) mammography with diffusion-weighted imaging and T2-weighted sequences. Materials and Methods From an asymptomatic screening cohort, 50 women with mammographically suspicious findings were examined with contrast-enhanced breast MRI (ceMRI) at 1.5T. Out of this protocol an unenhanced, abbreviated diffusion-weighted imaging protocol (ueMRI) including T2-weighted, (T2w), diffusion-weighted imaging (DWI), and DWI with background suppression (DWIBS) sequences and corresponding apparent diffusion coefficient (ADC) maps were extracted. From ueMRI-derived radiomic features, three Lasso-supervised machine-learning classifiers were constructed and compared with the clinical performance of a highly experienced radiologist: 1) univariate mean ADC model, 2) unconstrained radiomic model, 3) constrained radiomic model with mandatory inclusion of mean ADC. Results The unconstrained and constrained radiomic classifiers consisted of 11 parameters each and achieved differentiation of malignant from benign lesions with a .632 + bootstrap receiver operating characteristics (ROC) area under the curve (AUC) of 84.2%/85.1%, compared to 77.4% for mean ADC and 95.9%/95.9% for the experienced radiologist using ceMRI/ueMRI. Conclusion In this pilot study we identified two ueMRI radiomics classifiers that performed well in the differentiation of malignant from benign lesions and achieved higher performance than the mean ADC parameter alone. Classification was lower than the almost perfect performance of a highly experienced breast radiologist. The potential of radiomics to provide a training-independent diagnostic decision tool is indicated. A performance reaching the human expert would be highly desirable and based on our results is considered possible when the concept is extended in larger cohorts with further development and validation of the technique. Level of Evidence: 1 Technical Efficacy: Stage 2 J. MAGN. RESON. IMAGING 2017;46:604–616
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- 2017
7. Adiabatically prepared spin-lock approach for T1ρ-based dynamic glucose enhanced MRI at ultrahigh fields
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Heinz Peter Schlemmer, Johannes Windschuh, Sibu Mundiyanapurath, Daniel Paech, Alexander Radbruch, Peter Bachert, Sebastian Bickelhaupt, David Bonekamp, Moritz Zaiss, Patrick Schuenke, Mark E. Ladd, C Koehler, and Andreas Korzowski
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Scanner ,Materials science ,medicine.diagnostic_test ,Field (physics) ,Image quality ,Magnetic resonance imaging ,030218 nuclear medicine & medical imaging ,Magnetic field ,03 medical and health sciences ,0302 clinical medicine ,Nuclear magnetic resonance ,medicine ,Radiology, Nuclear Medicine and imaging ,Sensitivity (control systems) ,Molecular imaging ,Spin lock ,030217 neurology & neurosurgery - Abstract
Purpose Chemical exchange sensitive spin-lock and related techniques allow to observe the uptake of administered D-glucose in vivo. The exchange-weighting increases with the magnetic field strength, but inhomogeneities in the radiofrequency (RF) field at ultrahigh field whole-body scanners lead to artifacts in conventional spin-lock experiments. Thus, our aim was the development of an adiabatically prepared T1ρ-based imaging sequence applicable to studies of glucose metabolism in tumor patients at ultrahigh field strengths. Methods An adiabatically prepared on-resonant spin-lock approach was realized at a 7 Tesla whole-body scanner and compared with conventional spin-lock. The insensitivity to RF field inhomogeneities as well as the chemical exchange sensitivity of the approach was investigated in simulations, model solutions and in the human brain. Results The suggested spin-lock approach was shown to be feasible for in vivo application at ultrahigh field whole-body scanners and showed substantially improved image quality compared with conventional spin-lock. The sensitivity of the presented method to glucose was verified in model solutions and a glucose contrast was observed in a glioblastoma patient after intravenous administration of glucose solution. Conclusion An adiabatically prepared spin-lock preparation was presented that enables a homogeneous and chemical exchange sensitive T1ρ-based imaging at ultra-high field whole-body scanners, e.g., for T1ρ-based dynamic glucose enhanced MRI. Magn Reson Med 78:215–225, 2017. © 2016 International Society for Magnetic Resonance in Medicine
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- 2016
8. Software-supported evaluation of gastric motility in MRI: A feasibility study
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Hanspeter Bouquet, Roger Cattin, Stephan Raible, Urs Bill, Michael A. Patak, Johannes M. Froehlich, and Sebastian Bickelhaupt
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medicine.medical_specialty ,business.industry ,Single measurement ,Gastric motility ,Motility ,Entire abdomen ,Surgery ,Software ,Oncology ,Coronal plane ,Assessment methods ,Medicine ,Radiology, Nuclear Medicine and imaging ,business ,Nuclear medicine ,Gastric corpus - Abstract
Introduction The aim of this study was to evaluate the feasibility of dedicated motility assessment software for quantitative evaluation of basic gastric motility and to validate it using manual measurements. Methods Ten patients (5 males/5 females, mean 41 years) out of a previous series of small bowel MR-enterography examinations with well visible stomachs were included in this Institutional Reviews Board approved, retrospective study. MRI (1.5-T, Siemens Sonata) was performed after standardised oral preparation (3% aqueous mannitol over 1 h). Coronal 2DtrueFISP (TR 283.8/TE 1.89/FOV400/10 mm slice) motility acquisitions covering the entire abdomen were performed in apnoea. For each patient, image analysis for assessment of gastric motility was performed both manually and using the dedicated software either the proximal (n = 5) or in the distal (n = 5) gastric corpus. The main quantitative endpoints (amplitude, frequency) describing gastric motility were compared using (paired) Student's t-Test. Results All motility curves qualitatively matched each other (10/10). No significant differences (P > 0.05) were found for amplitudes (mean: 18.17 mm manual; 17.78 mm software), contraction frequencies (5.1/min; 4.7/min) and mean lumen diameters (34.12 mm; 33.13 mm), respectively. Mean duration for a single measurement was significantly (P
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- 2013
9. Software-assisted small bowel motility analysis using free-breathing MRI: Feasibility study
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Johannes M. Froehlich, Michael A. Patak, Hanspeter Bouquet, Sebastian Bickelhaupt, Roger Cattin, Stephan Raible, and Urs Bill
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Reproducibility ,medicine.medical_specialty ,medicine.diagnostic_test ,Correlation coefficient ,business.industry ,Coefficient of variation ,Magnetic resonance imaging ,Standard deviation ,Surgery ,Software ,Linear regression ,medicine ,Breathing ,Radiology, Nuclear Medicine and imaging ,business ,Nuclear medicine - Abstract
Purpose To validate a software prototype allowing for small bowel motility analysis in free breathing by comparing it to manual measurements. Materials and Methods In all, 25 patients (15 male, 10 female; mean age 39 years) were included in this Institutional Review Board-approved, retrospective study. Magnetic resonance imaging (MRI) was performed on a 1.5T system after standardized preparation acquiring motility sequences in free breathing over 69–84 seconds. Small bowel motility was analyzed manually and with the software. Functional parameters, measurement time, and reproducibility were compared using the coefficient of variance and paired Student's t-test. Correlation was analyzed using Pearson's correlation coefficient and linear regression. Results The 25 segments were analyzed twice both by hand and using the software with automatic breathing correction. All assessed parameters significantly correlated between the methods (P < 0.01), but the scattering of repeated measurements was significantly (P < 0.01) lower using the software (3.90%, standard deviation [SD] ± 5.69) than manual examinations (9.77%, SD ± 11.08). The time needed was significantly less (P < 0.001) with the software (4.52 minutes, SD ± 1.58) compared to manual measurement, lasting 17.48 minutes for manual (SD ± 1.75 minutes). Conclusion The use of the software proves reliable and faster small bowel motility measurements in free-breathing MRI compared to manual analyses. The new technique allows for analyses of prolonged sequences acquired in free breathing, improving the informative value of the examinations by amplifying the evaluable data. J. Magn. Reson. Imaging 2014;39:17–23. © 2013 Wiley Periodicals, Inc.
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- 2013
10. Automatic detection of small bowel contraction frequencies in motility plots using lomb-scargle periodogram and sinus-fitting method-initial experience
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Hanspeter Bouquet, Michael A. Patak, Urs Bill, Roger Cattin, Johannes M. Froehlich, Sebastian Bickelhaupt, and Stephan Raible
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Contraction (grammar) ,Least-squares spectral analysis ,Intraclass correlation ,Computer science ,business.industry ,Slice thickness ,Significant difference ,Small bowel motility ,Repetition Time ,Statistics ,Periodogram ,Radiology, Nuclear Medicine and imaging ,Nuclear medicine ,business - Abstract
PURPOSE: Contraction frequencies are an important parameter for the analysis of bowel motility in MRI. The contraction curve can be rather noisy and the frequency-evaluation might be difficult. The aim was to evaluate manual calculations of small bowel contraction frequency in comparison with automatic calculations using two mathematically established methods. METHODS: The institutional-review-board approved study consisted of 48 segmental small-bowel motility-plots out of a previous study with 25 patients (15 men/10 women; mean 39 years, standard deviation ± 14.67) undergoing MRI (1.5 T, GE-Medical Systems; two-dimensional-Fiesta, pulse repetition time 2.91, echo time 1.25, flip-angle 45°, matrix 256 × 256, slice thickness 10 mm) were evaluated. Calculations of contraction frequency was performed either manually or using Lomb-Scargle-periodograms and Sinus-Fitting method. The results were compared using intraclass correlation coefficient, Friedman's-test and Wilcoxon-matched-paired-signed-rank-test (P
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- 2013
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