A5051865703- Advanced MRI Techniques and Applications
- Atomic and Subatomic Physics Research
- Advanced NMR Techniques and Applications
- Advanced Neuroimaging Techniques and Applications
- Medical Imaging Techniques and Applications
- Functional Brain Connectivity Studies
- Cardiac Imaging and Diagnostics
- Electron Spin Resonance Studies
- Lanthanide and Transition Metal Complexes
- MRI in cancer diagnosis
- NMR spectroscopy and applications
- Optical Imaging and Spectroscopy Techniques
- Nuclear Physics and Applications
- Advanced X-ray Imaging Techniques
- Ultrasound and Hyperthermia Applications
- Sparse and Compressive Sensing Techniques
- Advanced Fluorescence Microscopy Techniques
- Transcranial Magnetic Stimulation Studies
- Liver Disease Diagnosis and Treatment
- Radiomics and Machine Learning in Medical Imaging
- Cerebrovascular and Carotid Artery Diseases
- Photoreceptor and optogenetics research
- Microwave Imaging and Scattering Analysis
- Wireless Body Area Networks
- Metabolomics and Mass Spectrometry Studies
Max Planck Institute for Biological Cybernetics
2015-2024
Max Planck Society
2012-2021
University of Tübingen
2020
High Magnetic Field Laboratory
2016
Cognitive Neuroimaging Lab
2012
Medizinische Hochschule Hannover
2009
Roche (Switzerland)
2005
University of Würzburg
1996-2001
Relaxation times, transmit homogeneity, signal-to-noise ratio (SNR) and parallel imaging g-factor were determined in the human brain at 3T, 7T, 9.4T, using standard, tight-fitting coil arrays.The same subjects scanned all three field strengths, identical sequence parameters similar 31- or 32-channel receive arrays. The SNR of three-dimensional (3D) gradient echo images was a multiple replica approach corrected with measured flip angle T2 (*) distributions T1 white matter to obtain intrinsic...
Purpose Arranging transmit array elements in multiple rows provides an additional degree of freedom to correct B 1 + field inhomogeneities and achieve whole‐brain excitation at ultrahigh strengths. Receive arrays shaped the contours anatomy increase signal‐to‐noise ratio image. In this work, advantages offered by receive techniques are combined for human brain imaging 9.4 T. Methods A 16‐element dual‐row a 31‐element were developed. Based on accurate numerical model array, deposited power...
Abstract The optimization of k ‐space sampling for nonlinear sparse MRI reconstruction is phrased as a Bayesian experimental design problem. inference approximated by novel relaxation to standard signal processing primitives, resulting in an efficient algorithm Cartesian and spiral trajectories. On clinical resolution brain image data from Siemens 3T scanner, automatically optimized trajectories lead significantly improved images, compared low‐pass, equispaced, or variable density randomized...
The development of novel radiofrequency (RF) coils for human ultrahigh‐field (≥7 T), non‐proton and body applications is an active field research in many MR groups. Any RF coil must meet the strict requirements safe application on humans with respect to mechanical electrical safety, as well specific absorption rate (SAR) limits. For this purpose, regulations such International Electrotechnical Commission (IEC) standard medical equipment, vendor‐suggested test specifications third party...
Abstract Fourier imaging modalities suffer from significant signal contamination between adjacent voxels, especially when the spatial resolution is comparable to size of anatomical structures. This can be positive or negative, depending on response function and geometry object. Such a situation arises in human cardiac 31 P chemical shift (CSI). Acquisition‐weighted CSI reduces this substantially, which demonstrated by comparing conventional Hanning‐weighted 3D P‐CSI experiments 13 healthy...
Purpose Subject motion can severely degrade MR images. A retrospective correction algorithm, Gradient‐based correction, which significantly reduces ghosting and blurring artifacts due to subject was proposed. The technique uses the raw data of standard imaging sequences; no sequence modifications or additional equipment such as tracking devices are required. Rigid is assumed. Methods approach iteratively searches for trajectory yielding sharpest image measured by entropy spatial gradients....
With the increasing use of ultrahigh‐field MR with multiple transmit channels, mapping B 1 + field has become a critical factor in many studies, leading to publication large number sequences for measurement flip angle recent years. In this article, accuracy, precision and practicability some most prominent these techniques are investigated both theoretically, using error propagation computations Monte‐Carlo simulations, experimentally different settings. For an exemplary experiment, which is...
Abstract Context Insulin action in the human brain influences eating behavior, cognition, and whole-body metabolism. Studies investigating insulin rely on intranasal application. Objective To investigate effects of three doses placebo as nasal sprays central autonomous nervous system analyze absorption into bloodstream. Design, Participants, Methods Nine healthy men received or 40 U, 80 160 U spray randomized order. Before after spray, activity was assessed by functional magnetic resonance...
Aims To determine individual glucose hydroxyl exchange rates at physiological conditions and use this information for numerical optimization of glucoCEST/CESL preparation. give guidelines in vivo measurement parameters clinical ultra‐high field strengths. Methods Five solution samples different pH values were measured 14.1 T various B 1 power levels. Multi‐B ‐Z‐spectra Bloch‐McConnell fits further improved by the fitting Z‐spectra five simultaneously. The obtained used a six‐pool simulation...
Purpose The increased signal‐to‐noise ratio and blood oxygen level dependent signal at ultra‐high field can only help to boost the resolution in functional MRI studies if spatial specificity of activation is improved. At a strength 9.4 T, both gradient‐echo spin‐echo based echo‐planar imaging were implemented applied investigate human MRI. A finger tapping paradigm was used acquire data with scan parameters similar standard neuroscientific applications. Methods Spatial resolution, echo,...
A multinuclei imaging setup with the capability to acquire both sodium ((23) Na) and proton ((1) H) signals at 9.4 Tesla is presented. The main objective was optimize coil performance (23) Na frequency while still having ability satisfactory (1) H images.The consisted of a combination three radio (RF) coils arranged in layers: innermost layer 27-channel receive helmet which surrounded by four-channel transceiver array. outer dipole array for B0 shimming anatomical localization. Transmit...
The aims of this study were to investigate the subjective discomfort and sensory side effects during ultrahigh field (UHF) magnetic resonance imaging (MRI) examinations in a large-scale evaluate differences between (MR) sites.Four MR sites with 7-T system 2 9.4-T participated multicenter total number 3457 completed questionnaires on causes sensations examination. For pooled retrospective analysis results from partially different questionnaires, all data adapted an answer option 4-point scale...
We demonstrated the feasibility of using bSSFP acquisitions for off-resonance insensitive high-resolution [6,6'-2H2]-glucose deuterium metabolic imaging (DMI) studies in healthy human brain at 9.4T. Balanced SSFP have potential to improve sensitivity DMI despite SNR loss phase-cycling and other scanner constraints.We investigated two variants acquisitions, namely uniform-weighted multi echo acquisition-weighted CSI with oral labelled-glucose intake. Phase-cycling was introduced make less...
Purpose To evaluate muscle perfusion in patients with peripheral arterial occlusive disease (PAOD) before and after percutaneous transluminal angioplasty (PTA) of the limb by means MR spin labeling (ASL) measurements during reactive hyperemia. Materials Methods Ten symptomatic PAOD affecting iliac or femoral vessels were investigated PTA. A pseudo‐continuous (PCASL) technique was applied. Perfusion measured soleus tibialis anterior Key parameters such as mean value (P hyp ), time‐to‐peak...
Purpose Investigation of the feasibility to perform high‐resolution quantitative sodium imaging at 9.4 Tesla (T). Methods A proton patch antenna was combined with a birdcage coil provide signal without compromising efficiency X‐nucleus coil. Sodium density weighted images nominal resolution 1 × 5 mm 3 were acquired within 30 min an ultrashort echo time sequence. The methods used for calibration as well B 0 , and off‐resonance correction verified on phantom five healthy volunteers. Results An...
Purpose To examine in vivo metabolic alterations the isocitrate dehydrogenase (IDH) mutated gliomas using magnetic resonance spectroscopy (MRS) at field 9.4T. Materials and Methods Spectra were acquired with a 9.4T whole‐body scanner use of custom‐built head coil (16 channel transmit 31 receive). A modified stimulated echo acquisition mode (STEAM) sequence was used for localization. Eighteen patients brain tumors probable glial origin participated this study. The study performed accordance...
Molecular imaging of cells and cellular processes can be achieved by tagging intracellular targets such as receptors, enzymes, or mRNA. Seeking to visualize the presence specific mRNAs magnetic resonance (MR) imaging, we coupled peptide nucleic acids (PNA) with gadolinium-based MR contrast agents using cell-penetrating peptides for delivery. Antisense mRNA DsRed2 protein was used proof principle. The conjugates were produced continuous solid-phase synthesis followed chelation gadolinium....
Abstract Purpose To develop and test a novel method for coil placement in interleaved transcranial magnetic stimulation (TMS)/functional MRI (fMRI) studies. Materials Methods Initially, desired TMS position at the subject's head is recorded using neuronavigation system. Subsequently, custom‐made holding device used inside MR scanner. The parameters of corresponding to prerecorded are automatically determined from fast structural image acquired directly before experiment. spatial accuracy our...