Learn More
Quantitative susceptibility mapping (QSM) based on gradient echo (GRE) magnetic resonance phase data is a novel technique for non-invasive assessment of magnetic tissue susceptibility differences. The method is expected to be an important means to determine iron distributions in vivo and may, thus, be instrumental for elucidating the physiological role of(More)
Quantitative magnetic susceptibility mapping (QSM) has recently been introduced to provide a novel quantitative and local MRI contrast. However, the anatomical contrast represented by in vivo susceptibility maps has not yet been compared systematically and comprehensively with gradient (recalled) echo (GRE) magnitude, frequency, and R(2)(*) images.(More)
Several gradient-echo fMRI blood oxygenation level-dependent (BOLD) effects are described in the literature: extravascular spin dephasing around capillaries and veins, intravascular phase changes, and transverse relaxation changes of blood. This work considers a series of tissue compartmentalized models incorporating each of these effects, and tries to(More)
Language acquisition in humans relies on abilities like abstraction and use of syntactic rules, which are absent in other animals. The neural correlate of acquiring new linguistic competence was investigated with two functional magnetic resonance imaging (fMRI) studies. German native speakers learned a sample of 'real' grammatical rules of different(More)
Breathing carbogen (5% CO2 / 95% O2) dramatically increases cerebral blood flow (CBF), which induces a blood oxygenation level dependent (BOLD) related vascular signal change due to the concomitantly increased oxyhemoglobin concentration in the veins. However, carbogen often causes discomfort due to its forced strong and deep breathing which also may lead(More)
BACKGROUND AND PURPOSE MR gradient echo imaging is sensitive to the magnetic susceptibility of different tissue types. The purpose of this study was to investigate the diagnostic potential of MR phase imaging of the human brain. METHODS High-spatial-resolution, T2*-weighted, single-echo images were acquired in five volunteers and one patient with a brain(More)
This paper reviews the recent development of a new high-resolution magnetic resonance imaging approach to visualizing small veins in the human brain with diameters in the sub-millimeter range, which is smaller than a voxel. It briefly introduces the physical background of the underlying bulk magnetic susceptibility effects, on which this approach is based,(More)
To investigate the influence of anisotropic electrical conductivity in white matter on the forward and inverse solution in electroencephalography (EEG) and magnetoencephalography (MEG) numerical simulation studies were performed. A high-resolution (1 mm3 isotropic) finite element model of a human head was implemented to study the sensitivity of EEG and MEG(More)
Diffusion tensor imaging (DTI) studies of schizophrenia have revealed white matter abnormalities in several areas of the brain. The functional impact on either psychopathology or cognition remains, however, poorly understood. Here we analysed both functional MRI (during a working memory task) and DTI data sets in 18 patients with schizophrenia and 18(More)
A novel noninvasive magnetic resonance imaging (MRI) method was developed to determine in vivo blood oxygen saturation and its changes during motor cortex activation in small cerebral veins. Specifically, based on susceptibility measurements in the resting states, pial veins were found to have a mean oxygen saturation of Yrest=0.544+/-0.029 averaged over 14(More)