Hans-Jörg Wittsack

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BACKGROUND AND PURPOSE Diffusion-weighted imaging (DWI) and perfusion-weighted imaging (PWI) are relatively new MR techniques increasingly used in acute stroke. During the first hours of stroke evolution, the regions with abnormal perfusion are typically larger than the DWI lesions, and this mismatch region has been suggested to be "tissue at risk." The aim(More)
Reading the facial expression of other people is a fundamental skill for social interaction. Human facial expressions of emotions are readily recognized but may also evoke the same experiential emotional state in the observer. We used event-related functional magnetic resonance imaging and multi-channel electroencephalography to determine in 14 right-handed(More)
As complex social beings, people communicate, in addition to spoken language, also via nonverbal behavior. In social face-to-face situations, people readily read the affect and intentions of others in their face expressions and gestures recognizing their meaning. Importantly, the addressee further has to discriminate the meanings of the seen communicative(More)
PURPOSE To evaluate the feasibility of diffusion-tensor (DT) imaging at 3 T for functional assessment of transplanted kidneys. MATERIALS AND METHODS This study was approved by the local ethics committee; written informed consent was obtained. Between August 2009 and October 2010, 40 renal transplant recipients were prospectively included in this study and(More)
The signal of diffusion-weighted imaging of the human kidney differs from the signal in brain examinations due to the different microscopic structure of the tissue. In the kidney, the deviation of the signal behavior of monoexponential characteristics is pronounced. The aim of the study was to analyze whether a mono- or biexponential or a distribution(More)
In neuroimaging studies of stroke patients, coactivation may account for increased recruitment of bilateral motor areas when moving the affected limb. Here we studied eight patients after stroke with fMRI and simultaneous EMG. Bilateral recruitment of premotor and primary motor cortices was evident in five patients with strictly unilateral performance per(More)
OBJECT The purpose of this study was to determine the predictive value of [18F]fluoroethyl-L-tyrosine (FET)-positron emission tomography (PET) and magnetic resonance (MR) spectroscopy for tumor diagnosis in patients with suspected gliomas. METHODS Both FET-PET and MR spectroscopy analyses were performed in 50 consecutive patients with newly diagnosed(More)
PURPOSE Mild swelling of astrocytes is proposed as a key event in the pathogenesis of hepatic encephalopathy. Proton MR spectroscopy ((1)H-MR spectroscopy), diffusion-weighted imaging (DWI), and magnetization transfer imaging were performed in patients with alcoholic and nonalcoholic liver cirrhosis and correlated with different clinical stages of hepatic(More)
The recognition of emotional facial expressions is an important means to adjust behavior in social interactions. As facial expressions widely differ in their duration and degree of expressiveness, they often manifest with short and transient expressions below the level of awareness. In this combined behavioral and fMRI study, we aimed at examining whether(More)
Over the last few years, several functionally distinct subregions of the posterior parietal cortex (PPC) have been shown to subserve oculomotor control. Since these areas seem to overlap with regions whose activation is related to attention, we used functional magnetic resonance imaging to compare the cerebral activation pattern evoked by eye movements with(More)