Christian P. Jansen

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PURPOSE The purpose of this prospective study was to determine the outcome of postprocedural cerebral diffusion-weighted (DW) MR lesions after carotid artery stent placement (CAS) and the incidence of new cerebral MR lesions 6 months after the procedure. MATERIALS AND METHODS DW and T2-weighted MR imaging of the brain and neurologic examinations were(More)
The quantitative assessment of cardiac motion is a fundamental concept to evaluate ventricular malfunction. We present a new optical-flow-based method for estimating heart motion from two-dimensional echocardiographic sequences. To account for typical heart motions, such as contraction/expansion and shear, we analyze the images locally by using a(More)
We present a new computational method for reconstructing a vector velocity field from scattered, pulsed-wave ultrasound Doppler data. The main difficulty is that the Doppler measurements are incomplete, for they do only capture the velocity component along the beam direction. We thus propose to combine measurements from different beam directions. However,(More)
Wavelet-based methods have become most popular for the compression of two-dimensional medical images and sequences. The standard implementations consider data sizes that are powers of two. There is also a large body of literature treating issues such as the choice of the "optimal" wavelets and the performance comparison of competing algorithms. With the(More)
High resolution multidimensional image data yield huge datasets. For compression and analysis, 2D approaches are often used, neglecting the information coherence in higher dimensions, which can be exploited for improved compression. We designed a wavelet compression algorithm suited for data of arbitrary dimensions, and assessed its ability for compression(More)
Thousands of medical images are saved in databases every day and the need for algorithms able to handle such data in an unsupervised manner is steadily increasing. The classification of ultrasound images is an outstandingly difficult task, due to the high noise level of these images. We present a detailed description of an algorithm based on multiscale(More)
Marker-based optical tracking systems are often used to track objects that are equipped with a certain number of passive or active point markers. Fixed configurations of these markers, so-called rigid bodies, can be detected by, for example, infrared stereo-based camera systems, and their position and orientation can be reconstructed by corresponding(More)
We present a new framework to estimate and visualize heart motion from echocardiograms. For velocity estimation , we have developed a novel multiresolution optical flow algorithm. In order to account for typical heart motions like contraction/expansion and shear, we use a local affine model for the velocity in space and time. The motion parameters are(More)
BACKGROUND Introduction of combined antiretroviral therapy (cART) has improved survival of HIV infected individuals, while the relative contribution of liver-related mortality increased. Especially in HIV/HCV-coinfected patients hepatic fibrosis and portal hypertension represent the main causes of liver-related morbidity and mortality. Circulating miRNA-122(More)