Peter Roschmann
Philips
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Featured researches published by Peter Roschmann.
Magnetic Resonance in Medicine | 2001
Markus Weiger; Klaas P. Pruessmann; Christoph Leussler; Peter Roschmann; Peter Boesiger
In sensitivity encoding (SENSE), the effects of inhomogeneous spatial sensitivity of surface coils are utilized for signal localization in addition to common Fourier encoding using magnetic field gradients. Unlike standard Fourier MRI, SENSE images exhibit an inhomogeneous noise distribution, which crucially depends on the geometrical sensitivity relations of the coils used. Thus, for optimum signal‐to‐noise‐ratio (SNR) and noise homogeneity, specialized coil configurations are called for. In this article we study the implications of SENSE imaging for coil layout by means of simulations and imaging experiments in a phantom and in vivo. New, specific design principles are identified. For SENSE imaging, the elements of a coil array should be smaller than for common phased‐array imaging. Furthermore, adjacent coil elements should not overlap. Based on the findings of initial investigations, a configuration of six coils was designed and built specifically for cardiac applications. The in vivo evaluation of this array showed a considerable SNR increase in SENSE images, as compared with a conventional array. Magn Reson Med 45:495–504, 2001.
Journal of Computer Assisted Tomography | 1985
Sadek K. Hilal; A.A Maudsley; J. B. Ra; Howard E. Simon; Peter Roschmann; Stefan Wittekoek; Zang-Hee Cho; S. K. Mun
Surgicale report the first clinical nuclear magnetic resonance (NMR) images of cerebral sodium distribution in normal volunteers and in patients with a variety of pathological lesions. We have used a 1.5 T NMR magnet system. When compared with proton distribution, sodium, shows a greater vriation in its concentration from tissue to tissue and from normal to pathological conditions. Image contrast calculated on the basis of sodium concentration is 7 to 18 times greater than that of proton spin density. Normal images emphasize the extracellular compartments. In the clinical studies, areas of recent or old cerebral infarction and tumors show a pronounced increase of sodium content (300–400%). Actual measurements of image density values indicate that there is probably a further accentuation of the contrast by the increased “NMR visibility” of sodium in infarcted tissue. Sodium imaging may prove to be a more sensitive menas for early detection of some brain disorders than other imaging methods.
Magnetic Resonance in Medicine | 2007
Peter Vernickel; Peter Roschmann; Christian Findeklee; K.-M. Lüdeke; Ch. Leussler; J Overweg; Ulrich Katscher; I. Grässlin; K. Schünemann
Multichannel transmit magnetic resonance imaging (MR) systems have the potential to compensate for signal‐intensity variations occurring at higher field strengths due to wave propagation effects in tissue. Methods such as RF shimming and local excitation in combination with parallel transmission can be applied to compensate for these effects. Moreover, parallel transmission can be applied to ease the excitation of arbitrarily shaped magnetization patterns. The implementation of these methods adds new requirements in terms of MRI hardware. This article describes the design of a decoupled eight‐element transmit/receive body coil for 3T. The setup of the coil is explained, starting with standard single‐channel resonators. Special focus is placed on the decoupling of the elements to obtain independent RF resonators. After a brief discussion of the underlying theory, the properties and limitations of the coil are outlined. Finally, the functionality and capabilities of the coil are demonstrated using RF measurements as well as MRI sequences. Magn Reson Med 58:381–389, 2007.
Magnetic Resonance Imaging | 1988
Dirk Buikman; Thomas Helzel; Peter Roschmann
A new sensor principle for detection of patient movement in magnetic resonance imaging has been successfully applied for the reduction of motion artifacts. It uses a device that is already present in every MRI system, namely the rf coil. Patient movement within the coil causes changes in the rf impedance match of the coil, which can be measured as variations in the reflected rf power. The principle used for the detection of respiratory and cardiac motion is described, and experimental results measured with several coil arrangements are given. Images are presented which were acquired with respiratory gating derived from the rf body coil of a 2 Tesla whole body MRI system.
Magnetic Resonance Imaging | 1985
K.M. Lüdeke; Peter Roschmann; R. Tischler
NMR in Biomedicine | 1988
H. Bomsdorf; T. Helzel; D. Kunz; Peter Roschmann; O. Tschendel; J. Wieland
Magnetic Resonance in Medicine | 1997
Volker Rasche; Dietrich J. K. Holz; Jurgen Kohler; Roland Proksa; Peter Roschmann
Archive | 1988
Peter Roschmann
Archive | 1984
Peter Roschmann; Howard E. Simon
Archive | 1996
Volker Rasche; Peter Roschmann