Wolfgang Ruhm

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An experimental implementation and first performance analysis of parallel spatially selective excitation with an array of transmit coils and simultaneous transmission of individual waveforms on multiple channels is presented. This technique, also known as Transmit SENSE, uses the basic idea of parallel imaging to shorten the k-space trajectories that(More)
This work describes the first experimental realization of three-dimensional spatially selective excitation using parallel transmission in vivo. For the design of three-dimensional parallel excitation pulses with short durations and high excitation accuracy, the choice of a suitable transmit k-space trajectory is crucial. For this reason, the characteristics(More)
Introduction: Recently, first examples of inner-volume-imaging and motion artifact suppression based on Parallel EXcitation (PEX) have been presented [1]. However, in most PEX based applications, 3D selectivity has been achieved by 2D spatially selective excitation combined with perpendicular 1D slice selective refocusing. Therefore, the necessity of multi(More)
Multidimensional spatially selective excitation (SSE) has stimulated a variety of useful applications in magnetic resonance imaging and magnetic resonance spectroscopy, which have regained considerable interest after the recent introduction of parallel excitation. For SSE, radiofrequency pulses are designed specifically for certain time-courses of spatially(More)
With the recent proposal of using magnetic fields that are nonlinear by design for spatial encoding, new flexibility has been introduced to MR imaging. The new degrees of freedom in shaping the spatially encoding magnetic fields (SEMs) can be used to locally adapt the imaging resolution to features of the imaged object, e.g., anatomical structures, to(More)
Introduction: Parallel transmission has proven to provide good results for spatially selective excitation with reasonable RF-pulse durations [1]. For best spatial definition, exact matching of RF-pulses with a simultaneously played out gradient waveform, which defines a k-space position for every point in time, is crucial. However off-resonance effects and(More)
Introduction: In-vivo MR imaging on humans and animals is often affected by flow and motion of nuclear spins causing blurring and ghosting artifacts [1]. If these moving spins are not of direct investigational interest their effects need to be suppressed or compensated efficiently. For this purpose a variety of techniques has been developed, like(More)
PURPOSE Intercomparison of active dosemeters in the measurement of stray radiation at the Trento active-scanning proton therapy facility. METHODS EURADOS WG9 carried out a large intercomparison exercise to test different dosemeters while measuring secondary neutrons within a 230 MeV scanned proton therapy facility. Detectors included two Bonner Sphere(More)
Introduction: The concept of Parallel Excitation or Transmit SENSE [1-6] has shown its potential to reduce several problems of single channel excitation, e. g. offresonance or transverse relaxation effects, due to its pulse shortening capabilities. However, despite the shorter pulse lengths these deficiencies cannot be compensated completely. In this study(More)
Magnetic particle imaging (MPI) is a novel tracer-based in vivo imaging modality allowing quantitative measurements of the spatial distributions of superparamagnetic iron oxide (SPIO) nanoparticles in three dimensions (3D) and in real time using electromagnetic fields. However, MPI lacks the detection of morphological information which makes it difficult to(More)
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