Christian Findeklee

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The electric conductivity can potentially be used as an additional diagnostic parameter, e.g., in tumor diagnosis. Moreover, the electric conductivity, in connection with the electric field, can be used to estimate the local SAR distribution during MR measurements. In this study, a new approach, called electric properties tomography (EPT) is presented. It(More)
The current gold standard to estimate local and global specific energy absorption rate for MRI involves numerically modeling the patient and the transmit radiofrequency coil. Recently, a patient-individual method was presented, which estimated specific energy absorption rate from individually measured B(1) maps. This method, however, was restricted to(More)
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,(More)
Introduction Dielectric resonance effects diminish the quality of body MR images at main fields at 3T or above. Parallel RF transmission techniques bear the potential of compensating for these effects through RF shimming. Such techniques have been studied in simulations [1], and first multi-channel transmit systems were presented recently [2-4].(More)
The electrical conductivity of human tissue could be used as an additional diagnostic parameter or might be helpful for the prediction of the local SAR during MR measurements. In this study, the approach "Electric Properties Tomography" (EPT) is applied, which derives the patient's electric conductivity using a standard MR system. To this goal, the spatial(More)
The specific absorption rate (SAR) is an important safety criterion, limiting many MR protocols with respect to the achievable contrast and scan duration. Parallel transmission enables control of the radiofrequency field in space and time and hence allows for SAR management. However, a trade-off exists between radiofrequency pulse performance and SAR(More)
Introduction Tissue permittivity might serve as diagnostic parameter, e.g., for oncology [1]. However, the diagnostic use of the permittivity is significantly hampered by the lack of suitable methods to determine the permittivity in vivo. A possible approach for the determination of permittivity in vivo is given by analyzing the B1 map in the framework of(More)
Introduction Multi-channel transmit MR systems bear the potential of compensating signal intensity variations occurring at higher field strengths due to dielectric resonances. Methods like RF shimming [1] and local excitation [2] in combination with Transmit Sense [3] can be applied to compensate for these effects. Moreover, methods like Transmit Sense [3](More)
Introduction A TEM T/R head coil and a shielded birdcage T/R head coil operated at 298MHz/7T were both modeled using the Finite Difference Time Domain (FDTD) method. The two coils have approximately the same physical size. B 1-field and SAR were calculated for the two head coils loaded with a realistic human head model. B 1-field comparison shows a slightly(More)
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