@article{LagemaatMaasVosetal.2015,
  author    = {Lagemaat, Miriam W. and Maas, Marnix C. and Vos, Eline K. and Bitz, Andreas and Orzada, Stephan and Weiland, Elisabeth and Uden, Mark J. van and Kobus, Thiele and Heerschap, Arend and Scheenen, Tom W. J.},
  title     = {(31) P MR spectroscopic imaging of the human prostate at 7 T: T1 relaxation times, Nuclear Overhauser Effect, and spectral characterization},
  series = {Magnetic Resonance in Medicine},
  volume    = {73},
  journal   = {Magnetic Resonance in Medicine},
  number    = {3},
  publisher = {Wiley},
  address   = {Weinheim},
  issn      = {1522-2594},
  doi       = {10.1002/mrm.25209},
  pages     = {909 -- 920},
  year      = {2015},
  language  = {en}
}
@article{OrzadaSolbachGratzetal.2019,
  author    = {Orzada, Stephan and Solbach, Klaus and Gratz, Marcel and Brunheim, Sascha and Fiedler, Thomas M. and Johst, S{\"o}ren and Bitz, Andreas and Shooshtary, Samaneh and Abuelhaija, Asjraf and Voelker, Maximilian N. and Rietsch, Stefan H. G. and Kraff, Oliver and Maderwald, Stefan and Fl{\"o}ser, Martina and Oehmingen, Mark and Quick, Harald H. and Ladd, Mark E.},
  title     = {A 32-channel parallel transmit system add-on for 7T MRI},
  series = {Plos one},
  journal   = {Plos one},
  doi       = {10.1371/journal.pone.0222452},
  year      = {2019},
  language  = {en}
}
@article{OrzadaLaddBitz2016,
  author    = {Orzada, Stephan and Ladd, Mark E. and Bitz, Andreas},
  title     = {A method to approximate maximum local SAR in multichannel transmit MR systems without transmit phase information},
  series = {Magnetic Resonance in Medicine},
  volume    = {78},
  journal   = {Magnetic Resonance in Medicine},
  number    = {2},
  publisher = {International Society for Magnetic Resonance in Medicine},
  issn      = {1522-2594},
  doi       = {10.1002/mrm.26398},
  pages     = {805 -- 811},
  year      = {2016},
  abstract  = {Purpose To calculate local specific absorption rate (SAR) correctly, both the amplitude and phase of the signal in each transmit channel have to be known. In this work, we propose a method to derive a conservative upper bound for the local SAR, with a reasonable safety margin without knowledge of the transmit phases of the channels. Methods The proposed method uses virtual observation points (VOPs). Correction factors are calculated for each set of VOPs that prevent underestimation of local SAR when the VOPs are applied with the correct amplitudes but fixed phases. Results The proposed method proved to be superior to the worst-case calculation based on the maximum eigenvalue of the VOPs. The mean overestimation for six coil setups could be reduced, whereas no underestimation of the maximum local SAR occurred. In the best investigated case, the overestimation could be reduced from a factor of 3.3 to a factor of 1.7. Conclusion The upper bound for the local SAR calculated with the proposed method allows a fast estimation of the local SAR based on power measurements in the transmit channels and facilitates SAR monitoring in systems that do not have the capability to monitor transmit phases},
  language  = {en}
}
@article{RietschPfaffenrotBitzetal.2017,
  author    = {Rietsch, Stefan H. G. and Pfaffenrot, Viktor and Bitz, Andreas and Orzada, Stephan and Brunheim, Sascha and Lazik-Palm, Andrea and Theysohn, Jens M. and Ladd, Mark E. and Quick, Harald H. and Kraff, Oliver},
  title     = {An 8-channel transceiver 7-channel receive RF coil setup for high SNR ultrahigh-field MRI of the shoulder at 7T},
  series = {Medical Physics},
  journal   = {Medical Physics},
  number    = {Article in press},
  publisher = {Wiley},
  address   = {Hoboken},
  issn      = {0094-2405},
  doi       = {10.1002/mp.12612},
  year      = {2017},
  language  = {en}
}
@article{KraffBitzKruszonaetal.2009,
  author    = {Kraff, Oliver and Bitz, Andreas and Kruszona, Stefan and Orzada, Stephan and Schaefer, Lena C. and Theysohn, Jens M. and Maderwald, Stefan and Ladd, Mark E. and Quick, Harald H.},
  title     = {An eight-channel phased array RF coil for spine MR imaging at 7 T},
  series = {Investigative Radiology},
  volume    = {44},
  journal   = {Investigative Radiology},
  number    = {11},
  publisher = {Lippincott Williams \& Wilkins},
  issn      = {1536-0210},
  doi       = {10.1097/RLI.0b013e3181b24ab7},
  pages     = {734 -- 740},
  year      = {2009},
  language  = {en}
}
@article{OrzadaBitzJohstetal.2017,
  author    = {Orzada, Stephan and Bitz, Andreas and Johst, S{\"o}ren and Gratz, Marcel and V{\"o}lker, Maximilian N. and Kraff, Oliver and Abuelhaija, Ashraf and Fiedler, Thomas M. and Solbach, Klaus and Quick, Harald H. and Ladd, Mark E.},
  title     = {Analysis of an integrated 8-Channel Tx/Rx body array for use as a body coil in 7-Tesla MRI},
  series = {Frontiers in Physics},
  volume    = {5},
  journal   = {Frontiers in Physics},
  number    = {Jun},
  issn      = {2296-424X},
  doi       = {10.3389/fphy.2017.00017},
  year      = {2017},
  language  = {en}
}
@article{UmutluBitzMaderwaldetal.2013,
  author    = {Umutlu, Lale and Bitz, Andreas and Maderwald, Stefan and Orzada, Stephan and Kinner, Sonja and Kraff, Oliver and Brote, Irina and Ladd, Susanne C. and Schroeder, Tobias and Forsting, Michael},
  title     = {Contrast-enhanced ultra-high-field liver MRI: a feasibility trial},
  series = {European Journal of Radiology},
  volume    = {82},
  journal   = {European Journal of Radiology},
  number    = {5},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0720-048X},
  doi       = {10.1016/j.ejrad.2011.07.004},
  pages     = {760 -- 767},
  year      = {2013},
  language  = {en}
}
@article{RietschBrunheimOrzadaetal.2019,
  author    = {Rietsch, Stefan H. G. and Brunheim, Sascha and Orzada, Stephan and Voelker, Maximilian N. and Maderwald, Stefan and Bitz, Andreas and Gratz, Marcel and Ladd, Mark E. and Quick, Harald H.},
  title     = {Development and evaluation of a 16-channel receive-only RF coil to improve 7T ultra-high field body MRI with focus on the spine},
  series = {Magnetic Resonance in Medicine},
  journal   = {Magnetic Resonance in Medicine},
  number    = {Early view},
  publisher = {Wiley},
  address   = {Weinheim},
  issn      = {1522-2594},
  doi       = {10.1002/mrm.27731},
  year      = {2019},
  language  = {en}
}
@article{MaasVosLagemaatetal.2014,
  author    = {Maas, Marnix C. and Vos, Eline K. and Lagemaat, Miriam W. and Bitz, Andreas and Orzada, Stephan and Kobus, Thiele and Kraff, Oliver and Maderwald, Stefan and Ladd, Mark E. and Scheenen, Tom W. J.},
  title     = {Feasibility of T₂-weighted turbo spin echo imaging of the human prostate at 7 tesla},
  series = {Magnetic Resonance in Medicine},
  volume    = {71},
  journal   = {Magnetic Resonance in Medicine},
  number    = {5},
  publisher = {Wiley-VCH},
  address   = {Weinheim},
  issn      = {1522-2594},
  doi       = {10.1002/mrm.24818},
  pages     = {1711 -- 1719},
  year      = {2014},
  abstract  = {Purpose To demonstrate that high quality T₂-weighted (T2w) turbo spin-echo (TSE) imaging of the complete prostate can be achieved routinely and within safety limits at 7 T, using an external transceive body array coil only. Methods Nine healthy volunteers and 12 prostate cancer patients were scanned on a 7 T whole-body system. Preparation consisted of B₀ and radiofrequency shimming and localized flip angle calibration. T₁ and T₂ relaxation times were measured and used to define the T2w-TSE protocol. T2w imaging was performed using a TSE sequence (pulse repetition time/echo time 3000-3640/71 ms) with prolonged excitation and refocusing pulses to reduce specific absorption rate. Results High quality T2w TSE imaging was performed in less than 2 min in all subjects. Tumors of patients with gold-standard tumor localization (MR-guided biopsy or prostatectomy) were well visualized on 7 T imaging (n = 3). The number of consecutive slices achievable within a 10-g averaged specific absorption rate limit of 10 W/kg was ≥28 in all subjects, sufficient for full prostate coverage with 3-mm slices in at least one direction. Conclusion High quality T2w TSE prostate imaging can be performed routinely and within specific absorption rate limits at 7 T with an external transceive body array.},
  language  = {en}
}
@article{KobusBitzUdenetal.2012,
  author    = {Kobus, Thiele and Bitz, Andreas and Uden, Mark J. van and Lagemaat, Miram W. and Rothgang, Eva and Orzada, Stephan and Heerschap, Arend and Scheenen, Tom W. J.},
  title     = {In vivo 31P MR spectroscopic imaging of the human prostate at 7 T: safety and feasibility},
  series = {Magnetic Resonance in Medicine},
  volume    = {68},
  journal   = {Magnetic Resonance in Medicine},
  number    = {6},
  publisher = {Wiley-Liss},
  address   = {New York},
  issn      = {1522-2594},
  doi       = {10.1002/mrm.24175},
  pages     = {1683 -- 1695},
  year      = {2012},
  abstract  = {31P MR spectroscopic imaging of the human prostate provides information about phosphorylated metabolites that could be used for prostate cancer characterization. The sensitivity of a magnetic field strength of 7 T might enable 3D 31P MR spectroscopic imaging with relevant spatial resolution in a clinically acceptable measurement time. To this end, a 31P endorectal coil was developed and combined with an eight-channel 1H body-array coil to relate metabolic information to anatomical location. An extensive safety validation was performed to evaluate the specific absorption rate, the radiofrequency field distribution, and the temperature distribution of both coils. This validation consisted of detailed Finite Integration Technique simulations, confirmed by MR thermometry and Burn:x-wiley:07403194:media:MRM24175:tex2gif-stack-1 measurements in a phantom and in vivo temperature measurements. The safety studies demonstrated that the presence of the 31P endorectal coil had no influence on the specific absorption rate levels and temperature distribution of the external eight-channel 1H array coil. To stay within a 10 g averaged local specific absorption rate of 10 W/kg, a maximum time-averaged input power of 33 W for the 1H array coil was allowed. For transmitting with the 31P endorectal coil, our safety limit of less than 1°C temperature increase in vivo during a 15-min MR spectroscopic imaging experiment was reached at a time-averaged input power of 1.9 W. With this power setting, a second in vivo measurement was performed on a healthy volunteer. Using adiabatic excitation, 3D 31P MR spectroscopic imaging produced spectra from the entire prostate in 18 min with a spatial resolution of 4 cm3. The spectral resolution enabled the separate detection of phosphocholine, phosphoethanolamine, inorganic phosphate, and other metabolites that could play an important role in the characterization of prostate cancer.},
  language  = {en}
}