@article{OrzadaJohstMaderwaldetal.2013,
  author    = {Orzada, Stephan and Johst, S{\"o}ren and Maderwald, Stefan and Bitz, Andreas and Solbach, Klaus and Ladd, Mark E.},
  title     = {Mitigation of B1(+) inhomogeneity on single-channel transmit systems with TIAMO},
  series = {Magnetic Resonance in Medicine},
  volume    = {70},
  journal   = {Magnetic Resonance in Medicine},
  number    = {1},
  publisher = {Wiley},
  address   = {Weinheim},
  issn      = {1522-2594},
  doi       = {10.1002/mrm.24453},
  pages     = {290 -- 294},
  year      = {2013},
  language  = {en}
}
@article{UmutluOrzadaKinneretal.2011,
  author    = {Umutlu, Lale and Orzada, Stephan and Kinner, Sonja and Maderwald, Stefan and Bronte, Irina and Bitz, Andreas and Kraff, Oliver and Ladd, Susanne C. and Antoch, Gerald and Ladd, Mark E. and Quick, Harald H. and Lauenstein, Thomas C.},
  title     = {Renal imaging at 7 Tesla: preliminary results},
  series = {European Radiology},
  volume    = {21},
  journal   = {European Radiology},
  number    = {4},
  publisher = {Springer},
  address   = {Berlin},
  issn      = {1432-1084},
  pages     = {841 -- 849},
  year      = {2011},
  abstract  = {Objective To investigate the feasibility of 7T MR imaging of the kidneys utilising a custom-built 8-channel transmit/receive radiofrequency body coil. Methods In vivo unenhanced MR was performed in 8 healthy volunteers on a 7T whole-body MR system. After B0 shimming the following sequences were obtained: 1) 2D and 3D spoiled gradient-echo sequences (FLASH, VIBE), 2) T1-weighted 2D in and opposed phase 3) True-FISP imaging and 4) a T2-weighted turbo spin echo (TSE) sequence. Visual evaluation of the overall image quality was performed by two radiologists. Results Renal MRI at 7T was feasible in all eight subjects. Best image quality was found using T1-weighted gradient echo MRI, providing high anatomical details and excellent conspicuity of the non-enhanced vasculature. With successful shimming, B1 signal voids could be effectively reduced and/or shifted out of the region of interest in most sequence types. However, T2-weighted TSE imaging remained challenging and strongly impaired because of signal heterogeneities in three volunteers. Conclusion The results demonstrate the feasibility and diagnostic potential of dedicated 7T renal imaging. Further optimisation of imaging sequences and dedicated RF coil concepts are expected to improve the acquisition quality and ultimately provide high clinical diagnostic value.},
  language  = {en}
}
@article{UmutluMaderwaldKinneretal.2013,
  author    = {Umutlu, L. and Maderwald, S. and Kinner, S. and Kraff, O. and Bitz, Andreas and Orzada, S. and Johst, S. and Wrede, K. and Forsting, M. and Ladd, M. E. and Lauenstein, T. C. and Quick, H. H.},
  title     = {First-pass contrast-enhanced renal MRA at 7 Tesla: initial results},
  series = {European Radiology},
  volume    = {23},
  journal   = {European Radiology},
  number    = {4},
  publisher = {Springer},
  address   = {Berlin},
  issn      = {1432-1084},
  doi       = {10.1007/s00330-012-2666-0},
  pages     = {1059 -- 1066},
  year      = {2013},
  language  = {en}
}
@article{KraffWredeSchoembergetal.2013,
  author    = {Kraff, Oliver and Wrede, Karsten H. and Schoemberg, Tobias and Dammann, Philipp and Noureddine, Yacine and Orzada, Stephan and Ladd, Mark E. and Bitz, Andreas},
  title     = {MR safety assessment of potential RF heating from cranial fixation plates at 7 T},
  series = {Medical Physics},
  volume    = {40},
  journal   = {Medical Physics},
  number    = {4},
  publisher = {Wiley},
  address   = {Hoboken},
  issn      = {2473-4209},
  doi       = {10.1118/1.4795347},
  pages     = {042302-1 -- 042302-10},
  year      = {2013},
  language  = {en}
}
@article{BitzFelderWittig2013,
  author    = {Bitz, Andreas and Felder, Jorg and Wittig, Tilmann},
  title     = {Designing MRI Coils with Aid of Simulation},
  series = {Microwaves \& RF},
  volume    = {52},
  journal   = {Microwaves \& RF},
  number    = {7},
  publisher = {Penton},
  address   = {Cleveland, Ohio},
  issn      = {0745-2993},
  pages     = {56},
  year      = {2013},
  language  = {en}
}
@article{UmutluKraffFischeretal.2013,
  author    = {Umutlu, Lale and Kraff, Oliver and Fischer, Anja and Kinner, Sonja and Maderwald, Stefan and Nassenstein, Kai and Nensa, Felix and Gr{\"u}neisen, Johannes and Orzada, Stephan and Bitz, Andreas and Forsting, Michael and Ladd, Mark E. and Lauenstein, Thomas C.},
  title     = {Seven-Tesla MRI of the female pelvis},
  series = {European Radiology},
  volume    = {23},
  journal   = {European Radiology},
  number    = {9},
  publisher = {Springer},
  address   = {Berlin},
  issn      = {1432-1084},
  doi       = {10.1007/s00330-013-2868-0},
  pages     = {2364 -- 2373},
  year      = {2013},
  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{LagemaatVosMaasetal.2014,
  author    = {Lagemaat, Miriam W. and Vos, Eline K. and Maas, Marnix C. and Bitz, Andreas and Orzada, Stephan and Uden, Mark J. van and Kobus, Thiele and Heerschap, Arend and Scheenen, Tom W. J.},
  title     = {Phosphorus magnetic resonance spectroscopic imaging at 7 T in patients with prostate cancer},
  series = {Investigative Radiology},
  volume    = {49},
  journal   = {Investigative Radiology},
  number    = {5},
  publisher = {Lippincott Williams \& Wilkins},
  address   = {Philadelphia, Pa.},
  issn      = {1536-0210},
  doi       = {10.1097/RLI.0000000000000012},
  pages     = {363 -- 372},
  year      = {2014},
  abstract  = {Objectives The aim of this study was to identify characteristics of phosphorus (³¹P) spectra of the human prostate and to investigate changes of individual phospholipid metabolites in prostate cancer through in vivo ³¹P magnetic resonance spectroscopic imaging (MRSI) at 7 T. Materials and Methods In this institutional review board-approved study, 15 patients with biopsy-proven prostate cancer underwent T₂-weighted magnetic resonance imaging and 3-dimensional ³¹P MRSI at 7 T. Voxels were selected at the tumor location, in normal-appearing peripheral zone tissue, normal-appearing transition zone tissue, and in the base of the prostate close to the seminal vesicles. Phosphorus metabolite ratios were determined and compared between tissue types. Results Signals of phosphoethanolamine (PE) and phosphocholine (PC) were present and well resolved in most ³¹P spectra in the prostate. Glycerophosphocholine signals were observable in 43\% of the voxels in malignant tissue, but in only 10\% of the voxels in normal-appearing tissue away from the seminal vesicles. In many spectra, independent of tissue type, 2 peaks resonated in the chemical shift range of inorganic phosphate, possibly representing 2 separate pH compartments. The PC/PE ratio in the seminal vesicles was highly elevated compared with the prostate in 5 patients. A considerable overlap of ³¹P metabolite ratios was found between prostate cancer and normal-appearing prostate tissue, preventing direct discrimination of these tissues. The only 2 patients with high Gleason scores tumors (≥4+5) presented with high PC and glycerophosphocholine levels in their cancer lesions. Conclusions Phosphorus MRSI at 7 T shows distinct features of phospholipid metabolites in the prostate gland and its surrounding structures. In this exploratory study, no differences in ³¹P metabolite ratios were observed between prostate cancer and normal-appearing prostate tissue possibly because of the partial volume effects of small tumor foci in large MRSI voxels.},
  language  = {en}
}
@article{TheysohnKraffEilersetal.2014,
  author    = {Theysohn, Jens M. and Kraff, Oliver and Eilers, Kristina and Andrade, Dorian and Gerwig, Marcus and Timmann, Dagmar and Schmitt, Franz and Ladd, Mark E. and Ladd, Susanne C. and Bitz, Andreas},
  title     = {Vestibular effects of a 7 Tesla MRI examination compared to 1.5 T and 0 T in healthy volunteers},
  series = {PLoS one},
  volume    = {9},
  journal   = {PLoS one},
  number    = {3},
  publisher = {PLOS},
  address   = {San Francisco},
  issn      = {1932-6203},
  doi       = {10.1371/journal.pone.0092104},
  pages     = {e92104},
  year      = {2014},
  abstract  = {Ultra-high-field MRI (7 Tesla (T) and above) elicits more temporary side-effects compared to 1.5 T and 3 T, e.g. dizziness or "postural instability" even after exiting the scanner. The current study aims to assess quantitatively vestibular performance before and after exposure to different MRI scenarios at 7 T, 1.5 T and 0 T. Sway path and body axis rotation (Unterberger's stepping test) were quantitatively recorded in a total of 46 volunteers before, 2 minutes after, and 15 minutes after different exposure scenarios: 7 T head MRI (n = 27), 7 T no RF (n = 22), 7 T only B₀ (n = 20), 7 T in \& out B₀ (n = 20), 1.5 T no RF (n = 20), 0 T (n = 15). All exposure scenarios lasted 30 minutes except for brief one minute exposure in 7 T in \& out B₀. Both measures were documented utilizing a 3D ultrasound system. During sway path evaluation, the experiment was repeated with eyes both open and closed. Sway paths for all long-lasting 7 T scenarios (normal, no RF, only B₀) with eyes closed were significantly prolonged 2 minutes after exiting the scanner, normalizing after 15 minutes. Brief exposure to 7 T B₀ or 30 minutes exposure to 1.5 T or 0 T did not show significant changes. End positions after Unterberger's stepping test were significantly changed counter-clockwise after all 7 T scenarios, including the brief in \& out B₀ exposure. Shorter exposure resulted in a smaller alteration angle. In contrast to sway path, reversal of changes in body axis rotation was incomplete after 15 minutes. 1.5 T caused no rotational changes. The results show that exposure to the 7 Tesla static magnetic field causes only a temporary dysfunction or "over-compensation" of the vestibular system not measurable at 1.5 or 0 Tesla. Radiofrequency fields, gradient switching, and orthostatic dysregulation do not seem to play a role.},
  language  = {en}
}
@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}
}