@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{ElQuardiStreckertBitzetal.2011,
  author    = {El Quardi, A. and Streckert, J. and Bitz, Andreas and M{\"u}nkner, S. and Engel, J. and Hansen, V.},
  title     = {New fin-line devices for radiofrequency exposure of small biological samples in vitro allowing whole-cell patch clamp recordings},
  series = {Bioelectromagnetics},
  volume    = {32},
  journal   = {Bioelectromagnetics},
  number    = {2},
  publisher = {Wiley},
  address   = {Weinheim},
  issn      = {1521-186X},
  doi       = {10.1002/bem.20621},
  pages     = {102 -- 112},
  year      = {2011},
  abstract  = {The development and analysis of three waveguides for the exposure of small biological in vitro samples to mobile communication signals at 900 MHz (GSM, Global System for Mobile Communications), 1.8 GHz (GSM), and 2 GHz (UMTS, Universal Mobile Telecommunications System) is presented. The waveguides were based on a fin-line concept and the chamber containing the samples bathed in extracellular solution was placed onto two fins with a slot in between, where the exposure field concentrates. Measures were taken to allow for patch clamp recordings during radiofrequency (RF) exposure. The necessary power for the achievement of the maximum desired specific absorption rate (SAR) of 20 W/kg (average over the mass of the solution) was approximately Pin = 50 mW, Pin = 19 mW, and Pin = 18 mW for the 900 MHz, 1800 MHz, and 2 GHz devices, respectively. At 20 W/kg, a slight RF-induced temperature elevation in the solution of no more than 0.3 °C was detected, while no thermal offsets due to the electromagnetic exposure could be detected at the lower SAR settings (2, 0.2, and 0.02 W/kg). A deviation of 10\% from the intended solution volume yielded a calculated SAR deviation of 8\% from the desired value. A maximum ±10\% variation in the local SAR could occur when the position of the patch clamp electrode was altered within the area where the cells to be investigated were located.},
  language  = {en}
}
@article{SommerStreckertBitzetal.2004,
  author    = {Sommer, Angela M. and Streckert, Joachim and Bitz, Andreas and Hansen, Volkert W. and Lerchl, Alexander},
  title     = {No effects of GSM-modulated 900 MHz electromagnetic fields on survival rate and spontaneous development of lymphoma in female AKR/J mice},
  series = {BMC Cancer},
  volume    = {77},
  journal   = {BMC Cancer},
  number    = {4},
  doi       = {10.1186/1471-2407-4-77},
  year      = {2004},
  language  = {en}
}
@article{BitzZhouElQuardietal.2009,
  author    = {Bitz, Andreas and Zhou, Yi and El Quardi, Abdessamad and Streckert, Joachim},
  title     = {Occupational Exposure at Mobile Communication Base Station Antenna Sites},
  series = {Frequenz},
  volume    = {63},
  journal   = {Frequenz},
  number    = {7-8},
  issn      = {2191-6349},
  doi       = {10.1515/FREQ.2009.63.7-8.123},
  pages     = {123 -- 128},
  year      = {2009},
  language  = {en}
}
@article{OrzadaBitzSchaeferetal.2011,
  author    = {Orzada, Stephan and Bitz, Andreas and Sch{\"a}fer, Lena C. and Ladd, Susanne C. and Ladd, Mark E. and Maderwald, Stefan},
  title     = {Open design eight-channel transmit/receive coil for high-resolution and real-time ankle imaging at 7 T},
  series = {Medical Physics},
  volume    = {38},
  journal   = {Medical Physics},
  number    = {3},
  publisher = {Wiley},
  address   = {Hoboken},
  issn      = {2473-4209},
  doi       = {10.1118/1.3553399},
  pages     = {1162 -- 1167},
  year      = {2011},
  abstract  = {Purpose: At 1.5 T, real-time MRI of joint movement has been shown to be feasible. However, 7 T, provides higher SNR and thus an improved potential for parallel imaging acceleration. The purpose of this work was to build an open, U-shaped eight-channel transmit/receive microstrip coil for 7 T MRI to enable high-resolution and real-time imaging of the moving ankle joint. Methods: A U-shaped eight-channel transmit/receive array for the human ankle was built.urn:x-wiley:00942405:mp3399:equation:mp3399-math-0001-parameters and urn:x-wiley:00942405:mp3399:equation:mp3399-math-0002-factor were measured. SAR calculations of different ankle postures were performed to ensure patient safety. Inhomogeneities in the transmit field consequent to the open design were compensated for by the use of static RF shimming. High-resolution and real-time imaging was performed in human volunteers. Results: The presented array showed good performance with regard to patient comfort and image quality. High acceleration factors of up to 4 are feasible without visible acceleration artifacts. Reasonable image homogeneity was achieved with RF shimming. Conclusions: Open, noncylindrical designs for transmit/receive coils are practical at 7 T and real-time imaging of the moving joint is feasible with the presented coil design.},
  language  = {en}
}
@article{BankOrzadaSmitsetal.2015,
  author    = {Bank, Bart L. van de and Orzada, Stephan and Smits, Frits and Lagemaat, Miriam W. and Rodgers, Christopher T. and Bitz, Andreas and Scheenen, Tom W. J.},
  title     = {Optimized (31) P MRS in the human brain at 7 T with a dedicated RF coil setup},
  series = {NMR in Biomedicine},
  volume    = {28},
  journal   = {NMR in Biomedicine},
  number    = {11},
  publisher = {Wiley},
  address   = {Weinheim},
  issn      = {1099-1492},
  doi       = {10.1002/nbm.3422},
  pages     = {1570 -- 1578},
  year      = {2015},
  language  = {en}
}
@article{FiedlerOrzadaFloeseretal.2022,
  author    = {Fiedler, Thomas M. and Orzada, Stephan and Fl{\"o}ser, Martina and Rietsch, Stefan H. G. and Schmidt, Simon and Stelter, Jonathan K. and Wittrich, Marco and Quick, Harald H. and Bitz, Andreas and Ladd, Mark E.},
  title     = {Performance and safety assessment of an integrated transmitarray for body imaging at 7 T under consideration of specificabsorption rate, tissue temperature, and thermal dose},
  series = {NMR in Biomedicine},
  volume    = {35},
  journal   = {NMR in Biomedicine},
  number    = {5},
  publisher = {Wiley},
  issn      = {0952-3480 (Print)},
  doi       = {10.1002/nbm.4656},
  pages     = {1 -- 17},
  year      = {2022},
  abstract  = {In this study, the performance of an integrated body-imaging array for 7 T with 32 radiofrequency (RF) channels under consideration of local specific absorption rate (SAR), tissue temperature, and thermal dose limits was evaluated and the imaging performance was compared with a clinical 3 T body coil. Thirty-two transmit elements were placed in three rings between the bore liner and RF shield of the gradient coil. Slice-selective RF pulse optimizations for B1 shimming and spokes were performed for differently oriented slices in the body under consideration of realistic constraints for power and local SAR. To improve the B1+ homogeneity, safety assessments based on temperature and thermal dose were performed to possibly allow for higher input power for the pulse optimization than permissible with SAR limits. The results showed that using two spokes, the 7 T array outperformed the 3 T birdcage in all the considered regions of interest. However, a significantly higher SAR or lower duty cycle at 7 T is necessary in some cases to achieve similar B1+ homogeneity as at 3 T. The homogeneity in up to 50 cm-long coronal slices can particularly benefit from the high RF shim performance provided by the 32 RF channels. The thermal dose approach increases the allowable input power and the corresponding local SAR, in one example up to 100 W/kg, without limiting the exposure time necessary for an MR examination. In conclusion, the integrated antenna array at 7 T enables a clinical workflow for body imaging and comparable imaging performance to a conventional 3 T clinical body coil.},
  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{KlompBitzHeerschapetal.2009,
  author    = {Klomp, D. W. J. and Bitz, Andreas and Heerschap, A. and Scheenen, T. W. J.},
  title     = {Proton spectroscopic imaging of the human prostate at 7 T},
  series = {NMR in Biomedicine},
  volume    = {22},
  journal   = {NMR in Biomedicine},
  number    = {5},
  issn      = {1099-1492},
  doi       = {10.1002/nbm.1360},
  pages     = {495 -- 501},
  year      = {2009},
  language  = {en}
}
@article{NoureddineKraffLaddetal.2019,
  author    = {Noureddine, Yacine and Kraff, Oliver and Ladd, Mark E. and Wrede, Karsten and Chen, Bixia and Quick, Harald H. and Schaefers, Georg and Bitz, Andreas},
  title     = {Radiofrequency induced heating around aneurysm clips using a generic birdcage head coil at 7 Tesla under consideration of the minimum distance to decouple multiple aneurysm clips},
  series = {Magnetic Resonance in Medicine},
  journal   = {Magnetic Resonance in Medicine},
  number    = {Early view},
  publisher = {Wiley},
  address   = {Weinheim},
  issn      = {1522-2594},
  doi       = {10.1002/mrm.27835},
  pages     = {1 -- 17},
  year      = {2019},
  language  = {en}
}