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@ARTICLE{Himburg:305443,
      author       = {N. Himburg and M. Lutz and L. Mitschang and J. G. Frintz
                      and S. Schmitter$^*$},
      title        = {{F}lip {A}ngle {E}rrors in {A}ctual {F}lip {A}ngle
                      {I}maging {U}sing {P}olyvinylpyrrolidone/{W}ater-{B}ased
                      {P}hantoms.},
      journal      = {Magnetic resonance in medicine},
      volume       = {95},
      number       = {3},
      issn         = {1522-2594},
      address      = {New York, NY [u.a.]},
      publisher    = {Wiley-Liss},
      reportid     = {DKFZ-2025-02161},
      pages        = {1489-1502},
      year         = {2026},
      note         = {#LA:E020# / 2026 Mar;95(3):1489-1502. doi:
                      10.1002/mrm.70136. Epub 2025 Oct 18},
      abstract     = {The aim of this work is to report and investigate
                      unexpected errors in actual flip angle imaging (AFI) applied
                      to phantom fillings based on polyvinylpyrrolidone (PVP).Flip
                      angle maps of PVP/water mixtures with different PVP ratios
                      were acquired at 3 T and 7 T using a 3D cartesian AFI. The
                      influence of spoiling was investigated by varying the
                      RF-spoiling phase increment Φ0 for different settings of
                      the spoiling gradient moments. The results were compared
                      with a reference method and EPG simulations. AFI
                      measurements with varying TE were carried out to investigate
                      non-spoiling-related errors. Furthermore, 1H-NMR
                      spectroscopy was performed on PVP samples.Measurements
                      reveal spoiling curves of PVP/water mixtures that lack the
                      symmetry around Φ0 = 90° that has been observed in prior
                      work. Depending on the TE and PVP ratio, substantial
                      deviations from the reference value are found, which are not
                      observed in water samples. Varying the TE shows oscillatory
                      behavior of the AFI signals in PVP/water mixtures that match
                      with the existence of PVP bands found in 1H-NMR spectra.
                      Including a signal component with a precession frequency
                      that matches a PVP band into the simulations allows the
                      reproduction of the asymmetric spoiling curves.Under certain
                      conditions, AFI of PVP/water mixtures suffers from errors
                      originating from interferences of the water and PVP signal
                      components. This can severely reduce the accuracy of the AFI
                      and must be considered for B 1 + $$ {B}_1^{+} $$ mapping
                      with AFI. The impact of this effect can be reduced by
                      increased TE as well as high PVP ratios.},
      keywords     = {B 1 + $$ {B}_1^{+} $$ mapping (Other) / AFI (Other) / PVP
                      (Other) / RF spoiling (Other) / actual flip angle imaging
                      (Other) / ultrahigh field MRI (Other)},
      cin          = {E020},
      ddc          = {610},
      cid          = {I:(DE-He78)E020-20160331},
      pnm          = {315 - Bildgebung und Radioonkologie (POF4-315)},
      pid          = {G:(DE-HGF)POF4-315},
      typ          = {PUB:(DE-HGF)16},
      pubmed       = {pmid:41108649},
      doi          = {10.1002/mrm.70136},
      url          = {https://inrepo02.dkfz.de/record/305443},
}