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@ARTICLE{Tkotz:283203,
      author       = {K. Tkotz and A. Liebert and L. V. Gast and P. Zeiger and M.
                      Uder and M. Zaiss and A. Nagel$^*$},
      title        = {{M}ulti-echo-based fat artifact correction for {CEST} {MRI}
                      at 7 {T}.},
      journal      = {Magnetic resonance in medicine},
      volume       = {91},
      number       = {2},
      issn         = {1522-2594},
      address      = {New York, NY [u.a.]},
      publisher    = {Wiley-Liss},
      reportid     = {DKFZ-2023-01968},
      pages        = {481-496},
      year         = {2024},
      note         = {#LA:E020# / 2024 Feb;91(2):481-496},
      abstract     = {CEST MRI is influenced by fat signal, which can reduce the
                      apparent CEST contrast or lead to pseudo-CEST effects. Our
                      goal was to develop a fat artifact correction based on
                      multi-echo fat-water separation that functions stably for 7
                      T knee MRI data.Our proposed algorithm utilizes the full
                      complex data and a phase demodulation with an off-resonance
                      map estimation based on the Z-spectra prior to fat-water
                      separation to achieve stable fat artifact correction. Our
                      method was validated and compared to multi-echo-based
                      methods originally proposed for 3 T by Bloch-McConnell
                      simulations and phantom measurements. Moreover, the method
                      was applied to in vivo 7 T knee MRI examinations and
                      compared to Gaussian fat saturation and a published
                      single-echo Z-spectrum-based fat artifact correction
                      method.Phase demodulation prior to fat-water separation
                      reduced the occurrence of fat-water swaps. Utilizing the
                      complex signal data led to more stable correction results
                      than working with magnitude data, as was proposed for 3 T.
                      Our approach reduced pseudo-nuclear Overhauser effects
                      compared to the other correction methods. Thus, the mean
                      asymmetry contrast at 3.5 ppm in cartilage over five
                      volunteers increased from $-9.2\%$ (uncorrected) and
                      $-10.6\%$ (Z-spectrum-based) to $-1.5\%.$ Results showed
                      higher spatial stability than with the fat saturation
                      pulse.Our work demonstrates the feasibility of
                      multi-echo-based fat-water separation with an adaptive fat
                      model for fat artifact correction for CEST MRI at 7 T. Our
                      approach provided better fat artifact correction throughout
                      the entire spectrum and image than the fat saturation pulse
                      or Z-spectrum-based correction method for both phantom and
                      knee imaging results.},
      keywords     = {7 T (Other) / CEST (Other) / fat artifact (Other) /
                      fat-water separation (Other) / knee imaging (Other) /
                      nuclear Overhauser effect (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:37753844},
      doi          = {10.1002/mrm.29863},
      url          = {https://inrepo02.dkfz.de/record/283203},
}