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@ARTICLE{Romig:298224,
      author       = {S. Romig and K. John and S. Schmidt$^*$ and S. Schmitter
                      and S. Grundmann and M. Bruschewski},
      title        = {{I}mproving {MRI} turbulence quantification by addressing
                      the measurement errors caused by the derivatives of the
                      turbulent velocity field - {S}equence development and
                      in-vitro validation.},
      journal      = {Magnetic resonance imaging},
      volume       = {117},
      issn         = {0730-725X},
      address      = {Amsterdam [u.a.]},
      publisher    = {Elsevier Science},
      reportid     = {DKFZ-2025-00231},
      pages        = {110333},
      year         = {2025},
      note         = {Volume 117, April 2025, 110333},
      abstract     = {To improve the current method for MRI turbulence
                      quantification which is the intravoxel phase dispersion
                      (IVPD) method. Turbulence is commonly characterized by the
                      Reynolds stress tensor (RST) which describes the velocity
                      covariance matrix. A major source for systematic errors in
                      MRI is the sequence's sensitivity to the variance of the
                      derivatives of velocity, such as the acceleration variance,
                      which can lead to a substantial measurement bias.We
                      developed a Cartesian phase contrast sequence with fast
                      velocity encoding and two separately measured partial echoes
                      with opposite readout directions. This design aims to reduce
                      the high-order gradient moments that are responsible for the
                      described measurement error. Velocity encoding directions
                      follow the ICOSA6 scheme to capture the full RST. Turbulence
                      data is reconstructed using the intra-voxel phase dispersion
                      (IVPD) technique. We validated this sequence in vitro using
                      a periodic hill flow benchmark with highly anisotropic
                      turbulence. MRI data underwent extensive averaging, with
                      multiple velocity encoding values employed to reduce noise
                      and isolate systematic effects.The RST data obtained from
                      the new sequence agree well with the ground truth. Compared
                      to a state-of-the-art sequence, the maximum errors were
                      reduced by factor five.Simple adjustments to current MRI
                      protocols can greatly enhance turbulence measurement
                      accuracy through the reduction of high-order gradient
                      moments. The proposed measures include applying fast
                      velocity encoding, high readout bandwidth, and a highly
                      asymmetric readout. Ringing artifacts due to the asymmetric
                      readout can be removed via a second, inverted readout.},
      keywords     = {Intra-voxel phase dispersion (Other) / Phase contrast MRI
                      (Other) / Reynold stress tensor (Other) / Turbulence kinetic
                      energy (Other) / Turbulence quantification (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:39863025},
      doi          = {10.1016/j.mri.2025.110333},
      url          = {https://inrepo02.dkfz.de/record/298224},
}