TY  - JOUR
AU  - Romig, Swantje
AU  - John, Kristine
AU  - Schmidt, Simon
AU  - Schmitter, Sebastian
AU  - Grundmann, Sven
AU  - Bruschewski, Martin
TI  - Improving MRI turbulence quantification by addressing the measurement errors caused by the derivatives of the turbulent velocity field - Sequence development and in-vitro validation.
JO  - Magnetic resonance imaging
VL  - 117
SN  - 0730-725X
CY  - Amsterdam [u.a.]
PB  - Elsevier Science
M1  - DKFZ-2025-00231
SP  - 110333
PY  - 2025
N1  - Volume 117, April 2025, 110333
AB  - 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.
KW  - Intra-voxel phase dispersion (Other)
KW  - Phase contrast MRI (Other)
KW  - Reynold stress tensor (Other)
KW  - Turbulence kinetic energy (Other)
KW  - Turbulence quantification (Other)
LB  - PUB:(DE-HGF)16
C6  - pmid:39863025
DO  - DOI:10.1016/j.mri.2025.110333
UR  - https://inrepo02.dkfz.de/record/298224
ER  -