Reduction of vibration-induced signal loss by matching mechanical vibrational states: Application in high b-value diffusion-weighted MRS

Dominik Weidlich, Mark Zamskiy, Marcus Maeder, Stefan Ruschke, Steffen Marburg, Dimitrios C. Karampinos

Research output: Contribution to journalArticlepeer-review

9 Scopus citations

Abstract

Purpose: Diffusion encoding gradients are known to yield vibrations of the typical clinical MR scanner hardware with a frequency of 20 to 30 Hz, which may lead to signal loss in diffusion-weighted MR measurements. This work proposes to mitigate vibration-induced signal loss by introducing a vibration-matching gradient (VMG) to match vibrational states during the 2 diffusion gradient pulses. Theory and Methods: A theoretical description of displacements induced by gradient switching was introduced and modeled by a 2-mass-spring-damper system. An additional preceding VMG mimicking timing and properties of the diffusion encoding gradients was added to a high b-value diffusion-weighted MR spectroscopy sequence. Laser interferometry was employed to measure 3D displacements of a phantom surface. Lipid ADC was assessed in water–fat phantoms and in vivo in the tibial bone marrow of 3 volunteers. Results: The modeling and the laser interferometer measurements revealed that the displacement curves are more similar during the 2 diffusion gradients with the VMG compared to the standard sequence, resulting in less signal loss of the diffusion-weighted signal. Phantom results showed lipid ADC overestimation up to 119% with the standard sequence and an error of 5.5% with the VMG. An 18% to 35% lower coefficient of variation was obtained for in vivo lipid ADC measurement when employing the VMG. Conclusion: The application of the VMG reduces the signal loss introduced by hardware vibrations in a high b-value diffusion-weighted MRS sequence in phantoms and in vivo. Reference measurements based on laser interferometry and mechanical modelling confirmed the findings.

Original languageEnglish
Pages (from-to)39-51
Number of pages13
JournalMagnetic Resonance in Medicine
Volume84
Issue number1
DOIs
StatePublished - 1 Jul 2020

Keywords

  • artifact reduction
  • diffusion weighting
  • high b-value
  • mechanical vibrations
  • scanner table vibrations

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