A pneumatic phantom for mimicking respiration-induced artifacts in spinal MRI

Magn Reson Med. 2018 Jan;79(1):600-605. doi: 10.1002/mrm.26679. Epub 2017 Mar 20.

Abstract

Purpose: To design a phantom capable of mimicking human respiration to serve as a testing platform for correction of the static and time-evolving magnetic field distortions typically encountered in MRI of the spinal cord.

Methods: An inflation system to mimic the air variation of the human lungs was constructed. The inflation system was linked to a phantom containing synthetic lungs and an ex vivo human spine. The relationship between air pressure and phantom lung volume was evaluated via imaging experiment. The geometric distortion (pseudo-displacement) caused by the B0 inhomogeneities was measured on echo planar imaging slices for different air volumes.

Results: Linear and quadratic relations linking air pressure to phantom lung volume were observed with a Pearson correlation coefficient of 0.99. Air distribution was uneven across the synthetic lungs, exhibiting a left-to-right lung volume ratio of up to 5/4. The pseudo-displacement artifact of the spine caused by the air-filled lungs was observed.

Conclusion: The proposed phantom can reproduce the lung volume variation of human respiration and thus can serve as a reliable testing platform for the correction of the associated time-varying B0 field distortions. Details of the construction and code for the inflation system microcontroller are available for download as open source. Magn Reson Med 79:600-605, 2017. © 2017 International Society for Magnetic Resonance in Medicine.

Keywords: dynamic31P MRS; exercising muscle; multivoxel; spectroscopic localization.

MeSH terms

  • Air
  • Artifacts
  • Calibration
  • Echo-Planar Imaging*
  • Humans
  • Linear Models
  • Lung / diagnostic imaging*
  • Magnetic Fields
  • Magnetic Resonance Imaging*
  • Models, Anatomic
  • Phantoms, Imaging*
  • Pressure
  • Respiration
  • Spinal Cord / diagnostic imaging*
  • Spine / diagnostic imaging*