Retrospective respiratory self-gating and removal of bulk motion in pulmonary UTE MRI of neonates and adults

Magn Reson Med. 2017 Mar;77(3):1284-1295. doi: 10.1002/mrm.26212. Epub 2016 Mar 12.


Purpose: To implement pulmonary three-dimensional (3D) radial ultrashort echo-time (UTE) MRI in non-sedated, free-breathing neonates and adults with retrospective motion tracking of respiratory and intermittent bulk motion, to obtain diagnostic-quality, respiratory-gated images.

Methods: Pulmonary 3D radial UTE MRI was performed at 1.5 tesla (T) during free breathing in neonates and adult volunteers for validation. Motion-tracking waveforms were obtained from the time course of each free induction decay's initial point (i.e., k-space center), allowing for respiratory-gated image reconstructions that excluded data acquired during bulk motion. Tidal volumes were calculated from end-expiration and end-inspiration images. Respiratory rates were calculated from the Fourier transform of the motion-tracking waveform during quiet breathing, with comparison to physiologic prediction in neonates and validation with spirometry in adults.

Results: High-quality respiratory-gated anatomic images were obtained at inspiration and expiration, with less respiratory blurring at the expense of signal-to-noise for narrower gating windows. Inspiration-expiration volume differences agreed with physiologic predictions (neonates; Bland-Altman bias = 6.2 mL) and spirometric values (adults; bias = 0.11 L). MRI-measured respiratory rates compared well with the observed rates (biases = -0.5 and 0.2 breaths/min for neonates and adults, respectively).

Conclusions: Three-dimensional radial pulmonary UTE MRI allows for retrospective respiratory self-gating and removal of intermittent bulk motion in free-breathing, non-sedated neonates and adults. Magn Reson Med 77:1284-1295, 2017. © 2016 International Society for Magnetic Resonance in Medicine.

Keywords: 3D radial; lung MRI; neonatal; retrospective motion tracking; self-gating; ultrashort echo time.

Publication types

  • Evaluation Study

MeSH terms

  • Adult
  • Algorithms
  • Artifacts*
  • Bronchopulmonary Dysplasia / diagnostic imaging*
  • Female
  • Hernia, Diaphragmatic / diagnostic imaging*
  • Humans
  • Image Enhancement / methods*
  • Image Interpretation, Computer-Assisted / methods
  • Imaging, Three-Dimensional / methods
  • Infant, Newborn
  • Lung / diagnostic imaging*
  • Magnetic Resonance Imaging / methods*
  • Male
  • Motion
  • Reproducibility of Results
  • Respiratory Mechanics
  • Respiratory-Gated Imaging Techniques / methods*
  • Retrospective Studies
  • Sensitivity and Specificity
  • Subtraction Technique