title: Retrospective respiratory self-gating and removal of bulk motion in pulmonary UTE MRI of neonates and adults.
abstract: 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.
  
  
  
  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.
  
  
  
  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).
  
  
  
  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.
authors.affiliation: Center for Pulmonary Imaging Research, Division of Pulmonary Medicine and Department of Radiology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA.|Department of Physics, Washington University in St. Louis, St. Louis, Missouri, USA.
authors.forename: Nara S
authors.identifier: 0000-0002-6233-161X
authors.initials: NS
authors.lastname: Higano
authors.affiliation: Department of Medical Physics, University of Wisconsin-Madison, Madison, Wisconsin, USA.
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Hahn
authors.affiliation: Department of Radiology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA.
authors.forename: Jean A
authors.initials: JA
authors.lastname: Tkach
authors.affiliation: Center for Pulmonary Imaging Research, Division of Pulmonary Medicine and Department of Radiology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA.|Department of Physics, University of Cincinnati, Cincinnati, Ohio, USA.
authors.forename: Xuefeng
authors.initials: X
authors.lastname: Cao
authors.affiliation: Center for Pulmonary Imaging Research, Division of Pulmonary Medicine and Department of Radiology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA.
authors.forename: Laura L
authors.initials: LL
authors.lastname: Walkup
authors.affiliation: Center for Pulmonary Imaging Research, Division of Pulmonary Medicine and Department of Radiology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA.|Department of Physics, Washington University in St. Louis, St. Louis, Missouri, USA.
authors.forename: Robert P
authors.initials: RP
authors.lastname: Thomen
authors.affiliation: Division of Neonatology and Pulmonary Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA.
authors.forename: Stephanie L
authors.initials: SL
authors.lastname: Merhar
authors.affiliation: Division of Neonatology and Pulmonary Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA.
authors.forename: Paul S
authors.initials: PS
authors.lastname: Kingma
authors.affiliation: Department of Medical Physics, University of Wisconsin-Madison, Madison, Wisconsin, USA.|Department of Radiology, University of Wisconsin-Madison, Madison, Wisconsin, USA.
authors.forename: Sean B
authors.initials: SB
authors.lastname: Fain
authors.affiliation: Center for Pulmonary Imaging Research, Division of Pulmonary Medicine and Department of Radiology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA.|Department of Physics, Washington University in St. Louis, St. Louis, Missouri, USA.|Department of Radiology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA.
authors.forename: Jason C
authors.initials: JC
authors.lastname: Woods
mesh_terms: D000328:Adult; D000465:Algorithms; D016477:Artifacts; D001997:Bronchopulmonary Dysplasia / Q000000981:diagnostic imaging*; D005260:Female; D006548:Hernia, Diaphragmatic / Q000000981:diagnostic imaging*; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D021621:Imaging, Three-Dimensional / Q000379:methods; D007231:Infant, Newborn; D008168:Lung / Q000000981:diagnostic imaging*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D009038:Motion; D015203:Reproducibility of Results; D015656:Respiratory Mechanics; D055425:Respiratory-Gated Imaging Techniques / Q000379:methods*; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D013382:Subtraction Technique
keywords: 3D radial; lung MRI; neonatal; retrospective motion tracking; self-gating; ultrashort echo time