title: Free-breathing dynamic liver examination using a radial 3D T1-weighted gradient echo sequence with moderate undersampling for patients with limited breath-holding capacity.
abstract: OBJECTIVE
  To compare free-breathing radial VIBE with moderate undersampling (us-radial-VIBE) with a standard breathhold T1-weighted volumetric interpolated sequence (3D GRE VIBE) in patients unable to suspend respiration during dynamic liver examination.
  
  
  METHODS
  23 consecutive patients underwent dynamic liver MR examination using the free-breathing us-radial-VIBE sequence as part of their oncologic follow-up. All patients were eligible for the free-breathing protocol due to severe respiratory artifacts at the planning or precontrast sequences. The us-radial-VIBE acquisitions were compared to the patientś last staging liver MRI including a standard breathhold 3D GRE VIBE. For an objective image evaluation, signal intensity (SI), image noise (IN), signal-to-noise ratio (SNR) and contrast-enhancement ratio (CER) were compared. Representative image quality parameters, including typical artifacts were independently, retrospectively and blindly scored by four readers.
  
  
  RESULTS
  Us-radial-VIBE had significant lower SNR (p<0.0001) and higher IN (p<0.0001), whereas SI did not differ (p=0.62). Temporal resolution assessed with CER in the arterial phase showed higher values for us-radial-VIBE (p=0.028). Subjective image quality parameters received generally slightly higher scores for 3D GRE VIBE. In a smaller subgroup comprising patients with severe respiratory artifacts also at reference breathhold 3D GRE VIBE examination, us-radial-VIBE showed significantly higher image quality scores. Furthermore, there were generally more severe respiratory artifacts in 3D GRE VIBE, whereas streaking was characteristic in almost all us-radial-VIBE acquisitions but did not affect diagnostic validity.
  
  
  CONCLUSIONS
  Free-breathing dynamic liver imaging using us-radial-VIBE delivers accurate temporal resolution, low motion artifact susceptibility and good image quality and represents a promising alternative in patients unable to suspend respiration.
authors.affiliation: Department of Diagnostic and Interventional Radiology, University Hospital Frankfurt am Main, Germany. Electronic address: benjamin.kaltenbach@kgu.de.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Kaltenbach
authors.affiliation: Department of Diagnostic and Interventional Radiology, University Hospital Frankfurt am Main, Germany.
authors.forename: Andrei
authors.initials: A
authors.lastname: Roman
authors.affiliation: Department of Diagnostic and Interventional Radiology, University Hospital Frankfurt am Main, Germany.
authors.forename: Christoph
authors.initials: C
authors.lastname: Polkowski
authors.affiliation: Department of Diagnostic and Interventional Radiology, University Hospital Frankfurt am Main, Germany.
authors.forename: Tatjana
authors.initials: T
authors.lastname: Gruber-Rouh
authors.affiliation: Department of Diagnostic and Interventional Radiology, University Hospital Frankfurt am Main, Germany; Divison of Radiology and Nuclear Medicine, Kantonsspital, St. Gallen, Switzerland.
authors.forename: Ralf W
authors.initials: RW
authors.lastname: Bauer
authors.affiliation: Department of Diagnostic and Interventional Radiology, University Hospital Frankfurt am Main, Germany.
authors.forename: Renate
authors.initials: R
authors.lastname: Hammerstingl
authors.affiliation: Department of Diagnostic and Interventional Radiology, University Hospital Frankfurt am Main, Germany.
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Vogl
authors.affiliation: Department of Diagnostic and Interventional Radiology, University Hospital Frankfurt am Main, Germany.
authors.forename: Stephan
authors.initials: S
authors.lastname: Zangos
mesh_terms: D016477:Artifacts; D062485:Breath Holding; D003287:Contrast Media; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D021621:Imaging, Three-Dimensional / Q000379:methods; D008113:Liver Neoplasms / Q000175:diagnosis*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009038:Motion; D012119:Respiration; D012189:Retrospective Studies; D059629:Signal-To-Noise Ratio
chemical_list: D003287:Contrast Media
keywords: Dynamic liver MRI; Radial data sampling; Respiratory artifacts; Undersampled radial acquisition