title: Free-breathing radial 3D fat-suppressed T1-weighted gradient echo sequence: a viable alternative for contrast-enhanced liver imaging in patients unable to suspend respiration.
abstract: OBJECTIVE
  : To compare free-breathing radially sampled 3D fat suppressed T1-weighted gradient-echo acquisitions (radial volumetric interpolated breath-hold examination [VIBE]) with breath-hold (BH) and free-breathing conventional (rectilinearly sampled k-space) VIBE acquisitions for postcontrast imaging of the liver.
  
  
  METHODS
  : Eighteen consecutive patients referred for clinically indicated liver magnetic resonance imaging were imaged at 3 T. Three minutes after a single dose of gadolinium contrast injection, free-breathing radial VIBE, BH VIBE, and free-breathing VIBE with 4 averages were acquired in random order with matching sequence parameters. Radial VIBE was acquired with the "stack-of-stars" scheme, which uses conventional sampling in the slice direction and radial sampling in-plane.All image data sets were evaluated independently by 3 radiologists blinded to patient and sequence information. Each reader scored the following parameters: overall image quality, respiratory motion artifact, pulsation artifact, liver edge sharpness, and hepatic vessel clarity using a 5-point scale, with the highest score indicating the most optimum examination. Mixed model analysis of variance was used to compare sequences in terms of each measure of image quality.
  
  
  RESULTS
  : When scores were averaged over readers, there was no statistically significant difference between radial VIBE and BH VIBE regarding overall image quality (P = 0.1015), respiratory motion artifact (P = 1.0), and liver edge sharpness (P = 0.2955). Radial VIBE demonstrated significantly lower pulsation artifact (P < 0.0001), but had lower hepatic vessel clarity (P = 0.0176), when compared with BH VIBE. Radial VIBE had significantly higher image quality scores for all parameters when compared with free-breathing VIBE (P < 0.0001). Acquisition time for BH VIBE was 14 seconds and that of free-breathing radial VIBE and conventional VIBE with multiple averages was 56 seconds each.
  
  
  CONCLUSIONS
  : Radial VIBE can be performed during free breathing for contrast-enhanced imaging of the liver with comparable image quality to BH VIBE. However, further work is necessary to shorten the acquisition time to perform dynamic imaging.
authors.affiliation: New York University Langone Medical Center, Departments of Radiology, New York, USA. hersh.chandarana@nyumc.org
authors.forename: Hersh
authors.initials: H
authors.lastname: Chandarana
authors.forename: Tobias K
authors.initials: TK
authors.lastname: Block
authors.forename: Andrew B
authors.initials: AB
authors.lastname: Rosenkrantz
authors.forename: Ruth P
authors.initials: RP
authors.lastname: Lim
authors.forename: Danny
authors.initials: D
authors.lastname: Kim
authors.forename: David J
authors.initials: DJ
authors.lastname: Mossa
authors.forename: James S
authors.initials: JS
authors.lastname: Babb
authors.forename: Berthold
authors.initials: B
authors.lastname: Kiefer
authors.forename: Vivian S
authors.initials: VS
authors.lastname: Lee
mesh_terms: D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D016477:Artifacts; D003287:Contrast Media; D005260:Female; D019786:Gadolinium DTPA; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008107:Liver Diseases / Q000175:diagnosis*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012119:Respiration
chemical_list: D003287:Contrast Media; D019786:Gadolinium DTPA