title: Contrast-enhanced hepatic magnetic resonance angiography at 3 T: does parallel imaging improve image quality?
abstract: OBJECTIVE
  To evaluate whether hepatic magnetic resonance angiography (MRA) performed at 3 T and acquired with a parallel imaging acceleration factor of 2 provides satisfactory image quality and adequate contrast-to-noise, compared with an acquisition without parallel imaging.
  
  
  METHODS
  Ten volunteers underwent both a standard (A) and an experimental (B) MRA protocol. Both protocols used a gadoteridol dose of 20 mL injected at 2 mL/s in a 3-T magnetic resonance (MR) system. Protocol B was identical to protocol A, except protocol B was performed with a parallel imaging acceleration factor of 2. Contrast-to-noise ratios (CNRs) were calculated in the suprarenal abdominal aorta, the common hepatic artery, and the right and left hepatic arteries. The same 4 vessels were rated for quality of arterial visualization using a 5-point scale (1 = poor to 5 = excellent). The paired t test and Wilcoxon rank sum test were used for statistical analysis.
  
  
  RESULTS
  The CNRs and qualitative scores were higher in all 4 vessels using protocol B. Mean CNRs in the suprarenal abdominal aorta, common hepatic artery, and the right and left hepatic arteries were 31, 33, 28, and 22 for protocol A and 36, 40, 36, and 25 for protocol B, respectively (P < 0.05 except the left hepatic arteries [P = 0.35]). Mean qualitative scores of the same vessels were 4.3, 3.7, 3.1, and 2.9 using protocol A and 4.4, 3.8, 3.5, and 3.2 for protocol B, respectively (P > 0.44).
  
  
  CONCLUSIONS
  Parallel imaging performed in a 3-T MR system improves hepatic MRA both quantitatively and qualitatively.
authors.affiliation: Department of Radiology, Duke University Medical Center, Durham, NC 27710, USA. lisa.ho@duke.edu
authors.forename: Lisa M
authors.initials: LM
authors.lastname: Ho
authors.forename: Elmar M
authors.initials: EM
authors.lastname: Merkle
authors.forename: Erik K
authors.initials: EK
authors.lastname: Paulson
authors.forename: Brian M
authors.initials: BM
authors.lastname: Dale
mesh_terms: D000328:Adult; D003287:Contrast Media / Q000008:administration & dosage*; D005260:Female; D005682:Gadolinium; D006499:Hepatic Artery / Q000033:anatomy & histology*; D006571:Heterocyclic Compounds / Q000008:administration & dosage*; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007091:Image Processing, Computer-Assisted / Q000379:methods; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008280:Magnetics; D008297:Male; D009942:Organometallic Compounds / Q000008:administration & dosage*; D011446:Prospective Studies; D012016:Reference Values; D013997:Time Factors
chemical_list: D003287:Contrast Media; D006571:Heterocyclic Compounds; D009942:Organometallic Compounds; C062402:gadoteridol; D005682:Gadolinium