title: Usefulness of controlled aliasing in parallel imaging results in higher acceleration in gadoxetic acid-enhanced liver magnetic resonance imaging to clarify the hepatic arterial phase.
abstract: OBJECTIVE
  We aimed to determine whether the controlled aliasing in parallel imaging results in higher acceleration (CAIPIRINHA) technique could improve the image quality of the hepatic arterial phase of gadoxetic acid-enhanced liver magnetic resonance (MR) imaging.
  
  
  METHODS
  A total of 320 patients underwent gadoxetic acid-enhanced liver MR imaging: a conventional protocol (a fixed scan delay and 2-mL/s injection) using a standard 3-T MR system (Trio-Tim; Siemens, commercialized since 2005) (group A), an optimized protocol (bolus tracking and 1-mL/s injection) using a standard 3-T MR (group B), an optimized protocol using a new 3-T MR (Skyra; Siemens, commercialized since 2012) (group C), and an optimized protocol with CAIPIRINHA using a new 3-T MR (group D). The image quality of the hepatic arterial phase was graded using a 4-point rating scale from 1 (no artifacts) to 4 points (non-diagnostic images with severe artifacts). The differences in image quality scores among the 4 groups were evaluated. In addition, the detection rates of hypervascular hepatocellular carcinomas among the 4 groups were evaluated.
  
  
  RESULTS
  Scores of 4 points were observed in groups A (n = 7), B (n = 5), and C (n = 3) but not in group D. The median image quality score was 2 in groups A and B and 1 in groups C and D. From group A to group D, the median image quality score decreased significantly (P = 0.0001). The median image quality score was significantly lower in group D than in groups A and B (P = 0.0001 and 0.001, respectively), whereas there was no significant difference observed between groups C and D (P = 0.656). The detection rates of hypervascular hepatocellular carcinomas on the hepatic arterial phase were not significantly different among the groups (all P > 0.03), except between groups A and D (P = 0.007).
  
  
  CONCLUSIONS
  The CAIPIRINHA technique improved the image quality of hepatic arterial phase imaging with gadoxetic acid, reducing the number of non-diagnostic arterial phase studies.
authors.affiliation: From the *Department of Radiology, Korea University Guro Hospital, Korea University College of Medicine; †Siemens Healthcare, Seoul, Republic of Korea; ‡Siemens Healthcare, Oncology Application Development, Erlangen, Germany; and §Radiology & Interventional, Bayer HealthCare, Seoul, Republic of Korea.
authors.forename: Yang Shin
authors.initials: YS
authors.lastname: Park
authors.forename: Chang Hee
authors.initials: CH
authors.lastname: Lee
authors.forename: In Seong
authors.initials: IS
authors.lastname: Kim
authors.forename: Berthold
authors.initials: B
authors.lastname: Kiefer
authors.forename: Seung Tae
authors.initials: ST
authors.lastname: Woo
authors.forename: Kyeong Ah
authors.initials: KA
authors.lastname: Kim
authors.forename: Cheol Min
authors.initials: CM
authors.lastname: Park
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016477:Artifacts; D006528:Carcinoma, Hepatocellular / Q000473:pathology*; D003287:Contrast Media / Q000008:administration & dosage; D005260:Female; D019786:Gadolinium DTPA / Q000008:administration & dosage*; D006499:Hepatic Artery / Q000473:pathology*; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D008113:Liver Neoplasms / Q000473:pathology*; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009389:Neovascularization, Pathologic / Q000473:pathology*; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012680:Sensitivity and Specificity
chemical_list: D003287:Contrast Media; C073590:gadolinium ethoxybenzyl DTPA; D019786:Gadolinium DTPA