title: Feasibility of 5-minute delayed transition phase imaging with 30° flip angle in gadoxetic acid-enhanced 3D gradient-echo MRI of liver, compared with 20-minute delayed hepatocyte phase MRI with standard 10° flip angle.
abstract: OBJECTIVE
  The purpose of this study was to compare 5-minute delayed transitional phase imaging using a 30° flip angle (hereafter, 5 min-FA30) and 20-minute hepatocyte phase imaging using a 10° flip angle (hereafter, 20 min-FA10) in gadoxetic acid-enhanced MRI for focal hepatic lesion detection and lesion-to-liver contrast-to-noise ratio (CNR), and to determine whether 5 min-FA30 could replace 20 min-FA10 with a 15-minute time saving.
  
  
  METHODS
  One hundred sixteen patients with 282 focal hepatic lesions (size range, 0.2-12.5 cm; malignant, n = 146; benign, n = 136) underwent gadoxetic acid-enhanced MRI with 5 min-FA30 and 20 min-FA10 with a 3D T1-weighted gradient-echo sequence. Three radiologists independently assessed the presence of focal hepatic lesions using a 4-point scale, and detection sensitivity of focal hepatic lesions was calculated. Lesion-to-liver CNRs were calculated and compared in two image groups.
  
  
  RESULTS
  There was no significant difference in detection sensitivity of focal hepatic lesions for all three readers between 5 min-FA30 (mean, 95.4%) and 20 min-FA10 (mean, 95.6%), irrespective of lesion size or malignancy. The mean CNR on 5 min-FA30 (167.9 ± 84.1) was significantly higher than that on 20 min-FA10 (160.2 ± 79.5). However, the mean CNR difference between the two image groups was relatively small (7.8 ± 41.9).
  
  
  CONCLUSIONS
  Compared with 20 min-FA10, 5 min-FA30 provided higher CNR and similar sensitivity. These findings indicate that 5 min-FA30 could replace 20-min delayed hepatocyte phase imaging using a 10° flip angle with similar diagnostic performance and 15 minutes of time saving.
authors.affiliation: 1 Department of Radiology, Yonsei University College of Medicine, Gangnam Severance Hospital, 211 Eonjuro, Gangnam-gu, Seoul 135-720, Korea.
authors.forename: Eun-Suk
authors.initials: ES
authors.lastname: Cho
authors.forename: Jeong-Sik
authors.initials: JS
authors.lastname: Yu
authors.forename: Ah Young
authors.initials: AY
authors.lastname: Park
authors.forename: SeungTae
authors.initials: S
authors.lastname: Woo
authors.forename: Joo Hee
authors.initials: JH
authors.lastname: Kim
authors.forename: Jae-Joon
authors.initials: JJ
authors.lastname: Chung
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D003287:Contrast Media / Q000008:administration & dosage; D005240:Feasibility Studies; D005260:Female; D019786:Gadolinium DTPA / Q000008:administration & dosage; D022781:Hepatocytes / Q000473:pathology; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008107:Liver Diseases / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods* / Q000592:standards; D008297:Male; D015203:Reproducibility of Results; D056910:Republic of Korea; D012680:Sensitivity and Specificity; D013997:Time Factors
chemical_list: D003287:Contrast Media; C073590:gadolinium ethoxybenzyl DTPA; D019786:Gadolinium DTPA
keywords: MRI; flip angle; gadoxetic acid disodium; hepatocyte phase; liver