title: Optimizing signal intensity correction during evaluation of hepatic parenchymal enhancement on gadoxetate disodium-enhanced MRI: comparison of three methods.
abstract: OBJECTIVE
  To compare signal intensity (SI) correction using scale and rescale slopes with SI correction using SIs of spleen and muscle for quantifying multiphase hepatic contrast enhancement with Gd-EOB-DTPA by assessing their correlation with T1 values generated from Look-Locker turbo-field-echo (LL-TFE) sequence data (ER-T1).
  
  
  METHODS
  Thirty patients underwent Gd-EOB-DTPA-enhanced magnetic resonance imaging (MRI) in this prospective clinical study. For each patient, breath-hold T1-weighted fat-suppressed three-dimensional (3D) gradient echo sequences (e-THRIVE) were acquired before and 2 (first phase), 10 (second phase), and 20min (third phase) after intravenous Gd-EOB-DTPA. Look-Locker turbo-field-echo (LL-TFE) sequences were acquired before and 1.5 (first phase), 8 (second phase), and 18min (third phase) postcontrast. The liver parenchyma enhancement ratios (ER) of each phase were calculated using the SI from e-THRIVE sequences (ER-SI) and the T1 values generated from LL-TFE sequence data (ER-T1) respectively. ER-SIs were calculated in three ways: (1) comparing with splenic SI (ER-SI-s), (2) comparing with muscle SI (ER-SI-m), (3) using scale and rescale slopes obtained from DICOM headers (ER-SI-c), to eliminate the effects of receiver gain and scaling. For each of the first, second and third phases, correlation and agreement were assessed between each ER-SI and ER-T1.
  
  
  RESULTS
  In the first phase, all ER-SIs correlated weakly with ER-T1. In the second and third phases, ER-SI-c showed a stronger linear correlation with ER-T1 (r(2)=0.71-0.72, p<0.01) than did ER-SI-s (r(2)=0.37-0.39, p<0.01) or ER-SI-m (r(2)=0.30-0.41, p<0.01).
  
  
  CONCLUSIONS
  SI correction using scale and rescale slopes from DICOM data is the most acceptable algorithm for evaluating delayed-phase Gd-EOB-DTPA hepatic enhancement.
authors.affiliation: Department of Radiological Technology, Kinki University Hospital, 377-2 Ohno-Higashi, Osaka-Sayama, Osaka 589-8511, Japan; Division of Health Sciences, Graduate School of Medical Science, Kanazawa University, 5-11-80 Kodatsuno, Kanazawa, Ishikawa 920-0942, Japan. Electronic address: onoda@radt.med.kindai.ac.jp.
authors.forename: Minori
authors.initials: M
authors.lastname: Onoda
authors.affiliation: Department of Radiology, Kinki University Faculty of Medicine, 377-2 Ohno-Higashi, Osaka-Sayama, Osaka 589-8511, Japan. Electronic address: neneth@m.ehime-u.ac.jp.
authors.forename: Tomoko
authors.initials: T
authors.lastname: Hyodo
authors.affiliation: Department of Radiology, Kinki University Faculty of Medicine, 377-2 Ohno-Higashi, Osaka-Sayama, Osaka 589-8511, Japan. Electronic address: murakami@med.kindai.ac.jp.
authors.forename: Takamichi
authors.initials: T
authors.lastname: Murakami
authors.affiliation: Department of Radiology, Kinki University Faculty of Medicine, 377-2 Ohno-Higashi, Osaka-Sayama, Osaka 589-8511, Japan. Electronic address: okada777@med.u-ryukyu.ac.jp.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Okada
authors.affiliation: Department of Radiological Technology, Kinki University Hospital, 377-2 Ohno-Higashi, Osaka-Sayama, Osaka 589-8511, Japan. Electronic address: chuho@med.kindai.ac.jp.
authors.forename: Tatsuro
authors.initials: T
authors.lastname: Uto
authors.affiliation: Department of Radiology, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan. Electronic address: mhori@radiol.med.osaka-u.ac.jp.
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Hori
authors.affiliation: Division of Health Sciences, Graduate School of Medical Science, Kanazawa University, 5-11-80 Kodatsuno, Kanazawa, Ishikawa 920-0942, Japan. Electronic address: ramiyati@mhs.mp.kanazawa-u.ac.jp.
authors.forename: Tosiaki
authors.initials: T
authors.lastname: Miyati
mesh_terms: D000328:Adult; D000368:Aged; D003287:Contrast Media; D005260:Female; D019786:Gadolinium DTPA; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D008099:Liver / Q000473:pathology*; D008107:Liver Diseases / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012016:Reference Values; D012680:Sensitivity and Specificity; D013154:Spleen / Q000473:pathology*
chemical_list: D003287:Contrast Media; C073590:gadolinium ethoxybenzyl DTPA; D019786:Gadolinium DTPA
keywords: Gadoxetate disodium; Liver function tests; Magnetic resonance imaging