title: Gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid-enhanced MR finding of radiation-induced hepatic injury: relationship to absorbed dose and time course after irradiation.
abstract: OBJECTIVE
  To evaluate if Gd-EOB-DTPA-enhanced MRI could identify liver tissue damage caused by radiation exposure in patients undergoing external beam radiation therapy.
  
  
  METHODS
  We enrolled 11 patients who underwent Gd-EOB-DTPA-enhanced MRI during or after radiotherapy in which the radiation field included the liver. External beam radiotherapy was delivered through multiple fields using a 10-MV linear accelerator. The hepatobiliary phase images of Gd-EOB-DTPA-enhanced MRI were qualitatively evaluated for the presence of a decreased uptake of Gd-EOB-DTPA in the irradiated area in the liver. Next, signal intensity (SI) ratio of the irradiated area to the non-irradiated liver parenchyma was also calculated. The absorbed dose of the irradiated area in the liver was standardized using equivalent dose in 2Gy fraction (EQD2) and biological effective dose (BED). The results of qualitative analysis were compared with EQD2 or BED, and linear regression analysis was performed between EQD2 or BED and SI ratio.
  
  
  RESULTS
  Twenty-two irradiated areas were evaluated. Qualitative analysis revealed a decreased uptake of Gd-EOB-DTPA in 14 areas and no decreased uptake of Gd-EOB-DTPA in eight areas. The thresholds of EQD2 and BED causing a decreased uptake of Gd-EOB-DTPA were considered to be 24 to 29Gy and 29 to 35Gy, respectively. Quantitatively, SI ratio decreased as EQD2 or BED increased (r=0.89, p<0.001), and the inverse relationship between signal enhancement and the absorbed dose in the irradiated area was obtained. One area with EQD2 of 50Gy and BED of 60Gy showed a slightly decreased uptake of Gd-EOB-DTPA on the 40th day but a clearly decreased uptake of Gd-EOB-DTPA on the 123rd day from initiation of radiotherapy.
  
  
  CONCLUSIONS
  Gd-EOB-DTPA-enhanced MRI described RLI as a decreased uptake of Gd-EOB-DTPA matching the irradiated area. The occurrence of this finding was significantly correlated with the absorbed dose of the irradiated area in the liver.
authors.affiliation: Department of Clinical Radiology, Graduate School of Medical Sciences, Kyushu University.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Okamoto
authors.affiliation: Department of Clinical Radiology, Graduate School of Medical Sciences, Kyushu University. Electronic address: anishie@radiol.med.kyushu-u.ac.jp.
authors.forename: Akihiro
authors.initials: A
authors.lastname: Nishie
authors.affiliation: Department of Clinical Radiology, Graduate School of Medical Sciences, Kyushu University.
authors.forename: Yoshiki
authors.initials: Y
authors.lastname: Asayama
authors.affiliation: Department of Clinical Radiology, Graduate School of Medical Sciences, Kyushu University.
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Tajima
authors.affiliation: Department of Clinical Radiology, Graduate School of Medical Sciences, Kyushu University.
authors.forename: Kousei
authors.initials: K
authors.lastname: Ishigami
authors.affiliation: Department of Clinical Radiology, Graduate School of Medical Sciences, Kyushu University.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Kakihara
authors.affiliation: Department of Clinical Radiology, Graduate School of Medical Sciences, Kyushu University.
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Nakayama
authors.affiliation: Department of Clinical Radiology, Graduate School of Medical Sciences, Kyushu University.
authors.forename: Saiji
authors.initials: S
authors.lastname: Ohga
authors.affiliation: Department of Clinical Radiology, Graduate School of Medical Sciences, Kyushu University.
authors.forename: Tadamasa
authors.initials: T
authors.lastname: Yoshitake
authors.affiliation: Department of Clinical Radiology, Graduate School of Medical Sciences, Kyushu University.
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Shioyama
authors.affiliation: Department of Clinical Radiology, Graduate School of Medical Sciences, Kyushu University.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Honda
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D003287:Contrast Media / Q000008:administration & dosage / Q000493:pharmacokinetics*; D005260:Female; D019786:Gadolinium DTPA / Q000008:administration & dosage / Q000493:pharmacokinetics*; D006801:Humans; D008099:Liver / Q000528:radiation effects*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009369:Neoplasms / Q000532:radiotherapy*; D011832:Radiation Injuries / Q000175:diagnosis* / Q000378:metabolism; D012189:Retrospective Studies; D013997:Time Factors
chemical_list: D003287:Contrast Media; C073590:gadolinium ethoxybenzyl DTPA; D019786:Gadolinium DTPA
keywords: Biological effective dose; Gd-EOB-DTPA; MRI; Radiation hepatitis; Radiation-induced liver injury