title: Delayed hepatic signal recovery on ferucarbotran-enhanced magnetic resonance images in a rat model with regional liver irradiation.
abstract: OBJECTIVE
  To determine whether superparamagnetic iron oxide (SPIO)-enhanced magnetic resonance (MR) imaging could demonstrate signal recovery delay in irradiated areas of rat livers. We also investigated the relationship between MR imaging and histological findings.
  
  
  METHODS
  Twelve rats received 20 μmol iron/kg of SPIO followed by X-irradiation to the right upper abdomen 4 h later. Radiation doses were 0, 50 and 70 Gy. Hepatic signals were assessed on unenhanced T 2 (*) -weighted images for up to 7 days using a 9.4-Tesla scanner. The livers were excised on day 7 and examined histologically.
  
  
  RESULTS
  Normalized relative signal intensity of 70 Gy-irradiated right liver lobe (2.36 ± 0.22) and 50 Gy-irradiated right liver lobe (2.37 ± 0.46) was significantly lower than that of the non-irradiated right liver lobe (4.04 ± 0.28) on day 7, respectively (p < 0.05). Pearson product-moment correlation coefficient between relative intensity of the liver and the number of hepatic iron deposits was -0.588 (p < 0.01).
  
  
  CONCLUSIONS
  Superparamagnetic iron oxide-enhanced MR imaging could demonstrate signal recovery delay in irradiated areas of rat livers. It seems that the signal recovery delay in irradiated areas was due to SPIO-derived iron deposition. Hepatic signal recovery could be a novel diagnostic marker for delineation of irradiated areas.
authors.affiliation: Division of Functional Imaging, Research Center for Innovative Oncology, National Cancer Center Hospital East, 6-5-1, Kashiwanoha, Kashiwa, Chiba, 277-8577, Japan, tfuruta-tky@umin.ac.jp.
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Furuta
authors.forename: Masayuki
authors.initials: M
authors.lastname: Yamaguchi
authors.forename: Ryutaro
authors.initials: R
authors.lastname: Nakagami
authors.forename: Masaaki
authors.initials: M
authors.lastname: Akahane
authors.forename: Manabu
authors.initials: M
authors.lastname: Minami
authors.forename: Kuni
authors.initials: K
authors.lastname: Ohtomo
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Fujii
mesh_terms: D000818:Animals; D003287:Contrast Media / Q000493:pharmacokinetics*; D003911:Dextrans / Q000493:pharmacokinetics*; D004307:Dose-Response Relationship, Radiation; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D008099:Liver / Q000378:metabolism / Q000473:pathology* / Q000528:radiation effects*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D058185:Magnetite Nanoparticles; D008297:Male; D023421:Models, Animal; D011829:Radiation Dosage; D051381:Rats; D017208:Rats, Wistar; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D003287:Contrast Media; D003911:Dextrans; D058185:Magnetite Nanoparticles; C097921:ferumoxtran-10