title: Fetoplacental oxygenation in an intrauterine growth restriction rat model by using blood oxygen level-dependent MR imaging at 4.7 T.
abstract: OBJECTIVE
  To investigate blood oxygen level-dependent (BOLD) magnetic resonance (MR) imaging in an intrauterine growth restriction (IUGR) rat model as a noninvasive in vivo tool to evaluate the response of the fetoplacental units (FPUs) to oxygenation
  
  
  METHODS
  All procedures were approved by the animal care committee. The study was performed between February and July 2010. The IUGR model based on the ligation of the left uterine vascular pedicle at embryonic day 17 of gestation was validated by weighing placentas and fetuses after MR imaging. FPUs in the left and right uterine horns were IUGR cases and controls, respectively. A small-animal 4.7-T MR imager was used. Multiple gradient-echo sequence (repetition time msec/echo time msec, 800/1.8-49.8) was performed at embryonic day 19. T2* relaxation time was measured before and after maternal hyperoxygenation for live FPUs in placenta, fetal liver, and brain. The effect of hyperoxygenation on BOLD MR imaging was analyzed with change in T2* between hyperoxygenation and ambient air. After dissection, live fetuses from both horns were identified and weighed. Changes in T2* were compared based on Student t tests. A mixed model was used to compare BOLD effect among horns and organs.
  
  
  RESULTS
  Sixteen rats were studied. There was a significant fetal weight decrease in the IUGR FPUs (-21.9%; P < .001). Change in T2* differed significantly between IUGR cases and controls for placenta (5.25 msec vs 11.25 msec; P < .001) and fetal brain (3.7 msec vs 7.17 msec; P = .02), whereas there was no significant difference in the fetal liver (2.72 msec vs 3.18 msec; P = .47).
  
  
  CONCLUSIONS
  BOLD MR imaging at 4.7 T can be used to evaluate the response to oxygenation in normal and IUGR FPUs. This technique has a potential role in the assessment of human pregnancy.
authors.affiliation: INSERM, U970, Paris Cardiovascular Research Center-PARCC, Paris, France; Department of Obstetrics and Fetal Medicine, Paris Descartes University, Assistance Publique-Hôpitaux de Paris, Hôpital Necker-Enfants-Malades, 149 rue de Sèvres, Paris 75015, France; Department of Radiology, Paris Descartes University, Assistance Publique-Hôpitaux de Paris, Hôpital Robert Debré, Paris, France.
authors.forename: Gihad E
authors.initials: GE
authors.lastname: Chalouhi
authors.forename: Marianne
authors.initials: M
authors.lastname: Alison
authors.forename: Benjamin
authors.initials: B
authors.lastname: Deloison
authors.forename: Rokhaya
authors.initials: R
authors.lastname: Thiam
authors.forename: Gwennhael
authors.initials: G
authors.lastname: Autret
authors.forename: Daniel
authors.initials: D
authors.lastname: Balvay
authors.forename: Charles A
authors.initials: CA
authors.lastname: Cuenod
authors.forename: Olivier
authors.initials: O
authors.lastname: Clément
authors.forename: Laurent J
authors.initials: LJ
authors.lastname: Salomon
authors.forename: Nathalie
authors.initials: N
authors.lastname: Siauve
mesh_terms: D000818:Animals; D005260:Female; D005317:Fetal Growth Retardation / Q000097:blood* / Q000175:diagnosis*; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D010092:Oximetry / Q000379:methods*; D010100:Oxygen / Q000097:blood*; D021041:Placental Circulation; D011247:Pregnancy; D051381:Rats; D017207:Rats, Sprague-Dawley; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D010100:Oxygen