title: A comparison of fetal organ measurements by echo-planar magnetic resonance imaging and ultrasound.
abstract: OBJECTIVE
  To compare fetal organ size measured using echo-planar magnetic resonance imaging and 2D ultrasound. To determine the relative accuracy with which each technique can predict fetal growth restriction.
  
  
  METHODS
  A cross sectional, observational study comparing two different measurement techniques against a gold standard, in a normal clinical population and an abnormal population.
  
  
  METHODS
  Seventy-four pregnant women (33 who were ultimately found to be normal and 37 with fetal growth restricted fetuses) were recruited from the City Hospital Nottingham UK to be scanned once (at various gestations).
  
  
  METHODS
  Each fetus had a standard ultrasound biometry assessment followed by magnetic resonance imaging measurement of organ volumes.
  
  
  METHODS
  For each measurement for both techniques, the normal population was plotted with 90% confidence intervals. Fetal growth restricted subjects were compared with the normal population using this plot; 2 x 2 tables were created for each measurement. This was used to calculate the relative sensitivities and positive predictive value of the different measurements. A Bland-Altman plot was used to compare the ultrasound and magnetic resonance imaging measurements of fetal weight.
  
  
  RESULTS
  Brain sparing was seen in ultrasonic head circumference measurements, but an overall reduction in fetal growth restriction brain volume was apparent using magnetic resonance imaging at late gestations. Across the whole range of gestational ages, ultrasound assessment of fetal weight was the best predictor of fetal growth restriction.
  
  
  CONCLUSIONS
  Ultrasound fetal weight assessment appears to identify more fetuses with fetal growth restriction than abdominal circumference. The brain sparing apparent in ultrasonic head circumference measurements of fetuses with fetal growth restriction masks a reduction in brain volume observed with magnetic resonance imaging.
authors.affiliation: University Department of Obstetrics and Gynaecology, University of Nottingham, UK.
authors.forename: Keith R
authors.initials: KR
authors.lastname: Duncan
authors.forename: Bashar
authors.initials: B
authors.lastname: Issa
authors.forename: Rachel
authors.initials: R
authors.lastname: Moore
authors.forename: Philip N
authors.initials: PN
authors.lastname: Baker
authors.forename: Ian R
authors.initials: IR
authors.lastname: Johnson
authors.forename: Penny A
authors.initials: PA
authors.lastname: Gowland
mesh_terms: D000005:Abdomen / Q000196:embryology; D001921:Brain / Q000196:embryology; D003430:Cross-Sectional Studies; D017352:Echo-Planar Imaging / Q000592:standards*; D005260:Female; D005317:Fetal Growth Retardation / Q000175:diagnosis*; D020567:Fetal Weight; D006257:Head / Q000196:embryology; D006801:Humans; D008099:Liver / Q000196:embryology; D008168:Lung / Q000196:embryology; D009929:Organ Size / Q000502:physiology; D011247:Pregnancy; D011296:Prenatal Diagnosis / Q000592:standards*; D012680:Sensitivity and Specificity; D016216:Ultrasonography, Prenatal / Q000592:standards