title: Multilevel modeling of fetal and placental growth using echo-planar magnetic resonance imaging.
abstract: OBJECTIVE
  To quantify longitudinal increases in fetal, fetal liver, and fetal brain volume using echo-planar magnetic resonance imaging and to quantify the results using appropriate statistical modeling.
  
  
  METHODS
  Fifty-six singleton fetuses were studied using echo-planar (snap-shot) magnetic resonance imaging, between 19 weeks and term. They were assessed at a variety of different gestations and on a different number of occasions, thereby requiring multilevel statistical modeling to analyze the pattern of fetal growth.
  
  
  RESULTS
  Fetal volume varied according to the following equation: square root (radical) [fetal volume]=-37.71+2.17 x gestational age (GA)-0.004 x GA(2). The equation for fetal liver volume was radical[fetal liver volume]=9.47+0.56 x GA-0.02 x GA(2), for fetal brain volume was radical[fetal brain volume]=15.50+0.69 x GA-0.014 x GA(2), and for placental volume radical[placental volume]=28.54+0.95 x GA-0.039 x GA(2), where GA is the gestational age in weeks -30.
  
  
  CONCLUSIONS
  The assessment of fetal, fetal organ, and placental volume was feasible using echo-planar magnetic resonance imaging from 20 weeks to term. Multilevel statistical modeling can be applied to analyze sets of data with different measurements on different occasions. This information is useful clinically to assess abnormal fetal growth.
authors.affiliation: School of Human Development, Nottingham University, Nottingham, UK. keith.duncan@nottingham.ac.uk
authors.forename: K R
authors.initials: KR
authors.lastname: Duncan
authors.forename: D S
authors.initials: DS
authors.lastname: Sahota
authors.forename: P A
authors.initials: PA
authors.lastname: Gowland
authors.forename: R
authors.initials: R
authors.lastname: Moore
authors.forename: A
authors.initials: A
authors.lastname: Chang
authors.forename: P N
authors.initials: PN
authors.lastname: Baker
authors.forename: I R
authors.initials: IR
authors.lastname: Johnson
mesh_terms: D000328:Adult; D001921:Brain / Q000196:embryology; D017352:Echo-Planar Imaging; D005314:Embryonic and Fetal Development / Q000502:physiology*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007231:Infant, Newborn; D008099:Liver / Q000196:embryology; D008137:Longitudinal Studies; D008297:Male; D015233:Models, Statistical; D010920:Placenta / Q000502:physiology; D010929:Placentation; D011247:Pregnancy; D011446:Prospective Studies