title: Human long bone development in vivo: analysis of the distal femoral epimetaphysis on MR images of fetuses.
abstract: OBJECTIVE
  To investigate human long bone development in vivo by analyzing distal femoral epimetaphyseal structures and bone morphometrics on magnetic resonance (MR) images of fetuses.
  
  
  METHODS
  An institutional review board approved this retrospective study, and informed consent was waived. Included were 272 MR imaging examinations (April 2004-July 2011) in 253 fetuses with a mean gestational age (GA) of 26 weeks 6 days (range, 19 weeks 2 days to 35 weeks 6 days) without known musculoskeletal abnormalities. Two independent readers qualitatively analyzed epiphyseal and metaphyseal shape, secondary ossification, and the perichondrium on 1.5-T echo-planar MR images and correlated the results with the GA that was derived from previous fetal ultrasonography (US). Diaphyseal and epiphyseal morphometric measurements were correlated with GA by means of the Pearson correlation and linear regression. MR imaging measurements of diaphyseal length and US normative values were compared graphically. Interreader agreement analysis was performed with weighted κ statistics and the intraclass correlation coefficient.
  
  
  RESULTS
  With advancing GA, the epiphyseal shape changed from spherical (r(2) = 0.664) to hemispherical with a notch (r(2) = 0.804), and the metaphyseal shape changed from flat (r(2) = 0.766) to clearly undulated (r(2) = 0.669). Secondary ossification (r(2) = 0.777) was not observed until 25 weeks 3 days. The perichondrium decreased (r(2) = 0.684) from 20 weeks onward. Correlation coefficients were 0.897 for diaphyseal length, 0.738 for epiphyseal length, and 0.801 for epiphyseal width with respect to GA. The range of measurements of diaphyseal length was larger than that of the reported US normative values. Interreader agreement was good for bone morphometrics (intraclass correlation coefficient, 0.906-0.976), and moderate for bone characteristics (weighted κ, 0.448-0.848).
  
  
  CONCLUSIONS
  Prenatal MR imaging allows visualization of human bone development in vivo by means of epimetaphyseal characteristics and bone morphometrics.
  
  
  BACKGROUND
  http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.13112441/-/DC1.
authors: Department of Radiology, Division of Neuroradiology and Musculoskeletal Radiology, Medical University Vienna, Waehringer Guertel 18-20, A-1090 Vienna, Austria. stefan.nemec@meduniwien.ac.ata
authors: Ursula
authors: U
authors: Nemec
authors: Stefan F
authors: SF
authors: Nemec
authors: Michael
authors: M
authors: Weber
authors: Peter C
authors: PC
authors: Brugger
authors: Gregor
authors: G
authors: Kasprian
authors: Dieter
authors: D
authors: Bettelheim
authors: David L
authors: DL
authors: Rimoin
authors: Ralph S
authors: RS
authors: Lachman
authors: Gustavo
authors: G
authors: Malinger
authors: Daniela
authors: D
authors: Prayer
mesh_terms: D004838:Epiphyses / Q000196:embryology*; D005260:Female; D005269:Femur / Q000196:embryology*; D005865:Gestational Age; D006801:Humans; D016014:Linear Models; D008279:Magnetic Resonance Imaging / Q000379:methods*; D011247:Pregnancy; D012189:Retrospective Studies; D016216:Ultrasonography, Prenatal