title: The Gini coefficient: a methodological pilot study to assess fetal brain development employing postmortem diffusion MRI.
abstract: BACKGROUND
  Diffusion-weighted imaging (DWI) is important in the assessment of fetal brain development. However, it is clinically challenging and time-consuming to prepare neuromorphological examinations to assess real brain age and to detect abnormalities.
  
  
  OBJECTIVE
  To demonstrate that the Gini coefficient can be a simple, intuitive parameter for modelling fetal brain development.
  
  
  METHODS
  Postmortem fetal specimens(n = 28) were evaluated by diffusion-weighted imaging (DWI) on a 3-T MRI scanner using 60 directions, 0.7-mm isotropic voxels and b-values of 0, 150, 1,600 s/mm(2). Constrained spherical deconvolution (CSD) was used as the local diffusion model. Fractional anisotropy (FA), apparent diffusion coefficient (ADC) and complexity (CX) maps were generated. CX was defined as a novel diffusion metric. On the basis of those three parameters, the Gini coefficient was calculated.
  
  
  RESULTS
  Study of fetal brain development in postmortem specimens was feasible using DWI. The Gini coefficient could be calculated for the combination of the three diffusion parameters. This multidimensional Gini coefficient correlated well with age (Adjusted R(2) = 0.59) between the ages of 17 and 26 gestational weeks.
  
  
  CONCLUSIONS
  We propose a new method that uses an economics concept, the Gini coefficient, to describe the whole brain with one simple and intuitive measure, which can be used to assess the brain's developmental state.
authors.affiliation: Department of Pediatric Radiology, University Hospital Leipzig, Liebigstraße 20a, 04103, Leipzig, Germany, adrian.viehweger@googlemail.com.
authors.forename: Adrian
authors.initials: A
authors.lastname: Viehweger
authors.forename: Till
authors.initials: T
authors.lastname: Riffert
authors.forename: Bibek
authors.initials: B
authors.lastname: Dhital
authors.forename: Thomas R
authors.initials: TR
authors.lastname: Knösche
authors.forename: Alfred
authors.initials: A
authors.lastname: Anwander
authors.forename: Holger
authors.initials: H
authors.lastname: Stepan
authors.forename: Ina
authors.initials: I
authors.lastname: Sorge
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Hirsch
mesh_terms: D000465:Algorithms; D001344:Autopsy; D001921:Brain / Q000196:embryology* / Q000473:pathology*; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005240:Feasibility Studies; D005260:Female; D005865:Gestational Age; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008297:Male; D011296:Prenatal Diagnosis / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity