title: Identification of neonatal white matter on DTI: influence of more inclusive thresholds for atlas segmentation.
abstract: OBJECTIVE
  Semi-automated diffusion tensor imaging (DTI) analysis of white matter (WM) microstructure offers a clinically feasible technique to assess neonatal brain development and provide early prognosis, but is limited by variable methods and insufficient evidence regarding optimal parameters. The purpose of this research was to investigate the influence of threshold values on semi-automated, atlas-based brain segmentation in very-low-birth-weight (VLBW) preterm infants at near-term age.
  
  
  METHODS
  DTI scans were analyzed from 45 VLBW preterm neonates at near-term-age with no brain abnormalities evident on MRI. Brain regions were selected with a neonatal brain atlas and threshold values: trace <0.006 mm2/s, fractional anisotropy (FA)>0.15, FA>0.20, and FA>0.25. Relative regional volumes, FA, axial diffusivity (AD), and radial diffusivity (RD) were compared for twelve WM regions.
  
  
  RESULTS
  Near-term brain regions demonstrated differential effects from segmentation with the three FA thresholds. Regional DTI values and volumes selected in the PLIC, CereP, and RLC varied the least with the application of different FA thresholds. Overall, application of higher FA thresholds significantly reduced brain region volume selected, increased variability, and resulted in higher FA and lower RD values. The lower threshold FA>0.15 selected 78±21% of original volumes segmented by the atlas, compared to 38±12% using threshold FA>0.25.
  
  
  CONCLUSIONS
  Results indicate substantial and differential effects of atlas-based DTI threshold parameters on regional volume and diffusion scalars. A lower, more inclusive FA threshold than typically applied for adults is suggested for consistent analysis of WM regions in neonates.
authors.affiliation: Department of Orthopaedic Surgery, Stanford University School of Medicine, Stanford, CA, United States of America; Neonatal Neuroimaging Laboratory, Stanford University School of Medicine, Stanford, CA, United States of America.
authors.forename: Rachel L
authors.initials: RL
authors.lastname: Vassar
authors.affiliation: Department of Orthopaedic Surgery, Stanford University School of Medicine, Stanford, CA, United States of America; Neonatal Neuroimaging Laboratory, Stanford University School of Medicine, Stanford, CA, United States of America; Center for Interdisciplinary Brain Sciences Research, Stanford University School of Medicine, Stanford, CA, United States of America.
authors.forename: Naama
authors.initials: N
authors.lastname: Barnea-Goraly
authors.affiliation: Department of Orthopaedic Surgery, Stanford University School of Medicine, Stanford, CA, United States of America; Neonatal Neuroimaging Laboratory, Stanford University School of Medicine, Stanford, CA, United States of America.
authors.forename: Jessica
authors.initials: J
authors.lastname: Rose
mesh_terms: D016880:Anisotropy; D001921:Brain / Q000033:anatomy & histology* / Q000254:growth & development; D056324:Diffusion Tensor Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature; D019102:Infant, Very Low Birth Weight; D008279:Magnetic Resonance Imaging; D008297:Male; D066127:White Matter / Q000033:anatomy & histology* / Q000254:growth & development