title: Reliability and variability of diffusion tensor imaging (DTI) tractography in pediatric epilepsy.
abstract: BACKGROUND
  Diffusion tensor imaging (DTI) tractography is useful for isolating white matter (WM) trajectories and exploring microstructural integrity. Tractography can be performed on atypical brain anatomy when landmarks are malformed or displaced but has been criticized for its subjectivity even when investigators have advanced anatomical knowledge. Also, little is known about the variability and reliability of tractography as a tool for assessing white matter damage in clinical populations such as children with pediatric epilepsy.
  
  
  METHODS
  Children diagnosed with epilepsy [N=43, mean age=11.7 years, standard deviation=3.7 years, 53% male] underwent a DTI sequence (6 directions, 2×2×3 mm voxels). Tractography for six white matter tracts (anterior forceps, fornices, bilateral arcuate fasciculi, and bilateral anterior cingula) was conducted twice by two experienced tractographers. Percent coefficient of variation (CV; for measuring variability) and intraclass correlation coefficients (ICCs; for measuring reliability) were calculated for tract volume and diffusion variables (fractional anisotropy [FA], mean diffusivity [MD], axial diffusivity [AD] and radial diffusivity [RD]).
  
  
  RESULTS
  Diffusion variables showed low variability (CV=2.7-8.8%) and very high reliability (ICC=.97-.99) except for limbic tracts [fornix (ICC=.75-.94); cingulum (ICC=.71-.98)]. Tract volume measurements showed high variability (CV=21.9-62.0%) and moderate reliability (ICC=.54-.99). Overall, tract volume measurements were much more variable and less reliable than diffusion characteristics. Limbic structures showed more variability compared with others.
  
  
  CONCLUSIONS
  This suggests that DTI tractography and resulting diffusivity variables can reliably inform on the integrity of WM structures in a clinical sample with pediatric epilepsy and highlights the importance of reporting reliability information in studies that aim to answer clinical questions about WM integrity.
authors.affiliation: Alberta Children's Hospital, 2888 Shaganappi Tr NW, Calgary, AB T3B 6A8, Canada; Alberta Children's Hospital Research Institute (ACHRI), Room 293, Heritage Medical Research Building, 3330 Hospital Drive NW, Calgary, AB T2N 4N1, Canada. Electronic address: Helen.carlson@albertahealthservices.ca.
authors.forename: Helen L
authors.initials: HL
authors.lastname: Carlson
authors.affiliation: Alberta Children's Hospital, 2888 Shaganappi Tr NW, Calgary, AB T3B 6A8, Canada.
authors.forename: Christianne
authors.initials: C
authors.lastname: Laliberté
authors.affiliation: Alberta Children's Hospital, 2888 Shaganappi Tr NW, Calgary, AB T3B 6A8, Canada; Alberta Children's Hospital Research Institute (ACHRI), Room 293, Heritage Medical Research Building, 3330 Hospital Drive NW, Calgary, AB T2N 4N1, Canada; University of Calgary, 2500 University Dr. NW, Calgary, AB T2N 1N4, Canada.
authors.forename: Brian L
authors.initials: BL
authors.lastname: Brooks
authors.affiliation: Alberta Children's Hospital, 2888 Shaganappi Tr NW, Calgary, AB T3B 6A8, Canada; University of Calgary, 2500 University Dr. NW, Calgary, AB T2N 1N4, Canada.
authors.forename: Jacquie
authors.initials: J
authors.lastname: Hodge
authors.affiliation: Alberta Children's Hospital, 2888 Shaganappi Tr NW, Calgary, AB T3B 6A8, Canada; Alberta Children's Hospital Research Institute (ACHRI), Room 293, Heritage Medical Research Building, 3330 Hospital Drive NW, Calgary, AB T2N 4N1, Canada; University of Calgary, 2500 University Dr. NW, Calgary, AB T2N 1N4, Canada.
authors.forename: Adam
authors.initials: A
authors.lastname: Kirton
authors.affiliation: Alberta Children's Hospital, 2888 Shaganappi Tr NW, Calgary, AB T3B 6A8, Canada; Alberta Children's Hospital Research Institute (ACHRI), Room 293, Heritage Medical Research Building, 3330 Hospital Drive NW, Calgary, AB T2N 4N1, Canada; University of Calgary, 2500 University Dr. NW, Calgary, AB T2N 1N4, Canada.
authors.forename: Luis
authors.initials: L
authors.lastname: Bello-Espinosa
authors.affiliation: Alberta Children's Hospital, 2888 Shaganappi Tr NW, Calgary, AB T3B 6A8, Canada; Alberta Children's Hospital Research Institute (ACHRI), Room 293, Heritage Medical Research Building, 3330 Hospital Drive NW, Calgary, AB T2N 4N1, Canada; University of Calgary, 2500 University Dr. NW, Calgary, AB T2N 1N4, Canada; Foothills Medical Centre, 1403 29 Street NW, Calgary, AB T2N 2T9, Canada.
authors.forename: Walter
authors.initials: W
authors.lastname: Hader
authors.affiliation: Alberta Children's Hospital, 2888 Shaganappi Tr NW, Calgary, AB T3B 6A8, Canada; Alberta Children's Hospital Research Institute (ACHRI), Room 293, Heritage Medical Research Building, 3330 Hospital Drive NW, Calgary, AB T2N 4N1, Canada; University of Calgary, 2500 University Dr. NW, Calgary, AB T2N 1N4, Canada; Copeman Healthcare Centre, 400-628 12 Avenue SW, Calgary, AB T2R 0H6, Canada.
authors.forename: Elisabeth M S
authors.initials: EM
authors.lastname: Sherman
mesh_terms: D000293:Adolescent; D016880:Anisotropy; D000927:Anticonvulsants / Q000627:therapeutic use; D002648:Child; D002675:Child, Preschool; D056324:Diffusion Tensor Imaging / Q000379:methods*; D004827:Epilepsy / Q000188:drug therapy / Q000473:pathology*; D005260:Female; D005625:Frontal Lobe / Q000473:pathology; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D008032:Limbic System / Q000473:pathology; D008297:Male; D015588:Observer Variation; D015203:Reproducibility of Results; D066127:White Matter / Q000473:pathology
chemical_list: D000927:Anticonvulsants
keywords: DTI; Diffusion tensor imaging; Epilepsy; Pediatric; Reliability; Tractography