title: Diffusion tensor imaging of the cervical spinal cord in healthy adult population: normative values and measurement reproducibility at 3T MRI.
abstract: BACKGROUND
  Compared to diffusion tensor imaging (DTI) of the brain, there is a paucity of reports addressing the applicability of DTI in the evaluation of the spinal cord. Most normative data of cervical spinal cord DTI consist of relatively small and arbitrarily collected populations. Comprehensive normative data are necessary for clinical decision-making.
  
  
  OBJECTIVE
  To establish normal values for cervical spinal cord DTI metrics with region of interest (ROI)- and fiber tractography (FT)-based measurements and to assess the reproducibility of both measurement methods.
  
  
  METHODS
  Forty healthy adults underwent cervical spinal cord 3T MRI. Sagittal and axial conventional T2 sequences and DTI in the axial plane were performed. Whole cord fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values were determined at different cervical levels from C2 to C7 using the ROI method. DTI metrics (FA, axial, and radial diffusivities based on eigenvalues λ1, λ2, and λ3, and ADC) of the lateral and posterior funicles were measured at C3 level. FA and ADC of the whole cord and the lateral and posterior funicles were also measured using quantitative tractography. Intra- and inter-observer variation of the measurement methods were assessed.
  
  
  RESULTS
  Whole cord FA values decreased and ADC values increased in the rostral to caudal direction from C2 to C7. Between the individual white matter funicles no statistically significant difference for FA or ADC values was found. Both axial diffusivity and radial diffusivity of both lateral funicles differed significantly from those of the posterior funicle. Neither gender nor age correlated with any of the DTI metrics. Intra-observer variation of the measurements for whole cord FA and ADC showed almost perfect agreement with both ROI and tractography-based measurements. There was more variation in measurements of individual columns. Inter-observer agreement varied from moderate to strong for whole cord FA and ADC.
  
  
  CONCLUSIONS
  Both ROI- and FT-based measurements are applicable methods yielding reproducible results for cervical spinal cord DTI metrics. Normative values for both measurement methods are presented.
authors: Medical Imaging Centre, Department of Radiology, Tampere University Hospital, Tampere, Finland.
authors: Antti
authors: A
authors: Brander
authors: Eerika
authors: E
authors: Koskinen
authors: Teemu M
authors: TM
authors: Luoto
authors: Ullamari
authors: U
authors: Hakulinen
authors: Mika
authors: M
authors: Helminen
authors: Sirpa
authors: S
authors: Savilahti
authors: Pertti
authors: P
authors: Ryymin
authors: Prasun
authors: P
authors: Dastidar
authors: Juha
authors: J
authors: Ohman
mesh_terms: D000293:Adolescent; D000328:Adult; D002574:Cervical Vertebrae / Q000033:anatomy & histology*; D056324:Diffusion Tensor Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012016:Reference Values; D015203:Reproducibility of Results
keywords: CNS; MR diffusion/perfusion; adults; normal variants; spinal cord; tissue characterization