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AJNR - American Journal of Neuroradiology

Published ahead of print on March 20, 2008
doi: 10.3174/ajnr.A0998

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American Journal of Neuroradiology 29:1124-1127, June-July 2008
© 2008 American Society of Neuroradiology

BRAIN

Regional Differences in Diffusion Tensor Imaging Measurements: Assessment of Intrarater and Interrater Variability

A. Ozturk^a, A.D. Sasson^a, J.A.D. Farrell^a,b, B.A. Landman^c, A.C.B.S. da Motta^a, A. Aralasmak^d and D.M. Yousem^a

^a Russell H. Morgan Department of Radiology and Radiological Science, F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Md
^b Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, Md
^c Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, Md
^d Department of Radiology, Akdeniz University, Antalya, Turkey

Please address correspondence to David M. Yousem, Russell H. Morgan Department of Radiology and Radiological Sciences, Johns Hopkins Medical Institution, 600 N Wolfe St, Phipps B112, Baltimore, MD 21287; e-mail: dyousem1{at}jhu.edu

BACKGROUND AND PURPOSE: Diffusion tensor imaging (DTI) has become a valuable tool in both the research and clinical evaluation of subjects. We sought to quantify interobserver and intraobserver variability of diffusivity and diffusion anisotropy measurements with regard to specific regions of interest (ROIs).

MATERIALS AND METHODS: The subject group consisted of 5 healthy control subjects and 7 study subjects (all males; 16–19 years old; mean age = 17.5 years), as part of a protocol for closed head injury. Two whole-brain DTI scans were acquired on a 3T scanner for each subject. Analysis was performed using a ROI approach. Two independent observers analyzed the apparent diffusion coefficient (ADC) and fractional anisotropy (FA) indices in the corpus callosum, cortical spinal tract, internal capsules (ICs), basal ganglia, and centrum semiovale (CSO). Intraobserver and interobserver variability were calculated for the mean ADC, FA, and ordered eigenvalues of the diffusion tensor (₁, ₂, and ₃).

RESULTS: The overall statistic for intraobserver variability for both observers showed slight-to-substantial agreement ( = 0.02–0.69), however FA values in the CSO showed only slight agreement. Interobserver agreement was also slight to substantial for these DTI measurements with high variability in FA values in the IC and CSO.

CONCLUSIONS: When one is comparing 2 DTI measurements, it is important to assess intraobserver and interobserver variability. We recommend caution in the analysis of DTI contrasts in the IC and CSO, because we have found the widest range of variability in measurements within these structures.