PURPOSE: We compared results from various methods of analysis of diffusion tensor imaging (DTI) data from a single data set consisting of 10 healthy adolescents. METHODS: All subjects were imaged on a single 3T MRI system (single-shot echo-planar imaging (EPI) pulse sequence, b value 1000). We measured fractional anisotropy (FA), apparent diffusion coefficient (ADC), axial diffusivity and radial diffusivity values using 64 pixel rectangular regions of interest (ROIs) in the right-side, midline and left-side of the central portion of the splenium of the corpus callosum for fixed (i.e., at same sites in all subjects) and targeted (i.e., at sites of highest FA values) locations, We compared results with those obtained using 64 pixel oval ROIs and 100 pixel rectangular ROIs in same locations. Finally, we compared results from ROI-based methods and from tractography. All comparisons used the Wilcoxon signed rank test and the intraclass correlation of individual values. RESULTS: Compared to tractography, the average of mean ROI-based values was significantly higher for fixed FA (14%) and targeted FA (39%) values and significantly lower for ADC (16%) and radial diffusivity (38%) values. For solely ROI-based comparisons, significant differences were found in the following comparisons: 64 pixel ROI vs. 100 pixel ROI, oval ROI vs. rectangular ROI, targeted FA left of midline vs. mean targeted FA value, and targeted ROI right of midline vs. mean targeted FA value. CONCLUSION: Markedly different values were obtained when using either ROI-based or tractography-based techniques, or ROI analysis techniques that differ only relatively slightly
