Purpose : The objective of this study was to show an alteration in diffusion tensor indices caused by image averaging.
Materials and Methods : We recruited four healthy volunteers. The diffusion tensor images (DTI) were obtained with non-collinear motion-proving gradients along 12 axes and were repeated 10 times using a 3.0T MR scanner. The images were averaged in the order of the sessions. The fractional anisotropy (FA), apparent diffusion coefficient (ADC) and eigenvalues (
λ1,
λ2,
λ3) were calculated based on the regions of interest (ROIs) drawn on the commissural, association and projection fibers. To determine the alterations to the FA caused by image averaging, we performed a multiple regression analysis using statistical parametric mapping.
Results : The FA, ADC,
λ1 and
λ2 values tended to decrease, and the
λ3 value tended to increase in proportion to the number of averaging times in the ROI study. In the voxel-based analysis, the FA values significantly decreased proportionally with the increasing number of averaging times.
Conclusions : DTI analysis after image averaging is not desirable because the sharpness of the tensor can be lost.
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