Effect of scanner in longitudinal diffusion tensor imaging studies

Abstract

The purpose of this study was to evaluate the effects of longitudinal drift in scanner hardware, inter-scanner variability (bias), and scanner upgrade on longitudinal changes in global and regional diffusion properties using longitudinal data obtained on two scanners of the exact same model at one institution. A total of 224 normal subjects were scanned twice, at an interval of about 1 year, using two 3.0-T scanners of the exact same model. Both scanners were simultaneously upgraded during the study period. The subjects were divided into four groups according to the combination of scanners used. With use of tract-based spatial statistics, we evaluated the effects of scanner drift and inter-scanner variability (bias) on global and regional fractional anisotropy (FA), axial diffusivity (AD), and radial diffusivity (RD) changes of the white matter. Even with scanners of the exact same model, inter-scanner variability (bias) significantly affected longitudinal results. FA, AD, and RD of the white matter were relatively stable within the same scanner. We also investigated the effect of scanner upgrade on longitudinal FA, AD, and RD changes. The scanner upgrade included only software upgrade, not hardware upgrade; however, there was a significant effect of scanner upgrade on longitudinal results. These results indicate that inter-scanner variability and scanner upgrade can significantly affect the results of longitudinal diffusion tensor imaging studies.

Intersite Reliability of Diffusion Tensor Imaging on Two 3T Scanners

“…These data on reliability are similar to those of previous studies of DTI reliability. [2][3][4][5][6] The discrepancy between the CVs of ABA and TSA may be explained by image misregistration in the ABA. In VBA, the shapes of individual brains are normalized to a common coordinate space (e.g., ICBM-152 space), after which voxel-by-voxel analyses are performed.…”

Longitudinal White Matter Changes after Traumatic Axonal Injury

“…However, results from Takao and colleagues suggest scanner drift is neglible when using a skelontized data. 56 Another limitation is that TBSS is not ideal for use when WM is significantly compromised, as it is possible that the procedure excludes significantly compromised WM among patients and that the accurate identification of WM skeleton is negatively impacted by lesions in WM (Fig. S3).…”

A Validation Study of Multicenter Diffusion Tensor Imaging: Reliability of Fractional Anisotropy and Diffusivity Values

“…Adequate characterization of variability among scanner platforms will prove important for multicenter DTI-based trials. Given a larger number of subjects, voxel-based methods such as those used by Takao et al 25 may prove to be more powerful. However, this study shows that even with a limited dataset, it is possible to assess the reproducibility of diffusion tensor measures across a number of platforms.…”