The effect of a gadolinium-based contrast agent on diffusion tensor imaging

Objective

The aim of this study was to investigate in detail the effect of gadolinium contrast on diffusion tensor imaging scans. As the present literature offers conflicting results, we have included a large selection of indices in the analysis.

Materials and methods

Sixteen patients harboring an intra-axial contrast enhancing brain tumor were included in this study. Two diffusion tensor imaging scans were performed—one natively, and the second following a gadolinium contrast agent application. Maps of the invariant indices fractional anisotropy (FA), linear, planar, and spherical indices, trace, eigenvalues λ₁, λ₂, λ₃ as well as of the components of the diffusion tensor matrix Dxx, Dyy, Dzz, Dxy, Dxz and Dyz were co-registered and compared statistically with matching ROI pairs in the contrast enhancing areas, peritumoral edema and the normal appearing white matter.

Results

We have observed a significant increase in the FA and disproportional decrease of the eigenvalues in the post-contrast scans. In accordance with these findings, the spherical index was decreased and the linear and planar indices were increased. There was a significant decrease of all diagonal components of the diffusion tensor matrix. These changes have been strongest in the contrast enhancing areas, but there were also significant changes in the peritumoral edema and the normal appearing white matter.

Conclusion

Diffusion tensor imaging scans performed after gadolinium contrast agent administration may display artificially increased FA values due to disproportional changes of the measured eigenvalues. The distortion of the diffusion measurement is strongest in, but not limited to the contrasting areas.