The Deleterious Effect of Concomitant Gradient Fields on Diffusion Imaging

Corey Allan Baron¹, Robert Marc Lebel¹, Alan H. Wilman¹, Christian Beaulieu¹

Concomitant fields are small unavoidable magnetic field components that exist during the application of imaging gradients. They can usually be ignored for common pulse sequences. However, in diffusion tensor imaging, large gradients are required to sensitize the MR signal to water diffusion, and phase accrual from the concomitant fields can lead to image artefacts. This is of particular concern for eddy current cancelling diffusion preparations used in combination with systems having large gradients. We demonstrate that an erroneous increase in apparent diffusion coefficient can occur in phantom and human brain, and we propose and validate a prospective correction.