HySCO - Hyperelastic Susceptibility Artefact Correction

What is HySCO?

HySCO is an academic software for the correction of susceptibility artifacts in diffusion weighted images based on a reversed gradient based acquisition scheme. It is developed by Lars Ruthotto and Jan Modersitzki as an add-on to the registration toolbox FAIR.

HySCO requires the acquisition of a pair of images with reversed phase-encoding gradients that are oppositely affected by distortions. From the so-called "blip-up" and "blip-down" image data, HySCO estimates the field-inhomogeneity by solving a tailored image registration problem that incorporates a physical model of inhomogeneity artifacts in spin-echo MRI.

HySCO's name-giving component is a special nonlinear regularization functional, which is inspired by hyperelasticity. It ensures smoothness of the field inhomogeneity and invertibility of the geometrical transformations regardless of the actual choice of regularization parameters.

A quick demo

A typical HySCO result is visualized for one slice of a baseline image of a diffusion tensor data set. The initial blip-up and blip-down data is distorted oppositely along the anterior-posterior direction. Solving a tailored non-linear image registration model HySCO estimates the field-inhomogeneity. Finally, the data is corrected using a physical distortion model and blip-up and blip-down data are visually almost identical.

Read more

Ruthotto, L, Kugel, H, Olesch, J, Fischer, B, Modersitzki, J, Burger, M, and Wolters, C H.
Diffeomorphic Susceptibility Artefact Correction of Diffusion-Weighted Magnetic Resonance Images. Physics in Medicine and Biology, 57(18), 5715-5731; 2012.

Ruthotto, L, Mohammadi, S, Heck, C, Modersitzki, J, and Weiskopf, N.
HySCO - Hyperelastic Susceptibility Artifact Correction of DTI in SPM.
Presented at the Bildverarbeitung fuer die Medizin 2013.

J. Modersitzki: FAIR: Flexible Algorithms for Image Registration. SIAM, Philadelphia, 2009.