Optimization for diffusion MRI

Diffusion MRI (dMRI) is a useful probe of tissue microstructure, which can be used to derive biomarkers for diagnostics and treatment. Diffusion measurements using continuous gradient waveforms significantly expand the capabilities of conventional diffusion MRI [J6]. However, implementing them on real-world MR scanners is challenging due to the plethora of constraints imposed by hardware limitations and physiology.

Contributions

In collaboration with Filip Szczepankiewicz and others, we’ve developed the open-source library NOW that has established itself as the de facto standard tool for gradient waveform design for tensor-valued encoding in diffusion MRI. Since its introduction in 2015 [J1], the methodology and software has been extended and refined to capture additional effects, including Maxwell compensation [J3], motion compensation [J4] and cross-term compensation [J5]. We have also demonstrated that NOW enables diffusional variance decomposition (DIVIDE) on clinical MRI systems [J2].

References

Journal papers

[J1] Sjölund J, Szczepankiewicz F, Nilsson M, Topgaard D, Westin C-F, and Knutsson H. Constrained optimization of gradient waveforms for generalized diffusion encoding. Journal of Magnetic Resonance 261 (2015), 157-168.
[J2] Szczepankiewicz F , Sjölund J, Ståhlberg F, Lätt J, and Nilsson M. Tensor-valued diffusion encoding for diffusional variance decomposition (DIVIDE): Technical feasibility in clinical MRI systems. PLoS One (2019).
[J3] Szczepankiewicz F, Westin C F, and Nilsson, M. Maxwell‐compensated design of asymmetric gradient waveforms for tensor‐valued diffusion encoding. Magnetic resonance in medicine, 82(4), 1424-1437.
[J4] Szczepankiewicz F, Sjölund J, Dall’Armellina E, Plein S, Schneider E J, Teh I, and Westin C-F, Motion-compensated gradient waveforms for tensor-valued diffusion encoding by constrained numerical optimization. Magn Reson Med (2021)
[J5] Szczepankiewicz F and Sjölund J, Cross-term-compensated gradient waveform design for tensor-valued diffusion MRI. Journal of Magnetic Resonance (2021)
[J6] Szczepankiewicz F, Westin C-F, and Nilsson, M, Gradient waveform design for tensor-valued encoding in diffusion MRI. Journal of Neuroscience Methods (2021)