Product of Gaussian Mixture Diffusion Model for non-linear MRI Inversion
This addresses MRI reconstruction challenges for medical imaging by offering an incremental improvement in interpretability and efficiency over existing diffusion models.
The paper tackles the problem of MRI reconstruction by jointly estimating images and coil sensitivities using a lightweight, interpretable product of Gaussian mixture diffusion model, achieving results comparable to classical methods like total variation while enabling fast inference and robustness to out-of-distribution data.
Diffusion models have recently shown remarkable results in magnetic resonance imaging reconstruction. However, the employed networks typically are black-box estimators of the (smoothed) prior score with tens of millions of parameters, restricting interpretability and increasing reconstruction time. Furthermore, parallel imaging reconstruction algorithms either rely on off-line coil sensitivity estimation, which is prone to misalignment and restricting sampling trajectories, or perform per-coil reconstruction, making the computational cost proportional to the number of coils. To overcome this, we jointly reconstruct the image and the coil sensitivities using the lightweight, parameter-efficient, and interpretable product of Gaussian mixture diffusion model as an image prior and a classical smoothness priors on the coil sensitivities. The proposed method delivers promising results while allowing for fast inference and demonstrating robustness to contrast out-of-distribution data and sampling trajectories, comparable to classical variational penalties such as total variation. Finally, the probabilistic formulation allows the calculation of the posterior expectation and pixel-wise variance.