Double-Uncertainty Guided Spatial and Temporal Consistency Regularization Weighting for Learning-based Abdominal Registration

TL;DR

This paper introduces a novel registration framework that adaptively balances spatial and temporal regularization using a mean-teacher model, improving abdominal CT-MRI registration accuracy and smoothness without extensive hyperparameter tuning.

Contribution

It proposes a mean-teacher based registration method that automatically adjusts regularization weights via uncertainty estimation, addressing limitations of fixed-weight regularization in learning-based registration.

Findings

Enhanced registration accuracy on abdominal CT-MRI data.

Reduced need for hyperparameter tuning.

Improved balance between accuracy and smoothness.

Abstract

In order to tackle the difficulty associated with the ill-posed nature of the image registration problem, regularization is often used to constrain the solution space. For most learning-based registration approaches, the regularization usually has a fixed weight and only constrains the spatial transformation. Such convention has two limitations: (i) Besides the laborious grid search for the optimal fixed weight, the regularization strength of a specific image pair should be associated with the content of the images, thus the "one value fits all" training scheme is not ideal; (ii) Only spatially regularizing the transformation may neglect some informative clues related to the ill-posedness. In this study, we propose a mean-teacher based registration framework, which incorporates an additional temporal consistency regularization term by encouraging the teacher model's prediction to be consistent with that of the student model. More importantly, instead of searching for a fixed weight, the teacher enables automatically adjusting the weights of the spatial regularization and the temporal consistency regularization by taking advantage of the transformation uncertainty and appearance uncertainty. Extensive experiments on the challenging abdominal CT-MRI registration show that our training strategy can promisingly advance the original learning-based method in terms of efficient hyperparameter tuning and a better tradeoff between accuracy and smoothness.