Rotation Equivariant Convolutions in Deformable Registration of Brain MRI

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Hauptverfasser: Rezvani, Arghavan, Han, Kun, Wu, Anthony T., Khosravi, Pooya, Xie, Xiaohui
Format: Preprint
Veröffentlicht: 2026
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author Rezvani, Arghavan
Han, Kun
Wu, Anthony T.
Khosravi, Pooya
Xie, Xiaohui
author_facet Rezvani, Arghavan
Han, Kun
Wu, Anthony T.
Khosravi, Pooya
Xie, Xiaohui
contents Image registration is a fundamental task that aligns anatomical structures between images. While CNNs perform well, they lack rotation equivariance - a rotated input does not produce a correspondingly rotated output. This hinders performance by failing to exploit the rotational symmetries inherent in anatomical structures, particularly in brain MRI. In this work, we integrate rotation-equivariant convolutions into deformable brain MRI registration networks. We evaluate this approach by replacing standard encoders with equivariant ones in three baseline architectures, testing on multiple public brain MRI datasets. Our experiments demonstrate that equivariant encoders have three key advantages: 1) They achieve higher registration accuracy while reducing network parameters, confirming the benefit of this anatomical inductive bias. 2) They outperform baselines on rotated input pairs, demonstrating robustness to orientation variations common in clinical practice. 3) They show improved performance with less training data, indicating greater sample efficiency. Our results demonstrate that incorporating geometric priors is a critical step toward building more robust, accurate, and efficient registration models.
format Preprint
id arxiv_https___arxiv_org_abs_2604_08034
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Rotation Equivariant Convolutions in Deformable Registration of Brain MRI
Rezvani, Arghavan
Han, Kun
Wu, Anthony T.
Khosravi, Pooya
Xie, Xiaohui
Computer Vision and Pattern Recognition
Image registration is a fundamental task that aligns anatomical structures between images. While CNNs perform well, they lack rotation equivariance - a rotated input does not produce a correspondingly rotated output. This hinders performance by failing to exploit the rotational symmetries inherent in anatomical structures, particularly in brain MRI. In this work, we integrate rotation-equivariant convolutions into deformable brain MRI registration networks. We evaluate this approach by replacing standard encoders with equivariant ones in three baseline architectures, testing on multiple public brain MRI datasets. Our experiments demonstrate that equivariant encoders have three key advantages: 1) They achieve higher registration accuracy while reducing network parameters, confirming the benefit of this anatomical inductive bias. 2) They outperform baselines on rotated input pairs, demonstrating robustness to orientation variations common in clinical practice. 3) They show improved performance with less training data, indicating greater sample efficiency. Our results demonstrate that incorporating geometric priors is a critical step toward building more robust, accurate, and efficient registration models.
title Rotation Equivariant Convolutions in Deformable Registration of Brain MRI
topic Computer Vision and Pattern Recognition
url https://arxiv.org/abs/2604.08034