SOE: SO(3)-Equivariant 3D MRI Encoding

Fuente: arXiv
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Autori principali: He, Shizhe, Paschali, Magdalini, Ouyang, Jiahong, Masood, Adnan, Chaudhari, Akshay, Adeli, Ehsan
Natura: Preprint
Pubblicazione: 2024
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author He, Shizhe
Paschali, Magdalini
Ouyang, Jiahong
Masood, Adnan
Chaudhari, Akshay
Adeli, Ehsan
author_facet He, Shizhe
Paschali, Magdalini
Ouyang, Jiahong
Masood, Adnan
Chaudhari, Akshay
Adeli, Ehsan
contents Representation learning has become increasingly important, especially as powerful models have shifted towards learning latent representations before fine-tuning for downstream tasks. This approach is particularly valuable in leveraging the structural information within brain anatomy. However, a common limitation of recent models developed for MRIs is their tendency to ignore or remove geometric information, such as translation and rotation, thereby creating invariance with respect to geometric operations. We contend that incorporating knowledge about these geometric transformations into the model can significantly enhance its ability to learn more detailed anatomical information within brain structures. As a result, we propose a novel method for encoding 3D MRIs that enforces equivariance with respect to all rotations in 3D space, in other words, SO(3)-equivariance (SOE). By explicitly modeling this geometric equivariance in the representation space, we ensure that any rotational operation applied to the input image space is also reflected in the embedding representation space. This approach requires moving beyond traditional representation learning methods, as we need a representation vector space that allows for the application of the same SO(3) operation in that space. To facilitate this, we leverage the concept of vector neurons. The representation space formed by our method captures the brain's structural and anatomical information more effectively. We evaluate SOE pretrained on the structural MRIs of two public data sets with respect to the downstream task of predicting age and diagnosing Alzheimer's Disease from T1-weighted brain scans of the ADNI data set. We demonstrate that our approach not only outperforms other methods but is also robust against various degrees of rotation along different axes. The code is available at https://github.com/shizhehe/SOE-representation-learning.
format Preprint
id arxiv_https___arxiv_org_abs_2410_12053
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle SOE: SO(3)-Equivariant 3D MRI Encoding
He, Shizhe
Paschali, Magdalini
Ouyang, Jiahong
Masood, Adnan
Chaudhari, Akshay
Adeli, Ehsan
Computer Vision and Pattern Recognition
Representation learning has become increasingly important, especially as powerful models have shifted towards learning latent representations before fine-tuning for downstream tasks. This approach is particularly valuable in leveraging the structural information within brain anatomy. However, a common limitation of recent models developed for MRIs is their tendency to ignore or remove geometric information, such as translation and rotation, thereby creating invariance with respect to geometric operations. We contend that incorporating knowledge about these geometric transformations into the model can significantly enhance its ability to learn more detailed anatomical information within brain structures. As a result, we propose a novel method for encoding 3D MRIs that enforces equivariance with respect to all rotations in 3D space, in other words, SO(3)-equivariance (SOE). By explicitly modeling this geometric equivariance in the representation space, we ensure that any rotational operation applied to the input image space is also reflected in the embedding representation space. This approach requires moving beyond traditional representation learning methods, as we need a representation vector space that allows for the application of the same SO(3) operation in that space. To facilitate this, we leverage the concept of vector neurons. The representation space formed by our method captures the brain's structural and anatomical information more effectively. We evaluate SOE pretrained on the structural MRIs of two public data sets with respect to the downstream task of predicting age and diagnosing Alzheimer's Disease from T1-weighted brain scans of the ADNI data set. We demonstrate that our approach not only outperforms other methods but is also robust against various degrees of rotation along different axes. The code is available at https://github.com/shizhehe/SOE-representation-learning.
title SOE: SO(3)-Equivariant 3D MRI Encoding
topic Computer Vision and Pattern Recognition
url https://arxiv.org/abs/2410.12053