On the Degrees of Freedom of Gridded Control Points in Learning-Based Medical Image Registration

Fuente: arXiv
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Autori principali: Yan, Wen, Yang, Qianye, Wang, Yipei, Punwani, Shonit, Emberton, Mark, Stavrinides, Vasilis, Hu, Yipeng, Barratt, Dean
Natura: Preprint
Pubblicazione: 2026
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author Yan, Wen
Yang, Qianye
Wang, Yipei
Punwani, Shonit
Emberton, Mark
Stavrinides, Vasilis
Hu, Yipeng
Barratt, Dean
author_facet Yan, Wen
Yang, Qianye
Wang, Yipei
Punwani, Shonit
Emberton, Mark
Stavrinides, Vasilis
Hu, Yipeng
Barratt, Dean
contents Many registration problems are ill-posed in homogeneous or noisy regions, and dense voxel-wise decoders can be unnecessarily high-dimensional. A sparse control-point parameterisation provides a compact, smooth deformation representation while reducing memory and improving stability. This work investigates the required control points for learning-based registration network development. We present GridReg, a learning-based registration framework that replaces dense voxel-wise decoding with displacement predictions at a sparse grid of control points. This design substantially cuts the parameter count and memory while retaining registration accuracy. Multiscale 3D encoder feature maps are flattened into a 1D token sequence with positional encoding to retain spatial context. The model then predicts a sparse gridded deformation field using a cross-attention module. We further introduce grid-adaptive training, enabling an adaptive model to operate at multiple grid sizes at inference without retraining. This work quantitatively demonstrates the benefits of using sparse grids. Using three data sets for registering prostate gland, pelvic organs and neurological structures, the results suggested a significant improvement with the usage of grid-controled displacement field. Alternatively, the superior registration performance was obtained using the proposed approach, with a similar or less computational cost, compared with existing algorithms that predict DDFs or displacements sampled on scattered key points.
format Preprint
id arxiv_https___arxiv_org_abs_2603_16940
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle On the Degrees of Freedom of Gridded Control Points in Learning-Based Medical Image Registration
Yan, Wen
Yang, Qianye
Wang, Yipei
Punwani, Shonit
Emberton, Mark
Stavrinides, Vasilis
Hu, Yipeng
Barratt, Dean
Image and Video Processing
Artificial Intelligence
Computer Vision and Pattern Recognition
Many registration problems are ill-posed in homogeneous or noisy regions, and dense voxel-wise decoders can be unnecessarily high-dimensional. A sparse control-point parameterisation provides a compact, smooth deformation representation while reducing memory and improving stability. This work investigates the required control points for learning-based registration network development. We present GridReg, a learning-based registration framework that replaces dense voxel-wise decoding with displacement predictions at a sparse grid of control points. This design substantially cuts the parameter count and memory while retaining registration accuracy. Multiscale 3D encoder feature maps are flattened into a 1D token sequence with positional encoding to retain spatial context. The model then predicts a sparse gridded deformation field using a cross-attention module. We further introduce grid-adaptive training, enabling an adaptive model to operate at multiple grid sizes at inference without retraining. This work quantitatively demonstrates the benefits of using sparse grids. Using three data sets for registering prostate gland, pelvic organs and neurological structures, the results suggested a significant improvement with the usage of grid-controled displacement field. Alternatively, the superior registration performance was obtained using the proposed approach, with a similar or less computational cost, compared with existing algorithms that predict DDFs or displacements sampled on scattered key points.
title On the Degrees of Freedom of Gridded Control Points in Learning-Based Medical Image Registration
topic Image and Video Processing
Artificial Intelligence
Computer Vision and Pattern Recognition
url https://arxiv.org/abs/2603.16940