We present an efficient learning-based algorithm for deformable, pairwise 3D medical image registration. Current registration methods optimize an energy function independently for each pair of images, which can be time-consuming for large data. We define registration as a parametric function, and optimize its parameters given a set of images from a collection of interest. Given a new pair of scans, we can quickly compute a registration field by directly evaluating the function using the learned parameters. We model this function using a CNN, and use a spatial transform layer to reconstruct one image from another while imposing smoothness constraints on the registration field. The proposed method does not require supervised information such as ground truth registration fields or anatomical landmarks. We demonstrate registration accuracy comparable to state-of-the-art 3D image registration, while operating orders of magnitude faster in practice. Our method promises to significantly speed up medical image analysis and processing pipelines, while facilitating novel directions in learning-based registration and its applications. Our code is available at https://github.com/balakg/voxelmorph.

本文提出了一种基于学习的算法，用于变形、两两匹配的三维医学图像注册，通过使用卷积神经网络（CNN）模型并利用一个空间变换层，从而实现快速计算新的扫描成像时的配准场，且无需监督信息。我们可以在不破坏匹配场平滑性的前提下，底层地在一张图像中重构另一张图像，并在实践中将其速度提高数个数量级以上，从而有望显著加速医学图像分析和处理管道的速度，同时促进学习医学图像配准及其应用的新方向。

可变形医学图像配准的无监督学习模型