SAME: Deformable Image Registration based on Self-supervised Anatomical Embeddings
This work addresses fast and accurate medical image registration for healthcare applications, representing an incremental improvement by building on existing SAM embeddings.
The paper tackles unsupervised 3D medical image registration by introducing SAME, a method that uses self-supervised anatomical embeddings to enhance registration steps, resulting in improved Dice scores by at least 4.7% and 2.7% over baseline methods and being orders of magnitude faster.
In this work, we introduce a fast and accurate method for unsupervised 3D medical image registration. This work is built on top of a recent algorithm SAM, which is capable of computing dense anatomical/semantic correspondences between two images at the pixel level. Our method is named SAME, which breaks down image registration into three steps: affine transformation, coarse deformation, and deep deformable registration. Using SAM embeddings, we enhance these steps by finding more coherent correspondences, and providing features and a loss function with better semantic guidance. We collect a multi-phase chest computed tomography dataset with 35 annotated organs for each patient and conduct inter-subject registration for quantitative evaluation. Results show that SAME outperforms widely-used traditional registration techniques (Elastix FFD, ANTs SyN) and learning based VoxelMorph method by at least 4.7% and 2.7% in Dice scores for two separate tasks of within-contrast-phase and across-contrast-phase registration, respectively. SAME achieves the comparable performance to the best traditional registration method, DEEDS (from our evaluation), while being orders of magnitude faster (from 45 seconds to 1.2 seconds).