“…Using methodologies from "classical" iterative registration algorithms, learningbased methods have been proposed. Learning-based methods have used different architectures, such as convolutional neural networks [1][2] and vision transformers [3], different training strategies, such as generative adversarial networks [4,5], supervised [1,4], unsupervised [2,[6][7][8] or reinforcement learning [9][10][11], or different transformation constraints, based on parametric splines [6], diffeomorphism [12] and biomechanics [13]. Semi-supervised learning [14], few-shotand meta-learning [15][16], unsupervised contrastive learning [17], inference-time augmentation [16,18], and amortized hyperparameter learning [19] methodologies have also been used to improve data efficiency and generalizability.…”