“…Deep learning has demonstrated outstanding achievements in 3D medical image analysis [52,21,39,33], yet is heavily hampered by the expensive cost of the required expert annotations [49,23]. To address this problem, Self-Supervised Learning (SSL) has received significant attention due to its promising ability to learn representations without annotations [10,11,6,28,20], which has become an important label-efficient solution in 3D medical image analysis [69,50,32,2,34,36].…”