Abstract: Systems and methods for segmenting 3D images are provided. In an embodiment, the system includes a neural network having a low-resolution module trained to infer a complete low-resolution segmentation from an input low-resolution 3D image and to generate corresponding low-resolution feature maps; and a high-resolution module trained to infer a complete high-resolution segmentation from an input high-resolution 3D image and the feature maps from the low-resolution module. Methods for training the neural network and measuring a volume of an object using the 3D segmentations are also described.