1. A computer-implemented method for segmenting a three-dimensional medical image, the method comprising: receiving the three-dimensional medical image acquired by an imaging device; selecting a plurality of stacks of adjacent two-dimensional images from the three-dimensional medical image; segmenting, by a processor, each stack of adjacent two-dimensional images using a neural network model; and determining, by the processor, a label map for the three-dimensional medical image by aggregating the segmentation results from the plurality of stacks.