  Skull stripping for brain MR images is a basic segmentation task. Although
many methods have been proposed, most of them focused mainly on the adult MR
images. Skull stripping for infant MR images is more challenging due to the
small size and dynamic intensity changes of brain tissues during the early
ages. In this paper, we propose a novel CNN based framework to robustly extract
brain region from infant MR image without any human assistance. Specifically,
we propose a simplified but more robust flattened residual network architecture
(FRnet). We also introduce a new boundary loss function to highlight ambiguous
and low contrast regions between brain and non-brain regions. To make the whole
framework more robust to MR images with different imaging quality, we further
introduce an artifact simulator for data augmentation. We have trained and
tested our proposed framework on a large dataset (N=343), covering newborns to
48-month-olds, and obtained performance better than the state-of-the-art
methods in all age groups.
