  The bottleneck of convolutional neural networks (CNN) for medical imaging is
the number of annotated data required for training. Manual segmentation is
considered to be the "gold-standard". However, medical imaging datasets with
expert manual segmentation are scarce as this step is time-consuming and
expensive. We propose in this work the use of what we refer to as silver
standard masks for data augmentation in deep-learning-based skull-stripping
also known as brain extraction. We generated the silver standard masks using
the consensus algorithm Simultaneous Truth and Performance Level Estimation
(STAPLE). We evaluated CNN models generated by the silver and gold standard
masks. Then, we validated the silver standard masks for CNNs training in one
dataset, and showed its generalization to two other datasets. Our results
indicated that models generated with silver standard masks are comparable to
models generated with gold standard masks and have better generalizability.
Moreover, our results also indicate that silver standard masks could be used to
augment the input dataset at training stage, reducing the need for manual
segmentation at this step.
