  This paper presents a fully automated atlas-based pancreas segmentation
method from CT volumes utilizing 3D fully convolutional network (FCN)
feature-based pancreas localization. Segmentation of the pancreas is difficult
because it has larger inter-patient spatial variations than other organs.
Previous pancreas segmentation methods failed to deal with such variations. We
propose a fully automated pancreas segmentation method that contains novel
localization and segmentation. Since the pancreas neighbors many other organs,
its position and size are strongly related to the positions of the surrounding
organs. We estimate the position and the size of the pancreas (localized) from
global features by regression forests. As global features, we use intensity
differences and 3D FCN deep learned features, which include automatically
extracted essential features for segmentation. We chose 3D FCN features from a
trained 3D U-Net, which is trained to perform multi-organ segmentation. The
global features include both the pancreas and surrounding organ information.
After localization, a patient-specific probabilistic atlas-based pancreas
segmentation is performed. In evaluation results with 146 CT volumes, we
achieved 60.6% of the Jaccard index and 73.9% of the Dice overlap.
