  This paper presents a visualization method of intestine (the small and large
intestines) regions and their stenosed parts caused by ileus from CT volumes.
Since it is difficult for non-expert clinicians to find stenosed parts, the
intestine and its stenosed parts should be visualized intuitively. Furthermore,
the intestine regions of ileus cases are quite hard to be segmented. The
proposed method segments intestine regions by 3D FCN (3D U-Net). Intestine
regions are quite difficult to be segmented in ileus cases since the inside the
intestine is filled with fluids. These fluids have similar intensities with
intestinal wall on 3D CT volumes. We segment the intestine regions by using 3D
U-Net trained by a weak annotation approach. Weak-annotation makes possible to
train the 3D U-Net with small manually-traced label images of the intestine.
This avoids us to prepare many annotation labels of the intestine that has long
and winding shape. Each intestine segment is volume-rendered and colored based
on the distance from its endpoint in volume rendering. Stenosed parts (disjoint
points of an intestine segment) can be easily identified on such visualization.
In the experiments, we showed that stenosed parts were intuitively visualized
as endpoints of segmented regions, which are colored by red or blue.
