BACKGROUND: Multi-phase CT images are obtained sequentially after
the injection of contrast agents so that there is a large amount of local
deformation between images due to the respiratory and heart motion.
Therefore, a non-rigid registration technique is required in order to
establish the anatomical correspondence between the multi-phase CT images
for liver CAD (computer-aided diagnosis).
OBJECTIVE: In this paper, we propose the automatic detection method of
hepatocellular carcinomas using the non-rigid registration method of
multi-phase CT images.
METHODS: Global movements between multi-phase CT images are aligned by
rigid registration based on normalized mutual information. Local
deformations between multi-phase CT images are modeled by non-rigid
registration based on B-spline deformable model. After the registration of
multi-phase CT images, hepatocellular carcinomas are automatically detected
by analyzing the original and subtraction information of the registered
multi-phase CT images.
RESULTS: We applied our method to twenty five multi-phase CT datasets.
Experimental results showed that the multi-phase CT images were accurately
aligned. All of the hepatocellular carcinomas including small size ones in
our 25 subjects were accurately detected using our method.
CONCLUSION: We conclude that our method is useful for detecting
hepatocellular carcinomas.
