Optimal threshold for hepatic blood vessels based on structural analysis and cancer detection

Recently, high-resolution multislice CT images have been used in the diagnosis of hepatic cancer. In the conventional method of detecting hepatic cancer on the basis of three-dimensional images, it is difficult to detect cancers with a three-dimensional structure. This paper proposes a method of detection of liver cancer on the basis of three-dimensional hepatic blood vessel regions which are extracted by threshold processing. First, the liver entrance is located by tracing the blood vessels from the abdominal aorta. In order to detect the cancer, the hepatic vessel region must be extracted accurately. For this purpose, a method is proposed in which a temporary threshold is determined near the liver entrance, and the structure of the blood vessel is analyzed by adjusting the threshold from the temporary value in order to determine the optimal threshold. In the structural analysis, thinning is applied to the blood vessel and a directed graph is constructed. When the threshold is too low, a loop is produced due to overextraction of the blood vessel region. The optimal threshold is determined on the basis of this property. The cancer detection procedure is composed of two stages. Primary detection finds cancers contained in the extracted blood vessel region, and secondary detection finds cancers from the region that is not extracted. In experiments on seven cases, ten cancers were detected with three false positives. © 2005 Wiley Periodicals, Inc. Syst Comp Jpn, 36(7): 1–12, 2005; Published online in Wiley InterScience (www.interscience.wiley. com). DOI 10.1002/scj.20329