Automatic segmentation of liver region based on extracted blood vessels

With the rapid progress of CT (Computed Tomography) scanners, four-phase CT images with resolutions as high as 1 mm have started to be used for diagnosing liver diseases. The first-, second-, third-, and fourth-phase CT images correspond to before dye injection, the early stage, the full stage, and the wash-out stage of the injected dye. Such CT data offer useful information for diagnosing hepatic cancer. This paper describes an automatic method for segmenting the liver region using the blood vessel stream in the firstand third-phase CTs by tracing the portal vein and then the hepatic vein. First, the tracing of the veins is carried out by performing a 3D labeling operation in the region extracted with a threshold that separates blood vessels from liver soft tissue. The adjoining stomach and spleen regions are separated by applying erosion and dilation, which are 3D morphological operations. Then, an operation for determining the accurate liver region is carried out to derive an approximate liver region, by enlarging the liver blood vessel region by morphological dilation and then extracting the liver region with an optimal threshold. This method was applied to eight CT data. The resulting regions agree well with the manually detected regions. © 2004 Wiley Periodicals, Inc. Syst Comp Jpn, 35(5): 1–10, 2004; Published online in Wiley InterScience (www.interscience. wiley.com). DOI 10.1002/scj.10592