Ultrasound diagnosis of gallbladder carcinoma: categorized criteria for ultrasound cancer screening

Abstract

As ultrasound (US) is a simple and less invasive modality, it is widely used for mass screening. Both gallbladder polyps and thickened wall of the gallbladder are common US findings. The US screening is supposed to be extremely useful for the early detection of gallbladder carcinomas. On the other hand, the accuracy of US is strongly affected by both skill and knowledge of sonographers. US images of gallbladder lesions are classified into three types including pedunculated, broad based and wall-thickened ones. This classification is very important not only to make the differential diagnosis but also to evaluate the depth of invasion, since pedunculated lesions can be diagnosed as early carcinomas. To discriminate gallbladder carcinomas from other lesions, we should evaluate their size, internal echo texture, surface structure, layer structure of the gallbladder wall and findings of Doppler assessment. In addition, distention of the gallbladder and the extrahepatic bile duct, debris and slightly thickened wall of the gallbladder are also useful to detect occult lesions of the extrahepatic biliary tract. As the hypoechoic layer includes propria muscle and fibrous part of subserosal layer, the evaluation of the depth of cancer invasion is difficult. So, we should evaluate their morphological feature, size, internal echo texture and findings of enhanced US to make more precise diagnosis.