Role of US in the detection, characterization, and staging of cholangiocarcinoma

Cholangiocarcinoma is a rare tumor with a broad range of pathologic and cli nical manifestations that demonstrates a myriad of imaging findings. Recent experience indicates that a more definitive role is possible for ultrasono graphy (US) in the evaluation of cholangiocarcinoma. Dilatation of the intr ahepatic bile ducts is the most frequently seen US abnormality in patients with ductal cholangiocarcinoma. Klatskin tumors classically manifest as seg mental dilatation and nonunion of the right and left ducts at the porta hep atis. Papillary and nodular ductal cholangiocarcinoma are relatively easy t o see at US: Papillary tumors resemble polypoid intraluminal masses, wherea s nodular cholangiocarcinoma manifests as a discrete smooth mass with assoc iated mural thickening. Infiltrating ductal cholangiocarcinoma at the porta hepatis is the most common subtype but is the most difficult to appreciate at US. Peripheral cholangiocarcinoma may be either nodular or infiltrating at US: The nodular form predominates and appears as a solitary mass with a distinct right lobe predilection, whereas the infiltrative form is rare an d manifests as a diffusely abnormal liver echotexture. In capable hands, mo dem high-resolution US equipment with color Doppler imaging capability is h ighly sensitive in the detection, characterization, and determination of th e potential for resectability of cholangiocarcinoma. Thus, use of US may ob viate more invasive procedures in some patients and help identify those pat ients for whom further investigation would be contributory.