Current status in imaging of colorectal liver metastases

Colorectal cancer is a common malignancy that often metastasizes to the liver. Evaluation of the liver for metastases is important for staging and prognosis. Resection of limited hepatic metastases can result in prolonged survival. Imaging is vital to select appropriate patients to avoid unnecessary surgery. A variety of modern imaging tools can be used to detect and characterise hepatic lesions. These include contrast enhanced helical computed tomography (CT), CT arterial portography, magnetic resonance imaging (MRI) and intraoperative ultrasound (IOUS). Each has their advantages as well as disadvantages. Besides accuracy, availability, cost and presence of expertise determine the optimal modality or combination of modalities to use. The appearance of metastases on imaging can be correlated with histopathological abnormalities. Though metastases can often be distinguished from benign lesions, their appearances are by no means pathognomonic. Follow-up imaging for interval change and for assessment of response is often required.