Colorectal Cancer is most common in western countries. In 2007 in Austria 4462 new colorectal cancers were diagnosed. The most common place of metastasis is the liver. Approximately 15% of patients have metastasis at time of diagnosis of primary tumor and further 50% will develop metastases in the further course of the disease.However only 10-25% of patients are candidates for liver resection. New chemotherapeutics, new targeted therapies with monoclonal antibodies and better surgical techniques improved response rates, resection rates and overall survival. Owing to improved response rates metastases in the liver partially respectively completely disappeared, so that these lesions are not more visible in apparative diagnostic like CT-scan and MRI.