[Liver metastases of colorectal cancers. Detection and delineation of their extension using imaging].

Imaging is a mandatory step for detection, staging and follow-up of liver metastasis. Although ultrasonography is the best method for the detection of the tumors in patients with a low probability, CT greatly improves sensitivity for detection, and is therefore indicated for patients with a high probability for the diseases, despite its pitfalls like radiation dose, contrast media and cost. More over, since multidetector CT has been available, extended staging (chest, abdomen pelvis and brain when applicable) could be performed in a single session. CT is therefore the gold standard method for evaluation in patients with a detected lesion. No other modality is necessary in case of widespread disease. When the tumor is localized to the liver, or even in case of associated lung metastases, multidisciplinary staff relies on CT to decide which treatment is best applicable: surgery, neoadjuvant therapy followed by surgery or chemotherapy. If surgery is considered, additional imaging tests might be useful like CT arterial portography, which is more often replaced by MRI with liver specific contrast agents, and/or PET-scan. Follow-up of the diseases relies mainly on CT.