The committee considered contrast-enhanced ultrasound with SonoVue for investigating potential liver metastases in people with colorectal cancer and noted that NICE's guideline on colorectal cancer recommends the use of CT in staging of colorectal cancer, which includes the identification of liver metastases. Therefore, the use of contrast-enhanced ultrasound with SonoVue would only be applicable in a small number of cases (for example, if contrast-enhanced CT is not clinically appropriate, is not accessible, is not acceptable to the person, or is inconclusive). The committee considered the economic analysis performed by the external assessment group and noted that the base-case analysis showed that contrast-enhanced CT was cost effective; however, contrast-enhanced ultrasound with SonoVue generated equal benefits and was only £1 more costly. The committee considered a range of additional analyses performed by the external assessment group. In the base-case analysis it was assumed that people who were incorrectly diagnosed with liver metastases (false-positives) would receive biopsy and the incorrect diagnosis would be discovered before treatment. If this is not assumed, then people could receive unnecessary treatment and the lower specificity of contrast-enhanced ultrasound resulted in increased costs and reduced effectiveness. Contrast-enhanced MRI with gadolinium dominates all other tests under this assumption. The committee discussed that although the diagnostic pathway varies depending on the clinical scenario, most people would be unlikely to receive unnecessary treatment. This is because the multidisciplinary team would probably seek assurance (from further imaging or a watch and wait strategy) before starting treatment. Direct biopsies of liver metastases may make the metastases inoperable, so they are unlikely to be performed. Therefore, the committee recommended the use of contrast-enhanced ultrasound with SonoVue for investigating potential liver metastases from colorectal cancer, when contrast-enhanced CT is not clinically appropriate, is not accessible or is not acceptable to the person.