Detection of Colorectal Cancer Hepatic Metastases with Contrast-Enhanced Ultrasound: Comparison with Conventional B-Mode Ultrasound

The aim of this study was to assess whether contrast-enhanced ultrasound (CE-US) could provide improved diagnostic information in detecting liver metastases from colorectal cancer as compared to B-mode non-enhanced ultrasound (B-US). 32 patients (M/F 23/9, age range 48-82 years, mean 58.2 years) under chemotherapy for colorectal cancer were examined with B-US and CE-US using a second-generation ultrasound contrast agent and a dedicated protocol for contrast detection. The presence of focal liver lesions along with the number, size, pre- and post-contrast sonographic features were recorded digitally. Lesion conspicuity with a three-grade scoring scale was performed on both techniques and contrast intensity measurements were calculated for each focal lesion. CE-US detected 17% more metastases in patient-by-patient and lesion-by-lesion analysis. A statistically significant difference was found between the scoring mean values with regard to conspicuity of the lesions. Accurate characterization of the liver lesions was achievable only with contrast-enhanced technique. A quantitative contrast intensity measurement method confirmed the invariably washing-out vascular pattern in all metastases at sinusoidal-parenchymal liver phase. In conclusion, CE-US is superior to B-US and provides an effective tool in the investigation of colorectal cancer liver metastases.