Detection of Hepatic Metastases from Colorectal Cancer: Prospective Evaluation of Gray Scale US Versus SonoVue® Low Mechanical Index Real Time-Enhanced US as Compared with Multidetector-CT or Gd-BOPTA-MRI

Purpose: To compare ultrasound (US), low-mechanical index contrast enhanced US (CEUS) and multidetector-CT (MDCT) for the detection of hepatic metastases from colorectal cancer. Methods and Materials: From January to June 2006, 110 patients (65 males, 45 females; mean age 62 years; range 39 - 78) with suspected hepatic lesions from colorectal cancer were prospectively evaluated with US, CEUS and MDCT by two independent readers. Intraoperative ultrasonography (IOUS, n = 45) or a follow-up up for at least 6 months by using MDCT or Gd-BOPTA-enhanced MRI was considered the gold standard. McNemar test was employed. Results: Reference standards revealed 430 metastases in 110 patients. On a patient-by-patients analysis, CEUS improved US sensitivity from 67.4 - 71.6% to 93.4 - 95.8% (p < 0.05). On a lesion-by-lesion analysis, CEUS improved the sensitivity of US from 60.9 - 64.9% to 85.3 - 92.8% (p < 0.001). The specificity increased from 50 - 60% to 76.7 - 83.3%. No significant differences in sensitivity or specificity between CEUS and MDCT were found. Contrast-enhanced US was significantly more sensitive than baseline US in the detection of metastases smaller than 1 cm (p < 0.001) with an increase in sensitivity from 29.1 - 35% to 63.3 - 76.6% no significant statistical difference was identified when compared with MDCT (sensitivity of 73.3 - 75.8%). Conclusions: CEUS is significantly more accurate than US and highly comparable with MDCT in the detection of liver metastases from colorectal cancer. Therefore, in the evaluation of patients with suspected hepatic metastases from colorectal tumour, US examination must be performed after contrast administration.