Aim: To evaluate the role of low mechanical index (MI) contrast-enhanced sonography (CEUS) for the characterization of small hepatocellular carcinomas (HCC) in cirrhotic patients by comparing the results to ultrafast dynamic gadolinium-enhanced magnetic resonance imaging (MRI) studies.
Materials and methods: Between September 2003 and June 2004, 73 patients (49 male and 24 female; mean age, 63 years; age range, 40-84 years) with a single liver nodule (< or =30 mm) were selected to enter into the study. CEUS and MRI studies were performed in all patients on consecutive days. All lesions were histologically confirmed after both imaging studies. CEUS was performed at low MI after i.v. administration of the contrast agent SonoVue. The enhancement pattern related to tumor hypervascularity was analyzed. The Chi-square test was used for statistical analysis.
Results: HCCs < or =10 mm (11 cases): On CEUS, 3/11 HCCs were hypervascular, while 8/11 were not visible (sensitivity, 27.3%; specificity, 100%; positive predictive value, 100%; negative predictive value, 55.6%). MRI studies showed a typical pattern in eight HCCs (sensitivity, 72.7%; specificity, 90.0%; positive predictive value, 88.9%; negative predictive value, 75.0%). HCCs 11-30 mm (37 cases): On CEUS, 34/37 (91.9%) HCCs were hypervascular, 2/37 avascular, and 1/37 not visible (sensitivity, 91.9%; specificity, 93.3%; positive predictive value, 97.1%; negative predictive value, 82.4%). MRI studies showed a typical pattern in 35/37 HCCs (sensitivity, 94.6%; specificity, 86.7%; positive predictive value, 94.6%; negative predictive value, 86.7%). The overall concordance between CEUS and MRI results was 75.0%.
Conclusion: CEUS is a promising technique for the characterization of small HCCs in cirrhotic patients. It could be complementary to conventional sonography in evaluating focal liver lesions larger than 10 mm.