Objectives: The purpose of this prospective study was to elucidate the efficacy of using contrast-enhanced ultrasound to characterise focal hepatic lesions appearing non-hypervascular on contrast-enhanced CT in chronic liver diseases.
Methods: The study population included 22 patients with cirrhosis or chronic hepatitis, who between them had 27 focal hepatic lesions smaller than 20 mm (mean 13.9 ± 3.4) that appeared non-hypervascular on contrast-enhanced CT. Contrast-enhanced ultrasound with perflubutane microbubble agent (Sonazoid, 0.0075 ml kg(-1)) was performed prior to ultrasound-guided needle biopsy, and intensity analysis was done for hepatic lesions in the early phase (-60 s) and late phase (600 s post injection).
Results: All seven early-phase hyperenhanced lesions were hepatocellular carcinoma (HCC). 20 lesions iso- or hypoenhanced during the early phase consisted of 11 regenerative nodules (RNs) and 9 HCCs. HCC was more frequent in early-phase hyperenhanced lesions than in iso- or hypoenhanced lesions (p=0.0108). Both late-phase hypoenhanced lesions were HCCs, whereas 25 late-phase isoenhanced lesions consisted of 11 RNs and 14 HCCs. The enhancement patterns of the 11 RNs included isoenhanced appearance in both the early and late phases in 8 lesions, and early-phase hypoenhancement combined with late-phase isoenhancement in the remaining 3. Both of these enhancement patterns (i.e. either iso-iso or hypo-iso) were found in 9 malignant lesions, 9 (75%) of the 12 well-differentiated HCCs.
Conclusion: Hypervascularity on contrast-enhanced ultrasound with Sonazoid strongly suggested HCC regardless of non-hypervascularity on CT, and late-phase hypoenhancement was another possible finding of HCC. However, characterisation of hepatic lesions with other enhancement patterns was difficult using our technique.