Contrast-enhanced sonography in the diagnosis of small hepatocellular carcinoma < or =2 cm.

Purpose: To evaluate the usefulness of contrast-enhanced sonography (CEUS) in the diagnosis of small hepatocellular carcinoma (HCC) measuring < or =2 cm in diameter.

Methods: We identified 104 focal liver lesions measuring < or =2 cm in 104 consecutive patients who were enrolled for baseline sonography (BUS) and CEUS examination (49 HCCs, 55 non-HCCs). A real-time, contrast-specific mode of contrast pulse sequencing and a sulphur hexafluoride-filled microbubble contrast agent were used for CEUS. The diagnostic performances of BUS and CEUS in differentiating focal liver lesions (HCC or non-HCC) were analyzed and compared.

Results: On CEUS, 43 (87.8%) of the 49 HCC lesions were hyperenhanced, 5 (10.2%) were isoenhanced, and 1 (2%) was hypoenhanced during the arterial phase when compared with adjacent liver tissue. Thirty-nine (79.6%) HCCs exhibited washout from the portal phase to the late phase. The sensitivity, specificity, positive predictive value, negative predictive value, and overall accuracy before and after contrast agent administration were 28.6% (14/49) versus 79.6% (39/49) (p < 0.001), 94.5% (52/55) versus 92.7% (51/55) (p > 0.05), 82.4% (14/17) versus 90.7% (39/43) (p > 0.05), 59.8% (52/87) versus 90.7% (39/43) (p < 0.01), and 63.5% (66/104) versus 86.5% (90/104) (p < 0.001), respectively. No significant difference in diagnostic performance of CEUS was found between lesions measuring < or =1.5 cm and those 1.6-2 cm and between lesions located at a depth of < or =6 cm from the skin and those located deeper.

Conclusions: CEUS significantly improved the diagnostic performance in characterization of small HCCs < or =2 cm compared with BUS.