Objective: To investigate the diagnostic value of contrast-enhanced ultrasound (CEUS) enhancement patterns of hepatocellular carcinoma (HCC) smaller than 2 cm.
Methods: From 392 cases with focal liver lesions undergoing CEUS with SonoVue and Contrast Tuned Imaging (CnTI) technique, thirty six cirrhotic patients with thirty eight HCCs with histopathological diagnosis were retrospectively analyzed in this study. Surgery or needle biopsy was performed within fifteen days after CEUS. Twenty two tumors were finally diagnosed as moderately differentiated HCC, twelve as well differentiated HCC, and four as clear cell carcinomas using Edmondson Grade system. The enhancement patterns of different histopathological HCCs were analyzed.
Results: Before CEUS, only 16 lesions (42.1%) were diagnosed as malignant or possibly malignant. After CEUS, 38 HCCs were enhanced in different degrees following contrast administration,of which, all the 22 moderately differentiated HCCs presented typical "fast-in and fast-out" pattern with fast enhancement in arterial phase and then a quick wash-out in the parenchymal phase. Nine (75.0%) of the 12 well differentiated HCCs presented "fast-in and slow-out" pattern. One of the 4 clear cell carcinomas presented "fast-in and fast-out", one presented "fast-in and slow-out" and the other 2 presented "slightly slow-in and slow-out" pattern. According to the enhancement patterns, 76.3% (29 tumors) were considered as malignant, while 18.4% (7 tumors) as possibly malignant, only 5.3% (2 tumors smaller than 1.5 cm) could not be diagnosed by CEUS.
Conclusion: The identification of different enhancement patterns of various histological types of small HCCs could improve the diagnostic ability of ultrasound in cirrhotic liver. CEUS might be also helpful in detecting small HCCs. Thus CEUS could be a complementary method of enhanced CT and other imaging methods in early diagnosis of HCCs.