Ultrasonic characteristics of the small hepatocellular carcinoma.

Fifty five small hepatocellular carcinoma less than 5 cm in diameter among 41 patients were examined by linear arrayed electronic scanning system with 3.5 MHz transducer. Characteristics of the sonogram were enhanced posterior echoes of the tumor, mosaic pattern of internal echoes, halo and lateral shadows. These findings are appeared in 69%, 64%, 35% and 22% of tumors respectively. Among 45 tumors from 2.1 cm to 5 cm in diameter, these findings are appeared in 81%, 73%, 40% and 24% respectively. Among 10 tumors less than 2 cm in diameter, these characteristics were rare and these minimal hepatocellular carcinomas were demonstrated as a simple low echo area. Fifty tumors in 39 patients were resected. Lobulation of the hepatocellular carcinoma on the cut surface of the resected specimen and mosaic pattern on the sonogram are closely connected with each other. Thin fibrous capsule of the hepatocellular carcinoma corresponded to halo and lateral shadows. Posterior echo enhancement was due to the softness of the hepatocellular carcinoma. By those four characteristics, hepatocellular carcinoma can be differentiated from hemangioma and metastatic liver tumor.