Classification of ultrasonographic images of small hepatocellular carcinoma using galactose-based contrast agent: relation between image patterns and histologic features.
OBJECTIVE
The aim of this study was to establish the relation between observed ultrasonographic (US) images produced with a galactose-based contrast agent and histologic characteristics of small hepatocellular carcinomas (HCCs).


METHODS
A total of 64 nodules in 64 patients, 22 well differentiated and 42 moderately differentiated with a histologically proven HCC, smaller than 3.0 cm in diameter and who had undergone hepatectomy were consecutively examined by contrast-enhanced US using a galactose-based contrast agent. Perfusion images were acquired by intermittent high-intensity, harmonic power Doppler sonography using a high pulse-repetition frequency and high-pass filter setting. Perfusion images of the arterial and late phases were classified into several patterns and compared with the histologic findings obtained from resected specimens.


RESULTS
Most of the well- and moderately differentiated resected HCCs showed hyperechoic change during the arterial phase. However, 13 (59%) of the well-differentiated HCCs showed isoechoic change and 27 (64%) of the moderately differentiated HCCs showed hypoechoic change during the late phase. The difference is statistically significant (P < 0.0001). In a comparison of microscopic portal invasion (vp) of HCCs using enhanced US patterns, both vp(-) and vp(+) groups showed a high incidence of the hypervascular pattern during the arterial phase; in contrast, during the late phase 11 (73%) of 15 vp(+) nodules showed hypoechoic change with spotty signals. This difference is statistically significant (P < 0.0001) when compared with a high incidence (52%) of signal defect in the vp(-) group. The existence of well-differentiated components associated with the periphery of moderately differentiated HCCs also correlated closely with patterns during the late phase (P < 0.01).


CONCLUSIONS
Late-phase contrast-enhanced US images of small HCCs with a galactose-based contrast agent are useful for predicting specific histologic characteristics.
Department of Surgery, Otemae Hospital, 1-5-34 Otemae, Osaka, 540-0008, Japan. matsuday@chive.ocn.ne.jp.
Yasuo
Y
Matsuda
Department of Internal Medicine, Otemae Hospital, Osaka, Japan.
Iwao
I
Yabuuchi
Department of Surgery, Otemae Hospital, 1-5-34 Otemae, Osaka, 540-0008, Japan.
Toshikazu
T
Ito
Department of Pathology, Otemae Hospital, Osaka, Japan.
Ryoichi
R
Arima
contrast enhancement; galactose-based contrast agent; hepatocellular carcinoma; ultrasound