Department of Obstetrics and Gynecology, Okayama University Medical School
During the past 9 years, we have carried out the ultrasound examinations of 274 ovarian masses including 60 malignant cases. From the histological review, the solid part in the ovarian tumor is considered to be most important for evaluating the malignant tendency. Solid part is observed on the echogram in 96.7% of malignant cases, in 93.3% of borderline cases and in 50.5% of benign cases. These solid ehcoes are compared between three histological groups, concerning to three parameters, namely irregularity of outline, homogenuity of internal echoes and the level of echo amplitude. In malignant group, irregular shaped, heterogenous and high amplitude solid parts are more commonly observed than in benign group. And in the cases with the diameter of the solid part below 5 cm, there are statistically significant differences in two parameters, that is irregularity of outline and echo amplitude. We have also introduced two methods of tissue characterization using the newly developed ultrasonic diagnostic equipment. The first one is the quantitative analysis of ultrasound intensity level. The second one is the observation of changes of ultrasound frequency. These two new methods may promote our discriminatability of malignancy in the near future.