Attenuation coefficient and sound speed in human myometrium and uterine fibroid tumors.

OBJECTIVE

To develop a noninvasive method for treatment of uterine fibroid tumors using high-intensity focused ultrasound. Optimal high-intensity focused ultrasound treatment would be dependent on quantitative information about ultrasonic tissue characteristics.

METHODS

Ultrasonic attenuation and the sound speed of fresh human fibroid tumors and myometrium were measured as a function of frequency (1-3 MHz) by using a pulse transmission technique before and after in vitro high-intensity focused ultrasound treatment (3.5 MHz at an intensity of 2,000 W/cm2).

RESULTS

The ranges of the attenuation coefficients, before and after high-intensity focused ultrasound treatment, were 0.9 to 2.2 and 1.8 to 3.9 dB/cm2, respectively, for fibroid tumors and 0.5 to 1.6 and 1.7 to 3.3 dB/cm2, respectively, for myometrium. Although the sound speed appeared to be independent of frequency (1,611 to 1,616 m/s at 1 to 3 MHz) in both types of tissues, a slight increase of approximately 4 to 14 m/s was observed after high-intensity focused ultrasound treatment.

CONCLUSIONS

The results of this study represent our first reported values of the attenuation coefficient and sound speed in fibroid tumors and myometrium before and after high-intensity focused ultrasound treatment.