Experimental study on temperature rise of acoustic radiation force elastography.
BACKGROUND
Acoustic radiation force (ARF) elastography is potentially useful for imaging the elasticity of human tissue. Because a "push wave" that is used to generate ARF is a long burst wave comparable to that used in regular clinical imaging, detailed investigation of its safety is required.


METHODS
We focus on the transient temperature rise in the far field, where the beam paths are overlapped. Soft tissue mimicking a phantom and bone samples were exposed to a 2-MHz plane wave for 20 s. The temperature rises in the far field were measured using a thermocouple. The temperature rises at 1 ms, the time required for the displacement measurement, were estimated by fitting the experimental results. The results showed that the thermosensitivity of the bone was 36 times higher than that of the phantom, and the use of a repeated push wave may have exceeded the allowable maximum temperature rise, 1°C, on the bone surface.


CONCLUSIONS
In conclusion, the imaging area, including the path of the push wave, should be carefully checked and the time interval for consecutive use should be adjusted to prevent thermal risk on the surface of the bone.
CRL, Hitachi Ltd, 1-280 Higashi-koigakubo, Kokubunji, 185-8601, Japan. marie.tabaru.zx@hitachi.com.
Marie
M
Tabaru
CRL, Hitachi Ltd, 1-280 Higashi-koigakubo, Kokubunji, 185-8601, Japan.
Hideki
H
Yoshikawa
CRL, Hitachi Ltd, 1-280 Higashi-koigakubo, Kokubunji, 185-8601, Japan.
Takashi
T
Azuma
CRL, Hitachi Ltd, 1-280 Higashi-koigakubo, Kokubunji, 185-8601, Japan.
Rei
R
Asami
CRL, Hitachi Ltd, 1-280 Higashi-koigakubo, Kokubunji, 185-8601, Japan.
Kunio
K
Hashiba
Acoustic radiation force; Bone; Elastography; Functional diagnostic; Thermal safety