Department of Physiology and Biomedical Engineering, Mayo Clinic College of Medicine, Rochester, MN 55905, USA.
Ultrasound Med Biol. 2010 Feb;36(2):343-9. doi: 10.1016/j.ultrasmedbio.2009.10.003.
Vibro-acoustography (VA) is an imaging method that forms a two-dimensional (2-D) image by moving two cofocused ultrasound beams with slightly different frequencies over the object in a C-scan format and recording acoustic emission from the focal region at the difference frequency. This article studies tissue heating due to a VA scan using a concentric confocal transducer. The three-dimensional (3-D) ultrasound intensity field calculated by Field II is used with the bio-heat equation to estimate tissue heating due to ultrasound absorption. Results calculated with thermal conduction and with blood perfusion, with conduction and without perfusion and without conduction and without perfusion are compared. Maximum heating due to ultrasound absorption occurs in the transducer's near-field and maximum temperature rise in soft tissue during a single VA scan is below 0.05 degrees C for all three attenuation coefficients evaluated: 0.3, 0.5 and 0.7 dB/cm/MHz. Transducer self-heating during a single VA scan measured by a thermocouple is less than 0.27 degrees C.
超声声振造影（VA）是一种成像方法，它通过在 C 扫描格式下在物体上移动两个略微不同频率的共焦超声束，并记录来自焦域的差频声发射，从而形成二维（2-D）图像。本文研究了使用同心共焦换能器进行 VA 扫描引起的组织加热。使用 Field II 计算的三维（3-D）超声强度场与生物热方程一起用于估计由于超声吸收引起的组织加热。比较了考虑热传导和血液灌注、仅考虑热传导、不考虑热传导和血液灌注这三种情况下的结果。在近场中，由于超声吸收引起的最大加热发生在换能器中，在单个 VA 扫描过程中，在三种评估的衰减系数（0.3、0.5 和 0.7 dB/cm/MHz）下，软组织中的最大温升均低于 0.05 摄氏度。通过热电偶测量的单个 VA 扫描期间的换能器自加热小于 0.27 摄氏度。
