Pernot Matlieu, Tanter Mickael, Bercoff Jeremy, Waters Kendall R, Fink Mathias
Laboratoire Ondes et Acoustique, ESPCI, Université Paris VII, U.M.R. C.N.R.S. 7587, 10 rue Vauquelin, 75005 Paris, France.
IEEE Trans Ultrason Ferroelectr Freq Control. 2004 May;51(5):606-15.
The feasibility of temperature estimation during high-intensity focused ultrasound therapy using pulse-echo diagnostic ultrasound data has been demonstrated. This method is based upon the measurement of thermally-induced modifications in backscattered RF echoes due to thermal expansion and local changes in the speed of sound. It has been shown that strong ripple artifacts due to the thermo-acoustic lens effect severely corrupt the temperature estimates behind the heated region. We propose here a new imaging technique that improves the temperature estimation behind the heated region and reduces the variance of the temperature estimates in the entire image. We replaced the conventional beamforming on transmit with multiple steered plane wave insonifications using several subapertures. A two-dimensional temperature map is estimated from axial displacement maps between consecutive RF images of identically steered plane wave insonifications. Temperature estimation is then improved by averaging the two-dimensional maps from the multiple steered plane wave insonifications. Experiments were conducted in a tissue-mimicking gelatin-based phantom and in fresh bovine liver.
利用脉冲回波诊断超声数据在高强度聚焦超声治疗期间进行温度估计的可行性已得到证实。该方法基于对因热膨胀和声速局部变化而导致的反向散射射频回波中的热致变化的测量。结果表明，由于热声透镜效应产生的强烈波纹伪像严重破坏了加热区域后方的温度估计。我们在此提出一种新的成像技术，该技术可改善加热区域后方的温度估计，并降低整个图像中温度估计的方差。我们用使用几个子孔径的多个可控平面波声照射取代了传统的发射波束形成。从相同可控平面波声照射的连续射频图像之间的轴向位移图估计二维温度图。然后通过对多个可控平面波声照射的二维图进行平均来改善温度估计。实验在基于组织模拟明胶的体模和新鲜牛肝中进行。
