Postema Michiel, Bouakaz Ayache, Versluis Michel, de Jong Nico
IEEE Trans Ultrason Ferroelectr Freq Control. 2005 Jun;52(6):1035-41. doi: 10.1109/tuffc.2005.1504026.
We investigated gas release from two hardshelled ultrasound contrast agents by subjecting them to high-mechanical index (MI) ultrasound and simultaneously capturing high-speed photographs. At an insonifying frequency of 1.7 MHz, a larger percentage of contrast bubbles is seen to crack than at 0.5 MHz. Most of the released gas bubbles have equilibrium diameters between 1.25 and 1.75 microm. Their disappearance was observed optically. Free gas bubbles have equilibrium diameters smaller than the bubbles from which they have been released. Coalescence may account for the long dissolution times acoustically observed and published in previous studies. After sonic cracking, the cracked bubbles stay acoustically active.
我们通过对两种硬壳超声造影剂施加高机械指数（MI）超声并同时拍摄高速照片，研究了气体释放情况。在1.7MHz的超声频率下，与0.5MHz时相比，可观察到更大比例的造影剂气泡破裂。大多数释放出的气泡平衡直径在1.25至1.75微米之间。通过光学方法观察到它们的消失。游离气泡的平衡直径小于其释放源气泡的直径。聚并可能是先前研究中通过声学观察到并报道的较长溶解时间的原因。超声破裂后，破裂的气泡仍保持声学活性。
