Li Faqi, Gong Xiaobo, Xu Jie, Wang Zhibiao
Department of Biomedical Engineering, Chongqing Key Laboratory of Ultrasound Engineering in Medicine, Chongqing Medical University, Chongqing 400016, China.
Sheng Wu Yi Xue Gong Cheng Xue Za Zhi. 2009 Oct;26(5):936-40.
The dot-shaped coagulative necrosis induced by a single HIFU exposure can be considered as a basis for HIFU ablation of tumour. For complete ablation of tumour mass with HIFU, the crucial point is to create a complete line-shaped lesion by way of dot-shaped coagulative necrosis. At the beginning of this in vitro study, a dot-shaped coagulative necrosis with focal width (W) 3mm was induced in ox liver by HIFU (acoustical intensity (I(SAL)) 6500W/cm2; exposure time 1s) at focal depth 2cm. And then, we investigated the formation of line-shaped lesion under two different modes, namely, multiple dot-shaped coagulative necrosis overlapping and linear scanning. Under multiple dot-shaped coagulative necrosis overlapping mode, line-shaped lesion is formed by the combination of multiple dot-shaped coagulative necroses. With acoustical intensity (I(SAL)) 6500W/cm2 and exposure time is for each single exposure, different intervals (D) between two successive single exposures (1mm, 2mm, 2.5mm, 3mm, 4.5mm, 5mm) were applied to obtain line-shaped lesion. Under linear scanning mode, the intensity (I(SAL)) 6500W/cm2 and cycle 1 were set constant, and various scanning speeds (V) 1mm/s, 3mm/s, 6mm/s, 7mm/s were adopted to create line-shaped lesion. After the procedures, the tissues were dissected to obtain the maximum section of the line-shaped lesion. The results were as follows: under multiple dot-shaped coagulative necrosis overlapping mode, a complete line-shaped lesion could be formed when D < or = W, while an incomplete line-shape lesion was formed when D > W; under linear scanning mode, a complete line-shaped lesion could be formed using the scanning speed 3mm/s and cycle 1. The results validate that the complete line-shaped lesion can be created with the dosage and exposure parameters optimized for the dimension of a single dot-shaped coagulative necrosis as shown in this study.
单次高强度聚焦超声（HIFU）照射所诱导的点状凝固性坏死可被视为HIFU消融肿瘤的基础。对于用HIFU完全消融肿瘤块而言，关键在于通过点状凝固性坏死形成完整的线形病灶。在这项体外研究开始时，在聚焦深度2cm处，用HIFU（声强（I(SAL)）6500W/cm²；照射时间1s）在牛肝中诱导出焦点宽度（W）为3mm的点状凝固性坏死。然后，我们研究了在两种不同模式下，即多个点状凝固性坏死重叠和线性扫描，线形病灶的形成情况。在多个点状凝固性坏死重叠模式下，线形病灶由多个点状凝固性坏死组合而成。声强（I(SAL)）为6500W/cm²且每次单次照射的照射时间固定，对连续两次单次照射设置不同的间隔（D）（1mm、2mm、2.5mm、3mm、4.5mm、5mm）以获得线形病灶。在直线扫描模式下，将声强（I(SAL)）6,500W/cm²和周期1设置为恒定值，并采用不同的扫描速度（V）1mm/s、3mm/s、6mm/s、7mm/s来形成线形病灶。操作完成后，解剖组织以获得线形病灶的最大截面。结果如下：在多个点状凝固性坏死重叠模式下，当D≤W时可形成完整的线形病灶，而当D＞W时形成不完整的线形病灶；在直线扫描模式下，使用扫描速度3mm/s和周期1可形成完整的线形病灶。结果证实，如本研究所示，利用针对单个点状凝固性坏死尺寸优化的剂量和照射参数可形成完整的线形病灶。
