University of Cyprus, Nicosia, Cyprus.
Ultrasound Med Biol. 2010 Feb;36(2):306-12. doi: 10.1016/j.ultrasmedbio.2009.09.011. Epub 2010 Jan 4.
The aim of this study was to measure the relationship of image intensity with contrast agent concentration. In vitro experiments were performed with a flow phantom and a sulphur hexafluoride filled microbubble contrast agent (SonoVue) at different concentrations (0.004 per thousand to 4 per thousand) covering the range commonly encountered in clinical practice. The concentration of microbubbles in the contrast agent solutions was confirmed optically. Images were collected with a diagnostic ultrasound system (iU22, Phillips Medical Systems, Bothell, WA, USA) and with a nonlinear imaging technique (power modulation) at low mechanical index (MI=0.05) to avoid bubble destruction. The mean intensity within a region of interest was measured to produce time-intensity curves from linearized (absolute scale) data. The relationship of linearized image intensity to contrast agent concentration was found to be linear up to 1 per thousand and reached a plateau at approximately 2 per thousand. To operate in the linear range of the intensity-concentration relationship the contrast agent dose should be adjusted to avoid those high values in vivo and the highest dynamic range of the ultrasound system should be used to avoid unnecessary signal saturation.
本研究旨在测量图像强度与对比剂浓度的关系。在体外实验中，使用流动体模和六氟化硫微泡对比剂（声诺维）进行实验，浓度范围涵盖了临床实践中常见的浓度（千分之 0.004 至 4）。通过光学方法确认对比剂溶液中微泡的浓度。使用诊断超声系统（iU22，飞利浦医疗系统，华盛顿州 Bothell）和非线性成像技术（功率调制），在低机械指数（MI=0.05）下采集图像，以避免气泡破裂。在感兴趣区域内测量平均强度，从线性化（绝对标度）数据生成时间-强度曲线。结果发现，线性化图像强度与对比剂浓度的关系呈线性，直至 1 千分之，在约 2 千分之达到平台。为了在强度-浓度关系的线性范围内工作，应调整对比剂剂量以避免体内出现高值，并且应使用超声系统的最高动态范围以避免不必要的信号饱和。
