Characterization and evaluation of tissue-mimicking gelatin phantoms for use with MRgFUS.
Characterization and evaluation of tissue-mimicking gelatin phantoms for use with MRgFUS.
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DOI：
10.1186/s40349-015-0030-y
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发表时间：
2015
期刊：
影响因子：
--
通讯作者：
Christensen DA
中科院分区：
文献类型：
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作者：
Farrer AI;Odéen H;de Bever J;Coats B;Parker DL;Payne A;Christensen DA
一个能准确代表人体组织特性的组织模拟模型对于安全测试和验证新的成像技术非常重要。为了获得各种所需的人体组织特性，我们制造并测试了几种不同的明胶模型。这些幻影制造起来很简单，并且具有与软组织相同数量级的特性。这对于质量保证验证以及磁共振引导聚焦超声（MRgFUS）治疗技术的验证非常重要。在这项工作中呈现的幻影是由三种不同绽放值（125、175和250）的明胶粉末构成的，每一种都允许幻影的不同机械刚度。为了在软组织范围内达到衰减和声速值，在明胶幻影的配方中，用炼乳代替一半的水。这些声学特性，以及MR (T1和T2*)，力学（密度和杨氏模量）和热性能（热扩散率和比热容），是通过对所有三种类型的独立测量来表征明胶幻影的。还使用MRgFUS和MR测温法评估了模型的热重复性。所有测量值都在文献报道的软组织范围内。在使用低功率（6.6 W）超声，与高功率（高达22.0 W）超声交替进行的加热测试中，三种不同的花影均表现出可重复的温度升高（125开花为10.4±0.3°C， 175开花为10.2±0.3°C，所有6.6 W超声为250开花为10.8±0.2°C），加热持续时间为18.1 s。这些蒸发的牛奶修饰的明胶模型应该作为可靠的，一般的软组织模拟MRgFUS模型。
A tissue-mimicking phantom that accurately represents human-tissue properties is important for safety testing and for validating new imaging techniques. To achieve a variety of desired human-tissue properties, we have fabricated and tested several variations of gelatin phantoms. These phantoms are simple to manufacture and have properties in the same order of magnitude as those of soft tissues. This is important for quality-assurance verification as well as validation of magnetic resonance-guided focused ultrasound (MRgFUS) treatment techniques. The phantoms presented in this work were constructed from gelatin powders with three different bloom values (125, 175, and 250), each one allowing for a different mechanical stiffness of the phantom. Evaporated milk was used to replace half of the water in the recipe for the gelatin phantoms in order to achieve attenuation and speed of sound values in soft tissue ranges. These acoustic properties, along with MR (T1 and T2*), mechanical (density and Young’s modulus), and thermal properties (thermal diffusivity and specific heat capacity), were obtained through independent measurements for all three bloom types to characterize the gelatin phantoms. Thermal repeatability of the phantoms was also assessed using MRgFUS and MR thermometry. All the measured values fell within the literature-reported ranges of soft tissues. In heating tests using low-power (6.6 W) sonications, interleaved with high-power (up to 22.0 W) sonications, each of the three different bloom phantoms demonstrated repeatable temperature increases (10.4 ± 0.3 °C for 125-bloom, 10.2 ± 0.3 °C for 175-bloom, and 10.8 ± 0.2 °C for 250-bloom for all 6.6-W sonications) for heating durations of 18.1 s. These evaporated milk-modified gelatin phantoms should serve as reliable, general soft tissue-mimicking MRgFUS phantoms.