Department of Radiology and Imaging Sciences, University of Utah, Salt Lake City, UT, USA.
Department of Bioengineering, University of Utah, Salt Lake City, UT, USA.
Int J Hyperthermia. 2020;37(1):283-290. doi: 10.1080/02656736.2020.1739345.
To develop and characterize a tissue-mimicking phantom that enables the direct comparison of magnetic resonance (MR) and ultrasound (US) imaging techniques useful for monitoring high-intensity focused ultrasound (HIFU) treatments. With no additions, gelatin phantoms produce little if any scattering required for US imaging. This study characterizes the MR and US image characteristics as a function of psyllium husk concentration, which was added to increase US scattering. Gelatin phantoms were constructed with varying concentrations of psyllium husk. The effects of psyllium husk concentration on US B-mode and MR imaging were evaluated at nine different concentrations. T1, T2, and T2* MR maps were acquired. Acoustic properties (attenuation and speed of sound) were measured at frequencies of 0.6, 1.0, 1.8, and 3.0 MHz using a through-transmission technique. Phantom elastic properties were evaluated for both time and temperature dependence. Ultrasound image echogenicity increased with increasing psyllium husk concentration while quality of gradient-recalled echo MR images decreased with increasing concentration. For all phantoms, the measured speed of sound ranged between 1567-1569 m/s and the attenuation ranged between 0.42-0.44 dB/(cm·MHz). Measured T1 ranged from 974-1051 ms. The T2 and T2* values ranged from 97-108 ms and 48-88 ms, respectively, with both showing a decreasing trend with increased psyllium husk concentration. Phantom stiffness, measured using US shear-wave speed measurements, increased with age and decreased with increasing temperature. The presented dual-use tissue-mimicking phantom is easy to manufacture and can be used to compare and evaluate US-guided and MR-guided HIFU imaging protocols.
为了开发和描述一种组织模拟体，能够直接比较磁共振（MR）和超声（US）成像技术，这些技术可用于监测高强度聚焦超声（HIFU）治疗。在没有添加物的情况下，明胶体模产生的散射对于 US 成像来说很少或没有。本研究通过添加增加 US 散射的车前子壳来描述 MR 和 US 图像特征作为车前子壳浓度的函数。用不同浓度的车前子壳构建明胶体模。在九个不同浓度下评估车前子壳浓度对 US B 模式和 MR 成像的影响。获取 T1、T2 和 T2MR 图谱。使用透射技术在 0.6、1.0、1.8 和 3.0 MHz 的频率下测量声衰减和声速。评估了两种时间和温度依赖性的体模弹性特性。随着车前子壳浓度的增加，超声图像回声强度增加，而梯度回波 MR 图像质量随着浓度的增加而降低。对于所有的体模，测量的声速范围在 1567-1569 m/s 之间，衰减范围在 0.42-0.44 dB/（cm·MHz）之间。测量的 T1 范围在 974-1051 ms 之间。T2 和 T2值分别在 97-108 ms 和 48-88 ms 之间，随着车前子壳浓度的增加均呈下降趋势。使用 US 剪切波速度测量测量的体模硬度随年龄的增加而增加，随温度的升高而降低。所提出的双用途组织模拟体易于制造，可用于比较和评估 US 引导和 MR 引导 HIFU 成像方案。
