Abstract

Background

High-intensity focused ultrasound (HIFU) serves as a noninvasive stereotactic system for the ablation of brain metastases; however, treatments are limited to simple geometries and energy delivery is limited by the high acoustic attenuation of the calvarium. Minimally-invasive magnetic resonance-guided robotically-assisted (MRgRA) needle-based therapeutic ultrasound (NBTU) using multislice volumetric 2-D magnetic resonance thermal imaging (MRTI) overcomes these limitations and has potential to produce less collateral tissue damage than current methods.

Objective

To correlate multislice volumetric 2-D MRTI volumes with histologically confirmed regions of tissue damage in MRgRA NBTU.

Methods

Seven swine underwent a total of 8 frontal MRgRA NBTU lesions. MRTI ablation volumes were compared to histologic tissue damage on brain sections stained with 2,3,5-triphenyltetrazolium chloride (TTC). Bland-Altman analyses and correlation trends were used to compare MRTI and TTC ablation volumes.

Results

Data from the initial and third swine’s ablations were excluded due to sub-optimal tissue staining. For the remaining ablations (n = 6), the limits of agreement between the MRTI and histologic volumes ranged from −0.149 cm³ to 0.252 cm³ with a mean difference of 0.052 ± 0.042 cm³ (11.1%). There was a high correlation between the MRTI and histology volumes (r² = 0.831) with a strong linear relationship (r = 0.868).

Conclusion

We used a volumetric MRTI technique to accurately track thermal changes during MRgRA NBTU in preparation for human trials. Improved volumetric coverage with MRTI enhanced our delivery of therapy and has far-reaching implications for focused ultrasound in the broader clinical setting.

中文翻译：

---

用多层体积二维磁共振热成像预测消融区域

摘要

背景

高强度聚焦超声 (HIFU) 作为一种无创立体定向系统用于脑转移瘤的消融；然而，治疗仅限于简单的几何形状，能量传递受到颅骨高声衰减的限制。使用多层体积二维磁共振热成像 (MRTI) 的微创磁共振引导机器人辅助 (MRgRA) 基于针的治疗性超声 (NBTU) 克服了这些限制，并且有可能产生比当前方法更少的附带组织损伤。

客观的

将多层体积二维 MRTI 体积与 MRgRA NBTU 中组织学证实的组织损伤区域相关联。

方法

七头猪经历了总共 8 次正面 MRgRA NBTU 损伤。将 MRTI 消融体积与用 2,3,5-三苯基四唑氯化物 (TTC) 染色的脑切片上的组织学组织损伤进行比较。Bland-Altman 分析和相关趋势用于比较 MRTI 和 TTC 消融量。

结果

由于次优组织染色，排除了最初和第三次猪消融的数据。对于剩余的消融 ( n  = 6)，MRTI 和组织学体积之间的一致性范围为 -0.149 cm ³至 0.252 cm ³，平均差异为 0.052 ± 0.042 cm ³ (11.1%)。MRTI 和组织学体积之间存在高度相关性 ( r ² = 0.831)，具有强线性关系 ( r  = 0.868)。

结论

我们使用体积 MRTI 技术准确跟踪 MRgRA NBTU 期间的热变化，为人体试验做准备。MRTI 改善的体积覆盖增强了我们的治疗效果，并对更广泛的临床环境中的聚焦超声产生了深远的影响。