Influence of cerebrospinal fluid on power absorption during transcranial magnetic resonance-guided focused ultrasound treatment.
Influence of cerebrospinal fluid on power absorption during transcranial magnetic resonance-guided focused ultrasound treatment.
复制标题
脑脊液对经颅磁共振引导聚焦超声治疗过程中功率吸收的影响。
DOI：
10.1002/mp.16427
复制
发表时间：
2023
期刊：
影响因子：
3.8
通讯作者：
Parker,DennisL
中科院分区：
文献类型：
--
作者：
Slominski,Emma;Marchant,Joshua;Judd,Wesley;Alexander,MatthewD;Rolston,JohnD;Odéen,Henrik;Rieke,Viola;Christensen,DouglasA;Parker,DennisL
背景在经颅磁共振引导聚焦超声 (tcMRgFUS) 应用中通过颅骨聚焦超声时，超声束像差校正至关重要。目前的方法通过调整换能器元件相位来补偿颅骨特性（形状、厚度和声学特性）的变化，但没有考虑内部大脑解剖结构的变化。目的我们的目标是研究脑脊液（CSF）和大脑解剖结构对 tcMRgFUS 治疗中波束聚焦的影响。方法使用 20 名先前接受聚焦超声治疗致残性震颤的患者的成像数据进行模拟。混合角谱 (HAS) 方法用于测试脑脊液 (CSF) 和脑解剖结构在确定用于像差校正和光束聚焦的元素相位方面的效果。使用患者治疗过程中的计算机断层扫描 (CT) 和磁共振成像 (MRI) 图像来构建每位患者头部的分段模型。治疗模拟的分段模型由水、皮肤、脂肪、大脑、脑脊液、板层和皮质骨组成。用于治疗模拟的换能器元件相位是使用从所需焦点的时间反转来确定的，生成假设颅内体积中具有均匀大脑的一组相位，以及将CSF声学属性分配给CSF区域的第二组相位。此外，对于三名患者，还发现了单独包括 CSF 声速值与 CSF 衰减值相比的相对效果。结果我们发现，与不考虑 CSF 的相位校正相比，在相位规划期间包括 CSF 声学特性（声速和衰减）可将 20 名患者的焦点处吸收的超声功率密度比增加到 1.06 至 1.29 范围内（平均值为 17% ± 6%）。单独考虑 CSF 声速和 CSF 衰减表明，增加几乎完全是由于包括 CSF 声速；仅考虑 CSF 衰减的影响可以忽略不计。结论基于 HAS 模拟，使用形态逼真的 CSF 和大脑解剖结构确定治疗计划阶段，使超声局灶吸收功率密度增加高达 29%。未来需要开展工作来验证 CSF 模拟。
BackgroundUltrasound beam aberration correction is vital when focusing ultrasound through the skull bone in transcranial magnetic resonance‐guided focused ultrasound (tcMRgFUS) applications. Current methods make transducer element phase adjustments to compensate for the variation in skull properties (shape, thickness, and acoustic properties), but do not account for variations in the internal brain anatomy.PurposeOur objective is to investigate the effect of cerebrospinal fluid (CSF) and brain anatomy on beam focusing in tcMRgFUS treatments.MethodsSimulations were conducted with imaging data from 20 patients previously treated with focused ultrasound for disabling tremor. The Hybrid Angular Spectrum (HAS) method was used to test the effect of including cerebral spinal fluid (CSF) and brain anatomy in determining the element phases used for aberration correction and beam focusing. Computer tomography (CT) and magnetic resonance imaging (MRI) images from patient treatments were used to construct a segmented model of each patient's head. The segmented model for treatment simulation consisted of water, skin, fat, brain, CSF, diploë, and cortical bone. Transducer element phases used for treatment simulation were determined using time reversal from the desired focus, generating a set of phases assuming a homogeneous brain in the intracranial volume, and a second set of phases assigning CSF acoustic properties to regions of CSF. In addition, for three patients, the relative effect of separately including CSF speed of sound values compared to CSF attenuation values was found.ResultsWe found that including CSF acoustic properties (speed of sound and attenuation) during phase planning compared to phase correction without considering CSF increased the absorbed ultrasound power density ratios at the focus over a range of 1.06 to 1.29 (mean of 17% ± 6%) for 20 patients. Separately considering the CSF speed of sound and CSF attenuation showed that the increase was due almost entirely to including the CSF speed of sound; considering only the CSF attenuation had a negligible effect.ConclusionsBased on HAS simulations, treatment planning phase determination using morphologically realistic CSF and brain anatomy yielded an increase of up to 29% in the ultrasound focal absorbed power density. Future work will be required to validate the CSF simulations.