PDF(Pubmed)
Abstract：
OBJECTIVE: The study aims to provide insights on the practicality of using single-element transducers for transcranial Focused Ultrasound (tFUS) thermal applications.
METHODS: FUS sonications were performed through skull phantoms embedding agar-based tissue mimicking gels using a 1 MHz single-element spherically focused transducer. The skull phantoms were 3D printed with Acrylonitrile Butadiene Styrene (ABS) and Resin thermoplastics having the exact skull bone geometry of a healthy volunteer. The temperature field distribution during and after heating was monitored in a 3 T Magnetic Resonance Imaging (MRI) scanner using MR thermometry. The effect of the skull\'s thickness on intracranial heating was investigated.
RESULTS: A single FUS sonication at focal acoustic intensities close to 1580 W/cm2 for 60 s in free field heated up the agar phantom to ablative temperatures reaching about 90 °C (baseline of 37 °C). The ABS skull strongly blocked the ultrasonic waves, resulting in zero temperature increase within the phantom. Considerable heating was achieved through the Resin skull, but it remained at hyperthermia levels. Conversely, tFUS through a 1 mm Resin skull showed enhanced ultrasonic penetration and heating, with the focal temperature reaching 70 °C.
CONCLUSIONS: The ABS skull demonstrated poorer performance in terms of tFUS compared to the Resin skull owing to its higher ultrasonic attenuation and porosity. The thin Resin phantom of 1 mm thickness provided an efficient acoustic window for delivering tFUS and heating up deep phantom areas. The results of such studies could be particularly useful for accelerating the establishment of a wider range of tFUS applications.
METHODS: FUS sonications were performed through skull phantoms embedding agar-based tissue mimicking gels using a 1 MHz single-element spherically focused transducer. The skull phantoms were 3D printed with Acrylonitrile Butadiene Styrene (ABS) and Resin thermoplastics having the exact skull bone geometry of a healthy volunteer. The temperature field distribution during and after heating was monitored in a 3 T Magnetic Resonance Imaging (MRI) scanner using MR thermometry. The effect of the skull\'s thickness on intracranial heating was investigated.
RESULTS: A single FUS sonication at focal acoustic intensities close to 1580 W/cm2 for 60 s in free field heated up the agar phantom to ablative temperatures reaching about 90 °C (baseline of 37 °C). The ABS skull strongly blocked the ultrasonic waves, resulting in zero temperature increase within the phantom. Considerable heating was achieved through the Resin skull, but it remained at hyperthermia levels. Conversely, tFUS through a 1 mm Resin skull showed enhanced ultrasonic penetration and heating, with the focal temperature reaching 70 °C.
CONCLUSIONS: The ABS skull demonstrated poorer performance in terms of tFUS compared to the Resin skull owing to its higher ultrasonic attenuation and porosity. The thin Resin phantom of 1 mm thickness provided an efficient acoustic window for delivering tFUS and heating up deep phantom areas. The results of such studies could be particularly useful for accelerating the establishment of a wider range of tFUS applications.
摘要：
目的：该研究旨在就使用单元件换能器进行经颅聚焦超声（tFUS）热应用的实用性提供见解。
方法：使用1MHz单元素球形聚焦换能器，通过嵌入基于琼脂的组织模仿凝胶的颅骨体模进行FUS超声处理。头骨模型是用丙烯腈丁二烯苯乙烯（ABS）和树脂热塑性塑料3D打印的，具有健康志愿者的确切头骨几何形状。使用MR测温法在3T磁共振成像（MRI）扫描仪中监测加热期间和加热后的温度场分布。研究了颅骨厚度对颅内加热的影响。
结果:在接近1580W/cm2的焦点声强度下在自由场中进行60秒的单FUS超声处理,将琼脂体模加热至达到约90°C(基线为37°C)的消融温度。ABS头骨强烈阻挡超声波，导致体模内零温度增加。通过树脂头骨实现了相当大的加热，但它仍然处于高温水平。相反，通过1毫米树脂头骨的tFUS显示增强的超声波穿透和加热，焦点温度达到70℃。
结论：由于其更高的超声衰减和孔隙率，与树脂颅骨相比，ABS颅骨在tFUS方面表现较差。厚度为1毫米的薄树脂体模提供了一个有效的声学窗口，用于提供tFUS和加热深层体模区域。这些研究的结果对于加速建立更广泛的tFUS应用特别有用。
方法：使用1MHz单元素球形聚焦换能器，通过嵌入基于琼脂的组织模仿凝胶的颅骨体模进行FUS超声处理。头骨模型是用丙烯腈丁二烯苯乙烯（ABS）和树脂热塑性塑料3D打印的，具有健康志愿者的确切头骨几何形状。使用MR测温法在3T磁共振成像（MRI）扫描仪中监测加热期间和加热后的温度场分布。研究了颅骨厚度对颅内加热的影响。
结果:在接近1580W/cm2的焦点声强度下在自由场中进行60秒的单FUS超声处理,将琼脂体模加热至达到约90°C(基线为37°C)的消融温度。ABS头骨强烈阻挡超声波，导致体模内零温度增加。通过树脂头骨实现了相当大的加热，但它仍然处于高温水平。相反，通过1毫米树脂头骨的tFUS显示增强的超声波穿透和加热，焦点温度达到70℃。
结论：由于其更高的超声衰减和孔隙率，与树脂颅骨相比，ABS颅骨在tFUS方面表现较差。厚度为1毫米的薄树脂体模提供了一个有效的声学窗口，用于提供tFUS和加热深层体模区域。这些研究的结果对于加速建立更广泛的tFUS应用特别有用。
