Chan Hsin, Chang Hsin-Yun, Lin Win-Li, Chen Gin-Shin
Institute of Biomedical Engineering, National Taiwan University, Taipei 100, Taiwan.
Institute of Biomedical Engineering and Nanomedicine, National Health Research Institutes, Miaoli 35053, Taiwan.
Pharmaceutics. 2022 Sep 22;14(10):2012. doi: 10.3390/pharmaceutics14102012.
Mild hyperthermia can locally enhance permeability of the blood-tumor barrier in brain tumors, improving delivery of antitumor nanodrugs. However, a clinical transcranial focused ultrasound (FUS) system does not provide this modality yet. The study aimed at the development of the transcranial FUS technique dedicated for large-volume mild hyperthermia in the brain. Acoustic pressure, multiple-foci, temperature and thermal dose induced by FUS were simulated in the brain through the skull. A 1-MHz, 114-element, spherical helmet transducer was fabricated to verify large-volume hyperthermia in the phantom. The simulated results showed that two foci were simultaneously formed at (2, 0, 0) and (-2, 0, 0) and at (0, 2, 0) and (0, -2, 0), using the phases of focusing pattern 1 and the phases of focusing pattern 2, respectively. Switching two focusing patterns at 5 Hz produced a hyperthermic zone with an ellipsoid of 7 mm × 6 mm × 11 mm in the brain and the temperature was 41-45 °C in the ellipsoid as the maximum intensity was 150 W/cm and sonication time was 3 min. The phased array driven by switching two mode phases generated a 41 °C-contour region of 10 ± 1 mm × 8 ± 2 mm × 13 ± 2 mm in the phantom after 3-min sonication. Therefore, we have demonstrated our developed FUS technique for large-volume mild hyperthermia.
轻度体温升高可局部增强脑肿瘤中血脑屏障的通透性，改善抗肿瘤纳米药物的递送。然而，临床经颅聚焦超声（FUS）系统尚未提供这种方式。该研究旨在开发专用于大脑大容量轻度体温升高的经颅FUS技术。通过颅骨对FUS在大脑中诱导产生的声压、多焦点、温度和热剂量进行了模拟。制作了一个1MHz、114阵元的球形头盔换能器，以在体模中验证大容量热疗效果。模拟结果表明，分别使用聚焦模式1的相位和聚焦模式2的相位，在（2, 0, 0）和（-2, 0, 0）以及（0, 2, 0）和（0, -2, 0）处同时形成了两个焦点。以5Hz的频率切换两种聚焦模式，在大脑中产生了一个尺寸为7mm×6mm×11mm的椭球形热区，当最大强度为150W/cm²且超声处理时间为3分钟时，该椭球体内的温度为41 - 45°C。在超声处理3分钟后，由切换两种模式相位驱动的相控阵在体模中产生了一个尺寸为10±1mm×8±2mm×13±2mm、温度为41°C的轮廓区域。因此，我们展示了我们开发的用于大容量轻度体温升高的FUS技术。
