Dual-frequency focused ultrasound mm-level imaging and temperature trend monitor-ing system and Its Validation in a Cerebellar Target

4.1 temperature monitoring During the experiments, the focused transducer and receiving hydrophone were fixed within the tank coordinate system, whereas the animal was secured on a mechanical-arm support. The mechanical arm drove the animal to move relative to the acoustic system during scanning. A dual-frequency low-power imaging mode (20 W) was used for image acquisition, and tomography was performed through both the Cranial vault acoustic window and the Mouth nose leading edge acoustic window. Two-dimensional B-scans were acquired in the x–z plane under both acoustic windows with a step size of 0.5 mm. The scanning range was adjusted according to individual head size to ensure coverage of the skull boundary (Figure 7). Based on the tomographic results, the intervention target was selected, and high-power intervention (60 W) was then performed under the same dual-frequency setting. Post-intervention changes were subsequently evaluated by rescanning. To obtain temperature reference data in the postmortem experiments, a microchannel was created in the skull after target determination. A thermocouple was positioned near the preset target, and temperature and USAE amplitude were synchronously recorded during intervention for process-trend analysis. Temperature measurement was used only in the postmortem experiments and was not applied in the in vivo stage. 4.2 System feasibility was evaluated in phantom and ex vivo tissue experiments To evaluate the feasibility of the closed-loop workflow, imaging–intervention–reimaging experiments were performed in graphite phantoms and ex vivo bovine heart tissue, with simultaneous acquisition of thermocouple temperature and USAE amplitude for pro-cess-trend analysis. 4.5 Behavioral test The balance-beam test was used to assess motor coordination and balance after ultrasound intervention. The apparatus consisted of a beam 100 cm in length and 50 cm above the ground, with beam widths of 48, 24, and 12 mm. Animals were tested before intervention and again on days 4 and 8 after intervention. During each trial, the animals traversed the beam toward the endpoint platform, and the entire process was recorded. Traversal time, the number of foot slips, and failure events (defined as falling or failure to complete the task within the specified time limit) were recorded. The Shapiro‑Wilk test was used to assess the normality of data distribution. For normally distributed data, one‑way ANOVA was performed to compare differences among the three groups. Post hoc comparisons were conducted using the LSD test for data with homogeneity of variance, or the Tamhane T2 test for data with heterogeneity of variance. All statistical analyses were performed using IBM SPSS Statistics software version 24 (IBM Corporation, Armonk, NY, USA).4.1 温度监测 实验过程中，聚焦换能器与接收水听器固定于水槽坐标系内，实验动物则固定于机械臂支架上。扫描阶段，机械臂带动动物相对于声学系统完成相对运动。本研究采用双频低功率成像模式（20 W）开展图像采集，并分别通过颅顶声学窗口与口鼻前缘声学窗口进行断层扫描。在两种声学窗口下，均于x-z平面采集二维B型扫描图像，步长设置为0.5 mm。扫描范围需根据个体头部尺寸进行调整，以确保覆盖颅骨边界（图7）。基于断层扫描结果选定干预靶点后，在相同双频设置下启动60 W的高功率干预。随后通过重新扫描评估干预后的组织变化。为获取死后实验的温度参考数据，在确定靶点后于颅骨上构建微通道，将热电偶置于预设靶点附近，并在干预过程中同步记录温度与USAE幅值，用于过程趋势分析。温度测量仅应用于死后实验，活体阶段未采用该检测手段。 4.2 系统可行性评估 为评估闭环工作流程的可行性，本研究在石墨体模与离体牛心脏组织中开展了成像-干预-再成像实验，并同步采集热电偶温度与USAE幅值以进行过程趋势分析。 4.5 行为学测试 本研究采用平衡木实验评估超声干预后的运动协调能力与平衡功能。实验装置为一根长100 cm、距地面高度50 cm的横梁，其宽度分别设置为48 mm、24 mm与12 mm。实验动物分别于干预前、干预后第4天及第8天接受测试。每次测试中，动物需沿横梁走向终点平台，整个过程均被录制记录。研究记录了穿越时间、足部打滑次数以及失败事件（定义为跌落或未在指定时限内完成任务）。采用Shapiro-Wilk检验评估数据分布的正态性。对于符合正态分布的数据，采用单因素方差分析（one-way ANOVA）比较三组间的差异。方差齐性的数据采用LSD检验进行事后比较，方差不齐的数据则采用Tamhane T2检验。所有统计分析均使用IBM SPSS Statistics 24版本软件（美国纽约州阿蒙克市IBM公司）完成。