Dual-frequency focused ultrasound mm-level imaging and temperature trend monitor-ing system and Its Validation in a Cerebellar Target
Description
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).
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Institutions
- Chongqing Medical UniversityChongqing, Chongqing