## 3 Results and Discussion
### Results of Porcine Arteries Experiments  
Figure 14a demonstrates that when the treatment focus is positioned on the superior wall of the blood vessel, the area of high-brightness degeneration of the vessel appears solely on the superior surface portion of the vessel. Moreover, an elongated treatment period does not notably affect the inferior side of the vessel wall. The degeneration changes are more pronounced between 1 and 3 min of treatment time, after which there is less variation.  
In Figure 14b, when the treatment focus is located at the center of the vessel, the results exhibit no significant contraction or degeneration in the overall area of the vessel, nor any high-brightness degeneration. Consequently, positioning the focus in the middle of the vessel may not be suitable for a thick vessel with blood.  
As shown in Figure 14c, when the treatment focus is located on the inferior wall of the blood vessel, it is found that the area of high-brightness degeneration is only present on the inferior surface of the vessel, and prolonged treatment also has no significant effect on the superior surface. Similarly, more pronounced degeneration happens from 1 min to 3 min of treatment time, after which there is less change.  
The comparison results demonstrate that degeneration and deformation are more likely to occur when the focal point is situated on the blood vessel wall. Due to the blood's higher specific heat capacity, this may lead to less overall vasoconstriction for the same treatment energy. Consequently, it is reasonable to select the vessel wall as the focal point's location. Meanwhile, since skin burning may occur when the treatment point is placed on the superior wall, it is preferable to place the treatment point on the inferior wall to effectively prevent skin burns. On the other hand, when the treatment time lasts for 3 min, the degeneration degree of each treatment point shows no further change. This indicates that for vessels that have reached the threshold of local degeneration, the position of the therapeutic probe needs to be adjusted to avoid areas of fibrosis if they are to shrink further. It is suitable that limiting the treatment time to 1-3 min is better for the treatment of vessels with similar diameters.  
Figure 15 displays a comparison of vascular imaging before and after treatment of the inferior tube wall using a commercial Vevo 2100 small animal ultrasound system in combination with a 50 MHz center frequency linear array imaging probe. The untreated porcine artery area in Figure 15a is approximately 6.54 mm\({}^{2}\), with a maximum diameter of 3.143 mm and a minimum diameter of 2.648 mm. The treated pig artery section is displayed in Figure 15b, with an area of approximately 4.898 mm\({}^{2}\), a maximum diameter of 3.027 mm, and a minimum diameter of 1.987 mm. The cross-sectional area decreases by 25% after the treatment, while the minimum diameter decreases by 24%. The inferior wall of the vessel indicates notable shrinkage, consistent with the result of the high-light denaturation  
Figure 14: Results of different treatment foci on the ultrasound imaging function of the integrated system: (**a**) the treatment focus on the superior wall of the blood vessel; (**b**) the treatment focus on the middle of the blood vessel; (**c**) the treatment focus on the inferior wall of the blood vessel.  
on the inferior surface of the vessel after treatment in Figure 14c, thereby confirming the effectiveness of this innovative high-frequency ultrasound-guided integrated system for varicose vein ultrasound therapy under similar working conditions.