Abstract

Background

Varicose veins are a common disease that may significantly affect quality of life. Different approaches are currently used in clinical practice to treat this pathology.

Materials and methods

In thermal therapy (radiofrequency or laser therapy), the vein is directly heated to a high temperature to induce vein wall coagulation, and the heat induces denaturation of the intramural collagen, which results macroscopically in vein shrinkage. Thermal vein shrinkage is a physical indicator of the efficiency of endovenous treatment. High-intensity focused ultrasound (HIFU) is a noninvasive technique that can thermally coagulate vein walls and induce vein shrinkage. In this study, we evaluated the vein shrinkage induced in vivo by extracorporeal HIFU ablation of sheep veins: six lateral saphenous veins (3.4mm mean diameter) were sonicated for 8 s with 3MHz continuous waves. Ultrasound imaging was performed before and immediately post-HIFU to quantify the HIFU-induced shrinkage.

Results

Luminal constriction was observed in 100% (6/6) of the treated veins. The immediate findings showed a mean diameter constriction of 53%. The experimental HIFU-induced shrinkage data were used to validate a numerical model developed to predict the thermally induced vein contraction during HIFU treatment.

Conclusions

This model is based on the use of the k-wave library and published contraction rates of vessels immersed in hot water baths. The simulation results agreed well with those of in vivo experiments, showing a mean percent difference of 5%. The numerical model could thus be a valuable tool for optimizing ultrasound parameters as functions of the vein diameter, and future clinical trials are anticipated.

中文翻译：

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高强度聚焦超声热凝引起的静脉壁收缩：绵羊的数值模型和体内实验

摘要

背景

静脉曲张是一种常见疾病，可能会严重影响生活质量。当前在临床实践中使用不同的方法来治疗这种病理。

材料和方法

在热疗法（射频或激光疗法）中，将静脉直接加热至高温以引起静脉壁凝结，并且热量引起壁内胶原的变性，这从宏观上导致静脉收缩。静脉热收缩是静脉治疗效率的物理指标。高强度聚焦超声（HIFU）是一种非侵入性技术，可以热凝结静脉壁并引起静脉收缩。在这项研究中，我们评估了体外HIFU消融绵羊静脉在体内引起的静脉收缩：用3MHz连续波超声处理6条外侧隐静脉（平均直径3.4mm）超声8 s。在HIFU之前和之后立即进行超声成像以量化HIFU引起的收缩。

结果

在100％（6/6）的治疗静脉中观察到了光收缩。立即发现显示平均直径收缩为53％。实验性HIFU诱导的收缩数据用于验证建立的数值模型，该模型可预测HIFU治疗期间热诱导的静脉收缩。

结论

该模型基于k波库的使用和公开的浸入热水浴中的血管的收缩率。模拟结果与体内实验的结果非常吻合，平均差异为5％。因此，数值模型可能是优化超声参数作为静脉直径的函数的有价值的工具，并且有望进行未来的临床试验。