基于磁共振温度图的高强度聚焦超声治疗热剂量研究  

Research on Thermal Dose for High Intensity Focused Ultrasound Treatment Based on the Temperature-map of Magnetic Resonance Imaging

作　　者：刘莉莉[1] 李发琪[1] 龚晓波[1] 刘映江[1] 胡晓[1] 

机构地区：[1]重庆医科大学生物医学工程系重庆市超声医学工程重点实验室,重庆400016

出　　处：《生物医学工程学杂志》2010年第2期253-256,共4页Journal of Biomedical Engineering

基　　金：国家十一五科技支撑计划资助项目(2006BAI03A02);国家自然科学基金重点项目资助(30830040);重庆市科委攻关项目资助(渝科发计字[2007]11号CSTC;2007AA5020)

摘　　要：本实验研究基于磁共振T-Map的HIFU损伤组织的热剂量与实际凝固性坏死的关系。运用磁共振导航高强度聚焦超声治疗系统,使用1 MHz、焦距为150 mm、直径150 mm的聚焦超声换能器,定点辐照深度为20 mm的新鲜离体牛肝脏,辐照过程中用磁共振的测温序列采集各体素随时间变化的温度值并计算各体素的Eq43值,比较计算结果与发生凝固性坏死的Eq43参考阈值,判断该体素是否发生坏死。最后比较通过等效热剂量积分法得到的凝固性坏死面积和组织实际发生坏死的情况。结果表明基于磁共振T-Map的等效热剂量积分法得到的凝固性坏死的面积值能很好的反应实际发生凝固性坏死的情况,为HIFU治疗提供了一种新的判断凝固性坏死发生的方法,这种方法可以实时地反馈控制超声辐照剂量,提高了治疗的安全性。Based on the T-map of MRI,this research sought to address the relationship between the simulated threshold thermal dose of coagulation and actual the coagulation on histological slides.The MR imaging guided HIFU system was used,the parameters of therapeutic transducer were： frequency-1MHz,diameter-150mm,and focal length-150mm.In fresh beef liver tissue in vitro,sonications were delivered at a fixed depth of 20mm and at varying powers.The temperature-sensitive MR images obtained during the sonications were used to estimate the temperature,and the thermal dosage of each voxel in the target region was calculated.The thermal dosage of each voxel was compared with the reference threshold thermal dosage,so as to calculate the boundary and area of the coagulated tissue.After the exposure,the tissue was dissected along the maximal section of the coagulation necrosis,and the area of the biological focal region was measured.Results： The occurrence of tissue damage correlated well with the equivalent thermal dose calculation based on the T-mapping of MRI,and they share the same variation tendency.Conclusion： The equivalent thermal dose calculation based on the T-Map of MRI correlates well with the actual tissue damage,and so an index to predict the threshold for tissue damage in vivo is provided.This index offers improved online control over minimally invasive thermal treatments and increases the security of the therapy.

关 键 词：磁共振 温度图 高强度聚焦超声 热剂量 

分 类 号：R312[医药卫生—基础医学] R730.59