三维动脉自旋标记成像量化脑转移瘤放疗前后灌注变化的研究

侯传珂; 巩贯忠; 王俪臻; 苏亚; 卢洁; 尹勇

doi:10.3969/j.issn.1000-8179.2020.01.279

三维动脉自旋标记成像量化脑转移瘤放疗前后灌注变化的研究

Assessment of changes in perfusion after radiotherapy for brain metastasis using threedimensional arterial spin labeling

摘要

摘要:
目的应用三维动脉自旋标记（three-dimensional arterial spin labeling，3D-ASL）定量分析脑转移瘤（brain metastasis，BMs）患者放射治疗（放疗）过程中BMs肿瘤靶区、正常脑区域及瘤周水肿区的血流灌注变化。建立三者灌注变化与放疗剂量梯度的关系，为BMs患者进行个体化放疗提供参考依据。
方法收集2018年7月至2019年6月山东省肿瘤防治研究院26例BMs患者放疗前及放疗后的MR模拟定位图像（包括强化T1WI图像和3D-ASL的灌注图，由强化T1WI图像获得BMs肿瘤靶区，3D-ASL图像获得血流灌注信息）。分别定义强化T1WI中BMs高信号区、正常脑区域及瘤周水肿区为感兴趣区域（regions of interest，ROIs）。研究BMs肿瘤靶区放疗前后平均最大截面积、平均最大脑血流量（cerebral blood flow，CBF）的变化及相关性；分析不同剂量梯度下3个ROIs CBF值的变化规律。
结果 BMs肿瘤靶区放疗前后平均最大截面积和CBF值分别降低26.46%和29.64%（P < 0.05）。BMs肿瘤靶区在30~40、40~50 Gy和>50 Gy剂量梯度下，CBF放疗前后下降率分别为33.75%、24.61%和27.55%（P < 0.05），30~40 Gy时最大。正常脑区域在0~10、10~20、20~30、30~40、40~50 Gy和>50 Gy剂量梯度下，CBF放疗前后下降率分别为7.65%、11.12%、18.42%、20.23%、19.79%和17.89%（P < 0.05），30~40 Gy时最大。瘤周水肿区放疗后CBF下降率与剂量梯度增高同步。BMs肿瘤靶区放疗前后的灌注下降较正常脑区域和瘤周水肿区更为显著。
结论 3D-ASL可客观反映BMs肿瘤靶区、正常脑区域及瘤周水肿区放疗中灌注变化情况。依据CBF的变化，正常脑区域的放疗剂量建议控制在30 Gy以下，而肿瘤靶区高灌注区和瘤周水肿区应给予高剂量。

Abstract:
Objective This study aimed to quantitatively analyze changes in blood perfusion in brain metastases (BMs), normal brain areas, and peritumor edema areas during radiotherapy (RT) using three-dimensional arterial spin labeling (3D-ASL) in BMs patients. The associations between perfusion changes in the three brain regions and RT dose gradients need to be established to provide a reference for individualized RT for BMs patients.
Methods MR-simulated location images of 26 BMs patients before and after RT were collected (including enhanced T1W images and perfusion maps of 3D-ASL; BMs tumor target areas were identified using enhanced T1W images and perfusion information was obtained from 3D-ASL). The high signal areas of BMs on contrast-enhanced T1W images, normal brain areas, and peritumor edema areas were defined as regions of interest (ROIs). The changes and correlation of the mean maximum cross- sectional area and mean maximum cerebral blood flow (CBF) in BMs tumor target areas before and after RT were assessed. Changes in CBF values in the three ROIs under different dose gradients were analyzed.
Results The mean maximum cross-sectional area and CBF values of BMs decreased by 26.46% and 29.64%, respectively, after RT (both P < 0.05). The decreasing CBF rates in BMs at 30-40, 40-50, and >50 Gy dose gradients were 33.75%, 24.61%, and 27.55%, respectively (all P < 0.05). In normal brain areas, under dose gradients of 0-10, 10-20, 20-30, 30-40, 40-50, and >50 Gy, the decreasing CBF rates after RT were 7.65%, 11.12%, 18.42%, 20.23%, 19.79%, and 17.89%, respectively (all P < 0.05). The decreasing CBF rates in peritumor edema areas increased as dose gradients increased after RT. The perfusion changes in BMs after RT were more notable than those in normal brain areas and peritumor edema areas.
Conclusions Thus, 3D-ASL can objectively reflect changes in perfusion in BMs, normal brain areas, and peritumor edema areas. Based on changes in CBF, it is recommended to control the dose administered to normal brain areas to < 30 Gy, whereas high doses should be administered to tumor target areas with high perfusion and peritumor edema areas.

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