基于MR灌注成像进行脑转移瘤亚靶区分割的研究

Study of sub-region segmentation of brain metastases based on magnetic resonance perfusion imaging

目的探讨MR灌注成像进行脑转移瘤(BMs)亚靶区分割的可行性,为BMs患者基于血流灌注异质性引导个体化放疗提供参考。方法选取96例BMs放疗患者,肿瘤内部有坏死组55例,无坏死组41例,每位患者放疗前行CT模拟定位及MR模拟定位。应用MIM Maestro6.8.8软件分别在强化T_(1)WI图像和T_(2) Propeller图像中勾画大体肿瘤体积(GTV)及肿瘤坏死区(GTV_(N)),二者相减得肿瘤实性区(GTV_(S))。应用三维动脉自旋标记(3D-ASL)灌注成像的脑血流量图确定高灌注区(GTV_(H))与低灌注区(GTV_(L))。比较有、无坏死组亚靶区体积、占比及各亚靶区相关性。结果有、无坏死组GTV分别为19.56、7.34 cm^(3),GTV与坏死的ROC曲线AUC达0.749。有坏死组GTV_(N)、GTV_(S)、GTV_(H)、GTV_(L)占GTV比分别为20.47%、79.53%、33.03%、46.50%(P<0.05),其中GTVS与GTV的r值达0.963,GTV_(L)与GTV、GTV_(S)的r值分别达0.849、0.840,高于GTV_(H)与GTV、GTV_(S)的r值0.683、0.764(均P<0.05)。无坏死组GTV_(H)占GTV比高于有坏死组(58.95%∶33.03%,P<0.05),GTV_(L)占GTV比略低于有坏死组(41.05%∶46.50%,P>0.05)。GTV_(H)与GTV的r值高于GTV_(L)与GTV的(0.776∶0.574,P<0.05)。结论MR-3D-ASL可以定量分析BMs肿瘤靶区内异质性血流灌注,可用于指导亚靶区分割及肿瘤局部亚靶区剂量提升。

Objective To evaluate the feasibility of magnetic resonance(MR)perfusion imaging for sub-region segmentation of brain metastases(BMs),and to provide reference for individualized radiotherapy based on blood flow perfusion heterogeneity in BMs patients.Methods 96 BMs patients were selected,including 55 patients with necrosis and 41 without necrosis.Each patient was scanned with CT simulation and MR simulation before radiotherapy.MIM Maestro 6.8.8 software was used to delineate the gross tumor volume(GTV)and necrosis GTV(GTV_(N))from enhanced T_(1)W images and T_(2) Propeller images,respectively,and the solid GTV(GTV_(S))was obtained by the subtraction of the two.Then,the cerebral blood flow map of three dimensional arterial spin labeling(3D-ASL)was employed to determine the high perfused GTV(GTV_(H))and low perfused GTV(GTV_(L)).The volume and proportion of sub-regions were counted and compared between two groups and the correlation of each sub-region was analyzed.Results The volume of GTV in the necrosis and non-necrosis groups was 19.56 and 7.34 cm^(3),respectively.Besides,the AUC of the ROC between GTV volume and necrosis was 0.749.In the necrosis group,the ratio of GTV_(N),GTV_(S),GTV_(H) and GTV_(L) to GTV was 20.47%,79.53%,33.03%and 46.50%,respectively(all P<0.05).Among them,the r value between GTV_(S) and GTV was 0.963,0.849 for GTV_(L) and GTV,and 0.840 for GTV_(L) and GTV_(S),significantly higher than 0.683 for GTV_(H) and GTV and 0.764 for GTV_(H) and GTV_(S)(all P<0.05).In the non-necrosis group,the ratio of GTV_(H) to GTV was higher than that in the necrosis group(58.95%vs.33.03%,P<0.05).In addition,the ratio of GTV_(L) to GTV was slightly lower than that in the necrosis group(41.05%vs.46.50%,P>0.05).The r value between GTV_(H) and GTV was 0.776,significantly higher than 0.574 between GTV_(L) and GTV(P<0.05).Conclusion MR-3D-ASL can quantitatively analyze the heterogeneous blood perfusion of BMs,which could guide the sub-region segmentation and local dose escalation of tumors.