利用T1加权动态对比度增强灌注MRI技术确定脑胶质瘤放疗靶区的研究

The role of T1-weighted dynamic contrast-enhanced perfusion magnetic resonance imaging in gross target volume delineation of giioma patients

目的探讨利用T1加权动态对比度增强灌注MRI（DCEPMRI）技术在放疗中确定脑胶质瘤临床靶区的研究。方法对28例脑胶质瘤患者团注顺磁性造影剂Gd—DTPA后，采集其T1加权DCEPMRI，对获得图像用改进的Torts—Kermode两室分析模型和反卷积法进行处理分析得到微血管通透性相关定量参数Ktrans值及图，并比较最大病灶区所在层面常规增强MRI与T1加权DCEPMRI的Ktrans值及图，测量各个临床级别脑胶质瘤病灶面积差异。结果低级别胶质瘤微血管通透性较低、肿瘤浸润范围小，T1加权DCEPMRI与常规增强MRI所测病灶面积误差达0．2％-0．3％[I、Ⅱ级分别为2．93cm2：2．46cm2（t=6．90，P=0．000）、4．18cm2：3．21cm2（t=10．22，P=0．000）]；高级别胶质瘤微血管通透性较高、肿瘤浸润范围大，T1加权DCEPMRI与常规增强MRI所测量病灶面积误差达25．1％～26．3％[Ⅲ、Ⅳ级分别为6．46cm2：5．48cm2（t=10．83，P=0．000）、8．26cm2：6．52cm2（t=18．53，P=0．000）]。结论以T1加权DCEPMRI技术得到的微血管通透性相关定量参数Ktrans值及彩图为胶质瘤放疗靶区确定提供了更为准确信息，可作为评价肿瘤体积新方法。

Objective To investigate whether the Tl-weighted dynamic contrast-enhanced perfusion magnetic resonance imaging （DCEPMRI） technique can help to delineate the clinical target volume of brain glioma patients. Methods The DCE T1-weighted images from 28 glioma patients were collected after Gd- DTPA was injected. After the acquired images were processed and analyzed using modified Tofts-Kermode＇ two compartment analysis model and de-convolution method, the value and its pseudo mapping of quantitative parameter K related to microvascular permeability were obtained. The tumor size in the largest diameter slice measured both in routine enhanced MRI and Ktrans mapping of Tl-weighted DCEPMRI were compared. Results The vascular permeability and tumor infiltration was lower in low grade glioma, the difference of the tumor size between Tl-weighted DCEPMRI and routine enhanced MRI reached 0. 2% -0. 3% there was significant difference of tumor size between Tl-weighted DCEPMRI and routine enhanced MRI （ grade I and II grade with 2.93 cm2：2.46 cm2（t=6.90,P=0.000） and 4. 18 cm2：3.21 cm2（t= 10.22,P= 0. 000） ）. While in high grade glioma, the vascular permeability and the tumor infiltration were higher, the difference of the tumor size between Tl-weighted DCEPMRI and routine enhanced MRI reached 25% - 26% （the size of grade HI and IV were 6. 46 cm2 vs 5.48 cm2（t = 10. 83,P =0. 000） and 8.26 cm2 vs 6. 52 cm2 （t = 18. 53, P = 0. 000））. Conclusions The pseudo mapping of quantitative parameter K related to microvascular permeability acquired by Tl-weighted DCEPMRI reflect the infiltrating circumscription in glioma, T1-weighted DCEPMRI can provide more information in delineation the clinical target volume, and it can be used as a new method for tumor volume evaluation.