【摘要】 目的　运用磁共振灌注成像 (PWI)获取对比剂首过期间的兴趣区图像 ,研究Ⅱ～Ⅳ级星形胶质细胞瘤肿瘤血管的通透性。方法　Ⅱ～Ⅳ级星形胶质细胞瘤共 2 3例 ,常规MR检查后以双倍剂量钆喷替酸葡甲胺 (Gd DTPA)行灌注加权成像 (PWI) ,获取兴趣区准T2 (T2 )增强的灌注图像 ,绘制出病灶的信号强度下降百分率 时间曲线 ,根据首过期末信号下降百分率与首过时间之比计算肿瘤血管的相对通透性 (P )。结果　正常脑组织信号在首过期末几乎恢复至基线 ,胶质瘤则仍有一定程度的信号下降 ,对比剂再循环引起的信号下降最早发生于首过期结束后 5s。Ⅱ、Ⅲ和Ⅳ级星形胶质细胞瘤的P 值分别为 0 19～ 0 4 8(0 32± 0 0 9)、0 71～ 1 2 9(0 98± 0 16 )、1 4 0～ 2 2 4 (1 92± 0 2 1) ,各组P 值两两比较经t检验发现Ⅱ级、Ⅲ级和Ⅳ级的P 值任意两者间差异均有非常显著性意义 (Ⅱ /Ⅲ ,t=7 2 8,P <0 0 0 1;Ⅲ /Ⅳ ,t=8 2 7,P <0 0 0 1;Ⅱ /Ⅳ ,t=14 0 ,P <0 0 0 1)。结论　灌注成像对评价星形胶质细胞瘤肿瘤血管通透性具有重要作用 ,不同分级的星形胶质细胞瘤其肿瘤血管通透性存在显著差异更多还原

【Abstract】 Objective To study the potential of MR T 2 PWI in evaluating tumors vessel permeability of astrocytomas. Methods MR Perfusion imaging with double dosage of gadolinium was performed in 23 patients who had astrocytoma in pathology except Ⅰgrade, followed by conventional imaging to obtain T  2 enhanced perfusion images of regions of interest (ROI). The perfusion data were deconvoluted to get signal intensity decreased percentage time curves of lesions, which were used to calculated signal reduced ratio at the end of first pass (SRR end ) and the time of first pass (Δt). The P  represented of tumor vessel permeability was calculated, which is equal to the ratio of SRR end to Δt. Results Signal of normal brain was almost turn to base line at the end of first pass, but lesions of astrocytomas remain had some signal reduced. Minimal signal loss again occurred at least 5 seconds after the first pass of contrast agent, which was consistent with the recirculation of diluted contrast medium. The P* values in grade Ⅱ-Ⅳ astrocytomas were 0.19-0.48(0.32±0.09),0.71-1.29(0.98±0.16)and 1.40-2.24(1.92±0.21)respectively. The difference in P * values were statistically significant among the 3 groups (Ⅱ/Ⅲ, t =7.28, P <0.001;Ⅲ/Ⅳ, t =8.27 , P <0.001;Ⅱ/Ⅳ, t =14.0, P <0.001). Conclusion Perfusion MR imaging is very useful in the evaluation of tumor vessel permeability of astrocytomas and it can be used to help predict tumor grade of astrocytomas in preoperation.更多还原