MR氧摄取分数成像在星形细胞瘤分级的应用研究

目的探究基于非对称自旋回波(ASE)序列的氧摄取分数成像(OEF imaging)定量测量胶质瘤氧摄取分数的可行性,评价相关定量指标在星形细胞瘤分级诊断中的诊断性能。材料与方法 32例经病理诊断为星形细胞瘤的患者,其中Ⅱ级16例、Ⅲ级5例、Ⅳ级11例。所有受试对象扫描前均获得书面知情同意,扫描序列包括横断面T1WI、T2WI、T2 FLAIR、增强T1WI、ASE-OEF扫描。通过在肿瘤实体区手动绘制感兴趣区的方式测量肿瘤氧摄取分数(OEF),并对肿瘤标本进行ki-67免疫组化染色。采用独立样本t检验和单因素方差分析(oneway ANOVA)评价OEF定量指标在高低级别胶质瘤中的差异并与传统的MRI比较,采用受试者工作特征曲线进行诊断性能评价,采用Pearson相关分析OEF与Ki-67标记指数之间的相关性。结果增强扫描中,16例低级别胶质瘤10例表现为不强化,6例强化;16例高级别胶质瘤中,仅有1例不强化,其余15例表现为不同程度强化,差异有统计学差异(P=0.002)。高级别胶质瘤OEF明显高于低级别组,差异具有统计学意义(17.00±2.47、20.46±2.98,P0.01)。观察者间一致性分析显示ICC=0.89,表明测量结果具有良好的一致性。Ki-67 LI在高低级别胶质瘤中分别为48±54.01、5.8±8.76,差异具有统计学意义(P=0.01);Pearson相关分析表明Ki-67 LI与OEF存在中等的相关性(r=0.406,P0.05)。依据有无强化诊断高低级别胶质瘤的曲线下面积(AUC)为0.781,敏感度和特异度分别为93.8%和62.5%;定量指标OEF的诊断效能优于增强扫描,AUC为0.852,当取阈值为19.55时有最大的诊断效能,敏感度和特异度分别为81.3%和87.5%。结论基于EPI技术采集非对称自旋回波(ASE)序列可用于无创性测量肿瘤组织氧摄取分数;定量指标OEF能良好的鉴别高低级别胶质瘤,且能一定程度上反映肿瘤的增殖活性,在胶质瘤诊疗中具有较大的潜在应用前景。

The application of MR oxygen extraction fraction imaging in astrocytoma grading

Objective:To explore the feasibility of quantitative measuring glioma oxygen extraction fraction (OEF) with OEF-imaging based on asymmetric spin-echo and to evaluate the diagnostic performance of OEF-related quantitative index in differentiating low- and high-grade gliomas.Materials and Methods: Thirty-two patients who were diagnosed with glioma via histopathology were recruited in the study, among which 16 cases were astrocytoma (gradeⅡ), 5 cases of anaplastic astrocytoma and 11 cases of glioblastoma. The informed consent forms were obtained before the patients received MR scanning and the protocol employs axial T1WI、T2WI、T2FLAIR、SE-DWI、T1WI+C and ASE-OEF. The OEF of solid part of tumor and contralateral white matter was manually measured by. The statistic analysis was based on independent-samplet-test andone-way ANOVA, to identify the manifestation and diagnostic performance in low- and high-grade gliomas, thePearson correlation analysis was applied to analyze the correlation between OEF and Ki-67 labeling index (Ki-67 LI).Results:In enhancement scanning, nonenhancement showed in ten of 16 low-grade gliomas, while only one patient showed nonenhancement, the difference of enhancement in low- and high-grade glioma was signiifcant (P=0.002). The OEF in high-grade glioma was signiifcantly higher than that in low-grade glioma (17.00±2.47 VS 20.46±2.98,P<0.01), the intra-class correlation coefifcient was 0.89 indicating a good consistency in measurement results. The difference of Ki-67 LI in gliomas was signiifcant (48±54.01,5.8±8.76,P=0.01) and the Ki-67 LI was mildly correlated with OEF (r=0.406,P<0.05). The AUC of qualitative index depending on enhancement or nonenhancement in tumor solid part was 0.781 with 93.8% sensitivity and 62.5% speciifcity, while the AUC of OEF in differentiating low-and high-grade gliomas was 0.852 at a best threshold value of 19.55 with 81.3% sensitivity and 87.5% speciifcity.Conclusions:The ASE-MRI based on EPI can be applied in non-invasive measurement of glioma OEF. The quantitative parameter OEF is a excellent biomarker in differentiating high- and low-grade gliomas with good diagnstic performance and partly relfects the tumor proliferations. The potential application value of OEF in the diagnosis and management of glioma is worthwhile.