磁共振弥散张量成像对鉴别星形细胞肿瘤恶性程度的应用价值

Preoperative evaluation of tumor grade in gliomas using diffusion tensor imaging

目的:研究磁共振弥散张量成像对于鉴别低度恶性星形细胞肿瘤和高度恶性星形细胞肿瘤的价值。方法:对45例术前怀疑为星形细胞肿瘤患者进行了常规MRI及DTI检查。其中19例为低度恶性肿瘤(相当于WHO分级的Ⅰ或Ⅱ级),26例为高度恶性肿瘤(WHO分级的Ⅲ或Ⅳ级)。分别测量肿瘤实质部分的FA值和对侧正常额叶白质或枕叶白质的FA值。将肿瘤实质部分的FA值与正常对侧白质的FA值比较;比较低度恶性星形细胞肿瘤和高度恶性星形细胞肿瘤FA值的差异。结果:正常额叶或枕叶白质的FA值为0.40±0.02。星形细胞肿瘤的FA值低于正常枕叶和额叶白质的FA值;低度恶性星形细胞肿瘤的FA值(0.16±0.02)低于高度恶性肿瘤的FA值(0.23±0.02)。上述差别均具有统计学意义(P<0.05)。结论:星形细胞肿瘤的FA值较正常脑白质降低,低度恶性肿瘤的FA值低于高度恶性肿瘤的FA值。FA值在一定程度上反映了肿瘤组织的结构特点。磁共振弥散张量成像对于鉴别低度恶性星形细胞肿瘤和高度恶性肿瘤具有一定的意义,对于一些不典型病例可以考虑应用DTI鉴别星形细胞肿瘤的恶性程度。

Objectlve：To prospectively evaluate whether diffusion-tensor magnetic resonance （MR） imaging （DTI） depicts differences in low-grade gliomas （WttO grade Ⅰ and Ⅱ ） and lfigh-grade gliomas （WHO grade Ⅲ and Ⅳ） on the basis of measuring FA value of the tumor. Methods： Diffusion-tensor MR imaging was preoperatively performed in 45 patients （25 men, 20 women; mean age, 43 years） with histologically confirmed brain gliomas. 19 of the 45 tumors were low-grade gllomas （WHO grade Ⅰ or Ⅱ ） and 26 were highgrade gliomas （WHO grade Ⅲ or Ⅳ ）. Regions of interest were placed in tile tumor center. Fractional anisotropy （FA） ratios were calculated for regions of interest in relation to the NAWM of the contralateral frontal lobe and occipital lobe. Results： Median FA ratios for NAWM of the contralateral frontal lobe and occipital lobe were 0.40 ± 0.02 and 0.31 ± 0.04 respectively, for low-grade versus highgrade gliomas, were 0.12 ± 0.03 versus 0.24 ± 0.05, respectively. Differences in FA ratio between low-grade and high-grade tumors were significant （ P 〈 0.05）. Differences in FA ratio were significant between low-grade or high-grade gliomas and NAWM of the contralateral frontal lobe or occipital lobe. Conclusion： The FA value of gliomas is lower titan NAWM of the contralateral hemisphere, and FA value of low-grade glioma is lower titan high-grade gliomas. FA value in some degree reflects the histological structure of the brain tumor and DTI is helpful in discriminating low-grade from high-grade gliomas.