磁共振DTI及DTT在胶质瘤诊断及治疗中的应用

Application of MR diffusion tensor imaging and diffusion tensor tractography in diagnosis and treatment of glioma

目的:探讨磁共振弥散张量成像(DTI)对判断胶质瘤良恶性和侵袭性的价值及胶质瘤与脑白质结构间关系,观察纤维束受损情况,为制定胶质瘤手术方案提供影像学依据。方法:31例不同级别胶质瘤(低级别胶质瘤15例,高级别胶质瘤16例)患者均行常规磁共振成像(MRI)和DTI检查,分别绘制FA图、DEC图并重建弥散张量纤维素成橡(DTT)图。选择肿瘤实质、瘤周水肿及水肿边缘作为感兴趣区,分别比较不同级别胶质瘤相应感兴趣区内的rFA值,并观察肿瘤周围白质纤维束的改变。结果:低级别胶质瘤与高级别胶质瘤的平均rFA值均表现出实质部分(低级别组0.428±0.078,高级别组0.366±0.055)、瘤周水肿(低级别组0.578±0.120,高级别组0.458±0.158)、水肿边缘(低级别组0.834±0.074,高级别组0.676±0.138)的顺序递增的趋势。高级别胶质瘤组实质部分、瘤周水肿和水肿边缘的rFA值均较低级别胶质瘤组明显降低(P<0.05)。在FA图中各级别胶质瘤表现为不同程度的低信号。DEC图中病变区颜色黯淡混杂、纤维束整体形态异常。在DTT图中低级别胶质瘤多数表现为纤维束部分中断(12/15),少数表现为受压、偏移(3/15);高级别胶质瘤中,纤维束多呈现明显的变形移位,多数表现为纤维束明显中断、稀疏(13/16);少数表现为纤维束全部或大部分中断(2/16);1例主要表现为受压移位。结论:DTI能够在术前评价胶质瘤的恶性程度及瘤细胞侵袭性并能较全面地观察纤维束改变,可为胶质瘤手术方案的制定、判断手术效果及观察预后提供影像学依据。

Objective To evaluate the malignancy and invasion of gliomas preoperatively by diffusion tensor imaging （DTI）, and to study the relationship between gliomas and fiber tracts by diffusion tensor tractography （DTT）. Methods A total of 31 patients with grade Ⅰ to Ⅳ gliomas （15 cases of gradeⅠ and grade Ⅱ gliomas, 16 cases of grade Ⅲ and grade IV gliomas） underwent the conventional MRI and DTI. FA map and DEC map were writen and DTT map was reconstructed in order to make comparison of the rFA values between low-grade gliomas and highgrade gliomas in relative regions of interest （ROIs）, as well as to observe the changes of the white fiber tracts. Results A decreasing tendency of rFA values was observed as follow： solid portion lowest （0. 428 ± 0. 078）, followed by edema area （0. 578±0. 120） and edge of edema （0. 834±0. 074） in low-grade gliomas; as well as solid protion lowest （0. 366±0. 055）, followed by edema area （0. 458±0. 158） and edge of edema （0. 6766±0. 138） in high-grade gliomas. The rFA values of high-grade gliomas were significantly lower than those of low-grade gliomas in all ROIs （P〈0. 05）. All gliomas presented low signals differently on FA map. The tumor region showed ambiguity and disorder on DEC map. On DTT map, 3 of 15 low-grade gliomas showed deviation; the other 12 cases showed slight rarefaction; 13 of 16 high-grade discontinuation; 2 cases showed termination or interruption; gliomas showed significant destruction and partly 1 case mainly showed deviation and part of fiber tracts showed destruction. Conclusion DTI contributes to study malignancy and invasion of gliomas and provide more useful fiber information of gliomas preoperatively.