弥散张量成像(DTI)对肿瘤脑浸润的量化和应用

Quantification of brain invasion by DTI and its clinical application.

目的研究磁共振弥散张量成像对颅内肿瘤脑浸润程度的量化和临床应用。方法颅内肿瘤40例,其中脑胶质瘤20例,脑膜瘤12例,脑转移瘤8例,均经病理证实;建立不同颅内肿瘤的脑浸润病理标准,并以此标准分入各亚组;利用MRI常规成像和弥散张量成像(Diffusion Tensor Imaging,DTI)比较,确定并测量5个兴趣区(肿瘤实体区、瘤周水肿区、水肿外区、相对正常白质区和对侧白质区)的分量各向异性值(fractional anisotropy,FA);比较分析不同肿瘤FA值的差异及其与肿瘤脑浸润程度的相关性。结果脑胶质瘤中有10例的DTI图像超出常规MRI范围,脑膜瘤和脑转移瘤中未见;FA值由瘤体区向外呈递增趋势,其中胶质瘤组内最大增幅出现在瘤周水肿区和水肿外区之间,而脑膜瘤和脑转移瘤亚组出现在肿瘤实体区和瘤周水肿区之间;胶质瘤瘤周水肿区FA值与肿瘤脑浸润程度显著相关;在脑胶质瘤中有脑浸润者的瘤周水肿区FA值显著低于无脑浸润胶质瘤和非胶质来源肿瘤。结论DTI可用于量化比较不同脑肿瘤的脑浸润程度,其瘤周水肿区的FA值可用于指导脑胶质瘤的手术切除范围,对延缓复发、改善预后有较大意义。

Objective To quantitatively evaluate the brain invasion in varying intracranial tumors by diffuse tensor imaging （DTI）. Methods Forty patients with histologically confirmed intracranial tumors, including twenty gliomas with varying grades, twelve meningiomas and eight metastases, were included in this study. Tumors were classified into different subgroups according to the established pathological standards of brain invasion. All cases were preoperatively imaged using conventional MRI （ T1 weight image plain and enhancement scan, T2 weight image） and DTI sequences. Five regions of interest （ROI） including tumor, peritumoral edema, outer of edema, white matter and contralateral white matter region were drawn within the tumor and white matter at various distances from the tumor. FA value was calculated in every individual region. Results The abnormality on DTI was greater than that seen on conventional MR images in 10/20 patients （50%） with gliomas, whereas no difference was found in abnormality of DTI between meningiomas and metastases; FA values increased from inner area to outer area, and the maximum increasing in glioma group was observed from peritumoral edema region to outer region of edema; while those were observed from tumor to peritumoral edema area in the meningioma and metastases group. FA of peritumoral edema region was associated with degree of brain tumor invasion. FA values of gliomas with brain invasion in peritumoral edema area were significant less than those of non - glial tumors and gliomas without invasion. Conclusions DTI can be used to quantify the brain invasion of intracranial tumors. The FA of peritumoral edema region plays a very valuable role in making surgical strategy, reducing recurrence rate and improving outcome.