脑星形细胞瘤的MR灌注成像研究

The technique of MR perfusion and its application in evaluating cerebral astrocytoma

目的 :研究MR灌注成像的扫描技术、后处理技术及其评价脑星形细胞瘤的价值。方法 :本组病例包括星形细胞瘤 40例、转移瘤 3 0例、正常对照组 3 0例 ,均行MR平扫及灌注检查。结果 :不同部位的正常脑血流灌注量不一致。正常人脑灰、白质相对血容量rCBV(relativecerebralbloodvolume)值为 1.5 6± 0 .3 9。Ⅲ、Ⅳ级星形细胞瘤的rCBV值显著高于正常脑实质者 (P <0 .0 1) ,二者之间差异有显著性意义 ,但IV级星形细胞瘤的rCBV值变化较大。星形细胞瘤与转移瘤病变本身的rCBV值差异无显著性意义 (P >0 .0 5 ) ,但二者的rCBV值均高于正常脑实质。星形细胞瘤“邻近水肿区”的rCBV值显著高于转移瘤周围“邻近水肿区”的rCBV值 (P <0 .0 1) ,而星形细胞瘤、转移瘤“远离水肿区”的rCBV值间差异无显著性意义 (P >0 .0 5 )。结论 :MR灌注成像可精确提示正常脑实质及病变的血流状态 。

Objective:To study the scanning and postprocessing technique of MR perfusion and its application in evaluating cerebral astrocytoma.Methods:40 cases of astrocytoma,30 cases of metastasis and 30 normal cases as control group were performed plain and perfusion MR examination.40 frames were scanned totally,each comprising 5～6 slices,the scan time was 55s.All of the data were processed on twinstar workstation,the time-signal curve was converted into time-concentration curve.According to γ variation function,the rCBV(relative cerebral blood volume) was calculated.The perfusion state of normal and abnormal areas was analyzed.The value of rCBV of gray and white matter,lesion and perifocal edema was measured and compared.Results:The rCBV value of normal brain was 1.56±0.39.The rCBV values of grade Ⅲ and Ⅳ astrocytoma were higher than that of the normal brain (P<0.01),and there was statistically significant difference between them (P<0.01).The range of variation of rCBV of grade Ⅳ astrocytoma was obvious.There was no significant difference of rCBV between the lesions of astrocytoma and metastastis.There was statistically significant difference of rCBV value (P<0.01) of adjacent edema between astrocytoma and metastastis,and there was no significant difference in the areas far from the edema between two groups (P>0.05).Conclusion:The MR perfusion curve can accurately evaluate the blood flow of the normal and abnormal areas of the brain,and can differentiate the primary and secondary tumors.