SD大鼠骨肉瘤坏死区DWI的实验研究初探

目的:建立SD大鼠骨肉瘤模型,初步探讨DWI显示肿瘤坏死的价值。方法:将UMR-106细胞悬液接种于Sprague Dawley大鼠背部皮下,其中4周龄者16只,6周龄和8周龄者各4只。对所形成的肿瘤行MRI常规扫描、增强扫描及EPI-DWI成像并做病理对照。比较活肿瘤细胞区和坏死区的T1信号强度、T2信号强度、T1信号增加值、T1信号增强率及ADCm。结果:16只4周龄者均有肿瘤形成,6周龄者和8周龄者没有可用于实验的肿瘤形成。16只肿瘤形成者的MR扫描显示,活肿瘤细胞区和坏死区的T1、T2信号强度值之间差异无显著性意义(P>0.05)。两种组织的T1信号增加值、T1信号增强率之间差异有显著性意义(P<0.05)。两种参数确定肿瘤坏死区的敏感度为86.7%(13/15),特异度为38.5%(15/39),诊断符合率为51.9%(28/54)。活肿瘤细胞区与坏死区的ADCm之间差异有显著性意义(P<0.05),ADC值确定肿瘤坏死区的敏感度为93.3%(14/15),特异度为94.9%(37/39),诊断符合率为94.4%(51/54)。结论:EPI-DWI较传统MRI序列及增强扫描能更准确早期分辨SD大鼠骨肉瘤坏死区。

A Primary Experimental Study to Identify Necrosis of Sprague-Dawley Rat Osteosarcoma by DWI

Objective:To set up Sprague-Dawley Rat osteosarcoma model,and primarily to evaluate the role of EPI-DWI in the identification of the necrosis of the tumor.Methods:The tumor cells(UMR-106) were transplanted in the back of 16 male 4 weeks of age,4 male 6 weeks of age,and 4 male 8 weeks of age Sprague-Dawley rats by subcutaneous injection of a suspension respectively.After growing up,the transplanted tumors were scanned with MR system.Conventional sequences,contrast enhanced T_1-SE were obtained.EPI-DWI was performed.The MR images were compared with the pathologic sections.The signal intensity on T_1WI,T_2WI,postcontrast T_1WI and increasing rate of signal intensity pre-and postcontrast T_1WI and apparent diffusion coefficient value were compared between the viable and necrotic areas of the tumors.Results:The tumor grown up on all 16 male Sprague-Dawley rats of 4 weeks age,no tumor formation on the all rats of 6,or 8 weeks age.There was no significant difference between the signal intensity in the viable and necrotic areas of the tumors on T_1WI and T_2WI(P>0.05).There was significant difference between the signal intensity on postcontrast T_1WI in the viable and necrotic areas of the tumors(P<0.05).There was significant difference between the increasing rate of signal intensity in viable and necrotic areas of the tumors pre-and postcontrast T_1WI(P<0.05).According to the difference to identify the necrosis,its sensitivity was 86.7%(13/15),specificity was 38.5%(15/39) and veracity was 51.9%(28/54).There was significant difference between the apparent diffusion coefficient value in the viable and necrotic areas of the tumors(P<0.05).It was feasible to identify the necrotic regions by apparent diffusion coefficient values,and its sensitivity was 93.3%(14/15),specificity was 94.9%(37/39) and veracity was 94.4%(51/54).Conclusion:The viable and necrotic areas of the tumors could be differentiated by EPI-DWI more accurately and earlier than traditional MRI sequences and postcontrast scan.