小鼠原位移植性肝癌模型磁共振扩散加权成像实验研究

目的探讨1.5T磁共振扫描仪对小鼠原位移植性肝癌模型扩散加权成像(DWI)显示能力及较佳b值选择。方法对22只小鼠原位移植性肝癌模型进行多b值DWI成像及T2WI成像。计算不同图像中肿瘤信噪比(SNR)、肿瘤与肝脏对比噪声比(CNR)及信号强度比(SIR)等数据,并进行统计学分析。结果DWI成像能显示T2WI所显示的所有肿瘤。DWI显示病灶范围与T2WI无统计学差异(F=0.048,P>0.05)。DWI图像中肿瘤SNR、肿瘤与肝脏CNR及SIR随b值升高而降低,均高于T2WI图像,与T2WI间有统计学差异(FSNR=58.012,FCNR=47.743,FSIR=12.353,各组P<0.05)。b值600s/mm2与900s/mm2间肿瘤SNR、肿瘤与肝脏CNR无统计学差异,其他各b值间肿瘤SNR、肿瘤与肝脏CNR均有统计学差异。b值300、600、900s/mm2间及300与2000s/mm2间肿瘤与肝脏SIR无统计学差异,其他各b值间肿瘤与肝脏SIR均有统计学差异。结论1.5T磁共振可以对小鼠原位移植性肝癌模型进行DWI成像,b=900s/mm2是DWI成像较佳b值。

Experimental study on implanted liver tumor model in mice by diffusion weighted MR imaging

Objective To investigate the techniques of MR diffusion weighted imaging for mice model with implanted liver tumor at 1.5T MR scanner and select the reasonable b value of DWI sequence. Methods Twenty-two mice models with implanted liver tumor were imaged by using DWI (b=300, 600, 900, 2000 s/mm~2) and T2WI sequences at 1.5T MR scanner. The signal to noise ratio (SNR) of tumors, contrast to noise ratio (CNR) and signal intensity ratio (SIR) of tumors and normal liver were calculated and analyzed. Results On diffusion-weighted images, all the tumors of mice models appeared hyperintensity. The difference of tumor extension on DWI and T2WI was not statistically significant (F=0.048, P>0.05). The SNR of tumors, the CNR, SIR of tumors and normal liver decreased with the ascending of b value, and were significantly higher than that in T2WI (F_ SNR =58.012, P_ SNR <0.05; F_ CNR =47.743, P_ CNR <0.05; F_ SIR =12.353, P_ SIR <0.05). There were no statistical differences of the SNR of tumors, the CNR of tumors and normal liver in DWI with b=600 and 900 s/mm~2, and the differences existed in DWI with other b values. There were no statistical differences of the SIR of tumors and normal liver in DWI not only among b=300, 600, 900 s/mm~2, but also between b= 300 and 2000 s/mm~2, and the differences of SIR existed in DWI with other b values. Conclusion The diffusion-weighted image of mice model with implantable liver tumor could be acquired at 1.5T MR scanner. 900 s/mm~2 is reasonable b value for DWI sequence.