GE Signa Twinspeed 1.5T磁共振肝脏扩散加权成像的技术探讨

目的探讨高场强双梯度磁共振机(GE Signa Twinspeed 1.5T)的肝脏扩散加权成像技术(DWI).方法对20例正常肝脏进行扩散加权成像研究,分别改变重复时间(TR)及扩散敏感系数(b值),测定ADC值、信噪比、图像质量等.结果 b值固定,TR值改变,正常肝组织平均ADC值差异不显著(P>0.05);TR值固定,b值改变,ADC值随b值增大而减小(P<0.05,差异有显著性).b值越大,图像质量越差;b≥800 s/mm2时,图像几乎难以观察.结论 ADC值随b值的增大而减小.行肝脏扩散加权成像时,可适当减小TR值,以缩短扫描时间及患者的屏气时间,减少呼吸运动伪影.

Study of technology of liver diffusion-weighted imaging at GE Signa Twinspeed 1.5

Objective To study the technology of liver diffusion-weighted imaging (DWI) at 1.5T MR (GE Signa Twinspeed). Methods DWI and measurement of apparent diffusion coeffecient (ADC) value, signal-to-noise ratio (SNR) and the quality of images were performed in 20 healthy subjects by changing TR value and b value at 1.5T MRI. Results When b value was not changed and TR value was changed, the ADCs of normal livers were insignificantly different ( P >0.05), but when TR value was not changed and b value was changed, the ADCs of normal livers were significantly different ( P < 0.05 ). The ADC decreased as the b value increased. The higher the b value became, the worse the quality of the DWI. When b value equal or exceed 800 s/mm 2, the quality of the DWI was too bad to be analyzed. Conclusion ADC value decreases as b value increases. To reduce the time of holding breath and artifacts of the breath and to improve the accuracy of the ADC value and the quality of DWI, we suggest that TR value can be appropriately reduced in liver DWI.