摘要
目的：探讨在不同的扩散敏感系数（b值）下，肝脏血流灌注量的改变对肝右后叶、右前叶的表观扩散系数（ADC）值的影响。材料与方法：应用1.5T磁共振扫描系统对26例健康志愿者进行扩散加权成像（DWI）检查，在禁食水8小时和进食标准餐后1小时（可有效增加门脉及肝血窦的灌注量）后分别采集一次，比较进食前后的肝脏右后叶、右前叶ADC值的变化有无统计学意义，b值采用0，250，500，750s/mm2。结果：当b＝750s/mm2时，无论肝右后叶、右前叶，进食前后ADC值的改变均无统计学意义（t=1.419，P=0.178；t=1.943，P=0.072），当b＝250s/mm2时，进食前后的肝右后叶、右前叶ADC值改变均有统计学意义（t=3.839，P=0.002；t=5.178，P<0.001），当b＝500s/mm2时，在进食前后肝右后叶ADC值的改变无统计学意义（t=1.519，P=0.151），而右前叶ADC值的改变有统计学意义（t=2.449，P=0.028）。结论：选择禁食条件、测量肝右后叶并采用较大b值（b≥500s/mm2）可能成为一种避免血流灌注对肝ADC值测量影响的有效方法，为肝脏扩散成像提供稳定、优化的ADC值测量方案。
Abstract
Objective: To assess whether hepatic diffusion measurements are influenced by hepatic perfusion changes due to different b values in both posterior and anterior segments of right lobe. Materials and Methods: DWI was performed on a 1.5T MRI unit among 26 healthy volunteers after an 8h fast and 1h after a standard meal(which is regarded as an effective method to increase hepatic perfusion including portal venous flow and hepatic sinusoidal perfusion), we used a breath-hold technique for 20.5s at b-values of 750, 500 and 250 and 0s/mm2. The hepatic apparent diffusion coefficient(ADC) values were measured and compared due to different prandial states in both posterior and anterior segments of right lobe. Results: Compared the two sets of ADCs before and after meal, the ADC measurements using b=750s/mm2 in both posterior and anterior right lobe were unaffected by the perfusion changes(t=1.419, P=0.178; t=1.943, P=0.072) whereas the ADC values from b=250s/mm2 increased significantly after meal in both posterior and anterior segments of right lobe(t=3.839, P=0.002; t=5.178, P<0.001). As for b=500s/mm2, only the ADCs in the posterior right lobe was unchanged significantly after meal(t=1.519, P=0.151) when compared to the significantly changed ADCs in the anterior right lobe(t=2.449, P=0.028). Conclusion: With regard to the measurements of ADC, the effect of perfusion can be minimized at the higher b values(b≥500s/mm2) and in the posterior right lobe at the fasted state, which may offer the most consistent ADC values and optimized measuring conditions for further studies of hepatic DWI.
关键词
肝 /
磁共振成像
Key words
liver /
magnetic resonance imaging
石 喻;郭启勇;王晓明.
肝脏血流灌注对MR表观扩散系数值影响的初步研究[J]. 中国临床医学影像杂志. 2007, 18(8): 540-543
SHI Yu;GUO Qi-yong;WANG Xiao-ming.
Influence of blood perfusion on apparent diffusion coefficient measurement in the liver[J]. Journal of China Clinic Medical Imaging. 2007, 18(8): 540-543
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