钆喷酸葡铵和不同b值对肝扩散加权成像的影响

Effect of Gd-DTPA and different b values on diffusion-weighted imaging of the liver

目的探讨钆喷酸葡胺(Gd-DTPA)和不同b值对肝脏扩散加权成像(DWI)的影响。方法收集20例健康志愿者和61例临床怀疑肝肿瘤的患者,均行增强前、后两次DWI扫描,对比分析DWI图的信噪比(SNR)、对比信噪比(CNR)以及表观扩散系数(ADC)值。结果最终44例患者共56个病灶和20例正常肝志愿者纳入研究,分为正常肝组(20例),肝囊肿组(16个病灶),肝海绵状血管瘤组(14个病灶),肝细胞癌(HCC)组(15个病灶),肝转移瘤组(11个病灶)。相同b值下比较,增强前后两次DWI各组SNR值、CNR值差异均无统计学意义(P>0.05),增强后DWI所得平均ADC值较增强前DWI所得平均ADC值有所减小,但其差异无统计学意义(P>0.05)。不同b值下比较,增强后DWI各组的SNR值、CNR值差异均有统计学意义(P<0.05),各值随b值的增大而减小;ADC值差异除肝囊肿组、转移瘤组无统计学意义(P>0.05)外,其余组均有统计学差异(P<0.05),且ADC值随b值增大而减小。结论钆对比剂Gd-DTPA对肝脏DWI图像质量和ADC值无显著影响,注射钆对比剂后5 min行肝DWI是可行的;在满足肝DWI图SNR和CNR的前提下,选择小b值有利于病灶的检出。

Objective To investigate the effect of Gd-DTPA and different b values on diffusion-weighted imaging （DWI） of the liver. Methods 20 healthy volunteers and 61 patients with suspected liver lesions underwent contrast-enhanced MRI and DWI. The signal-to-noise ratio （SNR）, contrast-to-noise ratio （CNR）, and apparent diffusion coefficient （ADC） were compared between the DWI before and after intravenous administration of Gd-DTPA. Results 56 liver lesions in 44 patients included 16 cysts, 14 cav-ernous hemangiomas, 15 hepatocellular carcinomas （HCCs）, and 11 metastases. At the same b value, there was no significantly differ-ence （i^〉0.05） among the SNR, GNR, and ADC values. The SNR and CNR after intravenous Gd-DTPA decreased significantly with in- creasing b values （P〈0.05） whereas the ADCs were also significantly decreased （P〈0.05） in cavernous hemangiomas and HCCs, and not in cysts and metastases. Conclusion Gd-DTPA had no significant effect on the image quality and ADC values of the liver on DWI at 5 minutes after intravenous contrast injection. Smaller b values are more conducive to the detection of lesions with better SNR and CNR.