肝局灶性病变CT与MRI动态增强对照研究

Comparative Study of CT and MRI Dynamic Enhancement on Hepatic Focal Lesions

目的:探讨肝局灶性病变在CT和MRI动态增强中的影像差异及其原因,以提高对CT及MRI各自动态增强表现的认识。方法:搜集17例肝脏局灶性病变患者的临床资料,其中7例肝细胞肝癌,5例海绵状血管瘤,2例腺瘤,2例局灶结节性增生,1例转移瘤。全部病例均分别行CT及MRI的平扫和三期动态增强扫描;MRI采用SE序列加快速扰相梯度回波序列,将CT和MR动态增强图像进行对照观察,包括动态增强各期的强化范围、强化方式和强化幅度,强化幅度的比较用病灶密度(信号)与肝脏密度(信号)的比值进行比较。结果:肝癌、腺瘤和局灶结节性增生在CT与MRI上强化范围相似。1例肝癌动脉期强化幅度MRI大于CT,3例肝癌和2例局灶结节性增生门脉期及延迟期强化幅度MRI大于CT,2例腺瘤增强各期强化幅度MRI均大于CT,以动脉期差异最大。5例海绵状血管瘤强化范围动脉期及门脉期MRI大于CT,延迟期则相仿。1例转移瘤CT增强各期均未见明显强化,MRI门脉期及延迟期可见环状强化。结论:肝局灶性病变CT与MRI动态增强表现存在一定的差异,主要表现为部分病变增强各期强化幅度MRI大于CT,尤以动脉期差异最大;部分病变增强范围MRI大于CT。

Objective：To study the difference between CT and MRI dynamic enhancement on hepatic focal lesions and reasons for the difference. Methods ： CT and MRI contrast dynamic enhancement examinations were performed on 17 cases of hepatic focal lesions,including 7 hepatocellular liver cancers, 5 cavernous haemangiomas, 2 adenomas, 2 nodular hyperplasias and 1 hepatic metastasis. For spiral CT scanning,plain scans were performed first, then the patients were injected with Iopamidol,and triphase dynamic scans were carried out. For MRI, plain scans with sequences of SE and FMPSPGR were performed, followed by triphase dynamic scans enhanced with Gd-DTPA. The images from enhanced dynamic CT and MR scans were compared for the range, mode and amplitude of the enhancement at each phase （for the extent of enhancement, the ratio between the signal densities of focus and normal liver tissue was compared）. Results.. The ranges of enhancement of CT and MRI of liver cancer,adenoma and nodular hyperplasia were similar. In 1 case of liver cancer,the amplitude of enhancement of MRI was greater than that of CT at the arterial phase. As for 3 cases of liver cancer and 2 cases of nodular hyperplasia,the amplitude of enhancement of MRI was greater than that of CT at both portal vein and lag phases. In 2 cases of adenoma, MRI signal was more remarkably enhanced than CT signal at all 3 phases, with the arterial phase most significant. All 5 hepatic cavernous haemangioma cases showed more significant enhancement with MRI than with CT at both arterial and portal vein phases, but similar results at lag phase. For the only case of hepatic metastasis no obvious enhancement was seen on CT at all 3 phases,but ringlike enhancement was detected in MRI at portal vein phase, and the ring expanded towards the centre at the lag phase. Conclusion.. There was difference between CT and MRI contrast dynamic enhancement of hepatic focal lesions. The main difference lies in that the amplitudes of enhancement with MRI were greater than those with CT at different phases,especially at arterial phase. In certain lesions,the range of enhancement was greater with MRI than with CT.