为什么部分肝脏局灶病变在超顺磁氧化铁增强T_1WI上呈现高信号

目的:探讨肝脏病变在SPIO增强扫描T1WI上呈现高信号的机制.方法:肝脏局灶病变39例(56个病灶),其中33个恶性病灶(肝细胞癌10个、转移瘤21个、胆管细胞癌2个)和良性病灶23个(海绵状血管瘤9个,肝囊肿14个).平扫序列包括SE T1WI、FSPGR T1WI及FSE T2WI.SPIO(菲立磁)增强扫描序列包括FSE T2WI、SE T1WI(TE值分别为8 ms、20 ms)和 FSPGR T1WI(TE值分别为1.5 ms、4.2 ms).分析不同序列图像上病灶及肝实质的的信号变化.结果:在SPIO增强T1WI上,随着TE的延长,肝实质信号降低,肝内局灶病变信号相对增高.在SPIO增强长TE T1WI上,大部分恶性病灶及全部血管瘤呈相对高信号.结论:在SPIO增强T1WI上,SPIO对肝实质的T2*效应可能是部分局灶病变呈高信号的主要原因.

Why Some Hepatic Focal Lesions Are Hyperintense on SPIO-enhanced T1WI

Objective:To investigate the mechanism of hyperintensity of focal hepatic lesions on SPIO-enhanced T1WI.Methods:Of 39 patients with 56 focal liver lesions including 33 malignant tumors (10 hepatocellular carcinomas,21 metastases,2 cholangiocarcinomas) and 23 benign lesions (9 hemangiomas and 14 cysts) were analyzed.Images were obtained at a 1.5T MR scanner.The pre-contrast sequences included SE T1WI,FSPGR T1WI,and FSE T2WI.The SPIO enhanced sequences included FSE T2WI,SE T1WI with different TE (8ms,20ms),and FSPGR T1WI with different TE (1.5ms,4.2ms).The signal intensities of lesions and hepatic parenchyma in different sequences was analyzed.Results:On SPIO enhanced T1WI,followed the prolongation of TE,the signal intensity of the liver parenchyma decreased and the signal intensity of the lesions increased relatively.On post-contrast T1WI sequences with long TE,most of the malignant lesions and all hemangiomas showed hyperintensity.Conclusion:On SPIO enhanced T1WI sequence,T2* effect of SPIO on hepatic parenchyma around the focal lesions might be the main cause of hyperintensity of some focal hepatic lesions.