细菌性肝脓肿早期CT与MRI诊断现状及进展

Current state and progress on the diagnosis of early bacterial hepatic abscess with CT and MRI

在肝脓肿早期影像诊断中,CT增强扫描动脉期可能出现肝一过性密度(衰减)差异,静脉期"花簇征"或"蜂窝征",延迟期"逐渐充填征",为诊断该病的可靠征象;在肝动脉灌注成像(hepatic arterial perfusion,HAP)上,脓肿病变区及脓肿邻近区呈明显高灌注,脓肿内坏死区无灌注。肝脓肿在MRI平扫T_2WI上表现为高信号,而在T_1WI上为稍低信号;增强扫描动脉期可出现一过性强化信号,静脉期、延迟期与CT表现相似;在扩散加权成像(diffusionweighted imaging,DWI)上,脓肿未完全液化时表观扩散加权系数(apparent diffusion coefficient,ADC)值相对较低,DWI表现为高信号;灌注成像表现为时间-信号曲线(time-signal curve,TSC)呈速升-缓升型式。

Imaging diagnosis of early bacterial hepatic abscess（EBHA） mainly depends upon a series of characteristic signs which comprised transient hepatic attenuation difference（THAD） in postcontrast arterial phase,＂floral cluster＂signs or＂honey comb＂signs in portal venous phase,and＂gradual filling＂signs in delayed phase.On hepatic arterial perfusion images,EBHA lesions and their periphery areas were markedly high perfusion but necrotic areas were not enhanced.EBHA lesions were hyperintensity on precontrast MR T_2WI and slight hypointensity on T_1WI.During postcontrast arterial phase,EBHA lesions appeared as transient enhanced signals,during portal venous phase and delayed phase,MR findings of EBHA lesions were similar to those seen on CT images.On diffusion weight images（DWI）,EBHA lesions with incomplete liquefy appeared as relatively lower apparent diffusion coefficient（ADC） value,while DWI revealed hyperintensity. On perfusion images,time-signal curve（TSC） appeared as quick heighten-slow heighten pattern.