常规磁共振成像与磁共振弥散加权成像在不同分化小肝癌中的临床应用

Clinical application of conventional magnetic resonance imaging and diffusion-weighted imaging in differentiating histopathologicai types of small hepatocellular carcinoma

目的探讨常规磁共振成像（MRI）与磁共振弥散加权成像（DWI）在不同分化程度小肝癌（SHCC）的影像学特征及诊断价值。方法经病理结果证实的40例sHcC瘤灶分为4组：高分化组（n=6）、高中分化组（n=5）、中分化组（n=27）和中低分化组（n=2）。所有患者均行常规MRI和DWI（1．5T，b=0和600s／mm2）检查，对sHCC瘤灶的影像学特征进行观察，测量其ADC值并进行统计学分析。结果sHCC瘤灶T1WI上呈稍低／低信号有32例，呈稍高／高信号有4例（高分化组），呈等信号有4例（高中=2，中分化=2）。T2wI上呈稍高／N信号有39例，高分化组中1例呈等信号。瘤灶脂肪变为17例（17／40，42．5％，高=4，高中-1，中=12）。伴有包膜形成有67．5％（27／40，高=4，高中=3，中=18，中低=2）。增强扫描动脉期瘤灶呈多血供有32例，少血供有8例（高=3，中=4，中低=1）。DWI上除高分化组中3例呈等信号外（50％，3／6），其余37例均呈稍高／高信号。高、高中、中和中低分化组的sHCC病灶的平均ADC值分别为（1．757±0．337）×10-3、（1．917±0．574）×10-3、（1．816±0．545）×10-3和（1．723±0．217）×10-3，4组之间差别无统计学意义。结论常规MRI上高中、中、中低分化sHCC影像学表现较典型，DWI上均呈高信号；但部分高分化sHCC常规影像表现不典型，DWI上可呈等或高信号，此时动态密切随访至关重要。总之，常规MRI联合DwI检查有助于sHCC的早期诊断，尤其是不典型sHCC。

Objective To study the imaging apperances and the diagnostic value of conventional magnetic resonance imaging （MRI） and diffusion-weighted imaging （DWI） in differentiating histopathological types of small hepatocellular carcinoma （sHCC）. Methods 40 sHCC confirmed by hi topathology were classified into 4 groups according to their degree of differentiation： well （n： 6）, well-moderate （n=5）, moderate （n= 27） and moderate-poor （n= 2）. All patients received conven- tional MRI and DW1 （1. 5T, b = 0 and 600 s/mmz ） before the operation. The ADC values of the sHCC were measured and compared. Results On TlWI, 32 lesions showed hypointensity, 4 hyperin- tensity （well） and 4 isointensity （well-moderate= 2, moderate= 2）. On T2WI, hyperintensity was observed in 39 lesions and isointensity in 1 lesion （well）. Steatosis in the sHCC was seen in 17 of 40 lesions （17/40, 42.5 vf0, well= 4, well-moderate= 1 and moderate= 12）. A pseudocapsule was seen in 67.5 % sHCC （27/40, well=4, well-moderate 3, moderate= 18 and moderate-poor= 2）. 32 lesions showed hypervascularity on arterial phase, and 8 lesions showed hypovascularity （well= 3, moderate =4, moderate-poor= 1）. On DWI, 37 lesions showed hyperintensity, except for 3 lesions with well- differentiated sHCC which showed isointensity （50%, 3/6）. The mean ADC values4-S. D. of sHCC in the well, well-moderate, moderate and moderate-poor groups were （1.757 ±0.337）×10-3 （1. 917±0. 574） ×10-3, （1. 816 ± 0. 545）×10-3and （1. 723 ± 0. 217）×10-3 , respectively. There were no significant differences among the 4 groups. Conclusion The imaging appearances of well- moderate, moderate and moderate-poor sHCC on conventional MRI were classical which make diagno sis easy. Hyperintensity on DWI contributed to diagnosis. However, the imaging appearances of some well-differentiated sHCC were atypical. The lesions could be isointensity or hyperintensity on DWI. The combination of conventional MRI and DWI contributed to better diagnosis of sHCC, especial for atypical sHCC.