磁共振弥散加权成像信号强度评价肝细胞癌组织分化程度的价值

Value of diffusion weighted imaging signal intensity in evaluating histopathological differentiation of hepatocellular carcinoma

目的 分析在弥散加权成像（DWI）目测信号强度、量化信号强度（SI）值与肝细胞癌（HCC）组织分化程度的关系,探讨DWI信号强度评价HCC组织分化程度的价值.方法 将病理证实的224例HCC分为3组：高分化组（31例）,中分化组（169例）,低分化组（24例）.所有患者均行MPI平扫、增强和DWI（1.5T,b值为0,600 s/mm2）检查.评估HCC瘤灶DWI目测信号强度,测量SI值,分析DWI目测信号强度、SI值与HCC组织分化程度的关系.结果 （1）224例HCC在DWI上,56.7％呈明显高信号,24.1％呈中等高信号,19.2％呈等/略高信号.等/略高信号与明显高信号两组癌组织分化程度差异有统计学意义（P＜0.05）.等/略高信号组与中等高信号组、中等高信号组与明显高信号组肿瘤分化程度差异无统计学意义（P＞0.05）.HCC瘤灶DWI信号强度与组织分化程度两者呈较弱的负相关关系（r=-0.324,P＜0.05）,随着HCC瘤灶DWI目测信号强度增高,组织分化程度降低;（2）随着肿瘤分化程度的降低瘤灶SI值呈逐渐升高趋势,总体间差异有统计学意义（P＜0.05）.高分化HCC的SI值显著低于中、低分化HCC（P ＜0.05）;中分化HCC的SI值虽亦低于低分化HCC,但差异无统计学意义（P＞0.05）.ROC曲线分析显示DWI的SI值用于诊断高分化HCC的最佳临界点为66.5,其灵敏度和特异度分别为90.1％和71.9％.结论 随着瘤灶DWI目测信号强度、SI值的升高,HCC组织分化程度降低（P＜0.05）.然而,SI值只能预测高分化HCC,而无法预测中分化与低分化HCC.因此,DWI目测信号强度及SI值用于预测HCC组织分化程度的价值有限.

Objective To determine the relationship between visual signal intensity and quantitative signal intensity of HCC assessed with DWI and histopathological differentiation of HCC.Methods The MR examinations including MRI plain scan,LAVA dynamic enhanced scan and DWI （1.5T,b value：0 and 600 s/mm2） of 224 patients who had surgically resected HCCs were retrospectively reviewed.Histopathological examinations revealed that there were 31 well-,169 moderately-,and 24 poorly-differentiated HCCs.The incidence of each visually evaluated signal intensity and quantitative signal intensity of HCC assessed with DWI signal intensity and the relationship between signal intensity and histopathological differentiation were assessed for each sequence.Results （1） On DWI,56.7% of HCCs appeared as obviously hyperintense,24.1% tumors appeared as moderate hyperintense,and 19.2% tumors appeared as isotense or slight hyperintense to the surrounding hepatic parenchyma.There was a significant difference between isotense/slight hyperintense and obvious hyperintense and histopathological differentiation （P 〈 0.05）.There was no significant difference between isotense/slight hyperintense and moderate hyperintense and histopathological differentiation （P 〈 0.05）.There was no significant difference between moderate hyperintense and obvious hyperintense and histopathological differentiation （P 〉 0.05）.Visually evaluated signal Intensity of HCC showed an inverse correlation with histopathological differentiation （r =-0.324,P 〈 0.05）.On DWI,the tumors tended to show a brighter signal with decreasing histopathological differentiation.（2） There was a significant difference in DWI signal intensity value among the well,moderately and poorly differentiated HCCs （P 〈 0.05）.The SI value of well differentiated HCCs was lower than that of moderately differentiated HCCs and poorly differentiated HCCs （P 〈 0.05）.The SI value of moderately differentiated HCCs was lower than that of poorly differentiated HCCs.However,there was no significant difference between the SI value of the moderately and poorly differentiated HCCs （P 〉 0.05）.ROC analysis showed that the optimal cutoff point of SI value in diagnosing well differentiated HCCs was 66.5.A cutoff SI value equal to or less than 66.5 was used to differentiate well-differentiated HCC from moderately-and poorly-differentiated HCC with a sensitivity of 90.1% and a specificity of 71.9%.Conclusions On DWI,the tumors tended to show a brighter,visually evaluated signal intensity and higher quantitative signal intensity with decreasing histopathological differentiation （P 〈 0.05）.The quantitative signal intensity of HCC assessed with DWI signal intensity could only predict well differentiated HCC.It was limited in predicting histopathological differentiation of HCC using evaluating signal intensity and quantitative signal intensity of HCC assessed with DWI.