MR磁敏感加权成像对肝硬化背景下小肝癌的诊断价值

Value of MR susceptibility weighted imaging for characterization of small hepatocellular carcinoma in cirrhotic livers

目的探讨MR磁敏感加权成像（SWI）对肝硬化背景下小肝癌（sHCC）的诊断价值。方法前瞻性收集临床疑诊为肝细胞癌（HCC）需行腹部MRI检查的肝占位性病变患者272例，排除病灶直径〉3cm、无肝硬化、非HCC的患者，最终67例共84个结节纳入研究。其中包括DN患者12例共22个结节；sHCC患者包括DN癌变结节患者7例共8个结节，完全性HCC患者48例共54个结节。患者均行上腹部常规MRI和SWI检查。由2名分别具有12、4年腹部影像诊断经验的放射科医师（分别为医师1、医师2）采用双盲法对常规MRI、常规MRI联合SWI图像阅片，评价病灶信号特征及强化方式，并对诊断信心予以评分。采用Kappa检验评价2名医师诊断的一致性，应用t检验比较常规MRI及常规MRI联合SWI图像诊断信心评分的差异，以病理和综合随访结果为金标准，应用ROC评价2种阅片方法的诊断效能。结果2名医师对常规MRI图像和常规MRI联合SWI图像诊断的一致性均好，Kappa值分别为0．923和0．865。医师1采用常规MRI诊断sHCC的敏感度、特异度、准确度和ROC下面积分别为80．6％、81．8％、81．O％和0．804，采用常规MRI联合SWI诊断sHCC的上述值分别为93．5％、90．9％、92．9％和0．898；医师2采用常规MRI诊断sHCC的敏感度、特异度、准确度和ROC下面积分别为80．6％、77．3％、79．8％和0．782，采用常规MRI联合SWI诊断sHCC的上述值分别为85．5％、86．4％、85．7％和0．859。2名医师常规MRI联合SWI图像的诊断效能均高于常规MRI。医师1采用常规MRI及联合SWI诊断最大径〈2cm病灶（36个）的评分分别为（3．40±0．91）、（3．86±0．47）分，医师2分别为（3．41±0．92）、（3．85±0．57）分，差异均有统计学意义（t值分别为3．733和2．468，P值分别为0．001和0．018）。结论SWI与常规MRI结合可以提高肝硬化背景下sHCC的诊断效能。

Objective To investigate the value of susceptibility- weighted imaging （SWI） for characterization of small hepatocellular carcinoma （sHCC） in cirrhotic livers. Methods Two hundred seventy- two patients suspiciousof HCC underwent conventional MR imaging and susceptibility-weighted imaging （SWI）. Two hundred and five patients were excluded due to either size larger than 3.0 cm, no cirrhosis or HCC. Finally, a total of 84 hepatoeellular nodules in 67 patients were included in this prospective study. There were 22 DNs in 12 eases, 8 DNs with HCC foci in 7 cases, and 54 overt HCCs in 48 cases. Two abdominal radiologists independently evaluated signal intensity and enhancing pattern using conventional MRI set and conventional MRI combining with SWI set. A five-point scale was performed to evaluate diagnostic confidence of HCC. Kappa analysis was performed to assess interobserver agreement of the two sets by two readers.The diagnostic performance and confidence level were compared for each image set,ROC was used to evaluate the diagnostic efficiency.Results Good interobserver agreement was identified with a Kappa value of 0.923 for conventional MRI set and 0.865 for conventional MRI combining with SWI set, respectively. The diagnostic sensitivity, specificity, accuracy, and area under the ahemative- free response ROC （Az） were 80.6% and 80.6%, 81.8% and 77.3%, 81.0% and 79.8%, 0.804 and 0.782 using conventional MRI set, and 93.5% and 85.5%, 90.9% and 86.4%, 92.9% and 85.7%, 0.898 and 0.859 using conventional MRI combining with SWI set for reader 1 and reader 2, respectively.The diagnostic confidence level of conventional MRI combining with SWI set for diagnosis of HCC with less than 2 cm in size（n=36） was significantly higher than that of conventional MRI （reader 1, 3.86±0.47 vs 3.40±0.91;reader 2, 3.85±0.57 vs 3.41±0.92;t values were 3.733 and 2.468, P were 0.001 and 0.018）.Conclusion SWI can provide additional valuable information and improve diagnostic performance for characterization of sHCC in cirrhotic livers.