肝脏恶性肿瘤扩散加权成像与T2加权成像对比研究

目的比较肝脏扩散加权成像(DWI)和T2WI反映肝脏恶性肿瘤扩散特征、病理特征及肿瘤范围的价值.方法回顾性研究肝脏恶性肿瘤44例48灶(肝细胞癌30例30灶,肝转移瘤10例14灶,胆管细胞癌4例4灶),比较DWI与T2WI图像液体(脑脊液,胆囊胆汁)和肝脏恶性肿瘤的信号,肿瘤/肝脏信号强度比(SIR),对比噪声比(CNR)以及肿瘤范围,测量肿瘤表观扩散系数(ADC)值.结果在b=600 s/mm2的图像中,所有病例的脑脊液均显示为低信号.肝脏恶性肿瘤多表现为高信号,其信号分布特征与T2WI不同;肿瘤的信号强度和瘤/肝SIR,DWI与T2WI不相关;DWI信号强度与ADC值呈负相关.DWI的病灶对比噪声比高于T2WI,二者差异有显著性.DWI显示病灶范围与T2WI差异无显著性.结论b=600 s/mm2的肝脏DWI图像受T2穿透效应影响较小,能够较好地反映肝脏恶性肿瘤的扩散特征.DWI肿瘤对比噪声比更高,有助于病灶边界的确定.DWI反映的肝脏恶性肿瘤的扩散特征,可作为其影像学特征之一.

Comparison of diffusion-weighted imaging and T2-weighted imaging in hepatic malignant tumors

Objective To compare the value of diffusion-weighted imaging (DWI)and T2-weighted imaging (T2WI) in reflecting the diffusion and pathological characteristics, as well as extension of hepatic malignant tumors. Methods Forty-four patients with 48 lesions were retrospectively reviewed (30 hepatocellular carcinoma, 14 liver metastases, 4 cholangiocellular carcinoma). The signal intensity of fluid (cerebrospinal fluid and cystic bile) and hepatic malignant tumors, signal intensity ratio (SIR) of tumor/liver, contrast-to-noise ratio (CNR) of tumor, and extension of tumor both on DWI and T2WI were compared and apparent diffusion coefficient (ADC) values were measured. Results On DWI of b=600 s/mm2, cerebrospinal fluid appeared hypointensity in all cases. Most of the malignant tumors were hyperintensity on DWI, the distribution of signal was different from that of T2WI. Neither the signal intensity of tumor nor SIR was correlated between DWI and T2WI. The signal intensity and ADC value on DWI were negatively correlated. The CNR on DWI was higher than on T2WI and the difference was statistically significant. The difference of extension on DWI and T2WI was not statistically significant. Conclusion The signal intensity on DWI obtained with b=600 s/mm2 is less influenced by T2 shine through effect, thus reflects the diffusion characteristics of hepatic malignant tumors effectively. DWI is helpful to delineate the extension of tumor for its higher CNR. Thus the diffusion characteristics may be one of the imaging characteristics of hepatic malignant tumors.