MR扩散加权成像对经皮肝脏消融灶组织成分定性研究的初探

Diffusion-weighted MR imaging: characteristic study on tissue component in percutaneous ablative foci of the liver

目的评估MR扩散加权成像（DWI）对经皮肝脏消融灶的组织成分进行定性的能力。方法对48例因肝脏局灶性病变接受消融治疗的患者行常规MRI和DWI，与组织病理学改变对照，观察消融灶的MRI表现，测量各组织成分在DWI中的信号值与ADC值。不同b值下各组织成分的ADC值均数行单因素方差分析比较，每2组间数据用单因素方差分析的Bonferroni法比较。结果常规MRI和DWI信号强度不能准确区分消融灶各组织成分，但信号强度有利于各成分ADC值测量的准确定位。在b值500s／mm^2，各成分ADC值为：消融凝固性坏死（0．44±0．21）mm^2·s^-1·10^-3、肝充血（1．96±0．14）mm^2·s^-1·10^-3、肉芽组织（2．28±0．24）mm^2·s^-1·10^-3、存活肿瘤（1．24±0．08）mm^2·s^-1·10^-3、肝脏（1．69±0．08）mm^2·s^-1·10^-1，每2组数据间差异有统计学意义（F值为1280．49，多重比较每2组间均数差值为0．26～1．83，P〈0．05）。结论DWI能对肝脏消融灶各组织成分定性，有希望提高MRI判断消融后局部疗效的准确性。

Objective To evaluate the capacity of diffusion-weighted imaging （DWI） for characterization of tissue component in ablative loci of the liver. Methods Conventional MRI and DWI were performed in 48 patients who had experienced ablative therapy because of the hepatic tumors. MR manifestations of ablative loci were observed and compared with the pathological changes. The signal intensities and ADC values of different tissue components in ablative loci were measured. The means of ADC values in different b factor were compared with One-Way ANOVA, and multiple comparisons among data of different tissue components were made with Bonferroni. Results Different tissue components in ablative loci could not be correctly distinguished by conventional MRI and signal intensities of DWI. But the signal intensities were served as location of different tissue components in ablative loci for correct measurement of ADC values. In b = 500 s/mm^2, the ADC values of different tissue components in ablative loci （ unit： mm^2 · s^-1 · 10^-3 ） were as follow： ablative necrosis was 0. 44 ± 0. 21, hepatic congestion 1.96 ± 0. 14, granulation tissue 2. 28 ± 0. 24, viable tumor 1.24 ± 0. 08, and liver 1.69 ± 0. 08. As b factor increased, the ADC value became decreased. The ADC values of above-mentioned tissue components were significantly different （ F = 1280. 49, the differences of multiple comparisons among data of different tissue components were 0. 26 - 1.83, P 〈 0. 05 ）. Conclusion DWI can characterize and distinguish different tissue components of ablative loci in the liver by ADC value so that it is a valuable method for follow-up in ablative therapy of the patients with hepatic tumor.