磁共振弥散加权成像评价肝纤维化的临床病理对照研究

目的 探讨磁共振弥散加权成像(DWI)评价慢性病毒性肝炎患者纤维化和炎症程度的临床应用价值.方法 对85例慢性肝炎患者和22名健康志愿者进行前瞻性的DWI检查,选用5个不同b值(100、300、500、800、1000 s/mm2),测量不同b值条件下的肝脏表观弥散系数(ADC)值.对慢性肝炎患者肝穿刺病理改变进行纤维化分期和炎症分级.运用单因素方差分析比较不同纤维化分期之间和不同炎症分级之间ADC值的差异,运用Spearman相关分析探讨ADC值变化和纤维化分期、炎症分级之间的相关性.运用受试者工作曲线评估ADC值预测2期及以上肝纤维化、3期及以上肝纤维化、1级及以上炎症活动度的诊断效能.结果 ADC值与纤维化分期之间有中度负相关性,b值取800 s/mm2时相关性最佳(r=-0.697,P=0.000).在不同b值条件下,肝纤维化≤1期与≥12期之间、纤维化≤2期与≥3期之间肝脏ADC值进行比较,差异均有统计学意义(均P<0.05);在b值取800 s/mm2时,DWl诊断≥2期肝纤维化的曲线下面积为0.909,以ADC值≤1.26×10-3mm2/s为标准,敏感性和特异性分别为76.6%和88.3%;DWI诊断≥3期肝纤维化的曲线下面积为0.917,以ADC值≤1.19×10-3mm2/s为标准,敏感性为80.0%,特异性为91.5%.ADC值与炎症分级之间有轻中度负相关性.当b值取500 s/mm2时,诊断≥1级肝脏炎症活动度的曲线下面积为0.781,以ADC值≤1.54×10-3mm2/s为标准,敏感性为60.0%,特异性为86.4%.结论 磁共振弥散加权成像可以初步用于肝纤维化的分期和炎症的分级,为临床肝纤维化的早期诊断和治疗后的随访提供了新的手段.

Comparative study on clinical and pathological changes of liver fibrosis with diffusion-weighted imaging

Objective To evaluate the clinical practical value of apparent diffusion coefficient (ADC) measurements based on diffusion-weighted MR imaging (DWI) for quantification of liver fibrosis and inflammation for hepatitis viral infection.Methods Diffusion-weighted MRI with parallel imaging was prospectively performed on 85 patients with chronic hepatitis and on 22 healthy volunteers within a single breath-hold using a single-shot spin-echo echo-planar sequence at b values of 100, 300, 500,800 and 1000 s/mm2 respectively. ADC values of liver were measured with five different b values. The inflammation grades and fibrosis stages were evaluated histologically by biopsy. One-way analysis of variance and Spearman' s rank correlation test were used for statistical analysis. Receiver operating characteristics analysis was used to assess the performance of ADC in predicting the presence of stage ≥2 and stage ≥3 hepatic fibrosis, and grade ≥1 hepatic inflammation. Results There was moderate negative correlation between hepatic ADC values and fibrosis stage. And the best correlation was obtained for a b value of 800 s/mm2 (r = - 0. 697, P=0.000). At all b values there was a significant decrease in hepatic ADC in patients with stage ≤1versus stage ≥2 fibrosis and stage ≤2 versus stage ≥3 fibrosis (P <0. 05). Hepatic ADC was a significant predictor of stage ≥2 and ≥3 fibrosis. The areas under the curve were 0. 909 vs 0. 917, sensitivity 76. 6% vs 80. 0% and specificity 88. 3% vs 91.5% (ADC with a b value of 800 s/mm2, 1.26 × 10<'3> mm2/s or less and 1.19 × 10-3 mm2/s or less). There was weak to moderate negative correlation between ADCs and inflammation grade. Hepatic ADC was a significant predictor of grade ≥1 inflammation with an area under the curve of 0. 781, sensitivity of 60. 0% and specificity of 86. 4% (ADC with a b value of 500 s/mm2, 1.54 × 10-3 mm2/s or less). Conclusion The D WI measurement of hepatic ADC can be used to quantify liver fibrosis and inflammation. It will be a new approach for early diagnosis and therapeutic follow-up of hepatic fibrosis.