1H-MRS和MR双回波技术活体半定量评价酒精性与非酒精性脂肪肝大鼠模型

In vivo semiquantitative evaluation of liver fat content in alcoholic and nonalcoholic fatty liver rat models：comparison between dual-echo T1-weighted imaging and ~1H-MR spectroscopy with correlation of histopathology

目的探讨磁共振质子波谱成像(1H-MRS)技术和同、去相位(IP/OP)序列在酒精性脂肪肝(ALD)和非酒精性脂肪肝(NAFLD)大鼠模型中定量测定脂肪含量的价值。方法 120只雄性S-D大鼠随机分为对照组、实验组(高脂组、酒精组和酒精加高脂组),在第0,4,8,12周时进行IP/OP和1H-MRS扫描,计算IP/OP的FI(fatindex)指数和1H-MRS水、脂的RLC(relativelipidcontent)指数,将FI与RLC与病理结果对照。结果各组的FI指数和RLC均与病理学结果相关(P<0.01,r=0.54～0.96),RLC与病理的相关性(r=0.89～0.96)高于FI(r=0.54～0.85)。FI在正常与轻度、轻度与中度脂肪肝间无统计学差异,RLC在正常、轻、中、重度分级间均存在统计学差异(F=65.072,P<0.01)。非酒精性脂肪肝的RLC和FI与病理的相关程度相近(rRLC=0.886,rFI=0.854),酒精性脂肪肝的RLC与病理的相关性优于FI(rRLC=0.95～0.96,rFI=0.54～0.65)。结论对于轻度脂肪肝和ALD模型,1H-MRS比IP/OP诊断准确度更高;对于中重度和/或NAFLD模型,1H-MRS和IP/OP诊断价值相近。

Objective：To investigate the values of 1H-MR spectroscopy （1H-MRS） and gradient-echo T1-weighted MR imaging （in-phase and opposed-phase） in quantifying liver fat content （LFC） in rat models of both nonalcoholic fatty liver disease （NAFLD） and alcoholic liver disease （ALD）. Materials and Methods：Total 120 healthy Sprague-Dawle male rats were randomly divided into control group,fatty liver group,alcoholic fatty liver group,and mixed models group. At the baseline,4th,8th,and 12th week,at least 6 or more rats were selected to receive dual-echo T1W imaging and 1H-MRS of the liver. Fat indexes （FI） for dual-echo T1W imaging and relative lipid content （RLC） of 1H-MRS were measured and compared to pathological grades of fatty liver. Results：Both FI of dual-echo T1W and RLC of 1H-MRS were correlated linearly with the histopathological grading （P0.01,r=0.54–0.96）. RLC （r=0.89-0.96） showed much closer correlation with histopathology than FI （r=0.54–0.85） in all the experimental rat models. For FI,the differences between the normal and mild,mild and moderate steatosis were not significant （P0.05）,while RLC demonstrated significant differences between the normal and each grade of steatosis （P0.01）. For ALD,RLC and FI have the similar values as to fatty liver content （rRLC=0.886,rFI=0.854）,whereas RLC was superior to FI for NAFLD （rRLC=0.95–0.96,rFI=0.54-0.65）. Conclusion：In vivo 1H-MRS and dual-echo T1W can quantitatively evaluate both NAFLD and ALD in rat models. 1H-MRS is more accurate and reliable for discrimination mild fatty liver and in NAFLD.