~1H-MRS联合梯度回波化学位移MRI定量评估脂肪肝的价值

The value of ~1H-MRS combined with gradient-echo chemical shift MRI in quantitative evaluation of fatty liver

目的探讨3.0 T磁共振氢谱(proton magnetic resonance spectroscopy,~1H-MRS)联合梯度回波化学位移MRI在定量评估脂肪肝中的价值。方法对31例健康志愿者及22例可获得肝脏标本的患者行梯度回波T1加权同相位/去相位(in-phase/opposed-phase,IP/OP)成像及肝脏~1H-MRS检查。测得IP/OP的信号强度值(SIin,SIout),计算脂变指数(fat index,FI)。测定水峰及脂峰峰值(P_W,P_L)、水峰及脂峰峰下面积(A_W,A_L),计算肝细胞的相对脂肪含量(relative lipid content,RLC)。22例患者于MRI扫描后接受外科手术切除,进行组织学检查,并用图像分析软件测得肝细胞脂变细胞百分比(proportion of fatty degenerative cells,PFDC)。结果脂肪肝组FI、P_L、A_L及RLC的平均值均高于非脂肪肝组(P<0.05)。FI、P_L、A_L及RLC与PFDC之间存在正相关关系(P<0.05)。P_L、A_L、RLC在无脂肪肝组、轻度脂肪肝组与中重度脂肪肝组间比较差异均有统计学意义(P<0.05)。结论~1H-MRS联合梯度回波化学位移MRI可以在一定程度上区分有无脂肪肝;在脂肪肝定量分析方面,~1H-MRS较梯度回波化学位移MRI更具优越性;~1H-MRS有助于脂肪肝的分级,但对于无脂肪肝与轻度脂肪肝的鉴别价值有限。

Objective To investigate the value of proton magnetic resonance spectroscopy （^1 H-MRS） combined with gradient- echo chemical shift MRI in quantitative evaluation of fatty liver at 3.0 T MR Unit. Methods Gradient-echo T1 W in-phase/opposed- phase （IP/OP） images and 1H-MRS were performed in 31 healthy volunteers and 22 patients who were candidates for liver surgery. Signal intensities of IP＆OP （ SIin ＆ SIout ） were measured respectively. The fat index （FI） was calculated. The values of water peak （ PW ） and lipid peak （ PL ） , as well as the area under water peak （ Aw ） and lipid peak （ AL ） were measured, respectively. Then the relative lipid content of liver ceils （RLC） was calculated. Twenty-two patients accepted liver resection and histological examination after MRI scanning. The proportion of fatty degenerative ceils （PEDC） was calculated by image analysis software. Results The fatty liver group showed higher average values of FI, PL, AL and RLC compared to non-fatty liver group （P 〈 0. 05 ）. FI, PL, ALand RLC were positively correlated with the PFDC （P 〈 0. 05）. There were significant differences in PL, AL and RLC between non-and moderate-severe fatty liver group, as well as between mild and moderate-severe fatty liver group （P 〈 0. 05）. Conclusion ^1 H-MRS combined with gradient-echo chemical shift MRI can help to differentiate fatty liver patients from normal persons. In quantitative evaluation of fatty liver content, ^1H-MRS is superior to gradient-echo chemical shift MRI. ^1H-MRS can help to classify fatty liver, while the role is limited for the identification non-fatty liver and mild fatty liver.