Fast macromolecular proton fraction mapping of the human liver in vivo for quantitative assessment of hepatic fibrosis.
Fast macromolecular proton fraction mapping of the human liver in vivo for quantitative assessment of hepatic fibrosis.
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DOI：
10.1002/nbm.3437
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发表时间：
2015-12
影响因子：
2.9
通讯作者：
Ioannou GN
中科院分区：
文献类型：
--
作者：
Yarnykh VL;Tartaglione EV;Ioannou GN
大分子质子分数（MPF）是决定组织中磁化转移（MT）效应的定量MRI参数，定义为参与与可移动的水质子进行磁化交换的固定大分子质子的相对数量。由于强积金本身对胶原蛋白的高特异性，强积金具有定量评估纤维组织的潜力。本研究的目的是研究组织学上确定的纤维化阶段和肝实质MPF之间的关系，使用最近开发的快速单点临床靶向MPF制图方法测量。基于误差传播模型，对肝脏体内z谱进行分析，确定单点肝脏MPF测量的最佳饱和参数。16例慢性丙型肝炎病毒感染患者采用优化的肝脏MPF制图方案进行了3T MRI检查。14例患者既往肝活检组织学分期纤维化（METAVIR评分F0-F3）， 2例患者临床诊断为肝硬化（评分F4）。该方案包括4个屏气三维扫描，分辨率为2×3×6 mm3, 10个横切面：1)动态获取mt加权图像和参考图像；2)动态获取三幅图像进行变翻转角度T1映射；3)双回波B0图；4)实际翻转角成像B1图。以肝脏平均强积金为强积金直方图模式。临床显著纤维化患者（评分F2-F4， n=6）的MPF明显高于无纤维化或轻度纤维化患者（评分F0-F1， n=10）： 6.49±0.36%比5.94±0.26%，P<0.01 （Mann-Whitney检验）。MPF与纤维化评分呈强正相关，Spearman秩相关系数为0.80 （P<0.001）。本研究证明了体内人体肝脏快速MPF图谱的可行性，并证实了MPF在肝纤维化中增加并与纤维化分期相关的假设。MPF可作为肝纤维化的非侵入性成像生物标志物。
Macromolecular proton fraction (MPF) is a quantitative MRI parameter determining the magnetization transfer (MT) effect in tissues and defined as a relative amount of immobile macromolecular protons involved into magnetization exchange with mobile water protons. MPF has a potential for quantitative assessment of fibrous tissue due to intrinsically high MPF specific for collagen. The goal of this study was to investigate a relationship between histologically determined fibrosis stage and MPF in the liver parenchyma measured using a recently developed fast single-point clinically-targeted MPF mapping method. Optimal saturation parameters for single-point liver MPF measurements were determined from the analysis of liver Z-spectra in vivo based on the error propagation model. Sixteen patients with chronic hepatitis C viral infection underwent 3T MRI using an optimized liver MPF mapping protocol. Fourteen patients had prior liver biopsy with histologically staged fibrosis (METAVIR scores F0-F3), and two patients had clinically diagnosed cirrhosis (score F4 was assigned). The protocol included four breath-hold three-dimensional scans with 2×3×6 mm3 resolution and 10 transverse sections: 1) dynamic acquisition of MT-weighted and reference images; 2) dynamic acquisition of three images for variable flip angle T1 mapping; 3) dual-echo B0 map; and 4) actual flip-angle imaging B1 map. Average liver MPF was determined as the mode of MPF histograms. MPF was significantly increased in patients with clinically significant fibrosis (scores F2-F4, n=6) compared to patients with no or mild fibrosis (scores F0-F1, n=10): 6.49±0.36% vs. 5.94±0.26%, P<0.01 (Mann-Whitney test). MPF and fibrosis score were strongly positively correlated with the Spearman's rank correlation coefficient 0.80 (P<0.001). This study demonstrates the feasibility of fast MPF mapping of the human liver in vivo and confirms the hypothesis that MPF is increased in hepatic fibrosis and associated with fibrosis stage. MPF may be useful as a non-invasive imaging biomarker of hepatic fibrosis.