Objectives

Chemical Shift Encoded Magnetic Resonance Imaging (CSE-MRI)-based quantification of low-level (< 5% of proton density fat fraction—PDFF) fat infiltration requires highly accurate data reconstruction for the assessment of hepatic or pancreatic fat accumulation in diagnostics and biomedical research.

Materials and methods

We compare three software tools available for water/fat image reconstruction and PDFF quantification with MRS as the reference method. Based on the algorithm exploited in the tested software, the accuracy of fat fraction quantification varies. We evaluate them in phantom and in vivo MRS and MRI measurements.

Results

The signal model of Intralipid 20% emulsion used for phantoms was established for 3 T and 9.4 T fields. In all cases, we noticed a high coefficient of determination (R-squared) between MRS and MRI–PDFF measurements: in phantoms <0.9924–0.9990>; and in vivo <0.8069–0.9552>. Bland–Altman analysis was applied to phantom and in vivo measurements.

Discussion

Multi-echo MRI in combination with an advanced algorithm including multi-peak spectrum modeling appears as a valuable and accurate method for low-level PDFF quantification over large FOV in high resolution, and is much faster than MRS methods. The graph-cut algorithm (GC) showed the fewest water/fat swaps in the PDFF maps, and hence stands out as the most robust method of those tested.

中文翻译：

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3 T下的低水平脂肪含量定量：水脂重建和MR光谱分析不同工具的比较研究。

目标

基于化学位移编码磁共振成像（CSE-MRI）的低水平（<质子密度脂肪分数的不到5％– PDFF）脂肪浸润的定量分析需要高度准确的数据重建，以评估肝癌或胰腺脂肪在诊断和生物医学中的积累研究。

材料和方法

我们比较了三种可用于水/脂肪图像重建和PDFF量化的软件工具，并以MRS作为参考方法。基于测试软件中使用的算法，脂肪部分定量的准确性会有所不同。我们在幻像和体内MRS和MRI测量中评估它们。

结果

建立了3T和9.4T场的用于模型的脂质体内20％乳状液的信号模型。在所有情况下，我们都注意到在MRS和MRI–PDFF测量之间存在较高的确定系数（R平方）：幻像<0.9924–0.9990>；和体内<0.8069-0.9552>。Bland–Altman分析应用于幻像和体内测量。

讨论区

多回波MRI与包括多峰频谱建模在内的先进算法相结合，是对高分辨率大FOV上的低级PDFF量化的一种有价值且准确的方法，并且比MRS方法要快得多。图切算法（GC）显示了PDFF映射中最少的水/脂肪交换，因此在测试的那些方法中脱颖而出。