Quantification of pancreatic lipomatosis and liver steatosis by MRI: Comparison of in/opposed-phase and spectral-spatial excitation techniques
Quantification of pancreatic lipomatosis and liver steatosis by MRI: Comparison of in/opposed-phase and spectral-spatial excitation techniques
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DOI：
10.1097/rli.0b013e31816a88c6
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发表时间：
2008-05-01
影响因子：
6.7
通讯作者：
Schick, Fritz
中科院分区：
文献类型：
--
作者：
Schwenzer, Nina F.;Machann, Juergen;Schick, Fritz
目的：本研究的目标是应用 2 种已建立的磁共振 (MR) 成像技术评估胰腺和肝脏脂肪含量：同相/反相梯度回波 MR 成像和脂肪选择性光谱空间梯度回波成像。比较了两种方法的结果，并评估了 T1 和 T2* 相关校正的影响。研究了胰腺脂肪增多症与肝脏脂肪变性之间相关性的可能性。 材料和方法：对 17 名有 2 型糖尿病风险的志愿者（6 名男性，11 名女性；年龄，26-70 岁；体重指数，19.4-41.3 kg/m(2)；平均，31.7 kg/m(2)）进行检查。使用两种不同的梯度回波技术对肝脏和胰腺脂肪含量进行定量：一种使用具有 6 个二项式射频脉冲的光谱空间激励技术，该技术将化学位移选择性与同时切片选择性激励相结合。另一种基于双回波化学位移梯度回波 MR 的技术同时提供同相和反相图像。基于额外的 T2* 测量，估计和校正 T1 和个体 T2* 效应对使用同相/反相成像的结果的影响。结果：根据使用脂肪选择性光谱空间梯度回波序列记录的图像计算的脂肪含量与通过同相/反相成像确定的脂肪分数以及 T1/T2* 效应校正后的脂肪分数密切相关：胰腺 r = 0.93 (P < 0.0001) 和肝脏 r = 0.96 (P < 0.0001)。同相/反相成像显示胰腺脂肪含量在 1.6% 到 22.2% 之间（平均 8.8% +/- 5.7%），肝脏脂肪含量在 0.6% 到 33.3% 之间。 （平均值为 7.9% +/- 9.1%）。脂肪选择性光谱空间梯度回波序列显示胰腺脂质含量在 3.4% 到 16.1% 之间（平均值为 9.8% +/- 4.0%），肝脏脂肪含量在 0% 到 28.5% 之间（平均值为 8.8% +/- 8.3%）。这两种技术都没有发现胰腺和肝脏脂肪含量之间存在显着相关性。结论：所提出的结果表明，这两种方法都是胰腺和肝脏脂肪定量的可靠工具。然而，为了通过同相/反相技术可靠地评估定量脂肪，额外测量 T2* 似乎至关重要。
Objectives: The goal of the present study was the assessment of pancreatic and hepatic fat content applying 2 established magnetic resonance (MR) imaging techniques: in-phase/opposed-phase gradient-echo MR imaging and fat-selective spectral-spatial gradient-echo imaging. Results of both approaches were compared, and influences of T1- and T2*-related corrections were assessed. T possibility of a correlation between pancreatic lipomatosis and liver steatosis was investigated.Materials and Methods: Seventeen volunteers at risk for type 2 diabetes (6 male, 11 female; age, 26-70 years; body mass index, 19.4-41.3 kg/m(2); mean, 31.7 kg/m(2)) were examined. Liver and pancreas fat content were quantified with 2 different gradient-echo techniques: one uses a spectral-spatial excitation technique with 6 binomial radio frequency pulses, which combines chemical shift selectivity with simultaneous slice-selective excitation. The other technique based on double-echo chemical shift gradient-echo MR provides in- and opposed-phase images simultaneously. Influences of T1 and individual T2* effects on results using in-phase/opposed-phase imaging were estimated and corrected for, based on additional T2* measurements.Results: The fat content calculated from images recorded with the fat-selective spectral-spatial gradient-echo sequence correlated well with the fat fraction determined with in-phase/opposed-phase imaging and following correction for T1/T2* effects: pancreas r = 0.93 (P < 0.0001) and liver r = 0.96 (P < 0.0001). In-phase/opposed-phase imaging revealed a pancreatic fat content between 1.6% and 22.2% (mean, 8.8% +/- 5.7%) and a hepatic fat fraction between 0.6% and 33.3%. (mean, 7.9% +/- 9.1%). The fat-selective spectral-spatial gradient-echo sequence revealed a pancreatic lipid content between 3.4% and 16.1% (mean, 9.8% +/- 4.0%) and a hepatic fat content between 0% and 28.5% (mean, 8.8% +/- 8.3%). With neither technique was a substantial correlation between pancreatic and hepatic fat content found.Conclusion: The presented results suggest that both methods are reliable tools for pancreatic and hepatic fat quantification. However, for reliable assessment of quantitative fat by the in-phase/opposed-phase technique, an additional measurement of T2* seems crucial.