Zhong Xiaodong, Armstrong Tess, Nickel Marcel D, Kannengiesser Stephan A R, Pan Li, Dale Brian M, Deshpande Vibhas, Kiefer Berthold, Wu Holden H
MR R&D Collaborations, Siemens Healthcare, Los Angeles, California.
Department of Radiological Sciences, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California.
Magn Reson Med. 2020 Jun;83(6):1964-1978. doi: 10.1002/mrm.28052. Epub 2019 Nov 4.
To develop an accurate free-breathing 3D liver mapping approach and to evaluate it in vivo.
A free-breathing multi-echo stack-of-radial sequence was applied in 5 normal subjects and 6 patients at 3 Tesla. Respiratory motion compensation was implemented using the inherent self-gating signal. A breath-hold Cartesian acquisition was the reference standard. Proton density fat fraction and were measured and compared between radial and Cartesian methods using Bland-Altman plots. The normal subject results were fitted to a linear mixed model (P < .05 considered significant).
Free-breathing stack-of-radial without self-gating exhibited signal attenuation in echo images and artifactually elevated apparent values. In the Bland-Altman plots of normal subjects, compared to breath-hold Cartesian, free-breathing stack-of-radial acquisitions of 22, 30, 36, and 44 slices, had mean differences of 27.4, 19.4, 10.9, and 14.7 s with 800 radial views, and they had 18.4, 11.9, 9.7, and 27.7 s with 404 views, which were reduced to 0.4, 0.9, -0.2, and -0.7 s and to -1.7, -1.9, -2.1, and 0.5 s with self-gating, respectively. No substantial proton density fat fraction differences were found. The linear mixed model showed free-breathing radial results without self-gating were significantly biased by 17.2 s averagely (P = .002), which was eliminated with self-gating (P = .930). Proton density fat fraction results were not different (P > .234). For patients, Bland-Altman plots exhibited mean differences of 14.4 and 0.1 s for free-breathing stack-of-radial without self-gating and with self-gating, respectively, but no substantial proton density fat fraction differences.
The proposed self-gating method corrects the respiratory motion bias and enables accurate free-breathing stack-of-radial quantification of liver .
开发一种准确的自由呼吸三维肝脏映射方法并在体内进行评估。
在3特斯拉场强下，对5名正常受试者和6名患者应用自由呼吸多回波径向堆叠序列。使用固有的自门控信号实现呼吸运动补偿。屏气笛卡尔采集作为参考标准。使用布兰德-奥特曼图测量并比较径向和笛卡尔方法之间的质子密度脂肪分数。将正常受试者的结果拟合到线性混合模型（P <.05认为具有显著性）。
无自门控的自由呼吸径向堆叠在回波图像中表现出信号衰减，并且表观值出现人为升高。在正常受试者的布兰德-奥特曼图中，与屏气笛卡尔采集相比，22、30、36和44层的自由呼吸径向堆叠采集，在800个径向视图时平均差异分别为27.4、19.4、10.9和14.7秒，在404个视图时分别为18.4、11.9、9.7和27.7秒，而采用自门控时分别降至0.4、0.9、 -0.2和 -0.7秒以及 -1.7、 -1.9、 -2.1和0.5秒。未发现质子密度脂肪分数有实质性差异。线性混合模型显示，无自门控的自由呼吸径向结果平均有17.2秒的显著偏差（P =.002），采用自门控后偏差消除（P =.930）。质子密度脂肪分数结果无差异（P >.234）。对于患者，布兰德-奥特曼图显示无自门控和有自门控的自由呼吸径向堆叠的平均差异分别为14.4秒和0.1秒，但质子密度脂肪分数无实质性差异。
所提出的自门控方法纠正了呼吸运动偏差，并能够对肝脏进行准确的自由呼吸径向堆叠定量分析。
