Effect of respiratory motion on free-breathing 3D stack-of-radial liver R2*relaxometry and improved quantification accuracy using self-gating
Effect of respiratory motion on free-breathing 3D stack-of-radial liver R2*relaxometry and improved quantification accuracy using self-gating
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DOI：
10.1002/mrm.28052
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发表时间：
2019-11-04
影响因子：
3.3
通讯作者：
Wu, Holden H.
中科院分区：
文献类型：
--
作者：
Zhong, Xiaodong;Armstrong, Tess;Wu, Holden H.
目的建立一种精确的自由呼吸三维肝脏R2* 标测方法并进行活体评价。方法采用自由呼吸多回波放射状叠加序列对5例正常人和6例患者进行3 T超声心动图检查。使用固有的自门控信号实现呼吸运动补偿。屏气笛卡尔采集是参考标准。测量质子密度、脂肪分数和R2*，并使用Bland-Altman图比较径向和笛卡尔方法。将正常受试者结果拟合到线性混合模型（P <0.05被认为是显著的）。结果无自门控的自由呼吸放射状叠层在回波图像中表现出信号衰减和人为升高的表观R2* 值。在正常受试者的Bland-Altman图中，与22、30、36和44层的屏气笛卡尔、自由呼吸径向堆叠采集相比，800个径向视图的平均R2* 差异分别为27.4、19.4、10.9和14.7 s（-1），800个径向视图的平均R2* 差异分别为18.4、11.9、9.7、404个视图时为27.7 s（-1），自门控时分别为0.4、0.9、-0.2、-0.7 s（-1）和-1.7、-1.9、-2.1、0.5 s（-1）。线性混合模型显示，无自设门的自由呼吸径向R2* 结果平均有17.2 s（-1）的显著偏倚（P = 0.002），而自设门则消除了偏倚（P = 0.930）。质子密度脂肪分数结果无差异（P > 0.234）。对于患者，Bland-Altman图显示无自门控和有自门控的自由呼吸桡动脉叠层的平均R2* 差异分别为14.4和0.1 s（-1），但没有实质性的质子密度脂肪分数差异。结论所提出的自门控方法校正了呼吸运动偏差，并实现了肝脏R2* 的精确自由呼吸径向堆叠量化。
Purpose To develop an accurate free-breathing 3D liver R2* mapping approach and to evaluate it in vivo. Methods 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 R2* 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). Results Free-breathing stack-of-radial without self-gating exhibited signal attenuation in echo images and artifactually elevated apparent R2* 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 R2* differences of 27.4, 19.4, 10.9, and 14.7 s(-1) with 800 radial views, and they had 18.4, 11.9, 9.7, and 27.7 s(-1) with 404 views, which were reduced to 0.4, 0.9, -0.2, and -0.7 s(-1) and to -1.7, -1.9, -2.1, and 0.5 s(-1) with self-gating, respectively. No substantial proton density fat fraction differences were found. The linear mixed model showed free-breathing radial R2* results without self-gating were significantly biased by 17.2 s(-1) 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 R2* differences of 14.4 and 0.1 s(-1) for free-breathing stack-of-radial without self-gating and with self-gating, respectively, but no substantial proton density fat fraction differences. Conclusion The proposed self-gating method corrects the respiratory motion bias and enables accurate free-breathing stack-of-radial quantification of liver R2*.