小鼠肺脏的可变翻转角三维超短回波时间（UTE）T 映射：重复性评估
Variable flip angle 3D ultrashort echo time (UTE) T mapping of mouse lung: A repeatability assessment.
作者信息
Alamidi Daniel F, Smailagic Amir, Bidar Abdel W, Parker Nicole S, Olsson Marita, Hockings Paul D, Lagerstrand Kerstin M, Olsson Lars E
机构信息
Philips Health Systems, Stockholm, Sweden.
Department of Radiation Physics, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
出版信息
J Magn Reson Imaging. 2018 Mar 8. doi: 10.1002/jmri.25999.
BACKGROUND
Lung T is a potential translational biomarker of lung disease. The precision and repeatability of variable flip angle (VFA) T mapping using modern 3D ultrashort echo time (UTE) imaging of the whole lung needs to be established before it can be used to assess response to disease and therapy.
PURPOSE
To evaluate the feasibility of regional lung T quantification with VFA 3D-UTE and to investigate long- and short-term T repeatability in the lungs of naive mice.
STUDY TYPE
Prospective preclinical animal study.
POPULATION
Eight naive mice and phantoms.
FIELD STRENGTH/SEQUENCE: 3D free-breathing radial UTE (8 μs) at 4.7T.
ASSESSMENT
VFA 3D-UTE T calculations were validated against T values measured with inversion recovery (IR) in phantoms. Lung T and proton density (S ) measurements of whole lung and muscle were repeated five times over 1 month in free-breathing naive mice. Two consecutive T measurements were performed during one of the imaging sessions.
STATISTICAL TESTS
Agreement in T between VFA 3D-UTE and IR in phantoms was assessed using Bland-Altman and Pearson 's correlation analysis. The T repeatability in mice was evaluated using coefficient of variation (CV), repeated-measures analysis of variance (ANOVA), and paired t-test.
RESULTS
Good T agreement between the VFA 3D-UTE and IR methods was found in phantoms. T in lung and muscle showed a 5% and 3% CV (1255 ± 63 msec and 1432 ± 42 msec, respectively, mean ± SD) with no changes in T or S over a month. Consecutive measurements resulted in an increase of 2% in both lung T and S .
DATA CONCLUSION
VFA 3D-UTE shows promise as a reliable T mapping method that enables full lung coverage, high signal-to-noise ratio (∼25), and spatial resolution (300 μm) in freely breathing animals. The precision of the VFA 3D-UTE method will enable better design and powering of studies.
LEVEL OF EVIDENCE
1 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2018.
背景
肺T是肺部疾病一种潜在的转化生物标志物。在其用于评估疾病和治疗反应之前，需要确定使用现代全肺三维超短回波时间（UTE）成像的可变翻转角（VFA）T映射的精度和可重复性。
目的
评估采用VFA 3D-UTE进行局部肺T定量的可行性，并研究未接触过实验因素的小鼠肺部T的长期和短期可重复性。
研究类型
前瞻性临床前动物研究。
研究对象
八只未接触过实验因素的小鼠和模型。
场强/序列：4.7T下的三维自由呼吸径向UTE（8微秒）。
评估
VFA 3D-UTE T计算结果与模型中用反转恢复（IR）测量的T值进行了验证。在自由呼吸的未接触过实验因素的小鼠中，对全肺和肌肉的肺T和质子密度（S）测量在1个月内重复了5次。在其中一次成像过程中进行了连续两次T测量。
统计检验
使用Bland-Altman分析和Pearson相关分析评估模型中VFA 3D-UTE和IR之间T的一致性。使用变异系数（CV）、重复测量方差分析（ANOVA）和配对t检验评估小鼠中T的可重复性。
结果
在模型中发现VFA 3D-UTE和IR方法之间T具有良好的一致性。肺和肌肉中的T显示CV分别为5%和3%（分别为1255±63毫秒和1432±42毫秒，均值±标准差），且在一个月内T或S没有变化。连续测量导致肺T和S均增加2%。
数据结论
VFA 3D-UTE显示出有望成为一种可靠的T映射方法，该方法能够在自由呼吸的动物中实现全肺覆盖、高信噪比（约25）和空间分辨率（300微米）。VFA 3D-UTE方法的精度将有助于更好地设计研究并确定研究效能。
证据水平
1技术效能：2期《磁共振成像杂志》2018年。
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