Yang Bingjie, Metze Patrick, Balasch Anke, Stumpf Kilian, Beer Meinrad, Rottbauer Wolfgang, Rasche Volker
Department of Internal Medicine II, Ulm University Medical Centre, Ulm, Germany.
Department of Radiology, Ulm University Medical Centre, Ulm, Germany.
Quant Imaging Med Surg. 2022 Oct;12(10):4720-4733. doi: 10.21037/qims-22-92.
Imaging the lung parenchyma with magnetic resonance imaging (MRI) is challenging due to cardiac and respiratory motion, the low proton density and short T* relaxation time, and therefore not well established in the clinical routine. As a further step in facilitating lung MRI for longitudinal monitoring, this study aimed to assess the reproducibility of 2D ultrashort echo time (UTE)-derived lung function parameters in healthy subjects.
In this study, a 2D UTE technique was combined with tiny golden angle (tyGA) ordering. Data were acquired either during breath-holds (BH) or continuously during free-breathing (FB) at a field strength of 3T. Retrospective self-gating (image- and k-space-based) was used to reconstruct respiratory and cardiac multistage images from the FB acquisitions. The reproducibility of functional lung parameters derived from BH and FB acquisitions was assessed for three independent examinations (M1-3). M1 and M2 were acquired within 2 h, whereas M3 was acquired at least 14 d after M1/2. Different respiratory and cardiac phases were reconstructed for three coronal slices. Quantitative analysis including proton fraction ( ), apparent signal-to-noise ratio (apparent SNR), fractional ventilation (FV), and perfusion () was performed by two independent observers, and inter-measurement and inter-observer repeatability were assessed.
All scans could be performed successfully in all volunteers. Intraclass correlation coefficients (ICC) of inter-measurement and inter-observer variability, and Bland-Altman analysis showed good to very good reproducibility. Larger breathing amplitudes were observed in the BH acquisitions, which also showed lower reproducibility when compared with the FB acquisitions. For the FB approach, the ICC ranged between 0.70 and 0.98 for all measurements, and ranged between 0.86 and 0.97 for the two observers. No bias or significant differences were observed between the three measurements or the two observers in healthy volunteers.
The study proves the feasibility of FB 2D tyGA UTE for lung imaging. Functional parameters derived from FB acquisitions are reproducible in healthy volunteers, allowing for further investigation of this technique in patients with various underlying diseases.
由于心脏和呼吸运动、低质子密度以及短T*弛豫时间，利用磁共振成像（MRI）对肺实质进行成像具有挑战性，因此在临床常规检查中尚未得到很好的确立。作为促进肺部MRI进行纵向监测的进一步举措，本研究旨在评估健康受试者中二维超短回波时间（UTE）衍生的肺功能参数的可重复性。
在本研究中，二维UTE技术与微小黄金角（tyGA）排序相结合。数据在屏气（BH）期间或自由呼吸（FB）期间以3T的场强连续采集。回顾性自门控（基于图像和k空间）用于从FB采集中重建呼吸和心脏多阶段图像。对三次独立检查（M1 - 3）评估了从BH和FB采集中得出的功能性肺参数的可重复性。M1和M2在2小时内采集，而M3在M1/2之后至少14天采集。针对三个冠状切片重建了不同的呼吸和心脏相位。由两名独立观察者进行包括质子分数（ ）、表观信噪比（表观SNR）、分数通气（FV）和灌注（ ）的定量分析，并评估测量间和观察者间的重复性。
所有志愿者的扫描均能成功完成。测量间和观察者间变异性的组内相关系数（ICC）以及布兰德 - 奥特曼分析显示出良好到非常好的可重复性。在BH采集中观察到更大的呼吸幅度，与FB采集相比，其可重复性也更低。对于FB方法，所有测量的ICC在0.70至0.98之间，两名观察者的ICC在0.86至0.97之间。在健康志愿者中，三次测量或两名观察者之间未观察到偏差或显著差异。
该研究证明了FB二维tyGA UTE用于肺部成像的可行性。从FB采集中得出的功能参数在健康志愿者中具有可重复性，从而允许对该技术在患有各种基础疾病的患者中进行进一步研究。
