Tibiletti Marta, Bianchi Andrea, Stiller Detlef, Rasche Volker
Core Facility Small Animal MRI, 89081 Ulm, University, Albert-Einstein-Allee 23, 89081 Ulm, Germany.
In-Vivo Imaging Laboratory, Target Discovery Research, Boehringer Ingelheim Pharma, Birkendorfer Strasse 65, 88397 Biberach an der Riss, Germany.
NMR Biomed. 2016 Dec;29(12):1791-1799. doi: 10.1002/nbm.3657. Epub 2016 Nov 3.
Blood perfusion in lung parenchyma is an important property for assessing lung function. In small animals, its quantitation is limited even with radioactive isotopes or dynamic contrast-enhanced MRI techniques. In this study, the feasibility flow-sensitive alternating inversion recovery (FAIR) for the quantification of blood flow in lung parenchyma in free breathing rats at 7 T has been investigated. In order to obtain sufficient signal from the short T * lung parenchyma, a 2D ultra-short echo time (UTE) Look-Locker read-out has been implemented. Acquisitions were segmented to maintain acquisition time within an acceptable range. A method to perform retrospective respiratory gating (DC-SG) has been applied to investigate the impact of respiratory movement. Reproducibilities within and between sessions were estimated, and the ability of FAIR-UTE to identify the decrease of lung perfusion under hyperoxic conditions was tested. The implemented technique allowed for the visualization of lung parenchyma with excellent SNR and no respiratory artifact even in ungated acquisitions. Lung parenchyma perfusion was obtained as 32.54 ± 2.26 mL/g/min in the left lung, and 34.09 ± 2.75 mL/g/min in the right lung. Application of retrospective gating significantly but minimally changes the perfusion values, implying that respiratory gating may not be necessary with this center-our acquisition method. A decrease of 10% in lung perfusion was found between normoxic and hyperoxic conditions, proving the feasibility of the FAIR-UTE approach to quantify lung perfusion changes.
肺实质内的血液灌注是评估肺功能的一项重要指标。在小动物中，即使使用放射性同位素或动态对比增强磁共振成像技术，其定量分析也受到限制。在本研究中，已对在7T场强下自由呼吸大鼠肺实质血流定量的流动敏感交替反转恢复（FAIR）方法的可行性进行了研究。为了从短T*的肺实质中获得足够的信号，采用了二维超短回波时间（UTE）Look-Locker读出技术。采集过程进行了分段处理，以将采集时间保持在可接受范围内。应用一种进行回顾性呼吸门控（DC-SG）的方法来研究呼吸运动的影响。评估了不同时间段内及不同时间段间的可重复性，并测试了FAIR-UTE识别高氧条件下肺灌注降低的能力。所采用的技术能够实现肺实质的可视化，即使在非门控采集中也具有出色的信噪比且无呼吸伪影。左肺的肺实质灌注为32.54±2.26 mL/g/min，右肺为34.09±2.75 mL/g/min。回顾性门控的应用显著但轻微地改变了灌注值，这意味着采用本中心的采集方法可能无需进行呼吸门控。在常氧和高氧条件之间发现肺灌注降低了10%，证明了FAIR-UTE方法定量肺灌注变化的可行性。
