Sembhi Ramanpreet, Ranota Tuneesh, Fox Matthew, Couch Marcus, Li Tao, Ball Iain, Ouriadov Alexei
Department of Physics and Astronomy, The University of Western Ontario, London, ON N6A 3K7, Canada.
Faculty of Engineering, School of Biomedical Engineering, The University of Western Ontario, London, ON N6A 3K7, Canada.
Diagnostics (Basel). 2023 Jan 30;13(3):506. doi: 10.3390/diagnostics13030506.
Dynamic inhaled gas (He/Xe/F) MRI permits the acquisition of regional fractional-ventilation which is useful for detecting gas-trapping in lung-diseases such as lung fibrosis and COPD. Deninger's approach used for analyzing the wash-out data can be substituted with the stretched-exponential-model (SEM) because signal-intensity is attenuated as a function of wash-out-breath in F lung imaging. Thirteen normal-rats were studied using He/Xe and F MRI and the ventilation measurements were performed using two 3T clinical-scanners. Two Cartesian-sampling-schemes (Fast-Gradient-Recalled-Echo/X-Centric) were used to test the proposed method. The fully sampled dynamic wash-out images were retrospectively under-sampled (acceleration-factors (AF) of 10/14) using a varying-sampling-pattern in the wash-out direction. Mean fractional-ventilation maps using Deninger's and SEM-based approaches were generated. The mean fractional-ventilation-values generated for the fully sampled k-space case using the Deninger method were not significantly different from other fractional-ventilation-values generated for the non-accelerated/accelerated data using both Deninger and SEM methods ( > 0.05 for all cases/gases). We demonstrated the feasibility of the SEM-based approach using retrospective under-sampling, mimicking AF = 10/14 in a small-animal-cohort from the previously reported dynamic-lung studies. A pixel-by-pixel comparison of the Deninger-derived and SEM-derived fractional-ventilation-estimates obtained for AF = 10/14 (≤16% difference) has confirmed that even at AF = 14, the accuracy of the estimates is high enough to consider this method for prospective measurements.
动态吸入气体（氦/氙/氟）磁共振成像可获取区域分数通气，这对于检测诸如肺纤维化和慢性阻塞性肺疾病等肺部疾病中的气体潴留很有用。由于在氟肺成像中信号强度会随着呼出呼吸而衰减，用于分析呼出数据的德宁格方法可以用拉伸指数模型（SEM）替代。使用氦/氙和氟磁共振成像对13只正常大鼠进行了研究，并使用两台3T临床扫描仪进行通气测量。使用两种笛卡尔采样方案（快速梯度回波/ X中心）来测试所提出的方法。使用在呼出方向上变化的采样模式，对完全采样的动态呼出图像进行回顾性欠采样（加速因子（AF）为10/14）。生成了使用德宁格方法和基于SEM方法的平均分数通气图。使用德宁格方法为完全采样的k空间情况生成的平均分数通气值与使用德宁格和SEM方法为未加速/加速数据生成的其他分数通气值没有显著差异（所有情况/气体的P>0.05）。我们证明了在先前报道的动态肺研究中的小动物队列中，使用回顾性欠采样模仿AF = 10/14的基于SEM方法的可行性。对于AF = 10/14获得的德宁格衍生和SEM衍生的分数通气估计值的逐像素比较（差异≤16％）证实，即使在AF = 14时，估计的准确性也足够高，可以考虑将此方法用于前瞻性测量。
