DECS Imaging&Antibodies, AstraZeneca R&D, Mölndal, Sweden.
NMR Biomed. 2012 Jan;25(1):131-41. doi: 10.1002/nbm.1725. Epub 2011 Jul 7.
In preclinical research, allergic asthma is investigated in rats sensitised with the antigen ovalbumin (OVA), followed by a challenge with aerosolised OVA to induce an inflammatory reaction of the lower airways. This causes diffuse, nonfocal ventilation defects that lead to heterogeneously distributed signal intensities in hyperpolarised (HP) (3)He MR images, which are difficult to assess directly by diagnostic grading or volumetry. Texture analysis can characterise these changes and does not require segmentation of the lung structures prior to the analysis. The aim of this work was to evaluate a texture analysis approach to quantify changes in lung ventilation in HP (3)He MRI of OVA-challenged rats. OVA-challenged animals were treated with two different compound doses to evaluate the sensitivity of the texture analysis. Four groups were investigated using HP (3)He MRI at 4.7 T: controls, vehicle-treated, and low- and high-dose budesonide-treated rats. In addition, broncho-alveolar lavage was performed and the eosinophil cell count was used as a biological reference marker. First-order texture, geometrical features and features based on second-order statistics using run-length and grey-level co-occurrence matrices were calculated. In addition, wavelet transforms were applied to compute first-order statistics on multiple scales. The texture analysis was able to show significant differences between the control and untreated vehicle groups as well as between the vehicle and treatment groups. This is in agreement with the findings of the eosinophil cell counts, which were used as a marker for the severity of inflammation. However, not all features used in the different texture analysis methods could differentiate between the treatment groups. In conclusion, texture analysis can be used to quantify changes in lung ventilation as measured with HP (3)He MRI after therapeutic intervention with budesonide.
在临床前研究中，通过用抗原卵清蛋白（OVA）致敏大鼠来研究过敏性哮喘，然后用雾化 OVA 对其进行挑战以诱导下呼吸道的炎症反应。这会导致弥漫性、非局灶性通气缺陷，导致极化（3）氦磁共振图像中的信号强度不均匀分布，这些信号强度难以通过诊断分级或体积测量直接评估。纹理分析可以描述这些变化，并且在分析之前不需要对肺结构进行分割。本工作旨在评估一种纹理分析方法，以量化 OVA 挑战大鼠极化（3）氦 MRI 中肺通气的变化。用两种不同的化合物剂量处理 OVA 挑战的动物，以评估纹理分析的敏感性。在 4.7T 下使用极化（3）氦 MRI 研究了四个组：对照组、载体处理组、低剂量和高剂量布地奈德处理组。此外，还进行了支气管肺泡灌洗，并且嗜酸性粒细胞计数用作生物学参考标志物。计算了一阶纹理、几何特征和基于二阶统计的特征，使用游程长度和灰度共生矩阵。此外，还应用小波变换在多个尺度上计算一阶统计。纹理分析能够显示出对照组和未处理载体组之间以及载体组和治疗组之间的显著差异。这与嗜酸性粒细胞计数的结果一致，后者被用作炎症严重程度的标志物。然而，在不同的纹理分析方法中使用的并非所有特征都能够区分治疗组。总之，纹理分析可用于量化治疗性干预后极化（3）氦 MRI 测量的肺通气变化。
