Department of Internal Medicine, Division of Pulmonary and Critical Care Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
Acad Radiol. 2011 Aug;18(8):1014-23. doi: 10.1016/j.acra.2011.03.004. Epub 2011 May 18.
Evaluation of chest computed tomography (CT) is usually qualitative or semiquantitative, resulting in subjective descriptions often by different observers over time and imprecise determinations of disease severity within distorted lobes. There is a need for standardized imaging biomarkers to quantify regional disease, maximize diagnostic yield, and facilitate multicenter comparisons. We applied lobe-based voxelwise image analysis to derive regional air (Vair) and tissue (Vtissue) volumes and fractional tissue volume (FTV = tissue/[tissue+air] volume) as internally standardized parameter for assessing interstitial lung disease (ILD).
High-resolution CT was obtained at supine and prone end-inspiration and supine end-expiration in 29 patients with ILD and 20 normal subjects. Lobar Vair, Vtissue, and FTV were expressed along standard coordinate axes.
In normal subjects from end-inspiration to end-expiration, total Vair declined ~43%, FTV increased ~80%, but Vtissue remained unchanged. With increasing ILD, Vair declined and Vtissue rose in all lobes; FTV increased with a peripheral-to-central progression inversely correlated to spirometry and lung diffusing capacity (r(2) = 0.57-0.75, prone end-inspiration). Inter- and intralobar coefficients of variation of FTV increased 84-148% in mild-to-moderate ILD, indicating greater spatial heterogeneity, then normalized in severe ILD. Analysis of discontinuous images incurs <3% error compared to consecutive images.
These regional attenuation-based biomarkers could quantify heterogeneous parenchymal disease in distorted lobes, detect mild ILD involvement in all lobes and describe the pattern of disease progression. The next step would be to study a larger series, examine reproducibility and follow longitudinal changes in correlation with clinical and functional indices.
胸部计算机断层扫描（CT）的评估通常是定性或半定量的，导致不同观察者在不同时间进行主观描述，并且在扭曲的肺叶中对疾病严重程度的判断不准确。因此，需要标准化的成像生物标志物来量化区域性疾病，最大限度地提高诊断效果，并促进多中心比较。我们应用基于肺叶的体素图像分析来推导区域性空气（Vair）和组织（Vtissue）体积以及组织分数体积（FTV=组织/[组织+空气]体积），作为评估间质性肺病（ILD）的内部标准化参数。
在 29 例 ILD 患者和 20 例正常对照者中，分别在仰卧位和俯卧位吸气末及仰卧位呼气末进行高分辨率 CT 扫描。肺叶的 Vair、Vtissue 和 FTV 沿着标准坐标轴进行表达。
在正常对照者中，从吸气末到呼气末，总 Vair 下降约 43%，FTV 增加约 80%，但 Vtissue 保持不变。随着 ILD 的进展，所有肺叶的 Vair 下降，Vtissue 上升；FTV 随着从周边到中央的进展而增加，与肺量计和肺弥散量呈负相关（r²=0.57-0.75，俯卧位吸气末）。在轻度至中度 ILD 中，FTV 的肺叶内和肺叶间变异系数增加 84%-148%，表明空间异质性增加，然后在重度 ILD 中恢复正常。与连续图像相比，分析不连续图像的误差<3%。
这些基于区域性衰减的生物标志物可以量化扭曲肺叶中不均匀的实质疾病，检测所有肺叶中的轻度 ILD 受累，并描述疾病进展的模式。下一步将是研究更大的系列，检查重复性并与临床和功能指标进行纵向变化的相关性。
