Ohkubo Hirotsugu, Taniguchi Hiroyuki, Kondoh Yasuhiro, Yagi Mitsuaki, Furukawa Taiki, Johkoh Takeshi, Arakawa Hiroaki, Fukuoka Junya, Niimi Akio
Department of Respiratory Medicine, Allergy and Clinical Immunology, Nagoya City University Graduate School of Medical Sciences, Japan.
Department of Respiratory Medicine and Allergy, Tosei General Hospital, Japan.
Intern Med. 2018 Apr 1;57(7):929-937. doi: 10.2169/internalmedicine.9508-17. Epub 2017 Dec 21.
Objective An image analysis of high-resolution computed tomography (HRCT) can provide objective quantitation of the disease status in idiopathic pulmonary fibrosis (IPF). However, to our knowledge, no reports have investigated the utility of the normal lung volume for evaluating mortality from IPF. This study aimed to evaluate the relationship between the normally attenuated lung volume on HRCT as a percentage of whole-lung volume (NL%) and IPF mortality. Methods The NL% was determined by HRCT (between -950 and -701 Hounsfield units) using a density mask technique and volumetric software. The NL%, visual assessments of the normal lung by two radiologists, pulmonary function variables, and the gender, age, and physiology (GAP) index were retrospectively evaluated for 175 patients with IPF. Uni- and multivariate Cox proportional hazards analyses and C statistics for mortality were performed. Results The univariate Cox proportional hazards analysis identified the NL% as a prognostic factor [hazard ratio, 0.949; 95% confidence interval (CI), 0.936-0.964; p<0.0001]. In the multivariate analysis, the NL% was a prognostic factor, but the radiologists' visual assessment scores of normal lung were not. The C index increased when the NL% was included in the models of the pulmonary function variables. Furthermore, the C index for a combined model of GAP stage and categorized NL% (0.758; 95% CI, 0.751-0.762) was higher than for the model with the GAP stage alone (0.689; 95% CI, 0.672-0.709). Conclusion The NL% was a prognostic factor in our study population. Quantification of the normal lung using our method may help improve the IPF staging systems.
目的 高分辨率计算机断层扫描（HRCT）图像分析可对特发性肺纤维化（IPF）的疾病状态进行客观定量。然而，据我们所知，尚无报告研究正常肺容积在评估IPF死亡率方面的效用。本研究旨在评估HRCT上正常衰减肺容积占全肺容积的百分比（NL%）与IPF死亡率之间的关系。方法 使用密度掩膜技术和容积软件，通过HRCT（在-950至-701亨氏单位之间）确定NL%。对175例IPF患者的NL%、两位放射科医生对正常肺的视觉评估、肺功能变量以及性别、年龄和生理学（GAP）指数进行回顾性评估。进行单因素和多因素Cox比例风险分析以及死亡率的C统计量分析。结果 单因素Cox比例风险分析确定NL%为预后因素[风险比，0.949；95%置信区间（CI），0.936 - 0.964；p<0.0001]。在多因素分析中，NL%是预后因素，但放射科医生对正常肺的视觉评估分数不是。当NL%纳入肺功能变量模型时，C指数增加。此外，GAP分期和分类后的NL%联合模型的C指数（0.758；95%CI，0.751 - 0.762）高于仅含GAP分期的模型（0.689；95%CI，0.672 - 0.709）。结论 在我们的研究人群中，NL%是预后因素。使用我们的方法对正常肺进行定量可能有助于改进IPF分期系统。
