Ninaber Maarten K, Stolk Jan, Smit Jasper, Le Roy Ernest J, Kroft Lucia J M, Bakker M Els, de Vries Bouwstra Jeska K, Schouffoer Anne A, Staring Marius, Stoel Berend C
Department of Pulmonology, Leiden University Medical Center, Albinusdreef 2, 2333ZA Leiden, The Netherlands.
Department of Pulmonology, Leiden University Medical Center, Albinusdreef 2, 2333ZA Leiden, The Netherlands.
Eur J Radiol. 2015 May;84(5):975-9. doi: 10.1016/j.ejrad.2015.01.012. Epub 2015 Jan 22.
Interstitial lung disease occurs frequently in patients with systemic sclerosis (SSc). Quantitative computed tomography (CT) densitometry using the percentile density method may provide a sensitive assessment of lung structure for monitoring parenchymal damage. Therefore, we aimed to evaluate the optimal percentile density score in SSc by quantitative CT densitometry, against pulmonary function.
We investigated 41 SSc patients by chest CT scan, spirometry and gas transfer tests. Lung volumes and the nth percentile density (between 1 and 99%) of the entire lungs were calculated from CT histograms. The nth percentile density is defined as the threshold value of densities expressed in Hounsfield units. A prerequisite for an optimal percentage was its correlation with baseline DLCO %predicted. Two patients showed distinct changes in lung function 2 years after baseline. We obtained CT scans from these patients and performed progression analysis.
Regression analysis for the relation between DLCO %predicted and the nth percentile density was optimal at 85% (Perc85). There was significant agreement between Perc85 and DLCO %predicted (R=-0.49, P=0.001) and FVC %predicted (R=-0.64, P<0.001). Two patients showed a marked change in Perc85 over a 2 year period, but the localization of change differed clearly.
We identified Perc85 as optimal lung density parameter, which correlated significantly with DLCO and FVC, confirming a lung parenchymal structure-function relation in SSc. This provides support for future studies to determine whether structural changes do precede lung function decline.
间质性肺病在系统性硬化症（SSc）患者中频繁出现。使用百分位数密度法的定量计算机断层扫描（CT）密度测定法可为监测实质损伤的肺结构提供敏感评估。因此，我们旨在通过定量CT密度测定法评估SSc中最佳的百分位数密度评分，并与肺功能进行对比。
我们通过胸部CT扫描、肺量计和气体交换测试对41例SSc患者进行了研究。根据CT直方图计算肺容积和全肺的第n百分位数密度（1%至99%之间）。第n百分位数密度定义为以亨氏单位表示的密度阈值。最佳百分比的一个前提条件是其与预测的基线一氧化碳弥散量（DLCO）%相关。两名患者在基线后2年肺功能出现明显变化。我们获取了这些患者的CT扫描图像并进行了进展分析。
预测的DLCO%与第n百分位数密度之间的回归分析在85%（Perc85）时最为理想。Perc85与预测的DLCO%（R=-0.49，P=0.001）和预测的用力肺活量（FVC）%（R=-0.64，P<0.001）之间存在显著相关性。两名患者在2年期间Perc85出现了显著变化，但变化的部位明显不同。
我们确定Perc85为最佳肺密度参数，其与DLCO和FVC显著相关，证实了SSc中肺实质结构与功能的关系。这为未来研究确定结构变化是否确实先于肺功能下降提供了支持。
