Department of Radiology, Mayo Clinic.
Department of Radiology, University of Chicago Medicine, Chicago, IL.
J Thorac Imaging. 2018 May;33(3):197-203. doi: 10.1097/RTI.0000000000000319.
Differentiating between systemic sclerosis-related interstitial lung disease (SSc-ILD) and idiopathic pulmonary fibrosis (IPF) is important because of the differences in workup, prognosis, and treatment. However, there is much overlap in the appearance of these 2 entities on high-resolution computed tomography. We propose that inflammation and/or fibrosis focally or disproportionately involving the bilateral anterolateral upper lobes and posterosuperior lower lobes ["Four Corners" Sign (FCS)] is specific for SSc-ILD.
Randomized high-resolution computed tomography studies from 74 IPF and 73 SSc-ILD cases were evaluated by 2 thoracic radiologists blinded to all patient data. For each case the reviewers noted whether the FCS was present and assigned a confidence level on the basis of a 7-point Likert scale. The same process was then performed on a randomized external validation group of 42 SSc-ILD and 42 IPF cases.
For Likert scores of 6 or 7 ("mostly agree" or "entirely agree" that the FCS is present, respectively) the sensitivity in SSc was 16.4% (95% confidence interval, 9.7%, 26.6%), specificity 100.0% (95% confidence interval, 95.1%, 100.0%). There was a significant association between a confidently present FCS and SSc compared with a confidently present FCS and IPF (P=0.0003). Analysis on an external validation group of 42 SSc and 42 IPF cases conferred similarly high specificity for SSc in cases characterized as FCS with high confidence.
The FCS, a pattern of focal or disproportionate inflammation and/or fibrosis involving the bilateral anterolateral upper lobes and posterosuperior lower lobes, is specific for SSc-ILD when readers are confident of its presence.
系统性硬化症相关间质性肺病（SSc-ILD）和特发性肺纤维化（IPF）之间的鉴别很重要，因为这两种疾病在检查、预后和治疗方面存在差异。然而，这两种疾病在高分辨率计算机断层扫描（HRCT）上的表现有很多重叠。我们提出，炎症和/或纤维化局灶性或不成比例地累及双侧前外侧上叶和后上叶下叶（“四角”征（FCS））是 SSc-ILD 的特异性表现。
对 74 例 IPF 和 73 例 SSc-ILD 患者的随机 HRCT 研究进行了评估，由 2 位胸部放射科医师对所有患者数据进行了盲法评估。对于每例患者，评估者记录 FCS 是否存在，并根据 7 分李克特量表对置信度进行评分。然后，对随机选择的 42 例 SSc-ILD 和 42 例 IPF 患者的外部验证组进行了相同的评估。
对于 Likert 评分 6 或 7（分别表示“非常同意”或“完全同意” FCS 存在），SSc 的敏感性为 16.4%（95%置信区间，9.7%，26.6%），特异性为 100.0%（95%置信区间，95.1%，100.0%）。在有信心存在 FCS 的情况下，SSc 与有信心存在 FCS 的 IPF 之间存在显著相关性（P=0.0003）。对 42 例 SSc 和 42 例 IPF 患者的外部验证组进行分析，当读者对 FCS 的存在有高度信心时，SSc 的特异性也很高。
当读者对其存在有信心时，FCS（一种累及双侧前外侧上叶和后上叶下叶的局灶性或不成比例的炎症和/或纤维化模式）是 SSc-ILD 的特异性表现。
