Differentiating Smoking-Related Interstitial Fibrosis (SRIF) from Usual Interstitial Pneumonia (UIP) with Emphysema Using CT Features Based on Pathologically Proven Cases

Abstract

ObjectiveTo differentiate smoking-related interstitial fibrosis (SRIF) from usual interstitial pneumonia (UIP) with emphysema on CT in combined pulmonary fibrosis and emphysema (CPFE) patients.Materials and MethodsThis study was approved by the institutional review board and informed consent was waived. We included 65 patients who underwent lung biopsy under the suspicion of UIP pattern on HRCT, and after radiologic-pathologic correlation, they were divided into three groups: UIP without emphysema (n = 30), UIP with emphysema (n = 26), and SRIF (n = 9). The quantitative extent of emphysema in the entire lung was visually assessed and fibrotic patterns were qualitatively analyzed based on six characteristics (asymmetry, juxta-subpleural sparing, emphysema beside the honeycombing area, absence of ground grass attenuation/reticulation in honeycombing area, inhomogeneous honeycombing, and absence of honeycombing in the upper lobes). Kaplan-Meier analysis was used for survival analysis, and logistic regression with a receiver operating characteristic curve was used to predict the possibility of SRIF.ResultsIn qualitative analysis of fibrotic patterns, SRIF tended to exhibit more than three of six fibrotic features, whereas UIP with emphysema demonstrated about two of these characteristics (p = 0.035). In addition, SRIF had a higher extent of emphysema than UIP with emphysema when they have same amount of fibrosis (p = 0.014). In patients with SRIF, 5-year survival rate was 85.7%, while it was 40.7% in UIP with emphysema patients (p = 0.035).ConclusionFibrotic CT patterns and survival rate differed between SRIF and UIP with emphysema among CPFE patients, which explains the variable prognosis of CPFE.

Combined pulmonary fibrosis and emphysema as a clinicoradiologic entity: Characterization of presenting lung fibrosis and implications for survival

“…One of these possible entities may be smoking-related interstitial fibrosis (SRIF), a recently described interstitial disease characterized by uniquely hyalinized collagen bundles and non-inflammatory alveolar septal thickening [20]. Chae and colleagues compared the radiologic and clinical features of typical IPF with emphysema and pathologically defined SRIF, and noted improved survival in those with SRIF and more radiologically varied fibrotic findings [21]. Whether a portion of our unclassifiable CPFE may have represented pathologic SRIF is unknown, as only a few underwent pathologic assessment with none having these reported features.…”

Idiopathic pulmonary fibrosis: Significance of the usual interstitial pneumonia (UIP) CT-scan patterns defined in new international guidelines

“…We also identified significantly more smokers with lung emphysema in the indeterminate UIP group. Some scans reclassified as indeterminate for UIP with emphysema lesions may have been retrospectively related to both smoking-related interstitial fibrosis (SRIF) and airspace enlargement with fibrosis (AEF) entities (Figure 4) (24,25), which are associated with a slower clinical course than UIP (26). We have not categorized these entities because their diagnostic criteria are not yet sufficiently validated on CT without pathological confirmation.…”

Interstitial Lung Abnormalities: What Radiologists Should Know

“…Previous studies have shown that nonemphysematous cysts usually present as thin-walled, inhomogeneous-sized cysts, and they are characterized by relatively asymmetric distributions and less involvement of the juxta-subpleural parenchyma ( Fig. 9 ) ( 37 38 39 ). It is one of the imaging features that are predictive of ILA progression (odds ratio: 2.5; 95% CI: 1.3–5.1) and increased mortality (hazard ratio: 1.4; 95% CI: 1.1–1.8) ( 16 ), albeit not as strongly as the other features, including reticular markings and traction bronchiectasis.…”