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Radiology: Volume 268: Number 2-August 2013 n radiology.rsna.org 563 Purpose:To determine the prevalence of interstitial lung abnormalities (ILAs) at initial computed tomography (CT) examination and the rate of progression of ILAs on 2-year follow-up CT images in a National Lung Screening Trial population studied at a single site. Materials and Methods:The study was approved by the institutional review board and informed consent was obtained from all participants. Image review for this study was HIPAA compliant. We reviewed the CT images of 884 cigarette smokers who underwent low-dose CT at a single site in the National Lung Screening Trial. CT findings were categorized as having no evidence of ILA, equivocal for ILA, or ILA. We categorized the type of ILA as nonfibrotic (ground-glass opacity, consolidation, mosaic attenuation), or fibrotic (ground glass with reticular pattern, reticular pattern, honeycombing). We evaluated the temporal change of the CT findings (no change, improvement, or progression) of ILA at 2-year follow-up. A x 2 with Fisher exact test or unpaired t test was used to determine whether smoking parameters were associated with progression of ILA at 2-year follow-up CT. Results:The prevalence of ILA was 9.7% (86 of 884 participants; 95% confidence interval: 7.9%, 11.9%), with a further 11.5% (102 of 884 participants) who had findings equivocal for ILA. The pattern was fibrotic in 19 (2.1%), nonfibrotic in 52 (5.9%), and mixed fibrotic and nonfibrotic in 15 (1.7%) of the 86 participants with ILA. The percentage of current smokers (P = .001) and mean number of cigarette pack-years (P = .001) were significantly higher in those with ILA than those without. At 2-year follow-up of those with ILA (n = 79), findings of nonfibrotic ILA improved in 49% of cases and progressed in 11%. Fibrotic ILA improved in 0% and progressed in 37% of cases. Conclusion:ILA is common in cigarette smokers. Nonfibrotic ILA improved in about 50% of cases, and fibrotic ILA progressed in about 37%.q RSNA, 2013 interstitial lung abnormalities in a cT lung cancer screening Population: Prevalence and Progression Rate

No abstract

CT findings of extensive reticular pattern, traction bronchiectasis, and honeycombing are closely related to the presence of histologic fibrosis in chronic HP.

Background: Lymphangiogenesis responds to tissue injury as a key component of normal wound healing. The development of fi brosis in the idiopathic interstitial pneumonias may result from abnormal wound healing in response to injury. We hypothesize that increased lymphatic vessel (LV) length, a marker of lymphangiogenesis, is associated with parenchymal components of the fi broblast reticulum (organizing collagen, fi brotic collagen, and fi broblast foci), and its extent correlates with disease severity. Methods: We assessed stereologically the parenchymal structure of fi brotic lungs and its associated lymphatic network, which was highlighted immunohistochemically in age-matched samples of usual interstitial pneumonia (UIP), nonspecifi c interstitial pneumonia (NSIP) with FVC , 80%, COPD with a Global Initiative for Obstructive Lung Disease stage 0, and normal control lungs. Results: LV length density, as opposed to vessel volume density, was found to be associated with organizing and fi brotic collagen density ( P , .0001). Length density of LVs and the volume density of organizing and fi brotic collagen were signifi cantly associated with severity of both % FVC ( P , .001) and diffusing capacity of the lung for carbon monoxide ( P , .001). Conclusions: Severity of disease in UIP and NSIP is associated with increased LV length and is strongly associated with components of the fi broblast reticulum, namely organizing and fi brotic collagen, which supports a pathogenic role of LVs in these two diseases. Furthermore, the absence of defi nable differences between UIP and NSIP suggests that LVs are a unifying mechanism for the development of fi brosis in these fi brotic lung diseases. CHEST 2012; 142(6):1569-1576Abbreviations: D lco 5 diffusing capacity of lung for carbon monoxide; FF 5 fi broblast foci; GGO 5 ground-glass opacity; GOLD 5 Global Initiative for Obstructive Lung Disease; IIP 5 idiopathic interstitial pneumonia; IPF 5 idiopathic pulmonary fi brosis; LV 5 lymphatic vessel; NSIP 5 nonspecifi c interstitial pneumonia; UIP 5 usual interstitial pneumonia; VEGF 5 vascular endothelial growth factor