title: Respiratory bronchiolitis-associated interstitial lung disease: radiologic features with clinical and pathologic correlation.
abstract: The purpose of this work was to describe the radiographic and CT findings in patients with respiratory bronchiolitis-associated interstitial lung disease (RB-ILD) and to correlate them with clinical, physiologic, and pathologic features.
  
  
  
  RB-ILD was proved pathologically in all 21 patients. Sixteen (76%) patients were current smokers, and five (24%) patients were ex-smokers. The mean cigarette consumption was 38.7 pack-years. Chest radiographs and CT scans were semiquantitatively analyzed and correlated with clinical findings, physiologic measures, and a pathologic score of disease extent.
  
  
  
  The major radiographic findings were bronchial wall thickening in 16 patients (76%) and ground-glass opacity in 12 patients (57%). The predominant initial CT findings were central bronchial wall thickening (proximal to subsegmental bronchi) in 19 patients (90%), peripheral bronchial wall thickening (distal to subsegmental bronchi) in 18 patients (86%), centrilobular nodules in 15 patients (71%), and ground-glass opacity in 14 patients (67%), None of these CT findings had a significant zonal predominance. Other findings were upper lung predominant centrilobular emphysema (57%) and patchy areas of hypoattenuation (38%) with a lower lung predominance. Radiologic findings were similar in both current and ex-smokers. The amount of ground-glass opacity correlated inversely with arterial oxygen saturation ( r = -0.67, p = 0.04), and the areas of hypoattenuation correlated with alveolar-arterial oxygen gradient ( r = 0.56, p = 0.04). The extent of centrilobular nodules correlated with the extent of macrophages in respiratory bronchioles ( r = 0.53, p = 0.03) and with chronic inflammation of respiratory bronchioles ( r = 0.57, p = 0.02). The extent of ground-glass opacity correlated with the amount of macrophage accumulation in the alveoli and alveolar ducts ( r = 0.56, p < 0.01 and r = 0.54, p = 0.04, respectively). At follow-up CT after steroid treatment and smoking cessation, in nine patients, the extent of bronchial wall thickening, centrilobular nodules, and ground-glass opacity had decreased, but the areas of hypoattenuation had increased (p < 0.05).
  
  
  
  The CT findings of RB-ILD are centrilobular nodules, ground-glass opacity, and air trapping. These radiologic features, in patients with a history of heavy cigarette smoking, may differentiate RB-ILD from other interstitial lung diseases.
authors.affiliation: Department of Radiology, University of Colorado Health Sciences Center, Denver, CO 80262, USA.
authors.forename: Jai Soung
authors.initials: JS
authors.lastname: Park
authors.forename: Kevin K
authors.initials: KK
authors.lastname: Brown
authors.forename: Rubin M
authors.initials: RM
authors.lastname: Tuder
authors.forename: Valerie A E
authors.initials: VA
authors.lastname: Hale
authors.forename: Talmadge E
authors.initials: TE
authors.lastname: King
authors.forename: David A
authors.initials: DA
authors.lastname: Lynch
mesh_terms: D000328:Adult; D001988:Bronchiolitis / Q000000981:diagnostic imaging* / Q000473:pathology; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008168:Lung / Q000000981:diagnostic imaging / Q000473:pathology*; D017563:Lung Diseases, Interstitial / Q000000981:diagnostic imaging* / Q000473:pathology; D008297:Male; D012907:Smoking / Q000009:adverse effects; D013997:Time Factors; D014057:Tomography, X-Ray Computed / Q000379:methods