airways disease a radiologist s view

2. Airways Diseasea radiologist�s view David M Hansell Time limit = 20minsTime limit = 20mins

3. Basic HRCT features of bronchiectasis Small airways diseases Fundamental HRCT classification of small airways diseases Various conditions characterised by a component of small airways involvement

4. Definitions of bronchiectasis a selection: Pathological: abnormal irreversible dilatation of the bronchi (Thurlbeck 1995) Clinical: chronic purulent sputum production, ?amount, with or without exacerbations�. HRCT: Abnormal bronchial dilatation (compared with accompanying pulmonary artery), with or without bronchial wall thickening (Naidich 1982)

5. Radiographic diagnosis of bronchiectasis

7. Radiographic diagnosis of bronchiectasis ��abnormal chest radiograph in vast majority of patients with bronchographically proven bronchiectasis (Gudbjerg et al 1955, Woodring 1994) CXR sensitivity 88%, specificity 75% �A normal CXR almost always excludes relevant bronchiectasis and no further investigation seems necessary� (van der Bruggen-Bogaerts et al 1996)

8. HRCT versus pathologically confirmed bronchiectasis Thin-section CT findings compared with pathological findings of surgically resected lobes 47 lobes with bronchiectasis; 41/47 of which identified on HRCT Lack of tapering of airway lumen 37/41 Wall thickening 32/41 Bronchi visible in lung periphery 21/41

9. HRCT criteria for bronchiectasis Lack of tapering or flaring (long axis) �Signet ring� sign (short axis) Bronchi visible in outer third of lung Crowding of bronchi Mucus plugging (large or small airways) Areas of decreased attenuation (mosaicism)

17. Historical uses of the term �small airways diseases� (pre-imaging) Physiologists Anatomists Clinicians Classifications from the pathology literature

18. Myers & Colby 1993 Constrictive bronchiolitis (obliterative bronchiolitis, bronchiolitis obliterans) Cryptogenic organizing pneumonia (bronchiolitis obliterans organizing pneumonia [BOOP], proliferative bronchiolitis) Acute bronchiolitis (infectious bronchiolitis) Small airways disease (adult bronchiolitis) Respiratory bronchiolitis (smoker�s bronchiolitis, respiratory bronchiolitis-associated interstitial lung disease) Mineral dust airways disease (early pneumoconiosis) Follicular bronchiolitis Diffuse panbronchiolitis

19. In the lungs of a 53 yr old cigarette smoker with rheumatoid arthritis� Constrictive bronchiolitis Bronchiectasis and exudative bronchiolitis Follicular bronchiolitis Respiratory bronchiolitis

20. Imaging approach to the two basic types of small airways disease: Constrictive (obliterative) bronchiolitis Indirect signs on HRCT Exudative bronchiolitis Direct signs on HRCT

22. Constrictive Bronchiolitis

23. Constrictive (obliterative) bronchiolitis The �purest� of small airways diseases Inflammation of the bronchioles with or without subsequent obliteration is the commonest lesion in the lungs (Thurlbeck 1995) Major component of heterogeneous group of disorders�

24. One categorisation of constrictive bronchiolitis: Trivial Mild viral lower respiratory infection, most asthmatics Expected Bronchiectasis Component of chronic diffuse lung disease Hypersensitivity pneumonitis, sarcoidosis, microcarcinoids Dominates clinical picture at presentation Post severe viral LRTI Connective tissue disorder, e.g. rheumatoid arthritis Post-transplantation (various) Fume inhalation

25. CXR features of Constrictive Bronchiolitis: Large or normal volume lungs Bronchial wall thickening* Areas of reduced vascularity*

27. HRCT signs of constrictive bronchiolitis (Inspiratory) Areas of decreased attenuation Geographical margins or indistinct swathes No architectural distortion Reduced calibre vessels within �black lung� Bronchial wall thickening and dilatation (variable severity)

28. �black lung, shut down vessels, bronchiectatic airways.

29.

33. HRCT signs of constrictive bronchiolitis (Expiratory) Enhancement of regional inhomogeneity (black -v- grey lung) No change cross-sectional area of affected (black) lung

34. Post BMTPost BMT

35. Rheumatoid related OBRheumatoid related OB

37. Constrictive bronchiolitis - interpretive difficulties Extent at which �black lung� becomes clinically significant Alternative or coexisting cause of mosaic attenuation pattern Similarities of HRCT pattern constrictive bronchiolitis with panacinar emphysema

38. Difficult differentiation between various causes of end stage �black lung�:

39. �Emphysema� in Bronchiectasis� 90 pts - bronchiectasis and emphysema scored on HRCT. Emphysema present in 41/90 pts, mainly localised to bronchiectatic segments 8/41 had functional evidence of emphysema; no relationship between Kco and emphysema extent on CT Conclusion: High prevalence of emphysema in patients with bronchiectasis Chest 1996;109:360

41. Exudative Bronchiolitis

43. Exudative bronchiolitis Non-infective causes (Japanese) diffuse panbronchiolitis Idiopathic bronchiectasis, cystic fibrosis, ABPA Infective causes Tuberculosis (conventional and atypical) Mycoplasma pneumoniae Opportunistic infections e.g. aspergillosis

44. Exudative bronchiolitis Prototype pathology = diffuse panbronchiolitis Chronic inflammatory exudate (foamy macrophages) in and around distended bronchioles Clinical: �sino-bronchial sepsis� syndrome (syn. Japanese panbronchiolitis) HRCT: distinctive combination of widespread V and Y-shaped opacities (tree-in-bud) and cylindrical bronchiectasis

45. �knobbly peripheral �vessels�, mild bronchiectasis

46. Note big airways �always� abnormal � useful if difficulty in deciding nature of nodularity. Relationship between big and small airways diseases�.Note big airways �always� abnormal � useful if difficulty in deciding nature of nodularity. Relationship between big and small airways diseases�.

49. Examples of other conditions characterised by small airways involvement: Hypersensitivity pneumonitis Pulmonary sarcoidosis Follicular bronchiolitis Micro-carcinoid tumourlets

50. Hypersensitivity pneumonitis and small airways involvement Pathology: interstitial lymphocytic infiltrate, bronchiolitis, scattered poorly formed granulomas HRCT: frequent combination of patchy air-trapping (on expiratory CT) on background of ground glass and poorly defined centrilobular nodules

54. Sarcoidosis and small airways involvement Pathology: peribronchiolar non-caseating granuloma may obstruct small airways HRCT: expiratory CT may show air-trapping at secondary pulmonary lobule level. Frequency and significance (diagnostic utility) uncertain

56. Follicular bronchiolitis Pathology: bronchiolar narrowing by adjacent lymphoid follicles +/- mural lymphocytic infiltrate HRCT: variable features - small nodules (centrilobular or bronchocentric). Overlap with lymphocytic interstitial pneumonia (LIP)

57. Micro-carcinoid tumourlets(neuroendocrine hyperplasia) Pathology: focal carcinoid-like tumourlets cause bronchiolar scarring. Causes mild to severe irreversible airflow obstruction HRCT: features consistent with constrictive bronchiolitis and nodules (resembling metastases, often bronchocentric)

58. Points Small airways diseases can be usefully divided into two broad types: CONSTRICTIVE -V- EXUDATIVE HRCT signs reflect this simple distinction Many diverse conditions are characterised by a component of small airways disease which is identifiable on HRCT