1. Obstructive Pulmonary Diseases of the Lower Airways…It’s not all Emphysema!
Karin and Jason Kuhl
4/14/04

2. What’s your differential diagnosis?
52 yo male with chronic cough, dyspnea, and occasional wheezing
100 pack year smoking history
PFT’s demonstrate an obstructive pattern

3. Obstructive Pulmonary Diseases
Any disease affecting the upper or lower airways can be associated with obstruction of airflow from the lungs.
This presentation will focus on those pathological processes primarily affecting the lower airways, including:
Emphysema
Chronic Bronchitis
Asthma
Bronchiectasis
Bronchiolitis obliterans (constrictive bronchiolitis)

4. COPD
Chronic obstructive pulmonary disease (COPD) is a general term lumping emphysema, chronic bronchitis, and asthma together.
COPD is not used to describe the other disease states resulting from chronic airflow obstruction.
Disadvantages of using the term COPD:
Other obstructive conditions are often over-looked.
Pathologic and physiologic mechanisms of these diseases are different.
Prognosis and treatment are disease specific.

5. Emphysema
Defined by the American Thoracic Society as “the permanent enlargement of the air spaces distal to the terminal bronchiole as a result of destruction of the alveolar walls without significant fibrosis.”

6. Three principle types:
Centriacinar (centrilobular)
Predominantly in upper lung zones.
Associated with smoking & pneumoconiosis.
Panacinar (panlobular)
More progressive, and with more severe symptoms because it involves the lower lung zones (areas of greater gas exchange).
Associated with alpha-1-antitrypsin deficiency.
Distal acinar (paraseptal)
Focal or multifocal disease.
Involves distal alveolar sacs and ducts, resulting in subpleural blebs and bullae.
More likely to cause spontaneous pneumothorax.

7. Pathology of the secondary pulmonary lobule:
Normal
Centriacinar
Panacinar
Paraseptal
Webb1

8. Protease-Anti-protease Theory:
Cotran2
Emphysema results from the destructive effect of high protease activity in subjects with low anti-protease activity.

9. Normal lung and emphysema:
Marc Gosselin, MD

10. Airflow obstruction is due to the loss of elastic recoil of the lung parenchyma.
Lynch3

11. Clinical manifestation:
Insidious onset
Dyspnea
Noncyanotic (pink puffer)
Mild cough
+/- Increased sputum
+/- Wheezing
 AP diameter
Usually thin

12. Chest radiographic findings:
Poor in evaluating very early disease due to limitations in small airway visualization.
As the disease progresses, radiograph can directly demonstrate disease pathology, as well as indirect signs of increased lung compliance and air-trapping.

13. Identification of emphysema on CXR:
Direct identification:
Irregular, asymmetric areas of decreased lung density.
Vascular deficiency:
Rapidly attenuating peripheral pulmonary arteries, may be absent peripherally
Increased branching angles
Smaller-than-expected caliber
Bullae
Saber-sheath trachea
Indirect identification:
Signs of hyperinflation:
Flattened diaphragm
Sterno-diaphragmatic angle >90o on lateral
Increased width of retrosternal air space
Increased AP diameter
Increased intercostal distance

14. Emphysema

15. Giant Bullous Emphysema (“Vanshing Lung” Syndrome)
Giant bulla with missing vascular shadows.

16. Emphysema: Trachea
Saber-sheath trachea.

17. CT findings:
Relatively well-defined, low attenuation areas with very thin (invisible) walls, surrounded by normal lung parenchyma.
As disease progresses:
Amount of intervening normal lung decreases.
Number and size of the pulmonary vessels decrease.
+/- Abnormal vessel branching angles (>90o), with vessel bowing around the bullae.

18. Centrilobular Emphysema

19. Emphysematous Bullae

20. Chronic Bronchitis
Presence of a chronic, productive cough for 3 or more months, in at least 2 consecutive years, when all other causes of cough have been excluded (clinical diagnosis).

21. Pathology:
Hypertrophy of the submucusal glands in the trachea and bronchi, and an increase in goblet cells in the small bronchi and bronchioles, leads to excessive mucus production and obstruction.
Caused by tobacco smoke and other inhaled pollutants, not infection.
Infection appears to be significant in maintaining the disease.

22. Cotran2

23. Airflow obstruction caused by:
Mucus plugging of large and small airway lumens.
Airway alterations:
Inflammatory infiltration
Bronchiolar wall fibrosis

24. Clinical manifestation:
Cough
Copious sputum
Cyanotic (blue bloater)
+/- dyspnea
+/- rhonchi/wheezing
Usually obese

25. Chest radiographic findings:
It is difficult to know which radiographic findings are attributable to chronic bronchitis, rather than to emphysema, because they commonly coexist.
Chest radiograph is often not reliable at detecting or excluding chronic bronchitis.
CXR is helpful in excluding diseases that can clinically mimic chronic bronchitis (TB, tumor, bronchiectasis, abscess).

26. Principle Radiographic abnormalities:
Thickening of bronchial walls
Overinflation*
Oligemia*
Evidence of Pulmonary Arterial Hypertension
*The overinflation and oligemia seen in chronic
bronchitis may also be due to superimposed emphysema.

27. Chronic Bronchitis Normal Exacerbation
Webb, RW1
Arrows show parallel linear shadows indicating bronchial wall thickening.

28. Chronic Bronchitis
Webb, RW1
Bronchogram shows dilation, narrowing, and abrupt termination (arrows)
of various small bronchi.

29. CT findings: Limited literature on CT features of chronic bronchitis.
Bronchial wall thickening has been documented in patients with chronic bronchitis, but has also been observed in patients without respiratory symptoms.

30. Chronic Bronchitis
CT?

31. Quantitative CT:
Spirometically triggered images at 10% and 90% vital capacity (VC) have been reported to be able to distinguish patients with chronic bronchitis from those with emphysema.
Patients with emphysema had significantly lower mean lung attenuation at 90% VC than normal subjects or patients with chronic bronchitis.
Attenuation was the same for normal subjects and those with chronic bronchitis.

32. Asthma
A chronic, relapsing inflammatory disorder characterized by hyperactive airways, leading to episodic, reversible bronchoconstriction.
Two Types:
Extrinsic: initiated by a type I hypersensitivity reaction, induced by exposure to an extrinsic antigen.
Intrinsic: initiated by diverse, non-immune mechanisms (stress, pulmonary infection, exercise, cold, etc.).

33. Pathology: Large & small airway mucus plugging
Airway infiltrated with inflammatory cells
Tissue edema & epithelial disruption
Sub-basement membrane collagen deposition
Hypertrophy of smooth muscle
Hypertrophy of submucosal glands
Cotran2

34. Obstruction is caused by:
Bronchoconstriction
Airway wall edema and inflammatory thickening
Mucus plugging

35. Clinical Manifestation:
Cough (usually worse at night)
Dyspnea
Wheezing
Chest tightness
Symptoms often worse with:
Exercise
Allergens
Smoke
Changes in weather
And many others…

36. Chest radiographic findings:
Bronchial wall thickening: Most Common
Air-trapping (hyperinflation found in 25%)
Atelectasis: From mucus plugging
+/- bronchial constriction
+/- bronchial dilatation

37. Asthma: Airway Thickening Most Common Finding

38. Asthma: Airway Thickening and Hyperinflation

39. Thin Section CT findings:
Bronchial wall thickening
Mucoid impaction
Mosaic lung attenuation with air trapping
Findings may be reversible with pharmacologic treatment.
Centrilobular thickening

40. Asthma: Airway Thickening and Lucent Areas of Decreased Ventilation (Mosaic Perfusion)

41. Bronchiectasis
A chronic, necrotizing infection of the bronchi & bronchioles, leading to abnormal, permanent dilatation of the involved airways.
May develop in association with:
Bronchial obstruction: localized (tumor, foreign body) or diffuse (asthma, chronic bronchitis)
Congenital/Hereditary: CF, Kartagener’s syndrome
Necrotizing pneumonia
Incidence markedly decreased, due to the advent of antibiotics and immunizations.

42. Pathology:
Obstruction and infection are the major influences associated with bronchiectasis.
Bronchial obstruction leads to atelectasis of airways distal to the obstruction.
Bronchial wall inflammation & intraluminal secretions cause dilatation of the patent airways proximal to the obstruction.

43. Pathology:
Process becomes irreversible if the obstruction persists or if there is added infection.
Vicious cycle of recurrent/chronic infections perpetuates the airway inflammation & dilatation, leading to extensive endobronchial destruction.

44. FYI: There are different types of bronchiectasis:
Cylindrical
Airway wall is regularly/uniformly dilated.
Varicose
Greater dilatation with alternating areas of constriction and dilatation.
Cystic
Progressive, distal enlargement resulting in sac-like terminations of the airways.
Cystic spaces can be several centimeters in diameter and contain air-fluid levels.
Most severe

45. Clinical Manifestations:
Chronic cough and expectoration of copious, purulent sputum.
+/- dyspnea
+/- hemoptysis
+/- fever, weight loss, anemia, clubbing

46. Chest radiographic findings:
Earliest finding is bronchial wall thickening
With further dilatation & wall thickening, see “tram lines” & “ring shadows” (Curved reticular opacities).
There is often initially some generalized overinflation of involved lobe (from concurrent small airways involvement).
In advanced stages, areas of atelectasis and collapse develop.

47. Bronchiectasis: Pathology and Bronchogram - Historical Imaging Method of Diagnosis

48. Bronchiectasis: Cystic Fibrosis

49. Most frequent CT findings:
Lack of tapering of the bronchial lumen
Bronchial wall thickening
Bronchial dilatation
Visualized peripheral bronchi
Mucus plugging
Most frequent
Less frequent

50. Bronchiectasis
Radiology 2002; 225:
Arrows demonstrating various grades of bronchial wall thickening,
with concurrent mucus plugging (arrowheads) in some bronchial lumens.

51. Cystic Bronchiectasis

52. Bronchiectasis or “Question Dogma” “Signet ring” sign Signet ring?
Solitaire ring?
Radiology 1999; 212: 67-68
“Question Dogma”
…Marc Gosselin, MD
“Signet ring” sign

53. Bronchiolitis Obliterans
Pathologic fibrosis (scarring) of the small airways, leading to luminal narrowing and irreversible airflow obstruction.
Virtually any inflammatory process that leads to scarring can cause BO.

54. Bronchiolitis Obliterans
May be seen as the result of:
Childhood viral infection (Swyer-James Syndrome)
Mycoplasma pneumonia
Toxic fume inhalation
Common pulmonary problem in patients with:
Rheumatoid arthritis (especially if taking penicillamine)
Chronic GVH following BMT
Chronic rejection after heart-lung or lung transplant

55. Pathology:
Submucosal and peribronchiolar inflammation and fibrosis cause concentric narrowing of the bronchiolar lumen and mucus stasis.
Complete obstruction of the airway occurs by either fibrosis squeezing the lumen shut, or intraluminal plug formation.
Alveolar ventilation beyond the obstruction continues via the terminal conducting airways, adding to the degree of air trapping.

56. Clinical manifestation:
Cough
Dyspnea
Fatigue
Diagnosis of BO:
Irreversible airflow obstruction with a FEV1 <60% of predicted in the absence of emphysema, chronic bronchitis, asthma, or other causes of airway obstruction.

57. Chest radiographic findings:
Chest radiograph often subtle findings.
May be able to discern hyperinflation due to:
Air trapping
Vessel attenuation
Bronchial wall thickening
Involvement of one lung usually represents Swyer-James Syndrome.

58. Classic Bronchiolitis Obliterans (History and CT), But given a diagnosis of emphysema. (We diagnosis what we know, so know a lot!)

59. CT findings: Mosaic attenuation Bronchial dilatation Air trapping
Expiratory HRCT facilitates detection of areas of decreased attenuation.

60. Bronchiolitis Obliterans
Radiology 2000; 216:
Single arrows: air trapping
Double arrows: subtle areas of relatively increased lung attenuation represent normal, collapsing lung

61. Inspiratory & expiratory views of bronchiolitis obliterans
Marc Gosselin, MD

62. Obstructive Pulmonary Diseases of the Lower Airways
Imaging can be helpful in diagnosing lower airway obstructive disease; however, there is much overlap in findings.
It is necessary to integrate the clinical presentation, abnormal physiology, and imaging findings to correctly diagnose the disorder.
Consider ALL obstructive pathology when first establishing your differential diagnosis.
Remember, it’s NOT all emphysema…

63. References:
Webb, RW. The Radiologic Clinics of North America: Imaging of obstructive Pulmonary Disease. W.B. Saunders Company. Philadelphia, PA. Vol. 36(1). January, 1998.
Cotran RS, Kumar V, Collins T. Robbins Pathologic Basis of Disease: 6th ed. W.B. Saunders Company. Philadelphia, PA pp:
Lynch DA, Newell JD, Lee JS. Imaging of Diffuse Lung Disease. B.D. Decker Inc. Hamilton, Ontario pp:
Sharma V, Shaaban AM, Berges G, Gosselin M. The radiological spectrum of small-airway disease. Seminars in Ultrasound, CT, and MRI. 23(4): , 2002.
Webb RW, Muller NL, Naidich DP. High-Resolution CT of the Lung: 3rd ed. Lippincott Williams & Wilkins. Philadelphia, PA pp: