Obstructive Pulmonary
Diseases of the Lower
Airways…It’s not all
Emphysema!
Karin and Jason Kuhl
4/14/04
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
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)
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.
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.”
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.
Pathology of the secondary
pulmonary lobule:
Normal
B. Centriacinar
C. Panacinar
D. Paraseptal
A.
Webb1
Protease-Anti-protease
Theory:
Cotran2

Emphysema results from the destructive effect of high
protease activity in subjects with low anti-protease activity.
Normal lung and emphysema:
Marc Gosselin, MD
Airflow obstruction is due to the loss of
elastic recoil of the lung parenchyma.
Lynch3
Clinical manifestation:

Insidious onset
 Dyspnea
 Noncyanotic (pink
puffer)
 Mild cough
 +/- Increased sputum
 +/- Wheezing
  AP diameter
 Usually thin
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.
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
Emphysema
Giant Bullous Emphysema
(“Vanshing Lung” Syndrome)
Giant bulla with missing vascular shadows.
Emphysema: Trachea
Saber-sheath trachea.
www.radiology.vcu.edu
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.
Centrilobular Emphysema
Emphysematous Bullae
www.ctsnet.org/doc/6761
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).
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.
Cotran2
Airflow obstruction caused by:

Mucus plugging of
large and small airway
lumens.
 Airway alterations:
– Inflammatory
infiltration
– Bronchiolar wall
fibrosis
Clinical manifestation:






Cough
Copious sputum
Cyanotic (blue
bloater)
+/- dyspnea
+/- rhonchi/wheezing
Usually obese
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).
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.
Chronic Bronchitis
Normal
Exacerbation
Webb, RW1
Arrows show parallel linear shadows indicating bronchial wall thickening.
Chronic Bronchitis
Webb, RW1
Bronchogram shows dilation, narrowing, and abrupt termination (arrows)
of various small bronchi.
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.
Chronic Bronchitis
CT?
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.
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.).
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
Obstruction is caused by:

Bronchoconstriction

Airway wall edema
and inflammatory
thickening

Mucus plugging
Clinical Manifestation:

Cough (usually worse at
night)
 Dyspnea
 Wheezing
 Chest tightness
 Symptoms often worse
with:
–
–
–
–
–
Exercise
Allergens
Smoke
Changes in weather
And many others…
Chest radiographic findings:

Bronchial wall thickening: Most Common
 Air-trapping (hyperinflation found in 25%)
 Atelectasis: From mucus plugging
 +/- bronchial constriction
 +/- bronchial dilatation
Asthma: Airway Thickening Most
Common Finding
Asthma: Airway Thickening and Hyperinflation
Thin Section CT findings:

Bronchial wall thickening
 Mucoid impaction
 Mosaic lung attenuation with air trapping
– Findings may be reversible with pharmacologic
treatment.

Centrilobular thickening
Asthma: Airway Thickening and Lucent Areas of
Decreased Ventilation (Mosaic Perfusion)
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.
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.
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.
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
Most severe
terminations of the airways.
– Cystic spaces can be several centimeters in diameter
and contain air-fluid levels.
Clinical Manifestations:

Chronic cough and
expectoration of
copious, purulent
sputum.
 +/- dyspnea
 +/- hemoptysis
 +/- fever, weight loss,
anemia, clubbing
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.
Bronchiectasis: Pathology and Bronchogram Historical Imaging Method of Diagnosis
Bronchiectasis: Cystic Fibrosis
Most frequent CT findings:
Most frequent
Less frequent

Lack of tapering of the bronchial
lumen
 Bronchial wall thickening
 Bronchial dilatation
 Visualized peripheral bronchi
 Mucus plugging
Bronchiectasis
Radiology 2002; 225: 663-672
Arrows demonstrating various grades of bronchial wall thickening,
with concurrent mucus plugging (arrowheads) in some bronchial lumens.
Cystic Bronchiectasis
www.emedicine.com
Bronchiectasis
Signet ring?
or
Solitaire ring?
Radiology 1999; 212: 67-68
“Signet ring” sign
“Question Dogma”
…Marc Gosselin, MD
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.
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
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.
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.
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.
Classic Bronchiolitis Obliterans (History and
CT), But given a diagnosis of emphysema. (We
diagnosis what we know, so know a lot!)
CT findings:

Mosaic attenuation
 Bronchial dilatation
 Air trapping
– Expiratory HRCT facilitates detection of areas
of decreased attenuation.
Bronchiolitis Obliterans
Radiology 2000; 216: 472-477
•Single arrows: air trapping
•Double arrows: subtle areas of relatively increased lung attenuation represent
normal, collapsing lung
Inspiratory & expiratory views
of bronchiolitis obliterans
Marc Gosselin, MD
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…
References:
1.
2.
3.
4.
5.
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. 1999. pp: 711-717.
Lynch DA, Newell JD, Lee JS. Imaging of Diffuse Lung Disease. B.D.
Decker Inc. Hamilton, Ontario. 2000. pp: 171-200.
Sharma V, Shaaban AM, Berges G, Gosselin M. The radiological spectrum
of small-airway disease. Seminars in Ultrasound, CT, and MRI. 23(4): 339351, 2002.
Webb RW, Muller NL, Naidich DP. High-Resolution CT of the Lung: 3rd
ed. Lippincott Williams & Wilkins. Philadelphia, PA. 2001. pp: 467-546.