THE BRONCHI

The trachea bifurcates, giving rise to the left and right main stem bronchi.

In adults, the right main stem bronchus is more vertical, wider by about 2 mm, andapproximately half the length of the left main stem bronchus.

BRONCHIAL ANATOMY

• The right main stem bronchus ends at the lateral origin of the right-upper-lobe bronchus, and the main stem continues as the bronchus intermedius, which terminates where the middle-lobe bronchus originates anterolaterally and the superior segmental bronchus to the right-lower-lobe originates.

BRONCHIAL ANATOMY

• The main airway continues as the lower-lobe bronchus, which divides into anterior, lateral, posterior, and medial basal segmental bronchi.

• Divisions on the left are similar except that there is a short left-upper-lobe bronchus, which bifurcates into the lingular bronchus and a short trunk that almost immediately divides into anterior and common apicoposterior segmental airways.

BRONCHIAL ANATOMY

• After giving rise to the superior segmental bronchus to the left lower lobe, the lower-lobe airway continues inferiorly, dividing into three or four basilar segmental bronchi (in some instances there is a common anteromedial bronchus).

• The airways, to the subsegmental level, are visualized with CT scanning when 3- to 5-mm thin-section collimation is used.

BRONCHIECTASIS

Bronchiectasis

• defined as irreversible dilatation of the bronchial tree, may cause chronic sputum production and hemoptysis, or it may be asymptomatic.

• Types:– cylindrical, – varicose, – cystic

1. Dyskinetic Cilia Syndrome

• represents a spectrum of genetically determined defects in ciliary structure and function that interfere with mucociliary clearance.

• Although the term immotile cilia syndrome has been used, in many cases the cilia demonstrate some motility (although dyskinetic).

• Conditions including situs inversus, paranasal sinusitis, and bronchiectasis (a triad representing Kartagener's syndrome); recurrent upper and lower respiratory tract infections; and immotile sperm and infertility have been described.

• Prognosis is generally good, and the diagnosis is compatible with a full life span.

2. Cystic Fibrosis

CF

• a relatively common genetic disorder • Affects the upper and lower respiratory tracts,

pancreas, liver and gallbladder, intestines, and genital tract.

• Approximately one in 1,600 live births is affected.

• autosomal recessive disease• occurspredominantly in Caucasians.

Chest radiographic findings

• in adult CF include peripheral nodular and nonvascular linear densities, specific findings of bronchiectasis, hyperinflation, atelectasis, and cystic air spaces

3. Swyer-James Syndrome

• Swyer-James syndrome (SJS), also known as Macleod's syndrome, is a postinfectious form of bronchiolitis obliterans (BO) that typically follows a viral respiratory

• infection in infancy or childhood. 27,118,119 Chest radiographic findings include a unilateral small lung with hyperlucency and air trapping ( Fig. 26-10). The air trapping

• results from gas which enters the air spaces by collateral air drift and cannot exit because of the bronchiolar obstruction. The hyperlucency is usually confined to one

• lobe or lung; the disease can be bilateral but is usually unilateral. The other diagnostic considerations when these findings are recognized include an obstructing

• tumor or foreign body in the airway. Bronchiectasis is present in some but not all cases of SJS.

• Swyer-James syndrome (SJS) (also known as Sywer-James-MacLeod syndrome andBret syndrome) is a rare lung condition that manifests as unilateral hemithorax lucencyas a result of post-infectious obliterative bronchiolitis.

Epidemiology

• The condition typically follows a viral respiratory infection (adenovirus) in infancy or childhood

Radiographic Features• Plain film• It is generally characterized on radiographs by a unilateral

small lung with hyperlucency and air trapping 2.• CT• CT shows the affected lung as being hyperlucent with

diminished vascularity. The size of the majority of the affected lobes are smaller although occasionally they can be normal 3. There is usually no anteroposterior gradient attenuation 4. Bronchiectasis may be present although this is not a universal finding 5.

• Nuclear medicine• Quantitative ventilation/perfusion lung scan shows a

photopaenic area in the affected aspect.

Broncholithiasis

• Broncholithiasis is a term given for the presence of calcified or ossified material within the lumen of the bronchus.

• A broncholith is usually formed by erosion by and extrusion of a calcified adjacent lymph node into the bronchial lumen and is usually associated with long-standing foci of necrotizing granulomatous lymphadenitis.

Bronchiolitis

• Bronchiolitis is a broad term that refers to any form of inflammation of the bronchioles. It can carry variable clinical, functional and morphological expression. Bronchiolar disease may be a primary or a secondary condition.

4 classifications (CT)• (1) centrilobular nodular or branching linear areas of

increased attenuation in patients with infectious bronchiolitis, diffuse panbronchiolitis, or bronchiolitis complicating diseases of bronchi;

• (2) ground-glass attenuation and consolidation in patients with bronchiolitis obliterans organizing pneumonia (BOOP) or respiratory bronchiolitis associated with smoking;

• (3) areas of decreased attenuation and perfusion in BO; and • (4) bronchiolocentric opacities seen with several forms of

chronic infiltrative lung disease, where CT may show associated findings for each particular disease.

Emphysema

• Pulmonary emphysema is defined as the "abnormal permanent enlargement of the airspaces distal to the terminal bronchioles accompanied by destruction of the alveolar wall and without obvious fibrosis". Emphysema is one of the entities grouped together as chronic obstructive pulmonary disease. Emphysema is best evaluated on CT, although indirect signs can be noticed on conventional radiography in a proportion of cases. This article focuses on panlobular emphysema, paraseptal emphysema, and in particular centrilobular emphysema.

Epidemiology• At the time of initial writing, approximately 210 million people are

affected worldwide leading to 3 million deaths annually.1 It is predominantly a disease of middle to late life owing to the cumulative effect of smoking and other environmental risk factors. It traditionally affected more men than women but with increased smoking and environmental risk factor exposure among women, the incidence is now equal between the sexes. Patients with genetic risk factors such as alpha-1-antitrypsin deficiency may present earlier according to phenotype.

• Risk factors include:• smoking: by far the most common• alpha-1-antitrypsin (AAT) deficiency• intravenous injection of methylphenidate (Ritalin lung)

• Emphysema is one of a heterogeneous group of pathological processes forming chronic obstructive pulmonary disease, and is itself a relatively vague term encompassing a number of entities and morphological patterns including:

• morphologic subtypes:– centrilobular emphysema (most common)– panlobular emphysema– paraseptal emphysema– paracicatricial emphysema– localised emphysema

• idiopathic giant bullous emphysema (or vanishing lung syndrome)• congenital lobar emphysema• pulmonary interstitial emphysema

Radiographic features• hyperinflation:

– flattened hemidiaphragm(s): most reliable sign– increased and usually irregular radiolucency of the lungs– increased retrosternal airspace– increased antero-posterior diameter of chest– widely spaced ribs– sternal bowing– tenting of the diaphragm– saber-sheath trachea

• vascular changes:– paucity of blood vessels, often distorted– pulmonary arterial hypertension

• pruning of peripheral vessels• increased calibre of central arteries• right ventricular enlargement

• It should be remembered, however, that the most common plain film appearance of COPD is "normal" and the role of chest radiography is to eliminate other causes of lung symptoms such as infection, bronchiectasis or cancer 6.

• Emphysema is one of a heterogeneous group of pathological processes forming chronic obstructive pulmonary disease, and is itself a relatively vague term encompassing a number of entities and morphological patterns including:

• morphologic subtypes:– centrilobular emphysema (most common)– panlobular emphysema– paraseptal emphysema– paracicatricial emphysema– localised emphysema

• idiopathic giant bullous emphysema (or vanishing lung syndrome)• congenital lobar emphysema• pulmonary interstitial emphysema

• CT• CT is currently the modality of choice for detecting

emphysema; HRCT is particularly effective. It should be noted, however, that there is relatively poor correlation between autopsy-proven emphysema, pulmonary function test abnormalities and CT with 20% of pathology-proven cases not being evident on CT and 40% of patients with abnormal CT having normal pulmonary function tests.

• CT is able to discriminate between centrilobular, panlobular, and paraseptal emphysema.

• Centrilobular emphysema• Centrilobular is by far the most common type

encountered, and is a common finding in asymptomatic elderly patients. It is predominantly located in the upper zones of each lobe (i.e. apical and posterior segments of the upper lobes, and superior segment of the lower lobes) and has a patchy distribution 4. It appears as focal lucencies (emphysematous spaces) which measure up to 1 cm in diameter, located centrally within the secondary pulmonary lobule, often with a central or peripheral dot representing the central bronchovascular bundle 2-4.

• Panlobular emphysema• Panlobular emphysema is predominantly

located in the lower lobes, has a uniform distribution across parts of the secondary pulmonary lobule, which are homogeneously reduced in attenuation 2-4.

• Paraseptal emphysema• Paraseptal emphysema is located adjacent to the

pleura and septal lines with a peripheral distribution within the secondary pulmonary lobule. The affected lobules are almost always subpleural, and demonstrate small focal lucencies up to 10 mm in size.

• Any lucency larger than 10 mm should be referred to as subpleural blebs or subpleural bullae (synonymous) 3.

• In all three subtypes, the emphysematous spaces are not bounded by any visible wall 3.

• What are the x-ray findings of emphysema?

• Lungs are large and hyper inflated.• Signs of hyperinflation are:

– Low set diaphragm– Flat diaphragm best determined by

lateral chest– Hyper lucent lung fields– Increased AP diameter– Increased retrosternal air– Vertical heart

• Signs of hyperinflation can be seen in emphysema, chronic bronchitis and asthma.

• We can call it emphysema only when hyperinflation is associated with blebs and paucity of vascular markings in the outer third of the film.

• Lateral chest is best to evaluate flattening of diaphragm, AP diameter and retrosternal air.

• This lateral chest shows:• Increased AP diameter• Low set flat diaphragms• Hyper lucent lung fields• Increased retrosternal air

encroaching on heart density

• Multiple blebs: Avascular zones surrounded by thin wall

Criteria for chest radiographic diagnosis of emphysema include two

or more of the following:• 1. Depression and flattening of the diaphragm on the posteroanterior

roentgenogram with blunting of costophrenic angles. The actual level of the diaphragm is not

• as significant as the contour. (This can be determined from a straight line connecting the costophrenic junction to the vertebrophrenic junction on each side; if

• the highest level of the contour is less than 1.5 cm above this line, the diaphragm can be recorded as flat.)

• 2. Irregular radiolucency of the lung, caused by irregularity in distribution of the emphysematous tissue destruction

• 3. Abnormal retrosternal radiolucency, as seen on lateral view, measuring 2.5 cm or more from the sternum to the most anterior margin of the ascending aorta

• 4. Flattening or even concavity of the diaphragm contour on the lateral chest radiograph, as determined by the presence of a sternodiaphragmatic angle of 90° or larger.