TRACHEAL DISORDERS

Dr.JINO JUSTIN.J

RADIOLOGY RESIDENT

RMMCH

TRACHEAThe trachea is a cylindrical tube that projects onto the spine

from C6 to the level of T5.

As it passes downwards, it follows the curvature of the spine,

and courses slightly backward.

Near the tracheal bifurcation, it deviates slightly to the right.

The subglottis ends 2 cm below the level of the vocal cords.

This corresponds cranially to the inferior margin of the cricoid

cartilage, which is the inferior margin of the larynx and forms

the only complete cartilage ring in the airway.

• 18-22 cartilaginous rings

• There are 2.1 rings/cm

• Becomes intrathoracic at 6th cartilaginous ring

• Length 9 -17 cm

• Intrathoracic portion: 6-15 cm

• Cross-section area of women about 40% less than men.

The membranous posterior membrane allows esophageal expansion during deglutition

Contains glands, small arteries, nerves, lymph vessels and elastic fibers

Trachealis muscle overlies esophageal muscle and epithelium

Tracheal dimensions

Trachea

– Average cross-sectional area of the male adult trachea is approximately 2.8 cm2

– Transverse (lateral) diameter is of 25 mm and sagittal diameter is of 27 mm are the upper limits of normal (males)

– The lower limit is normal for both transverse and sagittal diameters & it is about 13 mm in men and 10 mm in women

The cervical segment (extrathoracic) ends at the

sternal manubrium and encompasses about the

first six tracheal rings.

The U-shaped trachea is probably the most

frequent shape found.

A man’s cross sectional tracheal area is usually

about 40 percent larger than a woman’s.

Some facts about tracheal anatomy

The trachea is lined by ciliated columnar epithelium.

The trachea in children is very pliable. It may be

deviated to the right at almost 90° in a normal

expiratory film.

It only deviates to the left if the aortic arch is on the

right side.

•Relations of the trachea

•CERVICAL

The anterior relations are as

follows:

•Anterior:

Isthmus of thyroid anterior to

the second, third and fourth rings

Inferior thyroid veins

Strap muscles: Sternohyoid and

Sternothyroid

•Posterior:

Oesophagus

Recurrent laryngeal nerves

Lateral:

Lobes of thyroid gland

Common carotid artery.

Thoracic:

The thoracic relations are as follows:

• Anterior:

Brachiocephalic and left common carotid arteries

Left brachiocephalic vein

• Posterior: Oesophagus and left recurrent

laryngeal nerve

• Left lateral:

Arch of the aorta

Left common carotid and left subclavian arteries

• Right lateral: Right brachiocephalic artery

Right vagus nerve

Arch of the azygos vein

Pleura (in direct contact unlike the other side).

•BLOOD SUPPLY OF THE TRACHEA

The upper trachea is supplied by the inferior

thyroid artery and the lower part is supplied

by branches of the bronchial artery.

Venous drainage is to the inferior thyroid

venous plexus.

Mediastinal lymph nodes that drain the lung are named according to their

position:

Tracheobronchial nodes above the tracheobronchial junction

Right and left paratracheal nodes on either side of the trachea.

The trachea is seen as a midline

translucency with a slight inclination to the

right in its lower half.

Its lumen is 1.5-2 cm in diameter.

The right paratracheal stripe (normally < 3

mm) is formed by the right wall of the

trachea and the pleura, outlined on both

sides by air.

The left side of the trachea is not seen

separately from the mediastinal shadows.

A smooth indentation on the trachea is

commonly seen just above the bifurcation on

the left side. This is caused by the arch of the

aorta.

RADIOLOGICAL FEATURES OF TRACHEA ON LATERAL CHEST

RADIOGRAPHOn a lateral chest radiograph the trachea is seen to enter the thorax midway

between the sternum and the vertebrae.

Owing to some posterior inclination it ends closer to the vertebrae.

The posterior paratracheal stripe is formed by the posterior wall of the trachea

and the pleura and is visible if the lung passes behind the trachea.

The tracheo-oesophageal stripe is formed by the posterior wall of the trachea

and the anterior wall of the oesophagus.

It is visible if there is air in the oesophagus.

Disorders

• CONGENITAL ABNORMALITIES.

• TRACHEAL NARROWING.

• TRACHEAL WIDENING.

• TRACHEAL AGENESIS.

• TRACHEAL STENOSIS.

• TRACHEOMALACIA.

• Tracheobronchopathia Osteochondroplastica.

• Neoplasm

CONGENITAL ABNORMALITIES

• TRACHEOESOPHAGEAL FISTULA.

– USUALLY OCCURS IN ASSOCIATION WITH ESOPHAGEAL ATRESIA,CAN ALSO OCCUR AS AN ISOLATED ANOMALY.

– MAY ALSO BE ASSOCIATED WITH OTHER ABNORMALITIES LIKE

– DUE TO FAILED FUSION OF TRACHEO ESOPHAGEAL RIDGES during third week of embryological development.

– Commonly associated with vater complex– VERTEBRAL.

– ANAL.

– TRACHEO-OESOPHAGEAL.

– RENAL.

TYPES

• Type 1-esophageal agenesis{very rare}.

• Type 2-proximal and distal esophageal bud present,with a missing mid-segment.

• Type 3-3A,3B&3C.

• 3A-proximal esophageal termination on the lower trachea with distal esophageal bud.

• 3B-proximal esophageal atresia with distal end arising from the lower trachea or carina.(most common upto 90%of cases).

• 3C-proximal esophageal termination on the lower trachea or carina with distal esophagus arising from the carina.

• Type D-if two segments of esophagus communicates ,termed as H type fistula(resemblane of the letter H).

TRACHEAL AGENESIS

• Very rare and commonly associated with maternal polyhydramniaos.

C/F : Acute severe respiratory distress, absent cry, inability to intubate.

• Type 1 – Absent upper trachea with lower trachea connecting to the oesophagus

• Type 2 – Common bronchus connecting right and left main bronchi to oesophagus with absent trachea

• Type 3 -Right and left main bronchi arises independentaly from oesophagus

TRACHEAL NARROWING

• Other wise known as sub-glottic stenosis(just below the vocal cord).

• In babies and young children subglottis is the narrowest part of the airway and most stenosis do occur at this level.

• CAUSES

• Fibrosing Mediastinitis

• Post tracheostomy(most common).

• Wegeners granulomatosis.

• Idiopathic progressive sub-glottic stenosis.

• Amyloidosis.

• Benign tumors e.gCarcinoid.

• Tracheal trauma/rupture.

FIBROSING MEDIASTINITIS

• Usually occurs due to tuberculosis and histoplasmosis causing tracheal narrowing Fibrosing Mediastinitis –

Coronal CT Image• There is airway narrowing of the right

lower lobe bronchus. There is thickening of the right pleura and right interlobular septae. There are partially calcified right hilar and mediastinal lymph nodes

TRACHEOBRONCHOPATHIA OSTEOCHONROPLASTICA

• rare, benign disease• characterized by development of cartilaginous and osseous

nodules within submucosa of the tracheal and bronchial walls.• typical in men > 50yrs• C/F - incidental finding mostly.

- dyspnea, cough, hemoptysis&wheezingmay be present.

- Nodules tend to be localized to the submucosa directly associated with the tracheal cartilage, sparing the posterior

tracheal membrane .

• The nodules - 3 - 8 mm in diameter

usually calcified.

• irregular than normal cartilage calcification.

• Similar central bronchial calcification also is seen in many patients.

• No significant decrease in tracheal diameter is seen with forced expiration.

CT image at two levels shows nodular thickening and calcifi cation of the anterior and lateral tracheal wall. The posterior tracheal mem-brane is normal in thickness and devoid of calcifi cations

Diagrammatic representation of the appearance of the trachea in tracheobronchopathiaosteochondroplastica. Tracheal cartilages are thickened, with small irregular calcifi c nodules along their inner aspect, protruding into the tracheal lumen.

nodules arising from the anterior and lateral tracheal wall, projecting into the lumen. The nodules are uncalcified.

Bronchoscopy shows nodules arising from tracheal cartilage. The posterior trachea is normal.

Tracheal Stenosis

• Congenital tracheal stenosis may result from a ring-shaped tracheal cartilage.

• Acquired tracheal stenosis usually is due to prior intubation or tracheostomy.

• Progressive dyspnea following extubation typically is present.• Infl ammation and pressure necrosis of the tracheal mucosa most

commonly occur at either the tracheostomy stoma or at the level of the tube balloon, 1 to 1.5 cm proximal to the tube tip; the stenosis usually involves 1.5 to 2.5 cm of the tracheal wall.

• The extrathoracic trachea most often is involved.• Focal narrowing may be seen if the tube tip presses on one part of the

tracheal wall, usually the anterior wall.• Acute postintubation stenosis results from edema of the tracheal wall or

intraluminal granulation tissue. .

• Plain films - may show an eccentric or hourglass-shaped tracheal nar-rowing.

• On CT, this may be seen as eccentric or concentric soft tissue internal to normal-appearing tracheal cartilage. The outer tracheal wall has a normal appear-ance, without evidence of deformity or narrowing. Dynamic expiratory images show little change in tracheal dimensions.

• Acute and chronic stenosis may also result from sarcoidosis, histoplasmosis, Wegener’s granulomatosis, and ulcerative colitis.

Postintubation tracheal stenosis due to granulation tissue.

A: Near the thoracic inlet, the trachea appears normalB: Below the level shown in (A), focal narrowing of the tracheal lumen is associated with increased soft tissue (white arrows) within the tracheal lumen. The calcified tracheal cartilage (black arrows) appears normal, without evidence of deformity or collapse.

Coronal reconstruction in a patient with an hourglass-shaped tracheal stenosis following intubation. The tracheal wall appears normal (large arrows), and granulation tissue is seen narrowing the tracheal lumen (small arrows).

Postintubation tracheal stenosis due to stricture

CT image at two levels shows side-to-side narrowing of the tracheal lumen resulting from deformity of the tracheal cartilage (arrows).

Postintubation tracheal stenosis due to deformity of tracheal cartilage

CT shows side-to-side narrowing of the tracheal lumen resulting from deformity of the tracheal cartilage (arrows). The tracheal wall is outlined by mediastinal fat.B: Coronal reconstruction shows an hourglass-shaped stenosis, with inward collapse of

the tracheal wall (white arrows). Calcifi ed tracheal cartilage (black arrow) is displaced inward.C: Three-di-mensional reconstruction shows the hourglass-shaped stenosis.

AMYLOIDOSIS• rare • Symptoms - hoarseness, stridor, dyspnea, cough, hemoptysis, and

recurrent infections.• Primary tracheobronchial amyloidosis - usually confined to the airways,

with no evidence of concurrent parenchymal disease. • Deposits are multifocal or diffuse

submucosal in locationinvolve the length of the trachea

main bronchi also are commonly affected. • plain radiographs and CT

diffuse tracheobronchial amyloidosis usually leads to concentric or nodular thickening of the tracheal wall

Calcication or ossification is common. Malacia is not present.

Rarely, a single localized submucosal nodule is present, resulting in eccentric wall thickening.

Multiple isolated lesions also may be seen. Atelectasis may be associated with bronchial involvement.

• Tracheobronchial amyloidosis. CTs through the proximal trachea using lung (A) and soft tissue (B) windows show eccentric thickening of the tracheal wall (arrows)

CT shows nodular thickening and calcifi cation of the walls of the right main and right upper lobe bronchi (arrows). D: Coronal reforma-tionshows tracheal wall thickening (large arrows) and focal thickening and calcifi cation of bronchial walls (small arrows). Lymph node calcifi cationalso is visible

WEGENER’S GRANULOMATOSIS

• systemic vasculitis.

• 90% of cases, serum antineutrophil cytoplasmic antibodies characterized by a diffuse granular cytoplasmic immunofluorescent staining pattern (cytoplasmic antineutrophilcytoplasmic antibody [C-ANCA]) are present.

• tracheobronchial involvement - 15% to 25% of cases; • symptoms - hoarseness, cough, and stridor. • Subglottic tracheal involvement is most typical • variable involvement of the vocal cords, distal trachea, and

proximal main stem bronchi. • Abnormalities may be focal or diffuse.• Pathologic findings -

circumferential airway wall thickening and inflammation, concentric narrowing of the tracheal lumen; mucosal ulceration and destruction of the cricoid or

tracheal cartilage are less common. • Plain radiographs - tracheal narrowing on both the frontal

and lateral radiographs; this narrowing may be localized or diffuse.

CT findings

• focal or circumferential thickening of the tracheal wall

• an increase in the overall tracheal diameter due to wall thickening

• narrowing of the tracheal lumen

• Malacia may be present

• Proximal bronchi may be involved

• Subglottic tracheal stenosis in Wegener’s granulomatosis. A: Excessive soft tissue (arrows) is visible internal to the cricoid cartilage. B: Coronal reconstruction in subglottic stenosis due to Wegener’s granulomatosis. The focal narrow-ing (large arrows) is just below the level of the vocal cords (small arrows).

• Tracheal and bronchial narrowing in Wegener’s granulomatosis. A: Chest radiograph shows bilateral lung nodules (arrows)..B: CT shows tracheal narrowing associated with concentric thickening of the tracheal wall (arrows).

Tracheal and bronchial narrowing in Wegener’s granulomatosisC: At the level of the carina, bronchial wall thickening (arrow) also is seen

• Tracheomalacia in Wegener’s granulomatosis. A: CT image on inspiration shows the tracheal lumen to be slightly reduced in diameter. B: CT during dynamic forced expiration shows marked reduction in the tracheal lumen.

• Bronchial narrowing in Wegener’s granulomatosis. A: CT shows narrowing of the proxi-mal left main bronchus, associated with thickening of its wall (arrows). B: Three-dimensional recon-struction shows left main bronchus narrowing (arrows). The distal trachea is slightly narrowed.

SABER SHEATH TRACHEA

• almost always is associated with chronic obstructive pulmonary disease.

• characterized by marked decrease in the coronal diameter of the intrathoracic trachea associated with an increase in its sagittal diameter

• extrathoracic trachea is normal. • may involve the entire intrathoracic trachea• earliest stages it is visible only at the thoracic inlet. • thought to be due to chronic injury and malacia of tracheal

cartilage due to coughing or increased intrathoracicpressure.

• The main bronchi are of normal size.

• On frontal radiographs

a characteristic side-to-side narrowing of the tracheal lumen is visible beginning at the thoracic inlet

The right paratracheal stripe, primarily representing tracheal wall, appears normal or slightly increased in thickness.

• On the lateral radiograph

the tracheal diameter appears normal or slightly increased.

tracheal diameter on the lateral fi lm measures 1.5 times that seen on frontal fi lm, saber sheath trachea is considered to be present

CT

• inward displacement of the lateral portions of the tracheal wall and cartilage with side-to side narrowing of the lumen

• tracheal wall usually normal thickness.

• During forced expiration - further inward bowing of the tracheal walls in many patients.

Saber-sheath trachea in a patient with chronic obstructive pulmonary disease

• PA chest radiograph - hourglass-shaped narrowing of the intrathoracic trachea (black arrows). The extrathoracic trachea (white arrows) appears normal.

• lateral projection- the tracheal diameter appears increased (arrows).

SABER SHEATH –TRACHEA ON CT

• The extrathoracic trachea is normal.

• tracheal cartilage is calcified

• The intrathoracic trachea at two levels is markedly narrowed from side to side (arrows), with deformity of the tracheal cartilage.

• The sagittal tracheal diameter is increased. • The tracheal wall is otherwise normal in appearance.

RELAPSING POLYCHONDRITIS

• rare systemic disorder

• characterized by recurrent episodes of cartilage inflammation

• most commonly affecting the ear, nose, joints, and the laryngeal and tracheal cartilage

• The upper airways are affected >50% of cases

• recurrent pneumonia is most common cause of death.

• Diffuse tracheal involvement, characterized by a dense inflammatory exudate, is limited to the cartilage and perichondrium

• does not affect the mucosa or submucosa.

• Plain radiographs

cylindrical narrowing of the extrathoracic and intrathoracic trachea and main

bronchi

• CT

thickening of the anterior and lateral tracheal wall

the posterior membrane is of normal thickness

inner and outer margins of the thickened tracheal walls are smooth in contour.

Collapse of tracheal cartilage may be seen in chronic disease.

Narrowing of both the tracheal lumen and the main bronchi is often present.

Tracheomalacia is often present

Relapsing polychondritis. Chest radiograph shows cylindrical narrowing of the entire trachea (arrows).

Relapsing polychondritis. The anterior and lateral tracheal walls (i.e., the cartilaginous portions) are thickened (large arrows). The posterior tracheal membrane is of normal thickness (small arrow). This appearance is characteristic. B: Narrowing of the main bronchi also is seen. The anterior bronchial walls are thickened (large arrows), while the posterior wall of the bronchus appears normal (small arrow)

RELAPSING POLYCHONDRITIS

CT shows marked narrowing of the tracheal lumen, with typical thickening of the anterior and lateral tracheal walls.

RELAPSING POLYCHONDRITIS

Coronal reconstruction shows diffuse narrowing of the trachea with thickening of its lateral walls (arrows). Sagittal reformation shows diffuse narrowing of the trachea (arrows)

Relapsing polychondritis with tracheomalacia. Expiratory CT shows sig-nifi cant collapse of the tracheal lumen compared with an inspiratory scan .

TRACHEAL DIVERTICULUM

• focal herniation of tracheal mucosa through the tracheal wall.

• may be seen in normal subjects, although it tends to be associated with chronic obstructive pulmonary disease.

• usually is asymptomatic and is detected incidentally.• almost always occurs near the thoracic inlet, along the

posterolateral right trachea, between the cartilaginous and muscular portions of the tracheal wall

• Can appear as an isolated paratracheal air cyst , usually a few millimeters in diameter, or as an airfilled structure communicating with the tracheal lumen

• Tracheal diverticulum is easily seen on CT, but is rarely visible on plain radiographs.

Heal diverticulum in a patient with chronic obstructive pulmonary disease. A defect in the right posterolateral tracheal wall (small arrow) communicates with a small diverticulum (large arrow).

A paratracheal air cyst is present in the upper mediastinum, representing a diverticulum (arrow).

A defect in the right posterolateral tracheal wall (arrow) communicates with the diverticulum.

MOUNIER-KUHN SYNDROME(TRACHEOBRONCHOMEGALY)

• It is Common in men in third and fourth decadesTracheobronchomegaly refers to patients who have marked dilatation of the trachea and mainstem bronchi.

• It is often associated with tracheal diverticulosis, recurrent lower respiratory tract infection and bronchiectasis.

• Atrophy affects the elastic and muscular elements of both the cartilaginous and membranous parts of the trachea. The diagnosis is based on radiological findings. The immediate subglottic trachea has a normal diameter, but it expands as it passes to the carina and this dilatation often continues into the major bronchi.

Tracheal TumorsPrimary malignant

• Most common (85% of cases)

Squamous cell carcinoma

Adenoid cystic carcinoma

• Rare

Other types of bronchogenic carcinoma

Carcinoid tumor

Sarcoma

Lymphoma

Metastatic

• Direct invasion most common

Thyroid carcinoma

Laryngeal cancer

Lung cancer

Esophageal cancer

• Hematogenous metastases

Melanoma

Breast carcinoma

Colon carcinoma

Kidney carcinoma

Benign

Squamous cell papilloma

Papillomatosis

Hamartoma

Mesenchymal tumors

TUMOURS

• Benign

-It present as small, well defined intraluminalnodules

-papilloma, fibroma,chondroma,haemangioma

• Malignant

-Usually occurs close to the carina

-Mostly squamous,adenoid cystic or adenocarcinoma

-Extraluminal best assessed by CT finding

Squamous cell

carcinoma

• associated with smoking

• multifocal in 10% of cases

• often involving the distal trachea; a main bronchus also may be involved

Adenoid cystic carcinoma

• originates from tracheal mucous glands

• most common in the upper trachea

• less common than squamous cell carcinoma.

• often arises from the posterolateral tracheal wall

Adenoid cystic carcinoma of the proximal tra-chea. An eccentric narrowing (arrows) of the tracheal lumen is caused by a sessile mass arising from the right tracheal wall.

• Adenoid cystic carcinoma of the trachea. A large mass (large arrows) in the upper trachea markedly narrows the tracheal lumen (small arrow) and invades the medi-astinum

• On a sagittalreconstruction, the mass (arrows) can be seen to arise from the posterior tracheal wall. This location is typical of adenoid cystic carcinoma.

On CT

• a primary malignant tracheal tumor may appear as polypoid lesion, a focal sessile lesion, eccentric narrow-ing of the tracheal lumen, or circumferential wall thickening

• Attachment to the tracheal wall may be either broad based or narrow and pedunculated.

• CT may underestimate the longitudinal extent of the tumor; submucosal spread may be difficult to see on CT.

• However, CT is superior to bronchoscopy in evaluating extraluminal spread and the trachea distal to an obstructing lesion.

Adenoid cystic carcinoma results in a sessile mass (M) arising from the posterior tracheal wall and protruding into the tracheal lumen. The mass extends into the adjacent mediastinum (arrows).

CT appearances of primary tracheal tumor. A: Tracheal malignancies may appear polypoid, sessile, or circumferential

Metastases

• Metastases to the trachea may occur via direct extension or by hematogenous spread.

• Direct extension to involve the trachea most often is secondary to a primary tumor of the lung, larynx, esophagus, or thyroid.

• These tumors may compress the trachea, displacing tracheal cartilage inward, or may invade the tracheal lumen, with tumor being seen as abnormal tissue internal to tracheal cartilage .

• Hematogenous metastases usually originate from melanoma, or from carcinomas of the breast, colon, or kidney.

• On CT, hematogenous metastases may appear as single or multiple, sessile or pedunculated endotracheal lesions

Tracheal metastasis. Tracheal metastases may result in tracheal compression with inward displacement of the tracheal wall, an endotracheal mass, or a combination of these findings. A, B: There is narrowing of the trachea with an endoluminal mass (arrow)

Soft-tissue window at the same level as (B) shows a mass involving the right tracheal wall and mediastinal soft tissues (arrows)

Squamous cell papilloma

• most common benign tracheal tumor.

• It represents an abnormal proliferation of squamous epithelium

• may appear sessile, papillary, lobulated, or polypoid.

• Solitary papilloma is associated with smoking and is most common in adults.

• The condition of mul-tiple papillomas (i.e., papillomatosis) usually begins in child-hood with laryngeal involvement and is associated with human papillomavirus infection.

• On CT, a solitary papilloma appears as a well-circumscribed nodule that is confined to the tracheal wall and projects into the tracheal lumen;

• it often shows acute angles where it contacts the tracheal wall.

• Tracheal cartilage is unaffected.

• Papillomatosis is characterized by numerous nodules involving the entire length of the trachea or diffuse thickening of the tracheal wall .

• Other benign tracheal tumors include hamartoma and tumors of mesenchymal origin such as lipoma or chondroma.

Summary

• CT is currently the primary noninvasive examination to evaluate the trachea because it offers multiplanar capabilities, evaluates the morphology of the tracheal wall and lumen, and can be acquired in seconds.

• The trachea is supported by C-shaped cartilaginous rings anteriorly; the posterior trachea is primarily supported by the thin trachealis muscle.

• The lunate-shaped trachea on inspiration is highly suggestive of tracheomalacia.

• Traditionally, collapse of greater than 50% of the trachea during expiration was defined as tracheomalacia; however, recent evidence suggests that greater than 50% dynamic expiratory collapse can be seen in healthy patients.

• In saber-sheath trachea, only the coronal diameter of the intrathoracictrachea is narrowed; primarily men with chronic obstructive pulmonary disease are affected.

• The posterior wall of the trachea and the central bronchi are classically spared in both relapsing polychondritis and tracheobronchopathiaosteochondroplastica. However, the presence of focal coarse calcification and ossification is highly suggestive of tracheobronchopathiaosteochondroplastica rather than relapsing polychondritis.

• Nodular calcification of the trachea is common in tracheobronchopathiaosteochondroplastica and amyloidosis. However, amyloidosis tends to involve the airway concentrically, as opposed to tracheobronchopathiaosteochondroplastica which spares the posterior wall.

• Wegener granulomatosis most often affects the subglottic trachea but can be diffuse or multifocal.

• Mounier-Kuhn syndrome is unique among the diffuse tracheal diseases in that it results in diffuse airway dilatation. Diverticula project between the cartilaginous rings giving the trachea and proximal bronchi a corrugated appearance.

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