PEDIATRIC RESPIRATORY TRACT IMAGING

PEDIATRIC RESPIRATORY TRACT IMAGING IS VERY ESSENTIAL AND VERY EASY, IN THE FOLLOWING, WE WILL EXPLAIN IT IN VERY SIMPLE WORDS:

Upper Airway:

Approach:

  • Inspiratory stridor : is the most common indication for radiographic upper airway evaluation.
  • The main role of imaging is to identify conditions that need to be treated emergently & /or surgically (e.g., epiglottitis, foreign bodies).
  • Technique:
  1. Physician capable of emergency airway intervention should accompany child
  2. Obtain 3 films:

– Lateral neck: full inspiration, neck extended

– Anteroposterior (AP) and lateral chest: full inspiration, include upper airway.

 

  1. Fluoroscope the neck if radiographs are suboptimal or equivocal
  2. Primary diagnostic considerations:
  • Infection : epiglottitis, croup, abscess.
  • Foreign body : airway or pharyngo-esophageal.
  • Masses : lymphadenopathy, neoplasms.
  • Congenital abnormalities : webs, malacia
  1. If upper airway is normal, consider:
  • Pulmonary causes : foreign body, bronchiolitis.
  • Mediastinal causes: vascular rings, slings.
  • Congenital heart disease (CHD)

 

Normal appearance:

  • 3 anatomic regions:

– Supra-glottic region

– Glottic region : ventricle & true cords

– Sub-glottic region

  • Epiglottis & aryepiglottic folds are thin structures.
  • Glottic shoulders are seen on AP view.
  • Adenoids are visible at 3 to 6 months after birth.
  • Normal retropharyngeal soft tissue thickness (C1 C4) = three-fourths vertebral body width.

Laryngomalacia:

  • A common cause of stridor in the 1st year of life.
  • Immature laryngeal cartilage leads to supra-glottic collapse during inspiration.
  • Stridor improves with activity & is relieved by prone positioning or neck extension.
  • Self-limited course.
  • Diagnosis is established by fluoroscopy àlaryngeal collapse with inspiration.

Tracheomalacia:

  • Collapse of trachea with expiration.
  • May be focal or diffuse.
  • Focal type is usually Secondary to congenital anomalies that impress on the trachea, such as a vascular ring.

 

Webs:

  • Most common in the larynx.

Tracheal stenosis:

  • Diffuse hypoplasia, 30%
  • Focal ring-like stenosis, 50%
  • Funnel-like stenosis, 20%

Subglottic stenosis:

  • Fixed narrowing at level of cricoid. Failure of laryngeal recanalization in utero.

Epiglottitis:

  • Life-threatening bacterial infection of the upper airway.
  • Most commonly caused by Haemophilus influenzae.
  • Age: 3 to 6 years (older age group than with croup).
  • ttt is with àprophylactic intubation for 24 48 hours & antibiotics.
  • Clinical Findings

Fever

Dysphagia

Drooling

Sore throat

  • Radiographic Features:

Thickened aryepiglottic folds (hallmark)

Key radiographic view: lateral neck

Thickened epiglottis

Subglottic narrowing due to edema, 25%: indistinguishable from croup on AP view

Distention of hypopharynx

  

  • Pearls:
  • Other causes of enlarged epiglottis or aryepiglottic folds:

o   Caustic ingestion

o   Hereditary angioneurotic edema

o   Omega-shaped epiglottis : normal variant with normal aryepiglottic folds.

o   Stevens-Johnson syndrome

Croup:

  • Sub-glottic laryngotracheobronchitis.
  • Most commonly caused by parainfluenza virus.
  • Age: 6 months to 3 years (younger age group than epiglottitis).
  • Clinical Findings:

Barking cough

Upper respiratory tract infection

Self-limited

  • Radiographic Features:

Subglottic narrowing: inverted “V” or “steeple sign”.

Key view: AP view

Lateral view should be obtained to exclude à

Steeple sign : loss of subglottic shoulders.

  • Pearls:

Membranous croup:

Uncommon infection of bacterial origin Staphylococcus aureus.

Purulent membranes in subglottic trachea.

Epiglottitis may mimic croup on AP view.

 

Retropharyngeal abscess:

  • Typically due to the extension of a suppurative bacterial lymphadenitis, most commonly S. aureus, group B streptococci, oral flora.
  • Age  < 1 year.
  • Other causes include foreign body perforation and trauma.
  • Clinical Findings

Fever

Stiff neck

Dysphagia

Stridor (uncommon)

Most cases present as àcellulitis rather than a true abscess.

  • Radiographic Features:
o   Plain film findings : usually nonspecific.

o   Widened retropharyngeal space : most common finding

o   Air in soft tissues is specific for abscess.

o   Straightened cervical lordosis

o   CT is helpful to define superior & inferior mediastinal extent.

  • Main DDs:

Retropharyngeal hematoma

Neoplasm àe., rhabdomyosarcoma.

Lymphadenopathy

Tonsillar hypertrophy:

  • The tonsils consist of lymphoid tissue that encircles the pharynx.
  • 3 groups:

Pharyngeal tonsil (adenoids).

Palatine tonsil.

Lingual tonsil.

  • Tonsils enlarge secondary to infection and may obstruct nasopharynx & /or eustachian tubes.
  • Rarely, bacterial pharyngitis can lead to àa tonsillar abscess (quinsy abscess), which requires drainage.
  • Specific causes include:

                                      

o   Mononucleosis (Epstein-Barr virus)

o   Coxsackievirus (herpangina, hand-foot-mouth disease)

o   Adenovirus (pharyngoconjunctival fever)

o   Measles prodrome (rubeola)

o   Beta-Hemolytic Streptococcus (quinsy abscess)

  • Radiographic Features:
o   Mass in posterior nasopharynx (enlarged adenoids)

o   Mass near end of uvula (palatine tonsils)

o   CT is useful to determine the presence of a tonsillar abscess.

 

Airway foreign body (FB):

  • Common cause of respiratory distress.
  • Age à 6 months to 4 years.
  • Acute aspiration results in cough, stridor, wheezing; chronic FB causes à hemoptysis or recurrent pneumonia.
  • Location à right bronchi > left bronchi > larynx, trachea.
  • Radiographic Features:
Bronchial FB: o   Unilateral air tapping causing hyperlucent lung à 90%

o   Expiratory film or lateral decubitus àmakes air trapping more apparent.

o   Atelectasis is uncommon, 10%

o   Only 10% of FBs are radio-opaque.

o   Chest fluoroscopy or CT should be performed if plain film findings are equivocal.

Tracheal FB:

 

o   FB usually àlodges in sagittal plane

o   CXR is usually ànormal.

     

Mediastinum:

Thymus:

  • The ratio of thymus to body weight â with age.
  • Thymus is routinely identified on CXR from birth to 2 years of age.
  • Size & shape of the thymus are highly variable from person to person.

Common mediastinal tumors:

Anterior: o   Thymic hyperplasia & thymic variations in shape & size (most common)

o   Teratoma

o   T-cell lymphoma

o   Cystic hygroma

o   Thymomas are extremely rare.

Middle: o   Adenopathy (leukemia, lymphoma, TB)

o   Bronchopulmonary foregut malformation

Posterior: o   Neuroblastoma

o   Ganglioneuroma

o   Neurofibromatosis

o   Neurenteric cysts

o   Meningoceles

Pearls:

  • Any pediatric anterior mediastinal mass is considered thymus until proven otherwise.
  • Posterior mediastinal masses are the most common abnormal chest masses in infants

If you want to view Real Case Imaging of each disease , this link will be very helpful :

https://radiopaedia.org/playlists/6642

 

 

Leave a Reply

Your email address will not be published. Required fields are marked *