ROLE OF IMAGING IN

PEDIATRIC CHEST DISEASES

(STUDY OF 60 CASES)

A

DISSERATATION SUBMITTED TO

THE GUJARAT UNIVERSITY

FOR THE DEGREE OF

DOCTOR OF MEDICINE

(BRANCH-IX)

RADIODIAGNOSIS

GUIDED BY:

DR. P.A.AMIN

(M.D.)

PROFESSOR AND HEAD OF THE DEPARTMENT,

DEPARTMENT OF RADIOLOGY,

B.J. MEDICAL COLLEGE AND CIVIL HOSPITAL,

AHEMEDABAD-380016

SUBMITTED BY:

DR. RUSHABH G. SHAH

APRIL-2010

1

INTRODUCTION

Pediatric chest radiology is a complex subject and hence a full understanding of

all the relevant pathologies is necessary. Clinically the pediatric patient with a thoracic

disorder usually presents with fever, wheezing, shortness of breath, tachypnea ,

hoarseness, stridor, cough with or with out expectoration, feeding problems in newborn

patients etc. However, these signs and symptoms of thoracic disorders in pediatric

patients are relatively non-specific and often caused by multiple disorders of varying

pathogenesis. For example, wheezing can be caused by infection (viral or bacterial),

toxic exposure (inhalation), trauma (aspirated foreign body) or congenital anomalies

(such as tracheal compression by a vascular ring, such as a double aortic arch).

Radiation exposure in the first 10 years of life is estimated to produce a risk of

total aggregated detriment 5–7 times greater than exposure after the age of 50.

The role of diagnostic imaging is to provide the clinician probable underlying

etiology of the patients’ symptomatology with the knowledge of the relative advantages

and disadvantages of the various modalities for the wide range of disorders in infants

and children keeping the dosage of radiation minimum to the patient.

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AIMS AND OBJECTIVES

(1) To describe different modalities available for imaging of pediatric chest with their

advantages and disadvantages.

(2) To present a brief overview of the various chest pathologies in neonate and

children

(3) To consider radiological appearances of various chest pathologies

(4) To discuss current approaches for radiologic analysis and diagnosis of these

pathologies

(5) To consider role of imaging for providing anatomical operative planes for

surgeons.

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ANATOMY OF LUNG

THE LUNGS

Each lung is divided into lobes surrounded by pleura. There are two lobes on the left:

the upper and lower, separated by the major (oblique) fissure; and three on the right: the

upper, middle and lower lobes separated by the major (oblique) and minor (horizontal)

fissures. The fissures are frequently incomplete, particularly medially, containing

localized defects which form an alveolar pathway for collateral air drift and the spread of

disease.

For a fissure to be visualized on conventional radiographs, the X-ray beam has to be

tangential to the fissure. In most people, some or all of the minor fissure is seen in the

frontal projection, but neither major fissure can be identified. In the lateral view, both the

major and minor fissures are often identified, but usually only part of any fissure is seen;

in fact, it is very unusual to see both left and right major fissures in their entirety.

The major fissures have similar anatomy on the two sides. They run obliquely anteriorly

and inferiorly from approximately the fifth thoracic vertebra to pass through the hilum

and contact the diaphragm 0–3 cm behind the anterior costophrenic angle.

The minor fissure fans out anteriorly and laterally from the right hilum in a horizontal

direction to reach the chest wall. On a standard chest radiograph, the minor fissure

contacts the chest wall at the axillary portion of the right sixth rib.

THE CENTRAL AIRWAYS

The trachea is a straight tube that, in children and young adults, passes inferiorly and

posteriorly in the midline. In subjects with unfolding and ectasia of the aorta the trachea

may deviate to the right and may also bow forward. In cross-section the trachea is

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usually round, oval, or oval with a flattened posterior margin. The trachea divides into

the two mainstem bronchi at the carina. In children the angles are symmetrical. The

main stem bronchi further divide into lobar bronchus and then into segmental bronchus

dividing lungs into segments.

Nomenclature approved by the Thoracic Society is given as below:

UPPER LOBE

Right Left

1. Apical bronchus 1. Apicoposterior bronchus

2. Posterior bronchus 2. Anterior bronchus

3. Anterior bronchus

MIDDLE LOBE/LINGULA

4. Lateral bronchus 4. Superior bronchus

5. Medial bronchus 5. Inferior bronchus

LOWER LOBE

6. Apical bronchus 6. Apical bronchus

7. Medial basal (cardiac) 8. Anterior basal bronchus

8. Anterior basal bronchus 9. Lateral basal bronchus

9. Lateral basal bronchus 10. Posterior basal bronchus

10. Posterior basal bronchus

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MODALITIES FOR PEDIATRIC CHEST IMAGING

CHEST X RAY: - TECHNICAL FACTORS, VARIATIONS AND ARTEFACTS

Chest radiograph is usually the first imaging modality used for thoracic signs and

symptoms.

• Technical Factors of chest x ray in pediatric patient

A. LUNG VOLUME:-

Findings of a good inspiratory film:

• Heart projects below the dome less than 1/3rd

• Flat domes of diaphragm on frontal view

• Vertically oriented hemidiaphragms on lateral view

• Anterior 6th/ 7th rib crossing the diaphragm

• Triangle of air behind heart

B. POSITION OF THE PATIENT:-

In supine position, the vascular supply to upper and lower lobes is equal since

gravity has no effect as compared to child sitting or standing when due to gravity upper-

lobe vessels are less distended than lower-lobe vessels.

Findings of a rotated film:-

• Anterior ribs- not equidistant from ipsilateral pedicles

• Medial aspects of clavicles- asymmetrical in relation to midline

• Position of carina to the left of right pedicles (normally approx. right

pedicles)

• Ribs seen posteriorly

• Differential aeration of lung field

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C. PROJECTION OF THE X RAY:-

In supine film, there is inherent magnification of mediastinal structures and

absence of the effect of gravity on pulmonary vascularity.

D. ADEQUACY OF EXPOSURE:-

In properly exposed film, the detailed spine and pedicle through the heart and the

pulmonary vessels in the peripheral lung are visible. If only the spine but not the

pulmonary vessels are seen, the film is overexposed.

E. THYMUS:-

The mediastinum of infants including neonates appears abnormally wide or

misshapen, due to the variable appearance of the thymus. Enlargement of the thymus

may occur after an acute illness—normal ‘thymic rebound’, and may simulate

mediastinal mass. Features of normal thymus : lower attenuation structure allowing

vessels to be seen through it, uniform reflectivity on US and not displacing the trachea.

• Technical factors of chest x ray in neonate:

1. PA projection: - difficult to take in neonate.

2. AP projection: - supine, tube–film distance is 36–40 in.

3. Lateral projection :- by turning patient to one side “cross table lateral

view”- particularly for free air .

The normal appearance of neonatal chest differs from older pediatric chest. It is almost

cylindrical in shape, having horizontal ribs with higher anterior portions of diaphragm.

• Difficulties in interpretation of neonatal chest x ray due to technical and

anatomical factors:-

1. A normal neonate breathes at a rate of 30–50/min, and it is therefore difficult to get a

“good inspiratory film”.

2. The trachea in the neonate and young infant is “too long” for the contracted chest in

expiration and therefore buckles.

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3. Skin folds can be seen as curvilinear densities projecting over the lung bases laterally

mimicking a pneumothorax.

4. A rotated film can simulate abnormal mediastinal shift.

5. “Ductus bump”:- Frontal views in an infant shows “bump” in the upper mediastinum

caused by the superimposition of the main pulmonary artery, left pulmonary artery, and

ductus arteriosus. The latter gradually retracts, and the mass disappears by 3rd day.

• Neonatal Chest with Normally Positioned Tubes and Lines

The position of the tubes and lines on a neonatal chest x-ray should be:

1. Nasogastric tube tip: within the stomach

2. Feeding tube tip: within the third portion of the duodenum

3. Central venous line tip

From subclavian/jugular/antecubital approaches: within superior vena cava.

From a femoral approach: low in the inferior vena cava (below L3) or at the

junction of the inferior vena cava and right atrium

4. Umbilical artery catheter (UAC) tip: either high (between T7 and T11) or low

(Below L3). On the lateral film the UAC dips into the pelvis from the umbilicus

through one of the paired umbilical arteries and then courses through the

internal iliac artery and then into the common iliac artery and aorta. UAC

projects over the left side of the spine on the AP film.

5. Umbilical venous catheter (UVC) tip: at the junction of the right atrium and the

superior vena cava.On the lateral film the UVC extends cephalad from the

umbilicus through the umbilical vein and then courses into the portal vein,

across the ductus venosus, and into the inferior vena cava. The UVC projects

over right side of the spine on the AP film.

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FLOUROSCOPY

It has limited role due to high radiation dose, but may be useful for assessment of

diaphragmatic movement, air trapping, oesophageal lesions.

ULTRASONOGRAPHY

USG should be considered as a second line modality for the evaluation of those

processes which are intrathoracic but peripheral in location as there is no sound

transmission through air filled lungs3. USG is useful for presence and characterisation of

pleural effusions, chest wall leisons, peripheral lung lesions and anterior mediastinal

mass in young childern.

COMPUTED TOMOGRAPHY

CT is often considered when radiography is insufficient for the diagnosis or for

surgical planning. CT provides excellent global assessment of thoracic and intrathoracic

structure with the help of IV contrast media. HRCT provides early information regarding

diffuse pulmonary parenchymal disease. Relative disadvantages are need of sedation in

younger childern, artefacts due to cardiac and respiratory motions , less tissue contrast

due to paucity of mediastinal fat and risks of IV contrast.

MRI

MR imaging is considered as a problem solving tool in evaluation of chest wall,

spinal, paraspinal region and cardiovascular disease.

NUCLEAR MEDICINE

Nuclear medicine help delineate cardiac function, lung ventilation/perfusion,

pulmonary embolism and inflammtory lung disease.

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CLASSIFICATION OF PEDIATRIC CHEST PATHOLOGIES

Α) MEDICAL CONDITIONS:-

NEONATE INFANTS AND YOUNG CHILDERN

Transient tachypnea of newborn Infections

Hyaline membrane disease AIDS

Aspiration syndrome Aspiration pneumonia

Neonatal pneumonia Hilar adenopathy

Pulmonary Hemorrhage Cystic fibrosis

Complication of Therapy- Interstitial lung disease

Early:-

Pneumothorax

Pneumomediastinum

Pulmonary interstitial emphysema

Late:-

Bronchopulmonary dysplasia

Wilson- Mikity syndrome

Β) SURGICAL CONDITIONS:-

1. LUNG:-

Congenital:-

Abnormal lung bud development: - Congenital lobar emphysema

Unilateral pulmonary agenesis

Pulmonary hypoplasia and

Hypogenetic syndrome

Abnormal separation of lung bud: - Sequestration

Hamartomatous lesions: - Congenital cystic adenomatoid

Malformation (CCAM)

Lung cysts

Hamartoma

Vascular anomalies Congenital AV malformation

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Infective:-

Lung abscess

Hydatid cyst

Neoplastic:-

Metastasis

Pulmonary sarcoma/blastoma

2. AIRWAY:-

Congenital:-

Tracheo-esophageal fistula

Tracheal stenosis

Tracheomalacia

Infective:-

Bronchiectasis

Obstruction:-

Foreign body inhalation

3. MEDIASTINUM:-

Developmental:-

Lymphangioma

Anterior thoracic meningocele

Duplication cyst

Mediastinal mass: described below

4. PLEURAL AND CHEST WALL:-

Infective: - Empyema

Neoplastic:-

PNET (Primitive neuroectodermal tumor)

Ewing’s sarcoma

Rhabdomyosarcoma

5. DIPHRAGM:-

Diaphragmatic eventration

Diaphragmatic herniation

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CLASSIFICATION OF MEDIASTINAL MASSES

For classification of mediastinal masses, mediastinum is divided into three

compartments. For this various classifications have been given but most common

followed radiographically is as mentioned below:

Anterior: - The space in front of the heart and great vessels

Middle: - The space between the anterior and posterior mediastinal components,

including heart, airway, esophagus, and lymph nodes

Posterior: - Everything behind a line that passes through 1 cm behind anterior border of

vertebral body

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Category Anterior Middle PosteriorCongenital Normal thymus

Cystic Hygroma

Morgagni Hernia

Foregut Duplication Cyst

Bronchogenic Cyst

Esophageal duplication cyst

Neurenteric cyst

Cystic Hygroma

Hiatus hernia

Achalasia

Cardiomegaly

Vena caval enlargement

Bochdalek

Hernia

Foregut cysts

Hiatal Hernia

Inflammatory Lymphadenopathy Lymphadenopathy

Tuberculosis, sarcoidosis,

Histoplasmosis, Metastasis

Lymphoma

Paravertebral

abscess

Neoplastic Lymphoma & leukemia

Germ cell tumours

Thymoma

Thymolipoma

Extension of those arising from

Anterior mediastinum

Ganglion cell

tumour

Lymphoma

Mesenchymal

tumoursVascular Aortic aneurysm Aortic

aneurysm

Azygous &

hemiazygous

enlargementOther Paravertebral

Hematoma

Extramedullary

Hematopoesis

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RADIOLOGICAL APPEARANCES OF COMMON PEDIATRIC CHEST

DISEASES

Respiratory distress syndrome( RDS, or hyaline membrane disease, HMD):-

a. Preterm

b. Diffuse ground glass opacities- fine reticular shadows throughout

c. Accentuation of air bronchogram

d. Confluent shadows obscuring diaphragmatic and cardiac contour

e. Effusion is very rare

f. Traditionally low volume

Neonatal pneumonia:-

a. Any pattern possible (focal opacity, multifocal opacity, focal or diffuse ground

glass opacities)

b. Asymmetry of the findings is more favouring

c. Normal or increased lung volume

d. Term or preterm appearing child

e. Small to moderate pleural effusion is much more common

Aspiration syndromes: can be amniotic fluid alone, blood, or fluid with meconium—the

latter results in most severe changes)

a. Generally, term neonate

b. Patchy areas of hyperinflation and atelectasis (or other heterogeneous

opacities)

c. Pneumothorax or pneumomediastinum

d. Effusion is not typical

Transient tachypnea of the newborn (TTN) or retained foetal lung fluid

a. Term neonate

b. Increased lung volume

c. Streaky, predominantly central opacities

d. Usually symmetrical, more on right side

e. Small pleural effusion

f. Radiographic resolution by 48-72 hrs of age

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Pneumothorax:-

Air in pleural cavity, usually anterior and medial to lung

Increased radiolucency of hemithorax

Increased sharpness of mediastinal border from superior extent to diaphragm

Compression of thymus

Pneumomediastinum:-

Air in mediastinum, able to dissect into various spaces

Not associated with respiratory distress

Oval or round lucency on either side of diaphragm

Not extend to diaphragm due to its anterior location

Elevation of thymus

Pulmonary interstitial emphysema (PIE):-

Air leaking into the interstitial space and spreading throughout the lymphatics

and along the perivascular sheaths

Radiological appearance is of small bubbles of air radiating out from the hilum.

When severe, the lungs are overinflated.

PULMONARY INFECTIONS:-

Most common cause of respiratory related morbidity in pediatric patient.

Etiologies acco. To different ages:-

Congenital(at birth) Newborn(less than 1 mth)

Group B streptococcus Group B streptococcus

Gram –ve organisms Gram –ve organisms

Congenital viruses Staph. Aureus

Toxoplasmosis Chlamydia Trachomatis

Listeria Monocygenes Pneumocystis carinii

Viruses

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Early years (1 to 5 yrs) Older children (more than 5 yrs)

Viruses Viruses Streptococcus pneumoniae

Mycoplasma pneumoniae

H. Influenzae Strepto. Pneumoniae

Staph. Aureus H. Influenzae

Radiological appearance:

X RAY:-

Bacterial Pneumonia

Focal (more common than multifocal) opacity

Ill-defined margin

Air space involvement: air bronchogram (hallmark of airspace disease)

Lobar or segmental distribution

Normal lung volumes

Associated pleural effusion or empyema

Hilar adenopathy

Viral pneumonitis

Generally symmetric: centralized or diffuse

Interstitial Involvement

Peribronchial thickening

Streaky hilar opacities

On lateral, these superimpose to create full looking hila

Pitfall: may look like adenopathy

Hyperinflated lungs

Atelectasis

Hilar adenopathy

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Appearance specific to organism:-

Staph. Aureus: - Severe, necrotizing, segmental and lobar consolidation

Associated with cavitation and pneumatocele

Associated with pleural effusion and empyema

‘Ghost cavities’ may persist after resolution

Pertussis: - Classical finding is of shaggy heart border due to sublobar

Consolidation

Pneumocystis carinii pneumoniae:-

Most common opportunistic infection in children with HIV

Affects children between 3 months to 7 months

Radiographic appearance includes increased interstitial

markings, which spread from an initial perihilar distribution to the

periphery. Alveolar opacities often accompany progression of

interstitial disease

Round pneumonia:- In children less than 8 years of age in whom the collateral

pathways of circulation are not well developed, pneumonia can

have a very round appearance and mimic a mass8.In a child

with fever and appropriate symptoms, round pneumonia should

be the primary diagnosis when a round mass is seen on chest X

ray. Follow-up after antibiotic therapy needed to exclude an

underlying mass, such as a bronchogenic cyst. Most cases are

related to Streptococcal pneumoniae infection.

Fungal infection:- usually non specific, but hallmark is the prescence of nodules6.

USG:-

The role of USG for in infectious processes is primarily limited to evaluation of

the presence and of characteristics of pleural fluid, or in confirming that an opacity is

parenchymal and not pleural.

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CT:-

CT is used in evaluation of parenchymal infections that are not responsive to

therapy and associated with progressive consolidation or development for large pleural

fluid collection.

CT examination is the second-line modality in evaluation of pulmonary infectious

process following serial radiographs.

Findings include necrosis, cavitation, pleural abnormalities (bronchopleural

fistulae, fluid collections) or chest wall involvement.

IV contrast-enhanced CT is useful to define adjacent vessels, potential

enhancement of viable lung which may be atelectatic, or absence of enhancement of

consolidated lung suggesting necrosis.

It also gives the best assessment of the nature and extent of infection, including

the presence of pneumatocele formation.

PULMONARY TUBERCULOSIS:-

Lung is the most commonly involved organ by Mycobacterium.

Radiological manifestation includes:-

Primary pulmonary complex:

Consolidation:- usually single, < 2cm, homogneous with illdefined margins

Tuberculoma:- round/oval mass like opacity, more in upper lobes and on

right side

Satellite lesions in 80%, cavitation and calcification in 10 to 50%

Lymphnode:- In 96% of pts.

On same side, usually hilar or bronchial, then others are involved

CT usually shows > 2cm in size with central area of low density

with rim enhancement of irregular thick wall with preserved or

obliterated perinodal fat. Other patterns are homogenous

enhancement, uniform rim enhancement.

Airway involvement:- Atelectesis due to either primary endobronchial TB or

extrinsic compression by lymph node.

Pleural involvement:- Pleural effusion – absent or mild

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Progressive primary disease:-

Consolidation:- lobar or segmental

Collapse

Pleural involvement:- may be massive, can lead to empyema

Bronchogenic spread:- confluent multiple foci of alveolar shadows

Miliary tuberculosis: - tiny, pinpoint opacities uniformly through out both lung

Fields, more at bases.

Post primary lesion:-

Calcification, both parenchymal and nodal

Fibrosis

ASTHMA:-

Should be performed to exclude complication

Findings are signs of overinflation and bronchial wall thickening and peribronchial

cuffing.

CYSTIC FIBROSIS:-

Autosomal recessive disease associated with chronic pulmonary sepsis and

malabsorption (pancreatic exocrine insufficiency, cirrhosis, and gut involvement).

Early radiographic features include air trapping and bronchial wall thickening,

features that are radiographically indistinguishable from asthma or recurrent

pneumonia.

Later a diffuse interstitial pattern, bronchiectasis, cyst formation and changes of

pulmonary hypertension occurs.

LOBAR COLLAPSE:-

It is one of the common radiological manifestation of various pediatric chest

conditions. When these lobes collapse, they retain their hilar attachment, and the

other lobes often expand to compensate. The patterns of the lobar collapse are

identified in two ways: by seeing the collapsed lobe in a recognizable pattern,

and by noticing subtle shifts of intrathoracic structures such as the fissures

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between lobes of the lung and loss of normal radiological borders (silhouette

sign)

Things to determine when an opacity is seen that appears to be a lobar

collapse to identify the lobe involved and its probable etiology:

● Shift of mediastinum

● Deviation of major and minor fissure

● Silhouette of normal structures e.g. cardiac borders, diaphragmatic contour

● Pulled up or pulled down hila

● Elevation of dome of diaphragm

A common cause of lobar collapse in children is mucus plugging in postoperative and

asthmatic patients. Always look for foreign bodies by carefully examining the right and

left main-stem bronchi. Masses such as lymph nodes (due to tuberculosis,

other infections, or lymphoma), or extrinsic masses such as bronchogenic cysts, can

also cause lobar collapse.

CONGENITAL LUNG MALFORMATIONS

Solid mass-like Air-filled mass-like

Bronchogenic cyst CCAM

Pulmonary sequestration Congenital diaphragmatic hernia

Rarely, CCAM: more often air-filled CLE

Diaphragm elevation

Pneumatocele

CONGENITAL LOBAR EMPHYSEMA (CLE):-

Age & Sex: - less than 6 mths, male preponderance

Symptoms and signs:- Respiratory distress

Chest x ray:- Primary imaging tool

Predilection for the upper lobes and right middle lobe.

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Sequence of appearance: within 24 hrs, alveoli appear distended

and opaque, then gradually distends with air and shows acinar

shadowing, a reticular interstitial pattern and finally becomes

hyperlucent. Adjacent lobes are compressed, the ipsilateral

hemidiaphragm is depressed, and rib spacing is increased.

Differntial diagnosis:-

Attenuated lung markings seen in the overinflated lobe, helps to

differentiate it from a pneumothorax. With a pneumothorax, the

lung collapses around the hilum.

Other differential diagnosis include secondary lobar emphysema;

congenital lung cysts (including type I CCAM); pneumatoceles; and

the Swyer-James syndrome (unilateral hyperlucent lung).

CT scans:- demonstrates involved lobes or segments.The affected lobe is

overdistended and hypodense, with attenuated vascular markings.

Peripherally situated septa and vascular structure20.

No cysts or soft tissue are seen. CT is useful to exclude secondary

causes of lobar overinflation,i.e a vascular ring or a mediastinal

mass lesion.

CCAM(Congenital cystic adenomatoid malformation):-

CCAM results from a failure of normal bronchoalveolar development.There is

communication between the individual cysts within the CCAM and also with the

tracheo-bronchial tree.

Classification of Stocker11:-

Type I CCAMs: Most common, approx. 70%21

contain one or more cysts measuring over 2 cm in

diameter, surrounded by multiple smaller cysts.

Appearance:-

A multicystic lesion,although there can be one dominant cyst

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Mass effect can cause contralateral mediastinal shift,

inversion of the ipsilateral hemidiaphragm,and compression

and atelectasis of both ipsilateral and contralateral

pulmonary lobes. The involved lobe may herniate across the

midline to the opposite side

Type II CCAMs: 15 o 20%

contain cysts measuring up to 2 cm in diameter.

Asso. With other anomalies-renal ,cardiac & lung

Type III CCAMs: usually contain cysts less than 0.5 cm in diameter

seen as a homogeneous, soft tissue density mass.

Location:- Equal frequency in the upper and lower lobes, less often in right

middle lobe.Typically, they are unilobar, but multisegmental CCAMs

have been reported

Antenatal ultrasound examinations:-

An echogenic mass, which may/ may not contain cysts

May be associated with the development of maternal

polyhydramnios or fetal nonimmune hydrops fetalis.

CT scan:- Document the involved pulmonary segments or lobes

appears as a multicystic mass, with few air fluid levels and

fluid filled cysts.

Overinflation and lack of definite air bronchogram differentiates

it from necrotizing pneumonitis2.

Differential diagnosis:-

Diaphragmatic hernia ( Intact diaphragm & normal bowel pattern)

Pulmonary sequestration

CLE

Bronchogenic cyst

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SCIMITAR SYNDROME:-

Commonly affects right lung, which is hypoplastic and is drained by anomalous

vein that extends below the diaphragm to join IVC, hepatic or portal vein.

Chest Xray:- Small affected lung with small hilum with ipsilateral mediastinal shift

Curved turkish sword continuing below the diaphragm

BRONCHOPULMONARY SEQUESTRATION:-

Congenital mass of nonfunctioning lung tissue lacking communication with

tracheobronchial tree

2 types

Intralobar Extralobar

Presents with recurrent pneumonia Coincidental mass

Systemic bld supply Systemic bld supply

Drains into left atrium into systemic veins

Have normal pleural covering separate pleural covering

Older age infancy

Mostly in lower lobe,on left side on left side,conti with diaphragm

Features:

Spherical or triangular basal opacity, may be associated with emphysema of

surrounding lung tissue

Demonstration of abnormal vascular supply by angiography, CTA or MRA.

Cystic parenchymal lesion can be a presentation.

LUNG ABSCESS:-

Due to necrosis, suppuration and cavitation in localized infection in lung

Early stage:- discrete pneumonic consolidation on chest x ray

At this stage, CT may demonstrate low density area in area of

consolidation with no air bronchogram in region of abscess

Late stage:- Cavitary leison with air fluid level and thick and shaggy wall

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HYDATID CYST:-

Due to infestation with Echinococcus

CxR:- shows spherical or oval well defined homogenous opacity.

May be single, multiple, unilateral or bilateral

Rarely calcify.

USG shows characteristic cystic mass with floating membranes in lesions

abutting chest wall or diaphragm

CT or MR shows fluid content of cyst and floating membranes.

PULMONARY METASTASIS:-

In children, due to Wilm’s tumour, rhabdomyosarcoma, osteosarcoma , ewing’s

sarcoma, germ cell tumours, neuroblastoma, lymphoma and leukemia

TRACHEO-OESOPHAGEAL FISTULA:-

Most important congenital malformation of oesophagus

5 types, H type being commonly associated with respiratory distress

Demonstration by injecting contrast at various levels of esophagus

BRONCHIECTASIS:-

Localized irreversible dilatation of bronchial tree

Cystic fibrosis,most important cause in children

3 types:- cylindrical, varicose and saccular

CxR:- multiple cystic spaces with/without air fluid level, tramline shadows

due to bronchial wall thickening

CT(HRCT)- detects type, distribution, severity and extent of disease

Cylindrical:- dilated thick walled bronchi towards the periphery

On end on along with artery, signet ring sign

Varicose:- beaded bronchial lumen

Saccular:-marked dilatation of bronchi with cluster of cysts

FOREIGN BODY:-

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Most common cause of respiratory distress < 3yrs of age.

More on right side. Opaque being 5-15%

Findings:- Partial blockade- unilateral hyperlucency due to air trapping and

obstructive emphysema

Complete Blockade:- atelectasis with mediastinal shift to same side

Expiratory films, decubitus films with involved side dependent and fluoroscopy is

useful.

EMPYEMA:-

Due to bacterial infection, secondary to septic pulmonary emboli, lung abscess or

spread from adjacent infectious process

Fluid rich in protein and tend to loculate

CxR:- d/d from lung abscess & consolidation important

USG:- septation with echoes within fluid

CT:- localize site & extent of fluid collection, determine adequacy of tube

drainage, and to d/d between pulmonary and pleural lesion

Lenticular , obtuse angle of interface with chest wall and changes with change in

position of the patient.

Demonstrates “split pleura sign” and compression of adjacent structures.

D/D from lung abscess:- round shape, thick irregular wall,acute angle at interface

with chest wall and absence of evidence of lung compression, shows air bubbles

in wall.

Parietal pleural enhancement, parietal pleural thickening greater than 2 mm,

extrapleural thickening and increased attenuation of the extrapleural space, and

adjacent chest wall edema favours empyema more than transudative effusion

in

parapneumonic effusion.14,15.

PNET(ASKIN’S and EWING’S SARCOMA)

Most common chest wall tumours in children

Locally aggressive and associated with rib destruction and pleural effusion19

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Diffucult to d/d between two, only histology is useful.

DIAPHRAGMATIC HERNIA:-

Bochdalek’s hernia Morgagni’s hernia

More on left side More on right side

Posterolateral Anteromedial Earlier presentation

Late presentation

Large in size Small in size

Cystic/complex mass(solid mass if x ray has been taken before air enters bowel)

in hemithorax with mediastinal shift,failure to visualize stomach, abnormal

position of stomach and abdominal viscera and abnormal position of NG tube.

D/D from CCAM:- position of stomach normal,in diaphragmatic hernia either

stomach is not visualized or central in abdomen.

EVENTRATION OF DIAPHRAGM:-

d/t thin diaphragm, usually partial involving ½ to 1/3 of hemidiaphragm

usually anteromedial portion of right hemidiaphragm

CxR:- Elevated hemidiaphragm with smooth hump blending with contour of

hemidiaphragm

Poor or paradoxical movement

MEDIASTINAL MASSES:-

Cysts and Cystic Conditions Fat-containing masses

True thymic cysts Thymolipoma

Germ cell tumours Germ cell tumour (usually mature teratoma)

Lymphatic malformation Vascular malformations

Lymphoma

Thymoma

Foregut duplication cysts

Calcification

Germ cell tumour

26

Thymic cysts

THYMIC MASSES:-

Normal thymus

Thymic cysts:- developemntal, unilocular or multilocular

Thymoma:- 5-8%, after 10 yrs of age, calcification in 10%

GERM CELL TUMORS:-

2 age peaks: 2 yrs and adolescence

80% teratoma and benign, rest others

Calcification & areas of fat, displacement of adjacent structure

CYSTIC HYGROMA:-

Mostly in neck, 10% extend in mediastinum

Low attenuation cystic mass with insinuation in surrounding structures

NEUROGENIC TUMOURS:-

Neuroblastoma (malignant, < 5yrs), ganglioneuroblastoma(5-10yrs)

Ganglioneuroma(benign, >10yrs)

X ray:- paravertebral soft tissue mass with calcificaiton in 30%

Thinning, separation of ribs and enlargement of intervertebral foramina

CT:- Calcification in 90%12, inhomogenous enhancement

FOREGUT CYSTS:-

Bronchogenic cysts:-

Round/oval, unilocular, homogenous water density mass with well defined

borders

Types:-paratracheal, carinal, hilar and paraoesophageal

Oesophageal duplication cyst:-

Larger, to the right of midline extending in posterior medistinum

Approximately 60% of EDCs are located in the distal third of the esophagus, 17%

are in the middle third, and 23% are at the cervical level22.

Neurenteric cyst:-

Maintains connection with spinal canal, more on right side

27

Vertebral body anomalies are associated.

LYMPHOMA

Hodgkin’s disease NHL

Usually > 10 yrs Any age in children

Mostly localized. Mediastinal in 85% Disseminated in > 75%

Displacement is more likely Compression is more likely

Lung involvement in 10% of cases Pulmonary involvement is higher

INTERSTITIAL LUNG DISEASE:-

HRCT is the best investigation available for the evaluation of interstitial lung disease in

older children.

Findings are similar to that of adults: ground glass opacity, tree-in-bud, lobular air

trapping, reticular opacities, and centrilobular nodules.

Indications of HRCT in children:-

Infantile cellular interstitial pneumonitis and pulmonary interstitial glycogenosis

Chronic pneumonitis of infancy

Persistent tachypnea of infancy

Surfectant protein abnormality

Systemic disease: glycogen storage disorder, hemosiderosis, connective tissue

disorder

APPROACH TO EARLY DIAGNOSIS IN PEDIATRIC CHEST X RAY6

Large cystic hemithorax Large lucent hemithorax Large opaque hemithorax

CCAM Pneumothorax Pleural fluid

CDH Partially obstructed CDH

PIE lung CCAM

Pneumatocele Compensatory hyperinflation Neoplasm

28

REVIEW OF LITERATURE

1. In a 1986 publication, Swischuk LE, Hayden Jr CK9 et al evaluated the ability of

radiographic patterns of infection to predict whether or not a child had bacterial

pneumonia based on clinical criteria, such as rapid or short duration of illness, high

fever, high white blood cell count, and rapid response to antibiotics .There was no

analysis for organisms performed. They reported that the radiographic presentation

predicted which children meet the clinical criteria for bacterial illness with an accuracy

rate of 90%.

2. A study published by Ramnath et al 16 suggested a very simple ultrasound grading

system in which parapneumonic effusions were graded as low-grade

(anechoic fluid with no septations) or high-grade (presence of echogenic fronds,

septations, or loculations) Those patients with high-grade parapneumonic effusions, as

demonstrated by ultrasound, and treated with aggressive therapy had a 50% decrease

in duration of hospital stay as compared with those who were conservatively managed.\

3. In one study done by Donnelly LF, Klosterman LA studying role of imaging in

persistent or recurrent pneumonia, IV contrast-enhanced CT identified an underlying

suppurative cause of the persistent illness in 100% of patients15,17.

4.In a study done by Stigers KB, Woodring JH1 et al given lobar predilection of CLE,

most common site being left upper lobe(43%) followed by right middle lobe (32%) and

right lower lobe (20%).

5. Frush DP, Donnelly LF4 et al concluded that Helical CT is the imaging modality of

choice in sequestration in demonstration of systemic arterial supply and characterization

29

of lung lesion. They also demonstrated association of other anomalies with extralobar

sequestration in 65% of cases they studied.

6. Donnelly LF, Klosterman LA5 et al studied patients with cavitary necrosis and showed

that 41% of these patients were detected on x ray as compared to CT.

7. In evaluating trauma, Sivij CJ, Taylor GA7 et al showed that chest trauma is

responsible for 25% of deaths occurring in children due to trauma.

8. Siejel MJ10 et al stated that mediastinal lymphnodes generally are not seen on CT or

MR in children prior to puberty and their presence should be considered abnormal.

9. Whitsett JA, Pryhuber GS, Rice WR18 et al studied acute respiratory syndrome in

neonate and showed that approximately 50% of neonates born between 26 and 28

weeks and 20–30% of neonates born at 30–31 weeks of gestation develop RDS.

10. Conran RM, Stocker JT23 et al studied 50 cases of extralobar pulmonary

sequestration and showed its association with type II CCAM in 50% of cases.

11. Macpherson RI22 studied Gastrointestinal tract duplications anomalies and showed

distribution of esophageal duplication cyst: 60% in distal third, 17% in middle third and

23% in cervical third.

12. Billmire DF26 et al while studying germ cell tumours showed that Germ cell tumors

account for 6% to 18% of mediastinal tumors.

13. Fishman SJ25 et al showed that cystic hygroma are rare causes of mediastinal

masses.

30

14. Meza MP, Benson M, Slovis TL24 et al showed of all pediatric mediastinal masses

studied, 30% to 40% occur in the posterior mediastinum. Most (85%–90%) of these

masses are of neurogenic origin.

31

MATERIALS AND METHODS

Sixty patients were selected based on clinical suspicion from May2007 to

October2009. Patients below the age of 14 years have been considered. All patients

underwent chest xray as first line of investigation on bases of symptomatology.

Followed by this depending upon the need of the clinician further investigations were

carried out. Though heart is within the thoracic cage, I have excluded cardiovascular

system from my study to concentrate more over respiratory system problems. Those

patients were selected in whom more than one imaging modality was used for the

purpose of evaluation of condition.

X rays of patients were taken most of the times in PA position with appropriate

exposure factors either making the child stand or holding the infant by their parents and

keeping them protected with lead aprons. Rest of times supine AP x-ray was taken.

US was next investigation in patients having suspected pleural effusion.US was

performed on a Esaote, Philips unit, using 3.5 and 5.0 MHz transducers.

CT scan was performed when further evaluation was deemed necessary and

when the investigation was affordable and accessible to the patient. It was carried out

on helical CT unit of Schimazdu, civil hospital, Ahmedabad.

MRI was performed on Philips Gyroscan 0.5 T machine for the evaluation of

infective process involving spine and spinal canal.

Ultrasound guided fluid aspiration was done when indicated.

As most of the patients with pediatric chest diseases conservatively treated, they

were followed up to know the outcome of the therapy. In surgical conditions,outcome

and follow up whenever available were recorded. Imaging findings were correlated with

surgical and histopathological findings whenever available. The role of radiology played

in each case was critical.

32

OBSERVATION AND ANALYSIS

Table 1: Age distribution

Age group No. of patientsLess than or equal to 1 mths 3

1 mth to 1 yr 81 yr to 5 yr 245yr to 9 yr 179yr to 14 yr 8

Total 60

Out of the 60 patients, most common age of presentation with pediatric chest disease is

1 yr to 5 yr(40%).

Table 2 : Sex distribution

Sex of patient No. of patientsMale 41

Female 19Total 60

Out of studied 60 patients, majority are males (68%) as compared to females (32%).

Table 3: Presentation with respiratory symptoms

33

Symptom No. of patients PercentageFever 41 68%Cough with or without sputum production 48 80%SOB or breathing difficulty/ choking 26 43%Chest pain 12 20%

Major symptoms in pediatric chest symptomatology are cough with or without

expectoration (80%) followed by fever( 68%).

Table 4: Etiological classification of pediatric chest pathologies

Disease Group No. of Patients PercentageCongenital 10 15

Inflammatory 41 70Traumatic 1 1.6Neoplastic 2 3.3Interstitial 1 1.6

Other 6 10Total 60 100

In studied patients, major group of disease involving pediatric chest is inflammatory

(70%) followed by congenital (15%).

Table 5 : Regional involvement of pediatric chest

34

Region of chest involved No. of patientsParenchymal 23

Pleural 7Airway 6

Mediastinum 3Diaphragm 3Chestwall 1

Diaphragm and parenchymal 2Pleural and parenchymal 14

Multicompartemental 1Total 60

Most common region of chest involved in studied 60 pediatric patients is pulmonary

parenchyma (38%) followed by both pleural and parenchymal (23%) and pleural

disease(12%).

Table 6: X ray – CT correlation in relation to pulmonary and mediastinal pathology

PATHOLOGY X RAY CTAirbronchogram 9 16Soft tissue opacity in patient with

consolidation

16 20

Collapse 7 20Cavity 5 5Mediastinal shift 12 17Associated lymph node 0 6Calcification in lung parenchyma 1 1

35

Calcification in mediastinal mass 1 3Pneumomediastinum 0 1

Table 7:- X ray – CT correlation in pleural pathology

Pathology X ray CT Total no. of pt undergoing both x ray and

CT with pathologyPleural effusion 15 17 17Pneumothorax 6 8 8

CT showed effusion and pneumothorax in all patients as compared to x ray

demonstrating same in 88% and 75% of patients respectively.

Table 8:- X ray – USG correlation in pts with pleural effusion

Pleural fluid X ray USG Total No. of pts

undergoing both x

ray and USGPresent 8 12 12

X ray was able to detect pleural fluid in 67% of patients as compared to USG in patients

undergoing both x ray and USG.

36

Table 9:- USG –CT correlation in pleural collection in pts undergoing both USG

and CT*

Pleural collection USG CTFluid present 10 10Septation 8 0Echoes 7 0

USG showed presence of septation and echoes in majority of patients as compared to

CT which was not able to demonstrate the same in any patient.

*- Total number of patients undergoing USG and CT—10

Table 10:- X ray and CT correlation in pts with pleural effusion

Pleural fluid X ray CTPresent 15 18

X ray demonstrated pleural fluid in 83% of patients as compared to CT in patients

undergoing both X ray and CT.

Table 11:- X ray and CT demonstrating both pleural and pulmonary pathology

Pathology X ray

37

Only pleural pathology 6Only parenchymal pathology 1Both pleural and pulmonary pathology 7Total no. of patients detected by CT having both

pleural and pulmonary pathology

14

X ray was able to detect both pleural and pulmonary involvement in 50% of patients

studied.

DISCUSSION

In this study, 60 patients of pediatric age group with chest disease were studied by

various radiological methods based on clinical methodology.

• Most common age being presented with pediatric chest disease is between 1 yr to 5

yr (40%).

• Pediatric chest diseases are found to be more common is males in this study (68%).

• Most common symptomatology was found to be cough with or without expectoration

(80%) and fever (68%).

• Among the basic disease groups, the most common disease group is inflammatory

41 cases (70%) followed by congenital 10 cases (15%), foreign body 4 cases (7%),

rest comprising of neoplastic (2 cases), interstitial and traumatic and nonneoplastic

mediastinal mass (1case each).

• In this study, most common region of chest involved were pulmonary parenchyma

23 cases (38%), both pleural and parenchymal pathology 14 cases(23%), pleural

pathology 7 cases(12%) and airway involvement 6 cases(10%). Rest comprising of

mediastinum and diaphragmatic involvement in 5 cases each.

38

Congenital lesions:-

• Out of 10 cases of congenital origin, 5 are diaphragmatic in origin, 3 being

diaphragmatic hernia and 2 being eventration of diaphragm. Other four are

CCAM, CLE, lung aplasia, TOF with esophageal atresia and bronchopulmonary

sequestration.

• In diaphragmatic hernia, herniation of bowel loops noted in all cases and spleen

noted in one case which was better demonstrated on CT. Bowel loops were

easily visualized with barium examination.

• In CCAM and CLE, CT was useful to determine the lobar involvement and

guiding the surgeon.

• Esophageal atresia was seen as a curling of IFT in esophagus. There was

presence of gas in stomach, so the diagnosis is TOF with esophageal atresia.

• One case of bronchopulmonary sequestration appeared as patch of

consolidation on chest x ray and revealed to be a soft tissue density mass

supplied independently from a systemic artery arising from aorta. Thus CT was

essential for diagnosis.

Inflammatory lesions:-

• Out of 41 patients having inflammatory etiology, majority cases are of only

parenchymal involvement 17 cases (41.5%), both parenchymal and pleural

pathology 14 cases (34%), only pleural pathology 7 cases (17%), 2 cases of lung

involvement with mediastinal node involvement and one case of airway

involvement.

• Amongst these cases, 3 were in neonatal age group having bilateral diffuse

reticulonodular opacity diagnosed as respiratory distress syndrome.

39

• In this study, x ray was able to define the various characteristics such as ABG,

soft tissue opacity, collapse, and mediastinal shift in 56%, 80%, 35%, and 71 %

of patients respectively as compared to CT.

• In collapse which was not diagnosed on x ray were mostly resorptive in nature

and segmental in distribution.

• X ray did not demonstrated mediastinal lymph nodes in 6 pts detected having

lymph nodes on CT.

• X ray was able to demonstrate cavitary lesions in all 5 patients as their sizes

were large.

• For detection of pleural fluid, USG as well as CT shown better accuracy than x

ray.

• Out of 8 pts with pneumothorax, x ray diagnosed in 6 cases (75%) as compared

to CT in all patients.

• While for characterization of pleural fluid, USG showed presence of echoes and

septations in 8 patients. CT was not able to detect echoes and septations in any

patient.

• X ray showed simultaneous detection of both pulmonary and parenchymal

pathology in 50% of patients as compared to CT (7 out of 14 cases).

• One case of airway involvement showed bronchiectasis and it showed presence

of fluid levels on HRCT.

• Thus CT is useful in inflammatory lesions to characterize the lesion, extent of

involvement, associated pleural fluid and mediastinal nodal involvement and any

associated complication e.g. Brochopleural fistula, pneumatocele formation.

Airway involvement:-

There were 3 cases of hyperinflation on x ray among which CT was done in two cases

and showed presence of soft tissue density foreign body in one case. Another case was

diagnosed as ? Obstructive emphysema/?? CLE and was found to be foreign body on

bronchoscopy.

Another case showed presence of metallic foreign body in bronchus.

40

Traumatic lesions:-

• One studied case of trauma showed presence of bilateral subcutaneous

emphysema on x ray was found to be associated with pneumothorax and

Pneumomediastinum on CT.

Neoplastic lesions and mediastinal masses:-

• Out of 60 patients studied, two cases (3.6%) of neoplasm and 3 mediastinal

mass (5%) were found out.

• A case of neoplasm presented with opaque hemithorax on x ray showed large

necrotic chest wall neoplasm with invasion of pulmonary and mediastinal

compartments, diagnosed as PNET.

• Mediastinal masses were thymic germ cell tumour, bilateral paravertebral

abscess and pericardial cyst.

• One case of thymic germ cell tumour showed presence of calcification and fat in

the region of thymus and thymus was not seen separately from the lesion.

• The pericardial cyst was having partially calcified rim.

• Bilateral paravertebral abscess with calcification had same component in

epidural region of spinal canal with kyphoscoliosis of spine. Intraspinal extension

was better shown on MR examination.

Other:-

• One case of patient undergoing multiple blood transfusions noted having bilateral

diffuse alveolar opacities and was diagnosed as having idiopathic pulmonary

hemosiderosis.

41

CONCLUSION

Various imaging modalities such as X ray, USG, Flouroscopy, CT scan and MRI

are available for diagnosis and evaluation of pediatric chest lesions. They have many

advantages and disadvantages in common. It is difficult to isolate a single modality with

distinct advantage over others.

Chest radiography is the first and often only (e.g. for pneumonia) imaging

modality used to assess thoracic signs or symptoms providing a survey of lung

parenchyma, cardiovascular structures, mediastinum and chest wall structures.

Though air being highly reflective, USG is considered invaluable in evaluation of

pleural fluid, pleural masses, diaphragmatic lesions and evaluation of thymus as being

noninvasive and non radiating.

CT is though expensive and having higher radiation dosage, it is quite useful in

management of the patient with pediatric chest lesions demonstrating extent of the

lesion, particularly in congenital lung malformation. Simultaneous assessment of cross

sectional anatomy can be done. With IV contrast, it provides enhancement of vascular

structures. CT provides crucial diagnosis in conditions having similar appearance on

radiograph e.g. between pneumonia and sequestration, between pneumonia and AV

42

malformation having appearance of consolidation. Thus CT provides an excellent

anatomical guidance to the pediatric surgeon.

Need for longer duration of sedation and sophisticated softwares, MRI is

considered as a reserved modality particularly in evaluation of foregut malformation and

neurogenic tumours or inflammatory processes involving spine.

BIBLIOGRAPHY

1. Stigers KB, Woodring JH: The clinical & imaging spectrum of findings in CLE.

Pedia. Pulmonol 14: 160-170,1992

2. Nuchtern JG, Harberg FJ. Congenital lung cysts. Semin Pediatr Surg

1994;3:233–43.

3. Coley BD (2005) Pediatric chest ultrasound. In: Frush DP (ed) Pediatric

chest imaging, W.B. Saunders, Philadelphia, PA, pp 405-418

4. Frush DP, Donnelly LF: Pulmonary sequestration spectrum: A new spin with spiral CT.

AJR Am J Roentgenol 169: 679-682, 1997.

5. Donnelly LF, Klosterman LA: Cavitary necrosis complicating pneumonia in children

AJR Am J Roentgenol 171: 253-256, 1998.

43

6. Brown MJ, Miller RR, Muller NL: Acute lung disease in immunocompromised host: CT

and pathological examination findings.

Radiology 190: 247-254, 1994.

7. Sivit CJ, Taylor GA: Chest injury in children with blunt abdominal trauma: Evaluation

with CT.

Radiology 171: 815-818, 1989.

8. Rose RE, Ward BH. Spherical pneumonias in children simulating pulmonary and

mediastinal masses. Radiology 1973;106:179– 82

9. Swischuk LE, Hayden Jr CK. Viral vs. bacterial pulmonary infections in children (is

roentgenographic differentiation possible?).

Pediatr Radiol 1986;16:278–84.

10. Siegel MJ. Mediastinum In: Pediatric body CT

Lippincott Williams and Williams 1999:101-110

11. Stocker JT, Madewell JE, Drake RM. CCAM: classification and morphologic

spectrum. Hum Pathol 1977; 8:155– 71.

12. Strollo DC, Rosado-de-Christenson ML, Jett JR. Primary mediastinal tumors. Part II:

tumors of middle and posterior mediastinum. Chest 1997;112: 1344– 57.

13. Waite RJ, Carbonneau RJ, Balikian JP, et al. Parieta pleural changes in empyema:

appearance at CT. Radiology 1990;175:145– 50.

14. Muller NL. Imaging of the pleura. Radiology 1993; 186:297– 309.

15. Kendrick T, Ling H, Subramaniam R, et al. The value of early CT in complicated

childhood pneumonia. Pediatr Radiol 2002;32:16– 21.

44

16. Ramnath RR, Heller RM, Ben-Ami T, et al. Implications of early sonographic

evaluation of parapneumonic effusions in children with pneumonia. Pediatrics

1998;101:68–71.

17. Donnelly LF, Klosterman LA. The yield of CT of children who have complicated

pneumonia and noncontributory chest radiography.

AJR Am J Roentgenol 1998;170:1627– 31

18. Whitsett JA, Pryhuber GS, Rice WR, et al: Acute respiratory disorders.In:

Neonatology: pathophysiology and management of the newborn, 4th edn.

Philadelphia: JB Lippincott; 1994:429-452.

19. Fink IJ, Kurtz DW, Cazenave L, et al: Malignant thoracopulmonary small-cell (Askin)

tumour. Am J Roentgenol 1985; 145:517-520.

20. Patz Jr EF, Mu¨ ller NL, Swensen SJ, et al. Congenital cystic adenomatoid

malformation in adults: CT findings.J Comput Assist Tomogr 1995;19:361– 4.

21. Berrocal T, Madrid C, Novo S, et al. Congenital anomalies of the tracheobronchial

tree, lung, and mediastinum: embryology, radiology, and pathology.

Radiographics 2003;24:e17– 62.

22. Macpherson RI. Gastrointestinal tract duplications: clinical, pathologic, etiologic, and

radiologic considerations. Radiographics 1993;13:1063– 80.

23. Conran RM, Stocker JT. Extralobar sequestration with frequently associated CCAM,

type 2. Pediatr Dev Pathol 1999;2:454– 63.

24. Meza MP, Benson M, Slovis TL. Imaging of mediastinal masses in children.

Radiol Clin North Am 1993;31:583– 604.

45

25. Fishman SJ. Vascular anomalies of the mediastinum.

Semin Pediatr Surg 1999;8:92– 8.

26. Billmire DF. Germ cell, mesenchymal, and thymic tumors of the mediastinum.

Semin Pediatr Surg 1999; 8:85– 91

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