PCE chest interpretation an introduction

Question 1

What is Pneumomediastinum

Answer 1

Pneumomediastinum is a condition in which air is present in the mediastinum.

This condition can result from physical trauma or other situations that lead to air escaping from the lungs, airways or bowel into the chest cavity. Pneumomediastinum is a rare situation and occurs when air leaks into the mediastinum.

Question 2

What is Surgical Emphysema

Answer 2

Air in the subcutaneous tissue

Question 3

Contents of the thorax

Answer 3

Ribs
Left and right lungs
Costal cartilage
Heart
Thoracic vertebrae
Thymus
Cervical vertebrae
Liver
Sternum
Oesophagus
Scapulae
Trachea
Clavicles
Stomach
Intercostal muscles
Bronchi
Diaphragm
Breast & Nipple
Muscles
Spinal cord
Thoracic duct
Terminal chyli

Question 4

Blood vessels of the thorax

Answer 4

SVC
IVC
Aorta
Ascending
Descending
Thoracic
Carotids
Azygous vein
Pulmonary trunk, arteries & veins
Coronary arteries & veins
Subclavians
Brachiocephalics

Question 5

The lungs

Answer 5

Divided into lobes
Each lobe is further divided into segments
Lobes are separated by fissures
The oblique fissure separates the lower lobe from the upper lobe on the left and the middle and upper lobes on the right
This is not normally seen on a PA CXR
The horizontal fissure separates the middle and upper lobes on the right
Can be seen on many PA CXR
Location a concern rather than presence or absence

Question 6

Basic Observations

Answer 6

Patient Name, Age, Ethnicity
May give clues e.g. TB
Date of Radiograph
Side Marker
PA or AP
Heart size assessment
Centering
Sternoclavicular joints equidistance from midline
Artefacts

Question 7

Specific Areas: Neck and upper mediastinum

Answer 7

Trachea
Deviated or compressed: ? Thyroid

Soft Tissues
Surgical emphysema

Pneumomediastinum
Oesophageal rupture: v. important
Asthma: rarely significant

Question 8

Specific Areas: Mediastinum 1

Answer 8

Aortic Root of normal size and shape?
If small ? ASD: due to increased pulmonary blood flow: increased pulmonary markings
If large: ? Aneurysm

Left Mediastinal Border
Left hilum normally higher than right on PA view.
Shift of hilar point suggests volume change

Question 9

Specific Areas: Mediastinum 2

Answer 9

Below Left Hilar Shadow: Left atrial appendage
If prominent suggests Left atrial enlargement ? Mitral valve disease

Left Ventricular Contour
Enlargement CTR > 0.5 = cardiomegaly
Calcification suggests previous infarction +/- aneurysm formation

Question 10

Specific Areas: Mediastinum 3

Answer 10

Right Mediastinum
Right border = Right atrium
Should be sharp and distinct
Blurring of edge usually a Rt middle lobe pathology

Right hilum ? Normal size and position

Question 11

Specific Areas: Pleural Reflections

Answer 11

“Edges” of the lungs

Start at medial aspect of each hemidiaphragm and move laterally and upwards towards apices
Outline
Calcification
Blunting of costophrenic reflection
Fluid – on erect image only
Thickening

Question 12

Specific Areas: Lung Fields

Answer 12

Examine
Upper
Mid
Lower Zones in turns

Look for
Differences in density (unusual white/black areas)
Volume shift

Explain lines

Question 13

Consolidation

Answer 13

A pathological process filling alveoli with something other than air:
Pus (infection)
Blood
Fluid (pulmonary oedema)
Cells
Aspirate

Pneumonia is the most common cause of consolidation

Question 14

Note slide

What to look for
Heterogeneous (patchy) opacity (white) areas of lung “Shadowing”
Can affect part or all of lung
Can be uni- or bi-lateral

No volume change
i.e. all anatomical structures in correct place

Air-bronchogram
The internal tubular outline of a bronchus is visible within shadowing
Density difference between ‘normal’ air-filled airway and pus filled airway
An indication of pneumonia

Answer 14

Note slide

What to look for
Heterogeneous (patchy) opacity (white) areas of lung “Shadowing”
Can affect part or all of lung
Can be uni- or bi-lateral

No volume change
i.e. all anatomical structures in correct place

Air-bronchogram
The internal tubular outline of a bronchus is visible within shadowing
Density difference between ‘normal’ air-filled airway and pus filled airway
An indication of pneumonia

Question 15

The silhouette sign

Answer 15

Anatomical structures appear on x-rays if adjacent to a structure of different density (this gives contrast)

On a normal CXR heart and diaphragm borders are sharp due to the density difference with the adjacent lung

Consolidated lung has a similar density to heart and diaphragm, therefore the border will be blurred or missing

Knowledge of lobar anatomy important

Question 16

The silhouette sign
Border blurred/missing —- lobe affected
Right diaphragm —— Right lower lobe

Right heart border ——– Right middle lobe

Left diaphragm ——— Left lower lobe

Left heart border ———- Left upper lobe

Answer 16

The silhouette sign
Border blurred/missing —- lobe affected
Right diaphragm —— Right lower lobe

Right heart border ——– Right middle lobe

Left diaphragm ——— Left lower lobe

Left heart border ———- Left upper lobe

Question 17

Pulmonary collapse (atelectasis)
Collapse of one or more lobes (or individual segments of lobe)
Caused by obstruction to airways preventing inflation
Infection
Mucus plug
Tumour
Foreign body
ET tube
Can also be caused by fibrosis, post RT, TB

Question 18

Signs of collapse

Answer 18

Volume loss always evident

Signs can be very subtle especially if the collapse is advanced

Look for:
Movement of anatomical structures i.e. shift of hilar, heart, trachea, horizontal fissure
Over-inflation of adjacent lobs and/or opposite lung
“White” (opaque) areas
Raised diaphragm
Blurred borders – cardiac and diaphragm

Use silhouette sign to locate

Question 19

Pneumothorax

Answer 19

The presence of gas in the pleural space

Can be spontaneous with or without underlying lung disease
Also can be iatrogenic or traumatic

Look for:
Visible visceral pleural edge is seen as a very thin, sharp white line
No lung markings are seen peripheral to this line

A supine CXR can NOT rule out a pneumothorax