How to Read a Chest X-ray – A Step By Step Approach
Author(s): Dr Stephan Voigt, Consultant Radiologist
This article is an attempt to give the reader guidance how to read a chest Xray and below are two methods. There is no perfect way to read an x-ray. However, the important message I would like to give is, to adopt one or the other approach, and to use the chosen approach consistently.
On all Xrays check the following:
Check patient details
First name, surname, date of birth.
Check orientation, position and side description
Left, right, erect, ap, pa, supine, prone
Check additional information
inspiration, expiration
Check for rotation
measure the distance from the medial end of each clavicle to the spinous process of the vertebra at the same level, which should be equal
Check adequacy of inspiration
Nine pairs of ribs should be seen posteriorly in order to consider a chest x-ray adequate in terms of inspiration
Check penetration
one should barely see the thoracic vertebrae behind the heart
Check exposure
One needs to be able to identify both costophrenic angles and lung apices
Specific Radiological Check List:
A - Airway
Ensure trachea is visible and in midline
Trachea gets pushed away from abnormality, eg pleural effusion or tension pneumothorax
Trachea gets pulled towards abnormality, eg atelectasis
Trachea normally narrows at the vocal cords
View the carina, angle should be between 60 –100 degrees
Beware of things that may increase this angle, eg left atrial enlargement, lymph node enlargement and left upper lobe atelectasis
Follow out both main stem bronchi
Check for tubes, pacemaker, wires, lines foreign bodies etc
If an endotracheal tube is in place, check the positioning, the distal tip of the tube should be 3-4cm above the carina
Check for a widened mediastinum
Mass lesions (eg tumour, lymph nodes)
Inflammation (eg mediastinitis, granulomatous inflammation)
Trauma and dissection (eg haematoma, aneurysm of the major mediastinal vessels)
B – Bones
Check for fractures, dislocation, subluxation, osteoblastic or osteolytic lesions in clavicles, ribs, thoracic
Spine and humerus including osteoarthritic changes
At this time also check the soft tissues for subcutaneous air, foreign bodies and surgical clips
Caution with nipple shadows, which may mimic intrapulmonary nodules
compare side to side, if on both sides the “nodules” in question are in the same position, then they are likely to be due to nipple shadows
C - Cardiac
Check heart size and heart borders
Appropriate or blunted
Thin rim of air around the heart, think of pneumomediastinum
Check aorta
Widening, tortuosity, calcification
Check heart valves
Calcification, valve replacements
Check SVC, IVC, azygos vein
Widening, tortuosity
D – Diaphragm
Right hemidiaphragm
Should be higher than the left
If much higher, think of effusion, lobar collapse, diaphragmatic paralysis
If you cannot see parts of the diaphragm, consider infiltrate or effusion
If film is taken in erect or upright position you may see free air under the diaphragm if intra-abdominal perforation is present
E – Effusion
Effusions
Look for blunting of the costophrenic angle
Identify the major fissures, if you can see them more obvious than usual, then this could mean that fluid is tracking along the fissure
Check out the pleura
Thickening, loculations, calcifications and pneumothorax
F – Fields (Lungfields)
Check for infiltrates
Identify the location of infiltrates by use of known radiological phenomena, eg loss of heart borders or of the contour of the diaphragm
Remember that right middle lobe abuts the heart, but the right lower lobe does not
The lingula abuts the left side of the heart
Identify the pattern of infiltration
Interstitial pattern (reticular) versus alveolar (patchy or nodular) pattern
Lobar collapse
Look for air bronchograms, tram tracking, nodules, Kerley B lines
Pay attention to the apices
Check for granulomas, tumour and pneumothorax
G – Gastric Air Bubble
Check correct position
Beware of hiatus hernia
Look for fee air
Look for bowel loops between diaphragm and liver
H – Hilum
Check the position and size bilaterally
Enlarged lymph nodes
Calcified nodules
Mass lesions
Pulmonary arteries, if greater than 1.5cm think about possible causes of enlargement
Extended Radiological Check List – Lateral Film:
A - Airway
Ensure trachea is visible and in midline
Trachea gets pushed away from abnormality, eg pleural effusion or tension pneumothorax
Trachea gets pulled towards abnormality, eg atelectasis
Trachea normally narrows at the vocal cords
View the carina, angle should be between 60 –100 degrees
Beware of things that may increase this angle, eg left atrial enlargement, lymph node enlargement and left upper lobe atelectasis
Follow out both main stem bronchi
Check for tubes, pacemaker, wires, lines foreign bodies etc
If an endotracheal tube is in place, check the positioning, the distal tip of the tube should be 3-4cm above the carina
Check for a widened mediastinum
Mass lesions (eg tumour, lymph nodes)
Inflammation (eg mediastinitis, granulomatous inflammation)
Trauma and dissection (eg haematoma, aneurysm of the major mediastinal vessels)
B – Bones
Check the vertebral bodies and the sternum for fractures or other osteolytic changes
C – Cardiac
Check for enlargement of the right ventricle and right atrium (retrosternal and retrocardiac spaces)
Trace the aorta
D – Diaphragm
Check for fluid tracking up, costophrenic blunting and the associated hemidiaphragm
E – Effusions
Check to see the fissures here as well – both major fissures and the horizontal may be found in the lateral view
F – Fields
Check the translucency of the thoracic vertebrae in the lateral view, when there is a sudden change in transparency, then this is likely to be caused by infiltrate
Also try to find the infiltrate that you think you saw on the pa-film to verify existence and anatomical location
Pay special attention to the lower lung lobes
I would like to close with a clarification of two important radiological findings, whose understanding is very useful for a correct interpretation of chest x-ray findings.
The first is the silhouette sign, which can localise abnormalities on a pa-film without need for a lateral view. The loss of clarity of a structure, such as the hemidiaphragm or heart border, suggests that there is adjacent soft tissue shadowing, such as consolidated lung, even when the abnormality itself is not clearly visualised. The reason is, that borders, outlines and edges seen on plain radiographs depend on the presence of two adjacent areas of different density, Roughly speaking, only four different densities are detectable on plain films; air, fat, soft tissue and calcium (five if you include contrast such as barium). If two soft tissue densities lie adjacent, then they will not be visible separately (eg the left and right ventricles). If, however, they are separated by air, the boundaries of both will be seen.
The second important x-ray finding is the lung collapse. A collapse usually occurs due to proximal occlusion of a bronchus, causing subsequently a loss of aeration. The remaining air is gradually absorbed, and the lung loses volume. Proximal stenosing bronchogenic carcinoma, mucous plugging, fluid retention in major airways, inhaled foreign body or malposition of an endotracheal tube are the most common reasons for a lung collapse. Tracheal displacement or mediastinal shift towards the side of the collapse is often seen. Further findings are elevation of the hemidiaphragm, reduced vessel count on the side of the collapse or herniation of the opposite lung across the midline.
कोई टिप्पणी नहीं:
एक टिप्पणी भेजें