Chest X-rays Flashcards
What does attenuation refer to in radiology?
Refers to loss of energy. High attenuation – traps a lot of X-ray energy – bone. Lungs – low attenuation, so most X-ray photos pass through = black.
What is the silhouette sign?
Refers to loss of normal borders between thoracic structures. It is usually caused by an intrathoracic radiopaque mass that touches the border of the heart making it difficult to make out the heart border e.g., a pneumonia.
!!! How should you systematically approach CXR interpretation?
- PATIENT DETAILS
- Date and time of CXR. State you would like to compare to previous CXRs
- FILM – AP or PA
- RIPE – rotation, inspiration (can you see enough ribs?), penetration, exposure
- A – airways (tracheal deviation)
- B – breathing (opacification, lung markings, comment on HILAR, and pleura (thick?)). Refer to zones and say that lung markings reach all edges.
- C – circulation (size of heart, mediastinum, vessel distribution)
- D – diaphragm (costophrenic angles, cardio phrenic angles, hemidiaphragms are of normal curvature, pneumoperitoneum)
- E – everything else (bones, artificial devices)
- REVIEW AREAS – ABCD; abnormalities that are usually missed: Apices (pneumothorax?), Bones/soft tissue (fractures or densities), Cardiac shadow (is there a mass obscured by the heart shadow?), Diaphragm 11. Document
What is the difference between PA and AP? (x3) Cardiomegaly comments?
- AP has larger cardiac shadow and presence of scapula. You CANNOT comment on cardiomegaly when orientation is AP!
- Ribs look different too: in PA, you will see posterior ribs meet at the midline. In AP, costal cartilages in anterior ribs mean that you cannot visualise any ribs medially.
How should a CXR be rotated?
Sternal ends of the clavicles should sit symmetrically over the transverse processes of the 4th and 5th thoracic vertebrae. Rotated images could make normal structures look like masses.
How should a CXR be performed in relation to inspiration? !!! How many ribs should be visualised?
CXR should performed in inspiration – there should be 5-7 ribs visible ANTERIORLY (or 10 posteriorly). Poor inspiration can mimic cardiomegaly as the heart is usually pulled down and elongated with inspiration (by the diaphragm).
What is meant by good CXR penetration?
When the endplates of the cardiac vertebrae can just be visualised.
How does spatial resolution differ between CT and XR?
Ability to see two objects as separate: XR is BETTER.
How does contrast resolution differ between CT and XR?
Ability to see the difference between different tissue densities: CT is BETTER.
What is the azygo-oesophageal line on a CXR?
At the superior end of the line, there is a tear drop-like prominence coming away from the midline (indicated by top red arrow) – this is where the azygous system drains into the SVC.
What are the three bulges you would expect to see of the mediastinum in a CXR?
From superior to inferior: aortic knuckle, pulmonary outflow tract and left ventricle (all on the left border (or right side of image)).
How should the lung hila look in a CXR?
Left slightly higher than the right.
How should the heart look in a CXR?
Less than half the width of the thorax. 2/3 should lie to the left of the vertebral column.
In what scenario may heart look elongated?
It may appear elongated if lungs hyperinflated e.g., COPD.
How should the diaphragm look in a CXR?
Right side often slightly higher because of the liver.
What does consolidation refer to in radiology?
Indicates that there is a pathological process that has DISPLACED AIR in the lung airspaces, and is POORLY DEFINED and CONFLUENT (blending into one) e.g., infection, inflammation. Consolidation can also refer to a tumour or blood – not always infection!
What are the causes of consolidation in the lungs? (x5)
Pneumonia, oedema, haemorrhage, aspiration, some lung tumours.
What is the difference in consolidation between pneumonia and oedema?
Pneumonia consolidation is more FOCAL.
What is a nodule defined by on CXR?
A circular, dense structure less than 3cm. Can be well-defined or more defined.
What is a mass defined by on CXR?
A circular, dense structure more than 3cm. Can be well-defined or more defined.
What are the different types of lung opacities on CXR? (x6)
- Ground-glass
- Nodular
- Reticular (network of fine lines, interstitial)
- Alveolar (fluffy)
- Ring
- Linear
- May also be referred to as SHADOWING.
What does ground-glass opacification refer to in radiology?
Air in the airspace has not been completed DISPLACED i.e., does NOT obscure boundaries of tissues, but you can still observe something of INCREASED DENSITY. For example, CT shows:
What may the aetiology of nodular opacities be? (x4)
- Neoplasia: metaplasia, lung cancer, hamartoma, adenoma
- Infections: varicella pneumonia, septic emboli, abscess, hydatid
- Granulomas: military TB, sarcoidosis, histoplasmosis
- Pneumoconiosis (except asbestosis), Caplan’s syndrome
What is reticulonodular shadowing?
A type of opacification containing nodule opacities (you can literally see nodules), and reticular opacities (network of fine lines representing interstitial changes).
What is the aetiology of reticular opacification? (x4 (x5))
- Acute interstitial oedema
- Infection: acute (viral, bacterial) and chronic (TB)
- Fibrosis: usual interstitial pneumonia (UIP), non-specific interstitial pneumonia (NSIP), drugs (methotrexate, crack cocaine), connective tissue disorders (rheumatoid arthritis, SLE, sarcoidosis), industrial lung diseases (silicosis, asbestosis)
- Malignancy (lymphangitis carcinomatosa)
What does alveolar opacification look like?
Fluffy
What are ring opacities? (x2)
These appear when you visualise dilated bronchi end-on (seen in bronchitis or bronchiectasis), or cavitating lesions (such as abscess, tumour, or pulmonary infarct).
What are Kerley B lines?
Thin lines 1-2 cm in length in the periphery of the lung(s). They are perpendicular to the pleural surface and extend out. They represent thickened subpleural interlobular septa and are usually seen at the lung bases.
What is pneumomediastinum? Aetiology? (x2)
Air tracks along mediastinum, into the neck, due to rupture of alveolar wall or bronchial/oesophageal trauma.
Correct line/tube placement of: (i) CVC (central venous catheter), (ii) PICC, (iii) tunnelled line such as Hickman, (iv) endotracheal tube, (v) nasogastric tube, (vi) chest drain, (vii) cardiac pacemaker?
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What is sail’s sign? What is it a sign of?
Dense triangular opacity overlying the cardiac shadow with increased lucency of the left upper zone relative to the right upper zone. It is a sign of left lower lobe collapse with subsequent left upper lobe hyper-expansion.
What does this radiological image show?
The consolidation has an inferior border that indicates the border of the inferior superior lobe. This CXR is a right upper lobe pneumonia.
What does this radiological image show?
Nodule in upper zone of left lung. Could indicate vasculitis, tumour etc.
What does a pleural effusion look like on a CXR?
MENISCUS SIGN (laterally, the density moves superiorly), loss of costophrenic angle (note that ANY blunting is pathological – small blunting just means small/moderate effusion), and it is very dense. In patients with an erect CXR, the density is highest at the bottom of the effusion.
What does this CXR show? How do you differentiate from pleural effusion?
Collapse of the right lung (atelectasis). There is ‘white-out’ on the right side because when the lung has collapsed, all that is left behind is tissue and the lung interstitium. This can be differentiated from a pleural effusion, as atelectasis tends to result in opacification across the WHOLE lung, and if the effusion caused a tracheal/mediastinal shift, it would push away the mediastinum rather than pull at it.
What is pleural thickening on CXR?
Best seen at the lung edges and indicated by lobulated peripheral shadowing and loss of lung volume.
What are asbestos plaques on CXR?
Calcified asbestos related pleural plaques that are irregular, well-defined and classically said to look like holly leaves. Associated with pleural thickening.
What does this CXR show?
There are differences in density between the right side of the heart and the left. This patient has lung cancer above the black line on the left heart side. The tumour is superimposed onto the heart, hence increased density.
What does this CXR show? !!! Aetiology? (x3) Typical symptoms?
Bilateral HILAR lymphadenopathy. Aetiology may be TB, sarcoidosis or lymphoma. Symptoms tend to be SOB and cough.
What does this CXR show?
Pneumoperitoneum caused by perforation (air under diaphragm).
What does this CXR show?
Surgical slips on patient’s right shows Hx of mastectomy. Has got cannon ball lesions in liver and lesions in bone on left. So, patient has metastatic cancer. Surgical clips would signpost to Hx of cancer and help us with this diagnosis.
What does this CXR show?
Bilateral basal shadowing with apical sparing = COVID.
What does this CXR show?
Pericardial effusion because heart is more globular, large and rounded.
What does this CXR show?
Misplaced NG tube.
What does this CXR show?
This was a spontaneous hydropneumothorax, subsequently managed with pleural drain insertion. The straight air-fluid level is the typical appearance of a hydropneumothorax, as opposed to a meniscus observed in a pleural collection.
What is the ‘sail sign’?
Left lower lobe collapse
What is the golden S sign?
Right upper lobe collapse.
What does pericarditis look like on CXR?
There may be an increased cardiothoracic ratio with a globular or ‘flask-shaped’ outline if there is co-existing pericardial effusion. Manifestations of cardiogenic pulmonary oedema may also be present.
What does atypical pneumonia look like on CXR?
Opacification tends to be very widespread and not correlate with clinical picture. Opacification is bilateral and across whole lung. You can differentiate this from oedema as opacification is patchy (reticular nodular) and not fluffy. Atypical pneumonias include Mycoplasma, Chlamydophilia, and Legionella.
