Articles

Articles are a collaborative effort to provide a single canonical page on all topics relevant to the practice of radiology. As such, articles are written and edited by countless contributing members over a period of time. A global group of dedicated editors oversee accuracy, consulting with expert advisers, and constantly reviewing additions.

81 results found
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Adult chest radiograph common exam pathology

Adult chest radiograph common exam pathology is essential to consider in the build up to radiology exams. The list of potential diagnoses is apparently endless, but there are some favourites that seem to appear with more frequency. When dealing with the adult chest radiograph in the exam settin...
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Adult chest radiograph set-pieces

There are a number of adult chest radiograph set-pieces. These are based on common patterns of disease that are seen on chest radiographs. Make sure that you have relevant differentials for these appearances and a quick aural set-piece for them when they come up. Pulmonary parenchyma lobar col...
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Air space nodule

An air space nodule is a small (few millimeters to 1 cm), ill-defined, nodular opacity that is often centrilobular in location and is non-specific, seen in many conditions. Commonly it represents a focal area of consolidation or peribronchiolar inflammation, and can indicate endobronchial spread...
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Aortic nipple

An aortic nipple is seen in about 10% of PA chest x-rays on the lateral surface of the aortic arch/aortic knob. It represents the left superior intercostal vein. When prominent, superior vena cava obstruction should be considered as the left superior intercostal vein serves as a collateral path...
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Apical zone

The apical zone is one of the four chest radiograph zones and an important location for missed diagnoses when reporting a frontal chest radiograph and makes up one of the "check areas". It is sometimes thought of as a subdivision of the upper zone.  Radiographic features Plain radiograph port...
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Assessment of bones and soft tissue on chest x-ray

Described below are points to consider on assessment of bones and soft tissue on chest x-ray.  ribs rib fractures lesions (most commonly metastases): may appear as lucent and/or sclerotic; inverting contrast may help in identification previous surgery, e.g. thoracotomy with rib resection ve...
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Assessment of cardiomediastinal contours on chest x-ray (approach)

Described below is one approach to systematic assessment and associated pathology of the cardiomediastinal contours on chest x-ray. Mediastinum size: widened mediastinum can be seen in aortic dissection, traumatic aortic injuries abnormal contour, e.g. lymphadenopathy, anterior mediastinal m...
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Assessment of chest x-ray technical adequacy (approach)

Described below are some points on an approach to the assessment of the chest x-ray technical adequacy. Rarely, a technically inadequate chest x-ray will prohibit diagnostic interpretation but knowledge of the limitations will impact on diagnostic confidence.  Inspiratory effort anterior aspec...
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Assessment of lungs, pleura and airways on chest x-ray (approach)

Described below is one approach to the assessment of airways, lungs and pleura on chest x-ray. Start by assessing the tracheal air column, followed by the lungs and finally the pleural spaces.  Tracheobronchial tree assess position, should be central and deviation can be due to positive mass ...
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Assessment of pulmonary hila on chest x-ray (approach)

Described here are points to consider when approaching the assessment of the pulmonary hila on chest x-ray: shape normally appear as gentle C-shapes on either side contents: pulmonary arteries and veins, bronchi, lymph nodes position left hilum is normally 1-2 cm higher than the right low ...
Article

Bedside lung ultrasound in emergency (approach)

Bedside lung ultrasound in emergency (BLUE) is a basic point-of-care ultrasound (POCUS) examination performed for undifferentiated respiratory failure at the bedside, immediately after the physical examination, and before echocardiography. It has been designed as a fast (<3 minute), three-point...
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Big rib sign

The big rib sign is a sign to differentiate right and left ribs on lateral chest radiographs.  It exploits a technique of magnification differences on lateral projections between right and left ribs. For example, on right lateral projections the left ribs appear larger than right ribs.  This s...
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British Thoracic Society guidelines for pulmonary nodules

British Thoracic Society guidelines for pulmonary nodules were published in August 2015 for the management of pulmonary nodules seen on CT. In the United Kingdom, they supersede the Fleischner Society guidelines. They are based initially on identifying whether the nodule is solid or subsolid an...
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Brock model for pulmonary nodules

The Brock model, also known as the PanCan model, is a multivariable model that estimates the risk that a pulmonary nodule on CT scan is a lung cancer. The model was developed from participants enrolled in the Pan-Canadian Early Detection of Lung Cancer Study 1, has been validated in lung cancer...
Article

Bronchogenic cyst vs oesophageal duplication cyst

Bronchogenic cysts and oesophageal duplication cysts are embryological foregut duplication cysts and are also differential diagnoses for a cystic mediastinal mass. Differences Symptoms asymptomatic bronchogenic cyst symptomatic oesophageal cyst in the case of peptic ulceration Plain radiogr...
Article

Cardiac MRI

Cardiac MRI consists of using MRI to study heart anatomy, physiology and pathology. Advantages The main advantages of cardiac MRI in comparison with other techniques are: better definition of soft tissues use of different types of sequences improves diagnostic accuracy no ionising radiation...
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Cardiac silhouette

Cardiac silhouette refers to the outline of the heart as seen on frontal and lateral chest radiographs and forms part of the cardiomediastinal contour. The size and shape of the cardiac silhouette provide useful clues for underlying disease. Radiographic features From the frontal projection, t...
Article

Cardiothoracic ratio

The cardiothoracic ratio (CTR) aids in the detection of enlargement of the cardiac silhouette, which is most commonly from cardiomegaly but can be due to other processes such as a pericardial effusion.  Terminology Some report CTR as a percentage, however this is incorrect, as it is a ratio. ...
Article

Causes of perfusion defects on a VQ scan

There are several causes leading to a perfusion defect on a VQ scan with an acute pulmonary embolus being only one of them: Vascular causes acute pulmonary embolus previous pulmonary embolus (including fat embolism, thromboembolism, air embolism, tumour) vasculitides affecting the pulmonary ...
Article

Chest radiograph assessment using ABCDEFGHI

ABCDEFGHI can be used to guide a systematic interpretation of chest x-rays. Assessment of quality / Airway The quality of the image can be assessed using the mnemonic PIER: position: is this a supine AP file? PA? Lateral? inspiration: count the posterior ribs. You should see 10 to 11 ribs wi...
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Chest radiograph zones

The chest radiograph zones are useful when describing the location of pathology on a frontal chest radiograph. The chest radiograph is a 2D representation of a 3D structure. Since the interfaces between the lobes are orientated obliquely, it is often not possible to determine which lobe patholo...
Article

Chest x-ray: ABCDE (summary)

This is a basic article for medical students and other non-radiologists Chest x-ray review is a key competency for medical students, junior doctors and other allied health professionals. Using A, B, C, D, E is a helpful and systematic method for chest x-ray review: A: airways B: breathing (th...
Article

Chest x-ray airway (summary)

This is a basic article for medical students and other non-radiologists Chest x-ray review is a key competency for medical students, junior doctors and other allied health professionals. Using A, B, C, D, E is a helpful and systematic method for chest x-ray review where A refers to the assessme...
Article

Chest x-ray - an approach (summary)

This is a basic article for medical students and other non-radiologists Chest x-ray review is a key competency for medical students, junior doctors and other allied health professionals. Chest radiographs are frequently performed and a fantastic tool for making diagnoses of acute and chronic co...
Article

Chest x-ray: circulation (summary)

This is a basic article for medical students and other non-radiologists Chest x-ray review is a key competency for medical students, junior doctors and other allied health professionals. Using A, B, C, D, E is a helpful and systematic method for chest x-ray review where C refers to circulation ...
Article

Chest x-ray: disability (summary)

This is a basic article for medical students and other non-radiologists Chest x-ray review is a key competency for medical students, junior doctors and other allied health professionals. Using A, B, C, D, E is a helpful and systematic method for chest x-ray review where D refers to disability a...
Article

Chest x-ray: ET tube position (summary)

This is a basic article for medical students and other non-radiologists Chest x-ray ET (endotracheal) tube position should be assessed following initial placement and on subsequent radiographs. Reference article This is a summary article; we have a more in-depth reference article, see ETT. S...
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Chest x-ray (exposure summary)

This is a basic article for medical students and other non-radiologists Chest x-ray review is a key competency for medical students, junior doctors and other allied health professionals. Using A, B, C, D, E is a helpful and systematic method for chest x-ray review where E refers to "everything ...
Article

Chest x-ray: lines and tubes (summary)

This is a basic article for medical students and other non-radiologists Chest x-ray lines and tubes can be easily assessed and should be the first thing that you look at when reviewing a chest x-ray. Assessment of their position is important, but they also give you an idea about how sick the pa...
Article

Chest x-ray: PICC position (summary)

This is a basic article for medical students and other non-radiologists Chest x-ray PICC (peripherally inserted central catheter) position should be assessed following initial placement and on subsequent radiographs. Reference article This is a summary article; we do have a more in-depth refe...
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Computed tomography of the chest

Computed tomography (CT) of the chest is a cross-sectional evaluation of the heart, airways, lungs, mediastinum, and associated bones and soft tissues. Two key methods of image acquisition include: standard CT with 5 mm slice thickness for mediastinum and gross evaluation of lungs high-resolu...
Article

Congenital heart disease chest x-ray (an approach)

With the advent of echocardiography, and cardiac CT and MRI, the role of chest x-rays in evaluating congenital heart disease has been largely been relegated to one of historical and academic interest, although they continue to crop up in radiology exams. In most instances a definite diagnosis ca...
Article

CVC position on chest x-ray (summary)

This is a basic article for medical students and other non-radiologists Chest x-ray CVC (central venous catheter) position should be assessed following initial placement and on subsequent radiographs. Reference article This is a summary article; for a more in-depth reference article see centr...
Article

Diagnostic HRCT criteria for usual interstitial pneumonia (UIP) pattern - Fleischner society guideline (2018)

In 2018, the Fleischner Society provided updated diagnostic HRCT criteria for usual interstitial pneumonia (UIP) pattern based on literature review and the expert opinion of members. As a part of this white paper, diagnostic HRCT criteria for usual interstitial pneumonia (UIP) pattern were updat...
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Diffuse pulmonary nodules

Diffuse pulmonary nodules are usually seen as multiple pulmonary nodular opacifications on a HRCT chest scan. They can signify disease processes affecting either the interstitium or the airspace. They can range from a few millimetres to up to 1 cm and when very small and numerous there can be so...
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Diffuse pulmonary nodules on HRCT (an approach)

A number of differentials must be kept in mind while approaching diffuse pulmonary nodules. Interpretation is easier if nodules are the only abnormality. These differentials can be narrowed down based on the several criteria: Based on appearance  miliary nodules   miliary tuberculosis silic...
Article

Empyema vs pulmonary abscess

Distinguishing between an empyema and a peripherally located pulmonary abscess is essential. Lung abscesses are usually managed with prolonged antibiotics and physiotherapy with postural drainage whereas an empyema usually requires percutaneous or surgical drainage. Radiographic features Plai...
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Enlargement of the cardiac silhouette

Enlargement of the cardiac silhouette on a frontal (or PA) chest x-ray can be due to a number of causes 1: cardiomegaly (most common cause by far) pericardial effusion anterior mediastinal mass prominent epicardial fat pad expiratory radiograph AP projection (from supine radiographs taken ...
Article

Expiratory HRCT

Expiratory HRCT is an useful method for detecting small airway obstructive disease in which the air remain trapped in the small airways even after the expiration and appear as mosaic attenuation. Indication Ideally, an expiratory HRCT scan should be performed in all obstructive airway diseases...
Article

Flattening of the diaphragm

Flattening of the diaphragm is the most sensitive sign on chest radiographs for the presence of hyperinflation of the lungs, usually due to emphysema 1-2. The normal dome of each hemidiaphragm should rise at least 1.5 cm above a line connecting the costophrenic angle posteriorly and sternophren...
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Fleischner Society pulmonary nodule recommendations

The Fleischner Society pulmonary nodule recommendations are for the follow-up and management of pulmonary nodules detected incidentally on imaging. The guideline does not apply to patients <35 years or with a history of cancer or immunosuppression. The initial guideline was released in 2005 1; s...
Article

Fluoroscopic evaluation of oesophagectomy

Fluoroscopic evaluation of oesophagectomy is an important study, given the high rate of complication following oesophagectomy (~10-20% rate of leak). Although the approach will differ slightly depending on the type of oesophagectomy performed, the principles are similar. Procedure Preprocedura...
Article

Ground glass opacification

Ground glass opacification/opacity (GGO) is a descriptive term referring to an area of increased attenuation in the lung on computed tomography (CT) with preserved bronchial and vascular markings. It is a non-specific sign with a wide aetiology including infection, chronic interstitial disease a...
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Idiopathic interstitial pneumonias: HRCT chest approach

The approach to HRCT chest in patients with suspected idiopathic interstitial pneumonia (IIP) is with the aim to: make sure an appropriate study requested i.e. HRCT chest with optimal individually adjusted protocol and ensure adequacy of the HRCT chest quality (see imaging protocol below) meti...
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Incidental lung nodules

Incidental lung nodules are encountered commonly in normal clinical practice on CT. The risk of developing cancer in very small nodules (<5 mm) is very low. However, clear-cut recommendations are still not in place with high variation in practice amongst reporting radiologists 1. As a result, it...
Article

Increased retrosternal airspace

Increased retrosternal airspace is an indicator of hyperinflation of the lungs and is usually due to emphysema. The thickness of the space between the ascending aorta and the posterior margin of the sternum (3 cm inferior to the sternomanubrial joint) and is normally no more than 2.5 cm 1 altho...
Article

Isomerism

Isomerism is a term which in general means 'mirror-image'. It is used in the context of heterotaxy and is of two types: left isomerism right isomerism Left isomerism Mirror image of the structures on the left side of the chest along the left-right axis of the body, i.e. patients with isomeri...
Article

Left atrial enlargement

Left atrial enlargement may result from many conditions, either congenital or acquired. It has some characteristic findings on a frontal chest radiograph. CT or MRI may also be used for diagnosis. Clinical presentation An enlarged left atrium can have many clinical implications, such as: Ortn...
Article

Left upper lobe collapse

Left upper lobe collapse has distinctive features but can be challenging to identify on chest radiographs by the uninitiated. For a general discussion refer to the article on lobar collapse. Radiographic features Plain radiograph The left upper lobe collapses anteriorly becoming a thin sheet...
Article

Left upper lobe collapse in the exam

Getting a film with left upper lobe collapse in the exam is one of the many exam set-pieces that can be prepared for. Description This frontal chest radiograph shows a hazy (or veil-like*) opacification of the left hemithorax that is associated with superior displacement left hilum and horizon...
Article

Lines and tubes (chest radiograph)

Lines and tubes are important components in chest radiographic evaluation. Nasogastric (NG) tube See: nasogastric tube positioning.  Correct position NG tube tip ≥10 cm distal to the gastro-oesophageal junction i.e. below the left hemidiaphragm Complications insertion into trachea or bron...
Article

Lobar collapse (summary)

This is a basic article for medical students and other non-radiologists Lobar collapse is relatively common and occurs following obstruction of a bronchus. Gas is resorbed from the lung parenchyma distal to the obstruction resulting in the collapse of the lung, with volume reduction and negativ...
Article

Lower zone

The lower zone is one of the four chest radiograph zones.  Radiographic features Plain radiograph on frontal chest radiographs, extends inferiorly from the inferior aspect of the hilum to the hemidiaphragm
Article

Lung cancer (staging - IASLC 8th edition)

The IASLC (International Association for the Study of Lung Cancer) 8th edition lung cancer staging system was introduced in 2016 and supersedes the IASLC 7th edition.  TNM system T: primary tumour Tx: primary tumour cannot be assessed or tumour proven by the presence of malignant cells in spu...
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Mediastinal widening (differential)

The differential diagnoses for mediastinal widening include: traumatic aortic injury vascular anomalies unfolded aorta double SVC aberrant right subclavian artery azygous continuation of the IVC pneumomediastinum lung atelectasis pulmonary masses abutting the mediastinum mediastinal l...
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Mid zone

The mid (or middle) zone is one of the four chest radiograph zones.  Radiographic appearance Plain radiograph on frontal chest radiographs, extends between the superior and inferior aspects of the hilum
Article

Modified PIOPED criteria for diagnosis of pulmonary embolus

The modified PIOPED criteria for the diagnosis of pulmonary embolus (PE) determine the probability of pulmonary emboli following a VQ scan. Classification High probability two or more large mismatched segmental defects or equivalent moderate/large defects with a normal x-ray any perfusion de...
Article

Nasogastric tube position on chest x-ray (summary)

This is a basic article for medical students and other non-radiologists   Nasogastric (NG) tube position on chest x-ray should be assessed following initial placement and on subsequent radiographs. Reference article This is a summary article; we have a more in-depth reference article NGT. S...
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Neonatal chest radiograph in the exam setting

The neonatal chest radiograph in the exam setting may strike fear into the heart of many radiology registrars, but it need not! There are only a limited number of diagnoses that will be presented on such films and they are often highlighted by the history. Gestation First of all, have a look ...
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Neonatal pneumothorax

Neonatal pneumothorax describes pneumothoraces occurring in neonates. It is a life threatening condition, associated with high morbidity and mortality. The diagnosis is a challenge especially when the amount of air is small and may accumulate along the anterior or medial pleural space. Epidemio...
Article

Nipple markers

Nipple markers can be a useful technique in the evaluation of densities overlying the expected position of the nipple on a chest radiograph. Not uncommonly a small round opacity projects over the lower thorax on a chest radiograph (see: solitary pulmonary nodule). Often, especially in women, th...
Article

Oesophageal intubation

Oesophageal intubation refers to the incorrect placement of an endotracheal tube in the oesophagus. Within minutes its consequences can be catastrophic with the seriousness of its outcome depending largely on the timeliness of its diagnosis. Epidemiology Accidental oesophageal intubation can h...
Article

Pneumothorax

Pneumothorax refers to the presence of gas (air) in the pleural space. When this collection of gas is constantly enlarging with resulting compression of mediastinal structures, it can be life-threatening and is known as a tension pneumothorax. For those pneumothoraces occurring in neonates see t...
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Pneumothorax in the exam

Getting a film with a pneumothorax in the exam is one of the many exam set-pieces that can be prepared for.   It is unlikely that they will give you a simple pneumothorax - so, it is worth while considering the likely causes and whether it is under tension. Miss it at your peril (both in real l...
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Pulmonary nodule

Pulmonary nodules are small, rounded opacities within the pulmonary interstitium. Pulmonary nodules are common and, as the spatial resolution of CT scanners has increased, detection of smaller and smaller nodules has occurred, which are more often an incidental finding. Classification Pulmonar...
Article

Rapid ultrasound in shock

The rapid ultrasound in shock (RUSH) protocol is a structured point-of-care ultrasound (POCUS) examination performed at the time of presentation of a shocked patient. It is a more detailed and longer exam than the FAST scan, with the aim to differentiate between hypovolemic, cardiogenic, obstruc...
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Reticular and linear pulmonary opacification

In chest radiology, reticular and linear opacification refers to a broad subgroup of pulmonary opacification caused by a decrease in the gas to soft tissue ratio due to a pathological process centred in or around the pulmonary interstitium. This includes thickening of any of the interstitial com...
Article

Retrosternal airspace

The retrosternal airspace is seen as a normal lucency between the posterior aspect of the sternum and anterior aspect of the ascending aorta on lateral chest radiographs. This space normally measures less than 2.5 cm in width. Increased retrosternal airspace is a sign of pulmonary emphysema, whi...
Article

Retrotracheal space

The retrotracheal space (or Raider triangle) is a radiolucent mediastinal space best seen on lateral chest x-rays. It is normally triangular in shape but can vary greatly in size and shape depending on the patient's body habitus and lung volume 1. Boundaries anterior: posterior tracheal stripe...
Article

Review areas on chest x-ray

Review areas on a chest x-ray are common areas for missed findings, and special attention should be paid to them: lung apices: masses (e.g. Pancoast tumour), pneumothorax behind the heart: consolidation, masses, hiatus hernia below the diaphragm: free gas, lines and tubes (e.g. nasogastric tu...
Article

Right paratracheal stripe

The right paratracheal stripe is a normal finding on the frontal chest x-ray and represents the right tracheal wall, adjacent pleural surfaces and any mediastinal fat between them. It is visible because of the silhouette sign created by air within the trachea medially and air within the lung lat...
Article

Situs inversus

Situs inversus, short form of the Latin “situs inversus viscerum”, is a term used to describe the inverted position of chest and abdominal organs. It is called situs inversus totalis when there is a total transposition of abdominal and thoracic viscera (mirror image of internal organs normal pos...
Article

Small pulmonary nodules (HRCT chest approach)

Small pulmonary lung nodules refer to an HRCT chest imaging descriptor for 5-10 mm lung nodules and are divided into three main categories based on their distribution pattern: centrilobular perilymphatic random Approach Distribution Firstly, determine whether the nodules are perilymphatic ...
Article

Sniff test

The fluoroscopic sniff test, also known as diaphragm fluoroscopy, is a quick and easy real time fluoroscopic assessment of diaphragmatic motor function (excursion). It is used most often to confirm absence of muscular contraction of the diaphragm during inspiration in patients with phrenic nerve...
Article

Solitary pulmonary nodule (an approach)

A solitary pulmonary nodule, according to the Nomenclature Committee of the Fleischner Society, is defined as a rounded opacity, well or poorly-defined on a conventional radiograph, measuring up to 3 cm in diameter and is not associated with lymphadenopathy, atelectasis, or pneumonia. Several r...
Article

Sonographic approach to dyspnoea (mnemonic)

This mnemonic will help with the sonographic approach to the critically ill patient with dyspnoea: CHEST Mnemonic C: collapsed lung (pneumothorax)  ​absent anterior lung sliding / anterior B lines lung point present 1 H: heart failure (acute pulmonary oedema) diffuse bilateral anterior B ...
Article

Subpleural reticulation

Subpleural reticulation is a type of reticular interstitial pattern where the changes are typically in a peripheral subpleural distribution (i.e. adjacent to costal pleural surfaces, located ≤1 cm from the pleura according to some publications 4). Pathology It can arise in a number of patholog...
Article

Systematic chest radiograph assessment (approach)

One approach to a systematic chest radiograph assessment is as follows: projection assessment of the technical adequacy tubes and lines cardiomediastinal contours hila airways, lungs and pleura bones and soft tissue review areas Following a systematic approach on every chest radiograph ...
Article

Thoracoplasty

Thoracoplasty is a surgical procedure that was originally designed to permanently collapse the cavities of pulmonary tuberculosis by removing the ribs from the chest wall 1-3 . The resection of multiple ribs, allows the apposition of parietal to the visceral or mediastinal pleura. Until supplant...
Article

Triangle of safety

The triangle of safety is an anatomical region in the axilla that forms a guide as to the safe position for intercostal catheter (ICC) placement. With the arm abducted, the apex is the axilla, and the triangle is formed by the: lateral border of the pectoralis major anteriorly lateral border o...
Article

Unilateral hypertranslucent hemithorax

Unilateral hypertranslucent hemithorax has many potential causes. It may be the result of rotation away from an optimal position or because of pathology. Rotation A unilateral hypertranslucent hemithorax may be caused by the positioning of the patient. Rotation away from the radiation beam alt...

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