Left lower lobe collapse has distinctive features, and can be readily identified on frontal chest radiographs, provided attention is paid to the normal cardiomediastinal contours. However, the shadow cast by the heart does make it more difficult to see than the right lower lobe collapse.
For a ...
Large-cell lung cancer is one of the histological types of non-small cell carcinomas of the lung.
It is thought to account for approximately 10% of bronchogenic carcinoma 1.
Patients present with dyspnea, chronic cough and haemoptysis.
Adenocarcinoma of the lung is one of the non-small cell carcinomas of the lung and is a malignant tumour with glandular differentiation or mucin production. This tumour exhibits various patterns and degrees of differentiation, including lepidic, acinar, papillary, micropapillary, and solid with ...
The retro-aortic left brachiocephalic vein is a rare vascular variant where the left brachiocephalic vein passes more inferiorly through the superior mediastinum, coursing inferior to the aortic arch and posterior to the ascending aorta to join the right brachiocepahilc vein forming the superior...
Lung cancer, or frequently, if somewhat incorrectly, known as bronchogenic carcinoma, is a broad term referring to the main histological subtypes of primary lung malignancies that are mainly linked with inhaled carcinogens, smoking cigarettes in particular.
This article will broadly discuss al...
Organising pneumonia (OP) refers to a clinicopathological entity which is associated with nonspecific clinical findings, radiographic findings, and pulmonary function test results.
When an underlying cause is unknown it is classified as cryptogenic organising pneumonia (COP; also referred to as...
Octreotide scintigraphy uses 111In-labelled octreotide which is a somatostatin analog; it is also known as an OctreoscanTM, a brand name for 111In-labelled pentetreotide; pentetreotide is a DTPA-conjugated form of octreotide, originally manufactured by Mallinckrodt Nuclear Medicine LLC, which no...
Reversed halo sign, also known as the atoll sign, is defined as central ground-glass opacity surrounded by denser consolidation of crescentic (forming more than three-fourths of a circle) or ring (forming a complete circle) shape of at least 2 mm in thickness. It was initially described on high-...
The left atrium is one of the four chambers of the heart. It receives oxygenated blood from the pulmonary circulation that is then delivered to the left ventricle and then into the systemic circulation.
The left atrium is grossly cuboidal, and like the right atrium has an appenda...
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.
An enlarged left atrium can have many clinical implications, such as:
Behçet disease is a multisystemic and chronic inflammatory vasculitis of unknown aetiology.
The mean age at which Behçet disease occurs is 20-30 years. The disease is most prevalent in the Mediterranean region, Middle East and East Asia. The highest incidence has been reported in ...
Pulmonary arterial aneurysms refer to a focal dilatation of the pulmonary arterial system.
Overall it is considered a rare entity with autopsy prevalence rates of around 1 in 14,000 to 100,000 4,5.
A true pulmonary artery aneurysm results from dilatation of all three l...
Thoracic manifestations in Behçet disease have a wide spectrum of appearances.
The reported prevalence of thoracic involvement of Behçet disease is thought to range around 1-8% 2.
Chest HRCT can demonstrate the entire spectrum of thoracic manifestation...
Brachiocephalic veins (BCV), previously the innominate veins are large paired valveless asymmetric veins that drain the head, neck, upper limbs and part of the thorax and mediastinum.
In the root of the neck, the internal jugular and subclavian veins unite to form the bra...
The use of the aortic dissection detection risk score plus d-dimer is a proposed standardised strategy of safely ruling out the diagnosis of an acute aortic syndrome. Similar to how the pulmonary embolism rule-out criteria (PERC) negates the need for further workup of a pulmonary embolism.
Right upper lobe collapse has distinctive features, and is usually easily identified on frontal chest radiographs; much more so than left upper lobe collapse.
For a general discussion please refer to the article on lobar collapse.
Collapse of the right ...
The juxtaphrenic peak sign, also known as diaphragmatic tenting or Kattan sign, refers to the peaked or tented appearance of a hemidiaphragm which can occur in the setting of lobar collapse. It is caused by retraction of the lower end of diaphragm at an inferior accessory fissure (most common 1)...
Thoracic lymph nodes are divided into 14 stations as defined by the International Association for the Study of Lung Cancer (IASLC) 1, principally in the context of oncologic staging. For the purpose of prognostication, the stations may be grouped into 7 zones.
Station 1 (l...
Pulmonary embolism (PE) refers to embolic occlusion of the pulmonary arterial system. The majority of cases result from thrombotic occlusion, and therefore the condition is frequently termed pulmonary thromboembolism which is what this article mainly covers.
Other embolic sources include:
Tuberculosis encompasses an enormously wide disease spectrum affecting multiple organs and body systems predominantly caused by the organism Mycobacterium tuberculosis. A small proportion can also be caused Mycobacterium bovis.
Although tubeculsosis continues to be very common in...
This article lists examples of normal imaging of the chest and surrounding structures, divided by modality.
PA adult male
example 2: with inverted windows
PA adult female
example 3: with labels
A bridging bronchus is a rare congenital bronchial anomaly where there is an anomalous bronchus to the right lung arising from the left main bronchus. It has a high association with right upper lobe bronchus (pig bronchus) and congenital cardiac and vascular malformations, particularly a left pu...
Pulmonary and mediastinal involvement of sarcoidosis is extremely common, seen in over 90% of patients with sarcoidosis. Radiographic features are variable depending on the stage of the disease.
For a general discussion, please refer to the parent article: sarcoidosis.
Xenon-127 is a radiopharmaceutical principally used when a performing VQ scan. It is not a widely used alternative to xenon-133 with the main advantage being a higher proton energy allowing for post perfusion scanning.
photon energy: 203 KeV
physical half life: 36.3 days
Xenon-133 is a radiopharmaceutical principally used when a performing VQ scan. Inhalation of this gas can also be used to assess cerebral blood flow.
photon energy: 81 KeV
physical half-life: 5.27 days
biological half-life: 30 seconds
normal distribution: lungs
<15% of inhaled gas is absorb...
Tc-99m MAA (macroaggregated albumin) is one of the technetium radiopharmaceuticals used in lung perfusion imaging.
photon energy: 140 KeV
physical half life: 6 hours
biological half life: 2-3 hours
normal distribution: lungs, liver, spleen, kidneys
Tc-99m DTPA (diethylenetriamine-pentaacetic acid) (aerosol) is one of the technetium agents and is used in VQ imaging.
photon energy: 140 KeV
physical half life: 6 hours
biological half life: 1 hour
normal distribution: lungs
aerosol deposited in bronhoal...
Lung torsion is the rotation of a lung or lung lobe about its bronchovascular pedicle and resulting in ischemia. It is very rare, and typically occurs in the setting of lobectomy or pneumonectomy. It has also been reported as rare complication of less invasive procedures such as video-assisted t...
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...
Antiphospholipid syndrome is a systemic autoimmune disorder. It is usually defined as the clinical complex of vascular occlusion and ischaemic events occurring in patients who have circulating antiphospholipid antibodies.
Antiphospholipid syndrome is characterised by veno...
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
Cystic fibrosis (CF) is an autosomal recessive genetic disease that affects the exocrine function of the lungs, liver, pancreas, and small bowel resulting in progressive disability and multi-system failure. This article is a general discussion of the disease. Each organ system will be discussed ...
Lung fissures are a double-fold of visceral pleura that either completely or incompletely invaginate lung parenchyma to form the lung lobes.
Each lung has an oblique fissure separating the upper lobes from the lower lobes and the right lung has a horizontal fissure that separates the right upp...
A pulmonary pseudotumour is no more than 'something' which mimics a tumour. Most frequently the term is used to denote focal collections of fluid trapped in the pleural fissures. Other entities which have been described with the term pseudotumours include:
Solitary pulmonary nodule (SPN) is defined as a relatively well defined round or oval pulmonary parenchymal lesion equal or smaller than 30 mm in diameter. It is surrounded by pulmonary parenchyma and/or visceral pleura and is not associated with lymphadenopathy, atelectasis, or pneumonia 9.
Endobronchial metastases are an uncommon form of intrathoracic metastases. They are much less common than intrapulmonary metastases.
The clinical presentation varies and includes:
post-obstructive pneumonitis from distal obstruction
Desquamative interstitial pneumonia (DIP) is an interstitial pneumonia closely related to and thought to represent the end stage of respiratory bronchiolitis interstitial lung disease (RB-ILD). It is associated with heavy smoking.
It is considered one of the rarest of idiopathic i...
Small-cell lung cancer (SCLC), also known as oat-cell lung cancer, is a subtype of bronchogenic carcinoma separated from non-small-cell lung cancer (NSCLC) as it has a unique presentation, imaging appearances, treatment, and prognosis. SCLCs are neuroendocrine tumours of the lung that rapidly gr...
Aortic ductus diverticulum is a developmental outpouching of the thoracic aorta.
It is usually seen at the anteromedial aspect of the aorta at site of the ligamentum arteriosum, at the aortic isthmus. This is also the site of 90% of post-traumatic aortic injuries as the ligamentu...
Finger clubbing, also called "drumstick fingers", is a common clinical sign in patients with heart or lung disease. The term is used to describe an enlargement of the distal phalanges of the fingers, giving them a drumstick or club-like appearance.
The underlying pathogenesis of fin...
The peribronchovascular interstitium refers to the connective tissue sheath that encloses the bronchi, pulmonary arteries, and lymphatic vessels. It extends from the hilar regions through to the lung peripheries.
There are many diseases that may affect the peribronchovascular interstitium.
Acute respiratory distress syndrome (ARDS) is a form of acute lung injury (ALI) and occurs as a result of a severe pulmonary injury that causes alveolar damage heterogeneously throughout the lung. It can either result from a direct pulmonary source or as a response to systemic injury.
Poland syndrome refers to a congenital unilateral absence of the pectoralis major and minor muscles and is a recognised cause of unilateral hyperlucent hemithorax.
Poland syndrome is usually sporadic, although rare familial cases have been described 1. It is rare, with an estimat...
Pulmonary manifestations are relatively common in rheumatoid arthritis, and like many of its non-articular manifestations, tend to develop later in the disease.
Please refer to the related articles for a general discussion of rheumatoid arthritis, and for the specific discussion of its musculos...
A Bochdalek hernia is a form of congenital diaphragmatic hernia. They occur posteriorly and are due to a defect in the posterior attachment of the diaphragm when there is a failure of pleuroperitoneal membrane closure in utero. Retroperitoneal structures may prolapse through the defect, e.g. ret...
Ehlers-Danlos syndrome comprises a heterogeneous group of collagen disorders (hereditary connective tissue disease).
There is a recognised male predominance.
Clinically manifests by skin hyperelasticity and fragility, joint hypermobility and blood vessel fr...
Squamous cell carcinoma (SCC) is one of the non-small cell carcinomas of the lung, overtaken by adenocarcinoma of the lung as the most commonly encountered lung cancer.
Squamous cell carcinoma accounts for ~30-35% of all lung cancers and in most instances are due to heavy smoking...
The chest radiograph (also known as the chest x-ray or CXR) is the most ubiquitous radiological investigation.
The chest radiograph is performed for a broad content of indications, including but not limited to 1-4:
Superior mediastinum is an artificially divided wedge-shaped compartment of the mediastinum located between the thoracic plane inferiorly and the thoracic inlet superiorly. The inferior mediastinum, comprising of the anterior, middle and posterior parts, lies inferiorly.
Subcutaneous emphysema (or less correctly surgical emphysema), strictly speaking, refers to gas in the subcutaneous tissues. But the term is generally used to describe any soft tissue emphysema of the body wall or limbs since the gas often dissects into the deeper soft tissues and musculature al...
Sarcoidosis is a non-caseating granulomatous multi-system disease with a wide range of clinical and radiographic manifestations.
Individual systemic manifestations are discussed in respective articles:
pulmonary and mediastinal manifestations
Right middle lobe syndrome refers to chronic right middle lobe collapse, without an obstructing lesion. It is usually with associated bronchiectasis.
Right middle lobe syndrome is usually encountered in older adults, with a predilection for women (see Lady Windermere syndrome). I...
Upper lobe predominant pulmonary fibrosis can be associated with a number of pathologies. These include
cystic fibrosis: see pulmonary manifestations of cystic fibrosis
Langerhans cell histiocytosis
Diverticula are outpouchings of a hollow viscus and can be either true or false.
Diverticulum is the singular form and diverticula is the correct Latin plural form. 'Diverticuli' and 'diverticulae' are erroneous and should not be used (cf. septum).
contains all layers of the...
A detailed understanding of the structures that make up the normal contours of the heart and mediastinum (cardiomediastinal contour) on chest radiography is essential if abnormalities are to be detected.
Frontal view (PA/AP)
Right cardiomediastinal contour
From superior to inferior:
Right lower lobe collapse has distinctive features, and is usually relatively easily identified. The absence of overlying cardiomediastinal outline makes it easier to appreciate than left lower lobe collapse.
For a general discussion please refer to the article on lobar collapse.
Right middle lobe collapse (or simply termed middle lobe collapse) has distinctive features, but can be subtle on frontal chest radiographs.
For a general discussion please refer to the article on lobar collapse.
It is important to note that of all the lobes, the right middle lobe is the mo...
Pectus carinatum, otherwise known as a pigeon chest, refers to a chest wall deformity in which the sternum protrudes anteriorly. It is less common than pectus excavatum.
Patients may present with dyspnoea and exercise intolerance.
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...
The left superior intercostal vein drains the left posterosuperior hemithorax and is considered to be part of the azygos venous system even though it does not directly drain into the azygos vein.
Origin and course
The left superior intercostal vein forms by the union of the 2nd...
Pneumomediastinum is the presence of extraluminal gas within the mediastinum. Gas may originate from the lungs, trachea, central bronchi, oesophagus, and peritoneal cavity and track from the mediastinum to the neck or abdomen.
In the setting of trauma, if pneumomediastinum is visib...
Cystic bronchiectasis is one of the less common morphological forms of bronchiectasis. It is characterised by saccular dilatation of bronchi that extend to the pleural surfaces. When aggregated these may give a "bunch of grapes" like appearance. It may be present on its own or may be occur in co...
Richter transformation is defined as development of high-grade non-Hodgkin lymphoma (NHL) in patients with chronic lymphocytic leukaemia (CLL) or small lymphocytic lymphoma.
It has been expanded to include other lymphoid malignancies that develop in CLL patients, including Hodgkin disease, prol...
Coal workers' pneumoconiosis (CWP) is an occupational disease (type of pneumoconiosis) caused by exposure to coal dust free of silica (washed coal). Histologically, CWP is classified according to disease severity into simple (presence of coal macules) and complicated (with progressive massive fi...
Thalassaemia is an autosomal recessive haemoglobinopathy that originated in the Mediterranean region. The genetic defect causes a reduction in the rate of globin chain synthesis which causes the formation of abnormal haemoglobin molecules. The resultant microcytic anaemia is the characteristic p...
Lung involvement in polymyositis can have a number of manifestations inclusive of that resembling interstitial lung disease (for a general discussion of polymyositis - refer to the parent article).
The frequency of a radiographic parenchymal abnormality ...
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...
Lymphangioleiomyomatosis (LAM) is a rare multi-system disorder that can occur either sporadically or in association with the tuberous sclerosis complex (TSC) and is often considered a forme fruste of TSC.
It almost exclusively affects women of childbearing age 7. The estimated in...
The right pulmonary artery (RPA) is one of the branches of the pulmonary trunk, branching at the level of the transthoracic plane of Ludwig. It is longer than the left pulmonary artery and courses perpendicularly away from the pulmonary trunk and left pulmonary artery, between the superior vena ...
The pulmonary trunk or main pulmonary artery is the solitary arterial output from the right ventricle, transporting deoxygenated blood to the lungs for oxygenation.
The pulmonary trunk is approximately 50 mm long and 30 mm wide (most authors use 29 mm width as the cut-off of norm...
The left pulmonary artery (LPA) is one of the branches of the pulmonary trunk, branching at the level of the transthoracic plane of Ludwig. It is shorter than the right pulmonary artery and represents a direct posterior continuation of the pulmonary trunk. It arches posterosuperiorly over the su...
The superior vena cava (SVC) is a large valveless venous channel formed by the union of the brachiocephalic veins. It receives blood from the upper half of the body (except the heart) and returns it to the right atrium.
The SVC begins behind the lower border of the first right co...
Methotrexate lung disease is the specific aetiological type of drug-induced lung disease. It can occur due to the administration of methotrexate which is an antimetabolite, which is given for various reasons but commonly to treat rheumatoid arthritis. It is also given alone or in combination wit...
Cystic lung disease is an umbrella term used to group the conditions coursing with multiple lung cysts.
A lung cyst is a gas-filled structure with perceptible wall typically 1 mm in thickness but can be up to 4 mm. The diameter of a lung cyst is usually <1 cm. By conventional defini...
Pulmonary manifestations of leukaemia can be varied and can occur from both acute and chronic forms. They include:
pulmonary leukaemic infiltrates
all-trans retinoic acid (ATRA) syndr...
The point-of-care ultrasound (PoCUS) curriculum is one of our curriculum articles and aims to be a collection of articles that represent the core applications of ultrasonography in a point-of-care setting.
Point-of-care ultrasound refers to ultrasonography which may be simultaneously performed,...
Lung-RADSTM (or lung imaging reporting and data system) is a classification proposed to aid with findings in low-dose CT screening exams for lung cancer. The goal of the classification system is to standardize follow-up and management decisions. The system is similar to the Fleischner criteria b...
Septal lines, also known as Kerley lines, are seen when the interlobular septa in the pulmonary interstitium become prominent. This may be because of lymphatic engorgement or oedema of the connective tissues of the interlobular septa. They usually occur when pulmonary capillary wedge pressure re...
Sir Peter “PK” Kerley (1900-1979) was a globally-renowned cardiothoracic radiologist who is primarily remembered now for his Kerley lines but in his lifetime was famed for his uncanny imaging diagnostic abilities, co-editing the famous 'Textbook of X-ray Diagnosis', and co-founding the Faculty o...
This is a basic article for medical students and other non-radiologists
Heart failure is a syndrome of cardiac ventricular dysfunction, where the heart is unable to pump sufficiently to meet the body's blood flow requirements.
Although it is useful to divide the signs an...
Duplication of the oesophagus has a range of macroscopic appearances from complete (very rare) to partial cystic duplication (oesophageal duplication cyst). It is the second most common gastrointestinal tract duplication after that of the ileum.
A complete duplication is a rare ma...
The differential diagnosis for a posterior mediastinal mass includes:
neurogenic tumours - most common
nerve sheath tumours
malignant peripheral nerve sheath tumour
parasymphathetic ganglion tumours
Crazy paving refers to the appearance of ground-glass opacity with superimposed interlobular septal thickening and intralobular septal thickening, seen on chest HRCT. It is a non-specific finding that can be seen in a number of conditions.
Mediastinal lymphoma is common, either as part of disseminated disease or less commonly as the site of primary involvement.
Lymphomas are responsible for approximately 15% of all primary mediastinal masses, and 45% of anterior mediastinal masses in children 1. Only 10% of lymphoma...
Congenital tracheo-oesophageal fistula is a congenital pathological communication between the trachea and oesophagus.
Tracheo-oesophageal fistula and oesophageal atresia have a combined incidence of approximately 1 in 3500 live births 1-3,5. There is only a minimal hereditary/ge...
Pulmonary cysts are cystic spaces within the lung parenchyma that have a wall that measures between 1 and 4 mm. Lung cysts contain gas, not fluid.
The thickness of the wall is what distinguishes a cyst from a pulmonary cavity (that is defined as having a wall that is thicker than 4 mm). A bleb...
A cyst is an abnormal fluid-filled structure which is lined by epithelium; with one exception: lung cysts contain gas, not fluid. By contradistinction, a pseudocyst lacks an epithelial lining and instead has a vascular and fibrotic capsule.
Cysts are extremely common and found in most organs. E...
Histoplasmosis is an endemic mycosis caused by Histoplasma capsulatum.
Pulmonary histoplasmosis is the most common manifestation of this infectious disease. Disseminated or extra-pulmonary (pericardial, articular) histoplasmosis is often seen in immunosuppressed patients. As such, these are in...
Pulmonary mesenchymal cystic hamartomas (PMHCs) are a rare subtype of pulmonary hamartomas.
They usually comprise multiple bilateral cysts and nodules. The cyst walls are lined with normal respiratory epithelium and the nodules are permeated by scattered airways that are also lined w...
Pulmonary amyloidosis is a rare manifestation of amyloidosis characterised by the lung parenchyma involvement. Two patterns are described:
nodular parenchymal amyloidosis (more common)
diffuse parenchymal amyloidosis (least common type)
Sometimes tracheobronchial amyloidosis is included under...
Pulmonary blebs are small subpleural thin walled air containing spaces, not larger than 1-2 cm in diameter. Their walls are less than 1 mm thick. If they rupture, they allow air to escape into pleural space resulting in a spontaneous pneumothorax.
Blebs are a very common finding ...
There are several non lymphomatous lymphoid disorders that can affect the lung. This implies that they consist of lymphoid tissue but may not have progressed as far as an overt lymphoma. They include:
lymphocytic interstitial pneumonia
Ranke complex is seen in 'healed' primary pulmonary tuberculosis and consists of two components:
Ghon lesion: calcified parenchymal tuberculoma
ipsilateral calcified hilar node