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.

1,922 results found
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Garland triad

Garland triad, also known as the 1-2-3 sign or pawnbroker's sign, is a lymph node enlargement pattern on chest radiographs which has been described in sarcoidosis: right paratracheal nodes right hilar nodes left hilar nodes Hilar lymphadenopathy is symmetrical and usually massive. These so-c...
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Funnel trachea

Funnel trachea is a colloquialism for a congenital long-segment intrathoracic tracheal stenosis.  The diameter of the trachea immediately below the cricoid is normal, and becomes progressively more stenotic caudally. The posterior, membranous portion of the trachea may be partially or completel...
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Feline esophagus

Feline esophagus also known as esophageal shiver, refers to the transient transverse bands seen in the mid and lower esophagus on a double-contrast barium swallow. Pathology The appearance is almost always associated with active gastro-esophageal reflux 2,3 and is thought to be due to contract...
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Fibrinous pericarditis

Fibrinous pericarditis is an inflammatory process involving the pericardium, leading to a rough and granular appearance with numerous fibrous adhesions 4. Clinical presentation Pericardial friction rub may be heard. Pathology Etiology viral acute idiopathic tuberculosis pyogenic acute r...
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Erdheim-Chester disease

Erdheim-Chester disease (ECD) is a rare non-Langerhans cell, non-familial multisystemic histiocytosis, with widespread manifestations and of highly variable severity. The most common presenting symptom is bone pain. Epidemiology Erdheim-Chester disease is a rare, non-inherited disease of middl...
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Eosinophilic lung disease

Eosinophilic lung diseases are a heterogenous group of disorders that are characterized by excess infiltration of eosinophils within the lung interstitium and alveoli and are broadly divided into three main groups 1: idiopathic: unknown causes secondary: known causes eosinophilic vasculitis: ...
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Endobronchial metastases

Endobronchial metastases are an uncommon form of intrathoracic metastases. They are much less common than intrapulmonary metastases. Clinical presentation The clinical presentation varies and includes: hemoptysis cough post-obstructive pneumonitis from distal obstruction Pathology Frequen...
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Elevated hemidiaphragm

An elevated hemidiaphragm may result from direct and indirect causes which include: above the diaphragm 1 decreased lung volume atelectasis/collapse prior lobectomy or pneumonectomy pulmonary hypoplasia diaphragm 3-7 phrenic nerve palsy diaphragmatic eventration contralateral stroke: ...
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Eggshell calcification (lymph nodes)

Eggshell calcification refers to fine calcification seen at the periphery of a mass and usually relates to lamellar lymph node calcification. For similar appearance in the breast see eggshell calcification (breast). Terminology In 1967 Jacobsen and Felson published criteria to help "avoid over...
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Dysphagia lusoria

Dysphagia lusoria is an impairment of swallowing due to compression from an aberrant right subclavian artery (arteria lusoria). Clinical presentation Most patients with aberrant right subclavian arteries do not have symptoms. Some present with mild dysphagia, while a small minority have a seve...
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Ductus diverticulum

Aortic ductus diverticulum is a developmental outpouching of the thoracic aorta which may be mistaken for an acute aortic injury. Gross anatomy It is usually seen at the anteromedial aspect of the aorta at site of the aortic isthmus, where the ligamentum arteriosum attaches. It is also the sit...
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Diaphragmatic hernia

Diaphragmatic hernias (alternative plural: herniae) are defined as either congenital or acquired defects in the diaphragm. Demographics and etiology Congenital There are two main types of congenital diaphragmatic hernia (CDH)s which are uncommon yet distinct entities that usually occur on the...
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Azygo-esophageal recess deviation

The azygoesophageal recess (AER) is formed by the interface between the right lung and the mediastinal reflection of the azygos vein and oesphagus. The line has a variable appearance: in its upper third, it deviates to the right, where it may either be straight or concave relative to the right ...
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DeBakey classification

The DeBakey classification, along with the Stanford classification, is used to separate aortic dissections into those that need surgical repair, and those that usually require only medical management. Both the Stanford and DeBakey systems can be used to describe all forms of the acute aortic sy...
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Cystic (necrotic) lymph nodes

Cystic or necrotic appearing lymph nodes can be caused by a number of infectious, inflammatory or malignant conditions: Systemic squamous cell carcinoma metastases treated lymphoma leukemia plasmacytoid T-cell leukemia acute myeloid leukemia viral lymphadenitis herpes simplex lymphadenit...
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Cystic hygroma

Cystic hygroma, also known as cystic or nuchal lymphangioma, refers to the congenital macrocystic lymphatic malformations that most commonly occur in the cervicofacial regions, particularly at the posterior cervical triangle in infants. Terminology While these lesions are commonly known as cys...
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Cystic mediastinal masses

The differential diagnosis for cystic masses of the mediastinum include: foregut duplication cysts bronchogenic cyst esophageal duplication cyst neuroenteric cyst pericardial cyst meningocele lymphangioma thymic cyst cystic teratoma of mediastinum cystic degeneration of an intrathoraci...
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Cystic fibrosis

Cystic fibrosis (CF), also called mucoviscidosis, is an autosomal recessive genetic disease that affects the exocrine function of the lungs, liver, pancreas, small bowel, sweat glands, and the male genital system 11. This is resulting in progressive disability and multisystem failure. This artic...
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Croup

Croup, also known as acute laryngotracheobronchitis, is due to viral infection of the upper airway by parainfluenza virus or respiratory syncytial virus (RSV). Although imaging findings are not required for the diagnosis, classic findings of narrowing of the subglottic airway and dilatation of ...
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Crazy paving

Crazy paving refers to the appearance of ground-glass opacities with superimposed interlobular septal thickening and intralobular septal thickening, seen on chest HRCT or standard CT chest. It is a non-specific finding that can be seen in a number of conditions.  Pathology Etiology Common cau...
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Coracoclavicular joint

The coracoclavicular joint is a normal variant of the pectoral girdle, where the conoid tubercle of the clavicle appears enlarged or elongated, with a flattened inferior surface where it approximates the coracoid process of the scapula to form an articulation.  Epidemiology More common in Asia...
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Constrictive pericarditis

Constrictive pericarditis (or perhaps better termed pericardial constriction) is a type of pericarditis which leads to diastolic dysfunction and potential symptoms of right heart failure.  Epidemiology No single demographic is affected as there are numerous causes of constrictive pericarditis....
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Congenital diaphragmatic hernia

Congenital diaphragmatic herniation (CDH) accounts for a small proportion of all diaphragmatic herniae. However, it is one of the most common non-cardiac fetal intrathoracic anomalies. Epidemiology Congenital diaphragmatic hernias are seen in 1 of every 2000-4000 live births. 84% are left-side...
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Congenital cardiovascular anomalies

Congenital cardiovascular anomalies are relatively common, with an incidence of up to 1% if small muscular ventricular septal defects (VSDs) are included. As a group, there is a much greater frequency in syndromic infants and in those that are stillborn.  Epidemiology In a large study in the U...
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Congenital lobar overinflation

Congenital lobar overinflation (CLO), previously called congenital lobar emphysema, is a congenital lung abnormality that results in progressive overinflation of one or more lobes of a neonate's lung.  On imaging, it classically presents on chest radiographs as a hyperlucent lung segment with o...
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Congenital pulmonary airway malformation

Congenital pulmonary airway malformations (CPAM) are multicystic masses of segmental lung tissue with abnormal bronchial proliferation. CPAMs are considered part of the spectrum of bronchopulmonary foregut malformations. Terminology Until recently they were described as congenital cystic adeno...
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Coal workers' pneumoconiosis

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...
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Chronic unilateral airspace opacification (differential)

Chronic unilateral airspace opacification is a subset of the differential diagnoses for airspace opacification. An exhaustive list of all possible causes of chronic unilateral airspace opacities is long, but a useful framework is as follows: neoplastic post obstructive lymphoma lymphocytic ...
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Chronic bilateral airspace opacification (differential)

Chronic bilateral airspace opacification is a subset of the differential diagnosis for airspace opacification. An exhaustive list of all possible causes of chronic bilateral airspace opacities is long, but a useful framework is as follows: inflammatory sarcoidosis granulomatosis with polyangi...
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Central bronchiectasis

Distribution of bronchiectasis can help in narrowing the differential diagnosis. Central bronchiectasis is typically seen in: allergic bronchopulmonary aspergillosis (ABPA) congenital tracheobronchomegaly (also known as Mounier Kuhn syndrome) cystic fibrosis Williams Campbell syndrome (rare)...
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Carney triad

Carney triad is a rare syndrome defined by the coexistence of three tumors: extra-adrenal paraganglioma initially, only functioning extra-adrenal paragangliomas were included, but subsequent work includes non-functioning extra-adrenal paragangliomas 1 gastric gastrointestinal stromal tumors (...
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Carney complex

Carney complex (not to be confused with the Carney triad) is a rare multiple endocrine neoplasia syndrome characterized by 1-4: cardiac myxoma often multiple seen in two-thirds of patients with Carney complex skin pigmentation (blue nevi): especially of the face, trunk, lips, and sclera   M...
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Caplan syndrome

Caplan syndrome, also known as rheumatoid pneumoconiosis, is the combination of seropositive rheumatoid arthritis and a characteristic pattern of fibrosis. Although first described in coal miners (coal workers' pneumoconiosis), it has subsequently been found in patients with a variety of pneumo...
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Pulmonary cavity (mnemonic)

A particularly helpful mnemonic for causes of pulmonary cavities is: CAVITY Mnemonic C: cancer  lung cancer: most frequently squamous cell carcinoma (SCC) cavitary pulmonary metastasis(es): most frequently SCC A: autoimmune; granulomas from  granulomatosis with polyangiitis rheumatoid ar...
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Bronchiectasis

Bronchiectasis (plural: bronchiectases) is defined as an irreversible abnormal dilatation of the bronchial tree. It has a variety of underlying causes, with a common etiology of chronic inflammation. High-resolution CT is the most accurate modality for diagnosis. Epidemiology As there are many...
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Lung cancer

Lung cancer (primary 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, with cigarette smoke being a key culprit.  This art...
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Bronchial atresia

Bronchial atresia is a developmental anomaly characterized by focal obliteration of the proximal segment of a bronchus associated with hyperinflation of the distal lung.  On imaging, it commonly presents as a proximal focal tubular-shaped opacity radiating from the hilum associated with a dista...
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Bovine arch

Bovine arch is the most common variant of the aortic arch and occurs when the brachiocephalic (innominate) artery shares a common origin with the left common carotid artery.  Epidemiology A bovine arch is present in ~15% (range 8-25%) of the population and is more common in individuals of Afri...
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Bochdalek hernia

Bochdalek hernias , also known as pleuroperitoneal hernias, (alternative plural: herniae) are the commonest type 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 cl...
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Bifid rib

A bifid or forked or bifurcated rib is a congenital skeletal abnormality of the rib cage with the cleaved sternal end into two. They are thought to occur in ~0.2% of the population and there may be a female as well as right-sided predilection 2. Epidemiology Associations Bifid ribs can be see...
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Bat wing opacities (lungs)

Bat wing opacities, also known as butterfly opacities, refer to a pattern of bilateral perihilar lung shadowing. It is classically described on a frontal chest radiograph but can also refer to appearances on chest CT 3,4. Differential diagnosis Bat wing pulmonary opacities can be caused by: p...
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Azygos vein

The azygos vein is a unilateral vessel that ascends in the thorax to the right of the vertebral column, carrying deoxygenated blood from the posterior chest and abdominal walls. It forms part of the azygos venous system. Terminology The spelling azygous when referring to the vein is incorrect,...
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Azygos lobe

An azygos lobe is a normal variant that develops when a laterally displaced azygos vein creates a deep pleural fissure into the apical segment of the right upper lobe during embryological development. It is not a true accessory lobe as it does not have its own bronchus or corresponding specific ...
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Bochdalek hernia features (mnemonic)

A helpful mnemonic for remembering the features of a Bochdalek hernia is: 5 Bs Mnemonic B: Bochdalek B: big B: back and lateral, usually on the left side B: baby B: bad (associated with pulmonary hypoplasia) To remember the side in which a Bochdalek hernia more commonly occurs (and to co...
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Pulmonary aspergillosis

Pulmonary aspergillosis is a collective term used to refer to a number of conditions caused by infection with a fungus of the Aspergillus species (usually Aspergillus fumigatus). There are a number of recognized pulmonary forms, the number depending on the author 1,3,4 . Each form has specific ...
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Aortic arch

The aortic arch represents the direct continuation of the ascending aorta and represents a key area for a review of normal variant anatomy and a wide range of pathological processes that range from congenital anomalies to traumatic injury. Summary origin: continuation of the ascending aorta at...
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Aortic dissection

Aortic dissection is the prototype and most common form of acute aortic syndromes and a type of arterial dissection. It occurs when blood enters the medial layer of the aortic wall through a tear or penetrating ulcer in the intima and tracks longitudinally along with the media, forming a second ...
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Aortic intramural hematoma

Aortic intramural hematoma is an atypical form of aortic dissection due to a contained hemorrhage into the aortic wall usually from the vasa vasorum without an intimal tear. It forms part of the acute aortic syndrome spectrum along with penetrating atherosclerotic ulcer and classical aortic diss...
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Anterior mediastinal mass

Anterior mediastinal masses can be caused by neoplastic and non-neoplastic pathology. These masses arise in the anterior mediastinum, that portion of the mediastinum anterior to the pericardium and below the level of the clavicles.  Epidemiology The prevalence of anterior mediastinal masses on...
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Spinnaker sign (mediastinum)

The spinnaker sign (also known as the angel wing sign) is a sign of pneumomediastinum seen on neonatal chest radiographs. It refers to the thymus being outlined by air with each lobe displaced laterally and appearing like spinnaker sails. This is distinct from the sail sign appearance of the nor...
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Air crescent sign (lung)

An air crescent sign describes the crescent of air that can be seen in invasive aspergillosis, semi-invasive aspergillosis, or other processes that cause pulmonary necrosis. It usually heralds recovery and is the result of increased granulocyte activity. Terminology It should not be confused w...
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Air space opacities

The differential for air space opacities is extensive, and needs to be interpreted in context of chronicity (previous imaging) and clinical context. It is therefore useful to divide airspace opacities as follows: acute airspace opacities with lymph node enlargement acute airspace opacities: un...
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Allergic bronchopulmonary aspergillosis

Allergic bronchopulmonary aspergillosis (ABPA) is at the mild end of the spectrum of disease caused by pulmonary aspergillosis and can be classified as an eosinophilic lung disease 2-4.  Epidemiology This entity is most commonly encountered in patients with longstanding asthma, and only occasi...
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Idiopathic interstitial pneumonia (mnemonic)

Idiopathic interstitial pneumonias (IIPs) are diffuse interstitial lung diseases of unknown cause. A useful mnemonic for the American Thoracic Society-European Respiratory Society (ATS-ERS) classification of IIPs is: All Idiopathic Chronic Lung Disease aRe Nonspecifically Patterned The mnemoni...
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Air bronchogram

Air bronchogram refers to the phenomenon of air-filled bronchi (dark) being made visible by the opacification of surrounding alveoli (grey/white). It is almost always caused by a pathologic airspace/alveolar process, in which something other than air fills the alveoli. Air bronchograms will not ...
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Acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) is a form of acute lung injury 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. This is a disti...
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Acute airspace opacification with lymphadenopathy (differential)

Acute airspace opacification with lymphadenopathy is a subset of the differential diagnosis for generalized airspace opacification and includes: post-obstructive causes (usually chronic, but 'new' changes can occur) primary lung cancer pulmonary metastases lymphoma/leukemia infection prim...
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Acute unilateral airspace opacification (differential)

Acute unilateral airspace opacification is a subset of the differential diagnosis for airspace opacification.   Differential diagnosis The exhaustive list of all possible causes would be huge, but a useful framework includes: pus, i.e. pulmonary infection bacterial pneumonia fungal pneumoni...
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Acute bilateral airspace opacification (differential)

Acute bilateral airspace opacification is a subset of the larger differential diagnosis for airspace opacification. An exhaustive list of all possible causes of acute bilateral airspace opacities is long, but a useful way to consider the huge list is via the material within the airways: infecti...
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Acquired aortic conditions

There are many acquired aortic conditions. These include aortic dissection aortic rupture / transection ascending aortic aneurysm aortitis thoracic aortic injury abdominal aortic aneurysm inflammatory abdominal aortic aneurysm
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Achalasia

Achalasia (primary achalasia) is a failure of organized esophageal peristalsis causing impaired relaxation of the lower esophageal sphincter, and resulting in food stasis and often marked dilatation of the esophagus.  Obstruction of the distal esophagus from other non-functional etiologies, not...
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Aberrant right subclavian artery

Aberrant right subclavian arteries (ARSA), also known as arteria lusoria, are among the commonest aortic arch anomalies.  Epidemiology The estimated incidence is 0.5-2% 1. Associations as can be expected from the embryological development of the artery, the right recurrent laryngeal nerve...

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