Double aortic arches are the most common symptomatic type of the aortic arch variant. It may account for up to 50-60% of vascular rings.
Double aortic arch is mostly diagnosed in childhood due to symptoms related to esophageal and/or tracheal obstruction. Respiratory symp...
The double artery sign refers to the appearance of a non-dilated mucus-filled bronchus adjacent to a pulmonary artery producing the appearance of a "double artery" on CT chest. This sign is considered a feature of a central endobronchial lesion such as a mucus plug or neoplasm.
The double density sign can refer to several radiological signs:
double density sign (left atrial enlargement)
double density sign (berry aneurysm)
double density sign (osteoid osteoma)
The double diaphragm sign is one of several radiological signs seen with a pneumothorax in a supine patient.
Supine films are commonly performed in unwell patients, particularly in the ICU. In a supine patient with a pneumothorax, air may outline the anterior portions of the hemidiaphragm and c...
The double lumen cannula enables veno-venous extracorporeal membrane oxygenation (VV ECMO) to patients with severe respiratory failure. It is often used as a bridge to lung transplant.
The cannulation is usually performed via the right jugular vein. This position allows the patients to stay aw...
A double lumen endotracheal tube is a type of intubation device where there are two lumens.
It is designed to isolate the lungs from one another anatomically and/or physiologically:
anatomical lung separation: isolation of diseased lung from contaminating the non-diseased lung
The double lung point sign refers to a sharp boundary found between relatively aerated superior lung fields and coalescent "B‐lines" (representing interstitial edema) in the basal lung fields, with a reported sensitivity of 45.6%-76.7% and a specificity of 94.8%-100% 1,3 in diagnosing transient ...
Drowning is one of the most prevalent causes of non-natural death. According to the World Health Organization (WHO), an estimated 360,000 annual deaths occur due to drowning.
This article concerns itself with postmortem appearances in fatalities from drowning. For non-fatal pulmonary changes pl...
Drug and toxin induced pulmonary hypertension is one of the causes of pulmonary arterial hypertension. It falls under group 1.3 under the Dana point classification system of pulmonary hypertension.
A wide range of difference drugs have been associated with developing pulmonary hyper...
Drug-induced lung disease can result from a number of agents and may have a myriad of presentations, ranging from an adult respiratory distress syndrome type picture to established pulmonary fibrosis.
Due to this, it can be extremely difficult to pinpoint the offending agent on imaging appearan...
The drug rash with eosinophilia and systemic symptoms (DRESS) syndrome typically manifests as a skin rash, fever, lymph nodal enlargement with variable internal organ involvement, and represents a hypersensitivity reaction to medication.
Clinical presentation can be vari...
The ductus arteriosum (DA) (or arteriosus) is the thick short conduit for blood to bypass the non-ventilated lungs in the fetus. It is located between and connects the proximal left pulmonary artery and the undersurface of the aortic arch distal to the origin of the last branch of the arch, at t...
Aortic ductus diverticulum is a developmental outpouching of the thoracic aorta which may be mistaken for an acute aortic injury.
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...
Dynamic tracheal collapse refers to collapse of the trachea during expiration. It is perhaps best assessed on CT in the end expiratory phase. An inspiratory series is also useful for comparative purposes. The term excessive dynamic airway collapse (EDAC) refers to abnormal and exaggerated bulgin...
Dysphagia refers to subjective awareness of difficulty or obstruction during swallowing. It is a relatively common and increasingly prevalent clinical problem. Odynophagia is the term for painful swallowing.
Fluoroscopy is the mainstay of imaging assessment but manometry can help evaluate the e...
Dysphagia lusoria is an impairment of swallowing due to compression from an aberrant right subclavian artery (arteria lusoria).
Most patients with aberrant right subclavian arteries do not have symptoms. Some present with mild dysphagia, while a small minority have a seve...
Echogenic fetal lung lesions on antenatal ultrasound can be detected in a number of situations. They include:
Airway obstructions: lung are often enlarged and echogenic bilaterally
congenital high airways obstruction syndrome (CHAOS)
congenital tracheal stenosis
An ectopic meningioma (or primary ectopic meningioma) refers to rare situations where a meningioma arises outside the dura.
These can occur at various sites but usually occur in the head and neck region.
Reported sites include
ear and temporal bone
Epidermal growth factor receptor (EGFR) mutation can be expressed in a large proportion of non-small cell lung carcinomas (NSCLC). However, certain subtypes such as invasive mucinous adenocarcinoma of the lung can have very low expression.
The presence of this mutation can be assessed on biopsy...
The egg and banana sign is a sign for the diagnosis of pulmonary arterial hypertension (PAH) on axial CT/MR images. It refers to the appearance of the aortic arch (banana) next to a distorted main pulmonary artery (egg). Like an egg, the main pulmonary artery is preferentially dilated in the PA ...
Helpful mnemonics to remember the major causes of eggshell calcification of the nodes in the thorax and mediastinum are:
A Silly Cool Sergeant Likes His Tubercular Blast
Sara Samy Likes Her Smart ABC Mnemonic
A Silly Cool Sergeant Likes His Tubercular Blast
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).
In 1967 Jacobsen and Felson published criteria to help "avoid over-reading of t...
Ehlers-Danlos syndrome comprises a heterogeneous group of collagen disorders (hereditary connective tissue disease).
There is a recognized male predominance.
Clinically manifests by skin hyperelasticity and fragility, joint hypermobility and blood vessel fr...
The Eisenmenger syndrome is a complication of an uncorrected high-flow, high-pressure congenital heart anomaly leading to chronic pulmonary arterial hypertension and shunt reversal.
In general, the shunts that lead to Eisenmenger syndrome share high pressure and high flow 3. As su...
Elastofibroma dorsi is a benign soft-tissue tumor with a characteristic location and imaging appearance.
It is more frequently seen in older women, with a reported female predilection of 5-13:1. The estimated mean age at diagnosis is around 65-70 years.
An elephant trunk repair is a type of open repair procedure devised to address combined aneurysms, it is often a two staged procedure wherein the arch repair is facilitated by sternotomy and a second staged procedure is performed via left thoracotomy for the descending or thoracoabdominal aorta...
Elevated diaphragm refers to the symmetrical elevation of both domes of the diaphragm.
There is some overlap with causes of an elevated hemidiaphragm.
poor inspiratory effort
An elevated hemidiaphragm may result from direct and indirect causes which include:
above the diaphragm 1
decreased lung volume
prior lobectomy or pneumonectomy
phrenic nerve palsy
contralateral stroke: ...
The atypical 11th rib is one of two floating ribs.
The 11th rib has a single facet on its head for articulation with the T11 vertebra. It has a short neck and no tubercle. The angle is slight. Its costal groove is shallow. The internal surface of this rib faces slightl...
Eloesser flap is a single-stage procedure for the treatment of severe pleural empyema, and involves a U-shaped incision and the resection of a number of subjacent posterolateral ribs. The U-shaped flap is then folded into the pleural space creating a permanent communication.
Unlike the Clagett...
The empty cyst sign is described in hydatid disease. After rupture of the cyst and complete evacuation of its content, the pericyst becomes empty as an air-filled cyst on x-ray or CT 1,2. With superadded infection, an air-fluid level may appear within the cyst, mimicking a lung abscess 2.
Empyemas are purulent inflammatory collections within a body cavity. Contrast this with abscesses, which arise within parenchymal tissue, rather than occupying a pre-existing anatomical space.
Colloquially, the standalone term empyema is used to refer to thoracic empyemas but there...
Empyema necessitans (also sometimes spelled as empyema necessitasis) refers to extension of a pleural infection out of the thorax and into the neighboring chest wall and surrounding soft tissues, e.g. extension of an empyema outwith the pleural cavity.
It may either occur due the vir...
An empyema can resemble a pleural effusion and can mimic a peripheral pulmonary abscess. Features that help distinguish a pleural effusion from an empyema include:
Shape and location
form an obtuse angle with the chest wall
unilateral or markedly asymmetric whereas pleural ...
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.
An endobronchial hemangioma is a rare benign lesion which can occur in the tracheobronchial tree.
Patients may present with hemoptysis and cough.
Maybe be occult on chest radiographs. On CT usually seen as circumscribed lesions protruding into the ...
Endobronchial intubation is the not infrequent finding of the endotracheal tube located in a bronchus and is a trivial diagnosis to make in most instances provided an adequately penetrated chest radiograph is obtained. The incidence of endobronchial intubation is greatest following emergency int...
Endobronchial lipomas are rare benign lesions arising from the adipose tissue in the submucosal layer of the bronchial wall.
Rare benign tumor with a possible male predilection.
Presenting symptoms include a cough, sputum, hemoptysis and dyspnea; however, ...
Endobronchial lipomatous hamartoma is a type of hamartoma, found in the conducting airways, that can be considered as a variant of endobronchial hamartoma, with a predominant lipomatous component. In general endobronchial hamartomas are thought to contain more fat than parenchymal pulmonary ham...
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
Primary neoplasms which may result in endobronchial metastases may be memorized by utilizing the following mnemonic:
Kiss My RBC 1
K: Kaposi sarcoma
R: renal cell carcinoma
B: breast cancer
C: colorectal carcinoma, cervical carcinoma, carcinoid
Endobronchial valves are one-way valves that restrict airflow to a particular lung segment. The devices are inserted via bronchoscopy. They permit the drainage of airway secretions during the expiratory phase but restrict incoming airflow during inspiration 1.
They were originally designed as a...
Endogenous lipoid pneumonia, also known as idiopathic lipoid pneumonia, is of the of the two types of lipoid pneumonias. It is also sometimes known as “cholesterol pneumonia” or “golden pneumonia”
Please refer to the main article for a broad discussion, including clinical presentation, radiogra...
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)
anterior mediastinal mass
prominent epicardial fat pad
AP projection (from supine radiographs taken ...
Eosinophilic granulomatosis with polyangiitis (EGPA), previously known as the Churg-Strauss syndrome (CSS), refers to a small to medium vessel necrotizing pulmonary vasculitis. It is also classified under the spectrum of eosinophilic lung disease and as a type of pulmonary angiitis and granuloma...
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: ...
The eparterial bronchus is a synonymous term for the right superior lobar bronchus. Its name is derived from the bronchus being the only one originating superior to the level of the pulmonary artery. Conversely, all other bronchi can be referred to by their anatomical relationship to the pulmona...
Episternal (or suprasternal) ossicles are accessory bones and a normal variant of the sternum. They result from supernumerary ossification centers and are seen in ~4% (range 1-7%) of the population.
Episternal ossicles are usually located posterior or superior to the superior bor...
Epithelial-myoepithelial carcinoma of lung is a very rare type of lung carcinomas of the salivary gland type.
Diagnosis is based on the identification of myoepithelial cells, with spindle cells, clear cells, or plasmacytoid differentiation or a mixture of phenotypes, along with a var...
Erdheim-Chester disease 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.
Erdheim-Chester disease is a rare, non-inherited disease of middle age ...
Pulmonary manifestations of Erdheim-Chester disease are uncommon.
The lungs are affected in ~25% (range 20-35%) of cases 5.
Described findings include 1
symmetric reticular interstitial opacities
smooth interlobular septal thickening and fiss...
This is a basic article for medical students and other non-radiologists
Erect chest x-rays are standard positioning but are also a specific examination performed for the assessment of subdiaphragmatic free gas (pneumoperitoneum).
This is a summary article; we do not have a m...
Esophageal and esophagogastric junction adenocarcinoma staging refers to TNM staging of adenocarcinoma originating in the esophagus or esophagogastric junction (including tumors whose center is within the proximal 2 cm of the gastric cardia). Related histologies included in this system are high ...
Esophageal and esophagogastric junction squamous cell carcinoma staging refers to TNM staging of squamous cell carcinoma originating in the esophagus or esophagogastric junction (including tumors whose center is within the proximal 2 cm of the gastric cardia). Related histologies included in thi...
Endotracheal tubes (ETT) are wide-bore plastic tubes that are inserted into the trachea to allow artificial ventilation. Tubes come in a variety of sizes and have a balloon at the tip to ensure that gastric contents are not aspirated into the lungs. Adult tubes are usually approximately 1 cm in ...
Ewing sarcoma family of tumors (ESFT), also referred as Ewing sarcomas of the chest wall, are malignant tumors affecting children and young adults, originating either from the osseous structures or the soft tissues of the chest wall.
On imaging, they are usually characterized as a large extrap...
Excessive dynamic airway collapse (EDAC) refers to a dynamic form of central airway obstruction characterized by a decrease of ≥50% (more recent publications suggest >70%) in the cross-sectional area of the tracheobronchial lumen. Diagnosis is usually confirmed by dynamic cross sectional imaging...
Exogenous lipoid pneumonia is a form of lipoid pneumonia. Please refer to the main article for a broader discussion.
In terms of the onset of the presentation, it can be divided into two different forms:
acute exogenous lipoid pneumonia
uncommon and typically is caused by an episode of aspir...
The external (or outermost) intercostal muscles are important muscles of respiration. They number eleven on each side and are located in the intercostal space, expanding the transverse dimension of the thoracic cavity during inspiration.
The external intercostal muscles are the o...
Extracorporeal membrane oxygenation (ECMO) is used as a modified pulmonary or cardiopulmonary bypass technique in those with severe cardiac and/or respiratory failure refractory to conventional ventilatory support and medical intervention 1,3. There are two access paths for extracorporeal life s...
Extramedullary hematopoiesis is a response to the failure of erythropoiesis in the bone marrow.
This article aims to a general approach on the condition, for a dedicated discussion for a particularly involved organ, please refer to the specific articles on:
extramedullary hematopoiesis in the...
The extrapleural air sign is one of the many signs of pneumomediastinum, and was first described by Lillard and Allen in 1965. It is defined as the presence of gas between the parietal pleura and the diaphragm. On a lateral projection, the gas forms a radiolucent pocket of gas posterior to the d...
Extrapleural fat is benign condition and refers to relative diffuse deposition of fat outside the parietal pleura. It can occur in various locations but typically occurs along the chest wall. It is a component of the loose connective tissue of the endothoracic fascia and is most abundant along t...
The extrapleural fat sign is an imaging feature which can be seen on CT under certain circumstances. It occurs from the inward displacement of extrapleural fat by an extrapleural fluid collection, extrapleural hematoma or extrapleural mass. The presence of the extrapleural fat sign is indicative...
Extrapleural hematomas are uncommon and usually seen in the context of rib fracture, subclavian venous catheter traumatic insertion, and blunt chest injury.
Extrapleural hematomas result from the accumulation of blood in the extrapleural space where the overlying extrapleural fat is ...
The extrapleural sign, described by Ben Felson in 1973 1, refers to the appearance of a pulmonary opacity with oblique margins that taper slowly to the chest wall when the lesion is viewed tangentially to the x-ray beam. This appearance suggests that the lesion is pleural or extrapleural in natu...
An exudate is a collection that has a relatively high specific gravity and protein concentration. They occur as the result of an inflammatory process that either increases the permeability of the surrounding membrane or disrupts the ability of resorption of fluid. They may be secondary to:
F-18 fluorodeoxyglucose (FDG) embolism is a condition which results in uniform focal intense FDG-avid pulmonary focus without any underlying structural CT correlate with an unremarkable follow-up PET-CT scan 1. It is thought to occur as a result of clumping of FDG with blood when the blood is wi...
The fallen lung sign (also known as CT fallen lung sign) describes the appearance of collapsed lung away from the mediastinum encountered with tracheobronchial injury (in particular those >2 cm away from the carina). It is helpful to look for this rare but specific sign, in cases of unexplained ...
Familial Mediterranean fever (FMF) (also known as recurrent polyserositis) is a genetic autoimmune condition that is notable for its spontaneous self-limiting acute episodes of fever and serositis, especially peritonitis and synovitis.
Familial Mediterranean fever tends to be ethn...
The differential of a fat containing solitary pulmonary nodule is very narrow.
In a well circumscribed smooth or lobulated mass (especially if it has been largely stable in size over time) presence of fat is essentially pathognomonic of a pulmonary hamartoma, and usually not further assessment ...
There is a long list of fat containing thoracic lesions. They may involve the mediastinum, lung, pleura or chest wall.
Differential diagnosis includes:
intrapulmonary: fat containing pulmonary lesions
Fat embolism syndrome (FES) is a rare clinical condition caused by circulating fat emboli leading to a multisystemic dysfunction. The classical clinical triad consists of:
It occurs in ~2.5% (range 0.5-4%) of tho...
Fat stranding is a common sign seen on CT wherever fat can be found. It is most commonly seen in abdomen/pelvis, but can also be seen in retroperitoneum, thorax and subcutaneous tissues. It can be helpful in localizing both acute and chronic pathology.
Fat stranding c...
Fatty mediastinal masses are relatively uncommon, and the differential diagnosis is brief, including 1-4:
benign mature teratoma
extravasation of lipid-rich hyperalimentation fluid 3
fibrofatty replacement of the central portion of mediastinal l...
Feeding vessel sign consists of a distinct vessel leading directly to a nodule or a mass. This sign indicates either that the lesion has a haematogenous origin or that the disease process occurs near small pulmonary vessels.
A number of vessel-related non-neoplastic disorders of the lung produ...
Feingold syndrome is characterized by the combination of:
alimentary tract atresias especially esophageal atresia
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.
The appearance is almost always associated with active gastro-esophageal reflux 2,3 and is thought to be due to contract...
Felix Fleischner was a renowned chest radiologist who had two distinguished careers, first in Vienna, before the Second World War, and secondly in Boston, Massachusetts, after fleeing Europe in 1938. The Fleischner Society was named in dedication to him.
Felix George Fleischner was ...
A ferruginous body is a histological finding in interstitial lung disease that is a result inorganic dust inhalation.
Macrophage ingestion of the inorganic fiber results in a fibrotic reaction with encasement of the fiber in iron-rich material that is derived from proteins such as ferritin and ...
Fetal adenocarcinoma of the lung (FLAC) is a rare form of adenocarcinoma of lung (falls under invasive category).
Some reports suggest its occurence at ~0.1%-0.5% of all pulmonary neoplasms 1. Despite its "fetal" tissue morphology it typically presents in middle aged to elderly p...
The FEV1/FVC ratio (FEV1%), also known as the Tiffeneau-Pinelli index, is a spirometric parameter and refers to a calculated ratio which represents the proportion of a patients vital capacity that they are able to expire in the first second of forced expiration.
FEV1% is used in the diagnosis a...
Fibrinous pericarditis results from fine granular roughening of the pericardium.
Pericardial friction rub may be heard.
acute rheumatic fever
myocardial infarction: Dressler syndrome
chronic renal fail...
Fibrobullous disease is an observational finding where there are bullous spaces interspersed by areas of scarring (fibrosis). In general, there may be an apical predilection. This has been described in association with conditions such as:
ankylosing spondylitis 1
rheumatoid arthritis 2
Fibrosarcoma of the chest wall refers to a malignant tumor arising from the chest wall.
It typically presents in adults, although the age range of presentation is wide. It rarely occurs as a congenital form in infants and children 2.
In the thorax, fibrosarcomas usuall...
Fibrosing mediastinitis is a rare non-malignant acellular collagen and fibrous tissue proliferative condition occurring within the mediastinum. On imaging, the condition can sometimes mimic malignancy.
Although it can potentially present at any age, it typically presents in young ...
Fibrosing organizing pneumonia is a terms usually given in a situation to cases with previous organizing pneumonia which progresses with a fibrotic component. Many of these cases tend to be those of secondary organizing pneumonia.
Fibrothorax is defined as fibrosis within the pleural space and is sometimes referred to as pleural peel. It occurs secondary to the inflammatory response to one of the following events:
tuberculosis / tuberculous pleuritis / tuberculous empyema: mainly as a late sequela 3
The term fibrotic idiopathic interstitial pneumonia (FIIP) refers to a morphological subset of idiopathic interstitial pneumonia where there is greater than 5% of honeycombing present on HRCT 1.
fibrotic non specific interstitial pneumonitis
Fibrotic non-specific interstitial pneumonitis is a histological subtype of non-specific interstitial pneumonitis (NSIP). It is considered the more common form 1. This pattern manifests as chronic interstitial inflammation obscured by interstitial fibrosis (with dense collagen), a temporal homog...
The figure 3 sign is seen in aortic coarctation and is formed by prestenotic dilatation of the aortic arch and left subclavian artery, indentation at the coarctation site (also known as the "tuck"), and post-stenotic dilatation of the descending aorta.
On barium studies of the esophagus in pati...
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.
Finger clubbing presen...
The finger in glove sign can be seen on either a chest radiograph or CT chest and refers to the characteristic sign of a bronchocoele. The same appearance has also been referred to as:
rabbit ear appearance
mickey mouse appearance