Diverticula are out-pouchings of a hollow viscus and can be either true or false.
contains all layers of the wall of the parent organ (typically mucosa, muscular layer and serosa)
e.g. Meckel diverticulum
does not contain all layers (typically mu...
A "dot in box" appearance is a pattern that has been described with pulmonary lymphangitis carcinomatosis. The interlobular septal thickening from lympangitis forms polygonal arcades accounting for the box while the prominence of the centrilobular bronchovascular bundle is thought to represent ...
Double aortic arch is 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 of symptoms related to oesophageal and/or tracheal obstruction. Respiratory sym...
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 right jugular vein. This position allows the patients to stay awake ...
A double lumen endotracheal tube is a type of ETT where there are two lumens.
It is designed to isolate the lungs from one another anatomically and/or physiologically:
anatomical lung separation: isolatation of diseased lung from contaminating the non-diseased lung
Drowning is one of the most prevalent modalities of non-natural death. According to the 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 please refer to near-drowni...
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 can have a myriad of presentations, ranging from 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 appearances ...
Drug rash with eosinophilia and systemic symptoms (DRESS) is a syndrome reflects a marked hypersensitivity reaction to drugs / medications. It is characterised by skin rash, fever, lymph node enlargement, and internal organ involvement. In terms of internal organ involvement, it most commonly in...
The ductus arteriosum (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 the ao...
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...
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.
Fluoroscopy is the mainstay of imaging assessment but manometry can help evaluate the esophageal motor pattern and lower esophageal sp...
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
Eggshell calcification refers to fine calcification seen at the periphery of a mass and usually relates to 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 the incide...
A helpful mnemonic for major causes of eggshell calcification in the thorax and mediastinum is:
A Silly Cool Sergeant Likes His Tubercular Blast
C: coal workers' pneumoconiosis (CWP)
L: lymphoma: (postirradiation Hodgkin disease)
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...
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 are high pressure and high flow 3. As su...
Elastofibroma dorsi is a benign soft-tissue tumour 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 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
Elevated hemidiaphragms can result from many causes:
above the diaphragm 1
decreased lung volume
phrenic nerve palsy
contralateral stroke: usually middle cerebral artery distribut...
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...
Empyemas are purulent inflammatory collections within a body cavity. They are similar to abscesses, which arise within parenchymal tissue rather than occupying a pre-existing anatomical space.
Colloquially, the term empyema is used to refer to thoracic empyemas but there are variou...
Empyema necessitans (also sometimes spelt as empyema necessitasis) refers to extension of a pleural infection out of the thorax and into the neighbouring chest wall and surrounding soft tissues, e.g. extension of an empyema outwith the pleural cavity.
It may either occur due the viru...
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 empyema can resemble a pleural effusion and can mimic a peripheral pulmonary abscess, although a number of features usually enable distinction between the two (see empyema vs. lung abscess). Features that help distinguish a pleural effusion from an empyema include:
Shape and location
Endobronchial intubation is not infrequent 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 intubation.
The main issue with intub...
Endobronchial metastases (EBMs) are an uncommon form of intrathoracic metastases. They are much less common than intrapulmonary metastases.
The clinical presentation can vary and include
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
Kiss: Kaposi sarcoma
R: renal cell carcinoma
B: breast cancer
C: colorectal carcinoma, cervical carcinoma, carcinoid
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), is a small to medium vessel necrotising pulmonary vasculitis. It is also classified under the spectrum of eosinophilic lung disease and as a type of pulmonary angiitis and granulomatosis.
Eosinophilic lung diseases are heterogenous group of disorders that are characterised by excess infiltration of the eosinophils within the lung interstitium and alveoli and are broadly divided into three main groups 1:
idiopathic: unknown causes
secondary: known causes
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...
Epicardial (pericardial) fat pads are normal structures that lie in the cardiophrenic, more so on the right. Unsurprisingly, they are more prominent in obese patients.
They can be affected by fat necrosis (see: epipericardial fat necrosis).
Epipericardial fat necrosis is a rare self-limiting cause of an acute chest pain in an otherwise healthy individuals. It occurs within the mediastinum outside the pericardium.
The patient presents with an acute chest pain that may mimic other cardiopulmonary causes. It is...
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 (ECD) is a rare non-Langerhans cell, non-familial multisystemic granulomatosis, 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 midd...
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...
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 more in-depth reference article.
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 tumours (ESFT), also referred as Ewing sarcomas of the chest wall, are malignant tumours affecting children and young adults, originating either from the osseous structures or the soft tissues of the chest wall.
On imaging, they are usually characterised as a large extr...
Exogenous lipoid pneumonia is a form of lipoid pneumonia.
In terms of onset of presentation, it can divided into two different forms
acute exogenous lipoid pneumonia
uncommon and typically is caused by an episode of aspiration of a large quantity of a petroleum-based product.
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.
Ideally, an expiratory HRCT scan should be performed in all obstructive airway diseases...
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 haematopoiesis is a response to failure of erythropoiesis in the bone marrow.
chronic myelogenous leukaemia
myelofibrosis with myeloid metaplasia
sickle cell disease
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 the air between the parietal pleura and the diaphragm. On a lateral projection the air forms a radiolucent pocket of air posterior to the d...
Extrapleural fat is benign condition and refers to relaitve 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 an extrapleural fat stripe by an extrapleural fluid collection, extrapleural haematoma or extra pleural mass. The presence of the extrapleural fat sign i...
Extrapleural haematoma (EPH) is a rare situation, which usually occurs due to rib fracture or blunt chest injury.
EPH results from accumulation of blood in the extrapleural space where the overlying extrapleural fat is displaced centrally.
common: injury to intercostal ar...
The extrapleural sign, described by 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 extrapleural in nature, as opposed ...
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:
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...
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 th...
Fat stranding is a common sign on CT seen anywhere fat can be found but is most commonly seen in the abdomen/pelvis, but also in the retroperitoneum, thorax and subcutaneous tissues. It can be helpful in localising both acute and chronic pathology.
Fat stranding can a...
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 hematogenous origin or that the disease process occurs near small pulmonary vessels.
A number of vessel-related non-neoplastic disorders of the lung produc...
Feingold syndrome is characterised by the combination of:
alimentary tract atresias especially oesophageal atresia
Feline oesophagus also known as oesophageal shiver, refers to the transient transverse bands seen in the mid and lower oesophagus on a double contrast barium swallow.
The appearance is almost always associated with active gastro-oesophageal reflux 2,3 and is thought to be due to contraction of ...
A ferruginous body is a histological finding in interstitial lung disease that is a result inorganic dust inhalation.
Macrophage ingestion of the inorganic fibre results in a fibrotic reaction with encasement of the fibre in iron-rich material that is derived from proteins such as ferritin and ...
The FEV1/FVC ratio (or 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.
Is used in the diagnosis and assessment of obstructive ...
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...
Fibrosarcoma of the chest wall refers to a malignant tumour 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 usual...
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 ...
Fibrothorax is defined as fibrosis within the pleural space, and occurs secondary to the inflammatory response to one of the following events:
tuberculosis / tuberculous pleuritis - particularly as a late sequelae 3
asbestos related pleural disease
The term fibrotic idiopathic intersitial pneumonia (FIIP) is refers to a morphological subset of idiopathic interstitial pneumonia where there is great then 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 poststenotic dilatation of the descending aorta.
On barium studies of the oesophagus in pati...
The finger in glove sign can be seen on either 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
toothpaste shaped opacities
The first rib is the most superior of the twelve ribs. It is an atypical rib and is an important anatomical landmark and is one of the borders of the superior thoracic aperture.
Compared to a typical rib, the first rib is short and thick and it has a single articular f...
Flail chest or flail thoracic segment occurs when three or more contiguous ribs are fractured in two or more places. Clinically, a segment of only one or two ribs can act as a flail segment, hence there is some controversy between the clinical and radiological definitions.
The flat waist sign refers to flattening of the contours of the aortic arch and adjacent pulmonary trunk. It is seen in severe left lower lobe collapse and is caused by leftward displacement and rotation of the heart.
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...
Fleischner sign is a prominent central artery that can be caused either by pulmonary hypertension that develops or by distension of the vessel by a large pulmonary embolus. It can be seen on chest radiographs and CT pulmonary angiography.
It is seen most commonly in the setting of massive pulmo...
The Fleischner society pulmonary nodule recommendations are for the follow-up and management of pulmonary nodules smaller than 8 mm detected incidentally in patients >35 years on non-screening CT. The initial guidelines for the management of solid nodules were released in 2005 1, and guidelines...
The fluid bronchogram sign can be seen on chest CT or ultrasound as the presence of fluid attenuation material within respiratory bronchioles with surrounding collapsed or consolidated lung.
The presence of this sign suggests endobronchial obstruction as a precipitating cause for consolidation/...
The fluid colour sign is a diagnostic sign to differentiate a pleural effusion from pleural thickening by means of colour Doppler ultrasound. In the case of pleural effusion a colour signal is seen in the pleural fluid during respiratory and cardiac movement, whereas this colour signal is not se...
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.
Focal interstitial pulmonary fibrosis refers to a manifestation of pulmonary fibrosis where changes are confined and localised to a small region of the lung, they can arise of range of aetiologies with one rather common example being osteophyte induced adjacent pulmonary atelectasis and fibrosis...
Focal lymphoid hyperplasia of the lung refers to an abnormal accumulation of non-malignant lymphocytic aggregates within the lung.
It iwas previously known as pulmonary pseudolymphoma.
Clinical features can vary from being asymptomatic to various symptoms s...
Causes of focal pulmonary opacities on a chest radiograph can be remembered using the rather crude mnemonic:
F: 'fection (pulmonary infection)
F: 'farction (pulmonary infarction)
F: fluid (pulmonary oedema)
F: f***ed (lung cancer)
Follicular bronchiolitis (FB) is a nonneoplastic primary polyclonal B cell hyperplasia of the bronchus-associated lymphoid tissue (BALT) due to chronic exposure to antigens in those with underlying collagen vascular or immune deficiency diseases which usually manifested as small centrilobular gr...
The foramina of Morgagni, also known as the sternocostal triangles, are small defects in the posterior aspect of the anterior thoracic wall between the sternal and costal attachments of the diaphragm. The internal thoracic vessels descend through these foramina to become the superior epigastric ...
Foregut duplication cysts are type congenital duplication cyst. They are sometimes classified under broncho-pulmonary foregut malformations.
Entities that fall under forgut duplication cysts include:
other enteric cysts
oesophageal duplication cysts
Funnel trachea is a colloquialism for congenital long-segment intrathoracic tracheal stenosis.
The diameter of the trachea immediately below the cricoid is normal, and becomes becomes progressively more stenotic caudally. The posterior, membranous portion of the trachea may be partially or com...