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.

179 results found
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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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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 trapping

Air trapping in chest imaging refers to retention of excess gas (“air”) in all or part of the lung, especially during expiration, either as a result of complete or partial airway obstruction or as a result of local abnormalities in pulmonary compliance. It may also sometimes be observed in norma...
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A-line (ultrasound)

An a-line is an ultrasonographic artifact appreciated during the insonation of an aerated lung. 1 The term may be applied to the horizontal, echogenic long path reverberation artifacts that occur beneath the pleural line at multiples of the distance between the ultrasound probe and the visceral...
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Anterior bronchus sign

The anterior bronchus sign refers to the appearance of the anterior segmental bronchus of the upper lobes as seen on a frontal chest radiograph. Gross anatomy The anterior segment bronchus of the upper lobes courses anteriorly and laterally. When the orientation is predominantly anteriorly the...
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Antler sign (lung)

The antler sign is an uncommon sign of lung torsion on CT where branches from the main pulmonary artery all arise from a single side, indicating twisting of the lobe or lung. In the normal lung, the main pulmonary arteries are straight and lobar and segmental branches arise from it on both side...
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Atoll sign (disambiguation)

The atoll sign in radiology can refer to: reverse halo sign: atoll sign in thoracic CT atoll sign in liver MRI: suggestive of an inflammatory hepatic adenoma
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Ball of wool sign (hydatid cyst)

The ball of wool sign, also referred to as the yarn sign or congealed water lily sign, is an ultrasound appearance, representing degeneration of hydatid cysts (WHO class CE 4). The inner side of the cyst detaches from the cyst wall and folds on itself, causing a change from anechoic (fluid) to a...
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Bat wing opacities (lungs)

Bat wing or butterfly pulmonary opacities refer to a pattern of bilateral perihilar 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: pulmonary edema (es...
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Big rib sign

The big rib sign is a sign to differentiate right and left ribs on lateral chest radiographs.  It exploits a technique of magnification differences on lateral projections between right and left ribs. For example, on right lateral projections the left ribs appear larger than right ribs.  This s...
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B-line (ultrasound)

The B-line is an artifact relevant in lung ultrasonography. As originally described, it has seven defining features 1: a hydroaeric comet-tail artifact arising from the pleural line hyperechoic well-defined extending indefinitely erasing A-lines  moving in concert with lung sliding, if lung...
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Box-shaped heart

A box-shaped heart is a radiographic description given to the cardiac silhouette in some cases of Ebstein anomaly. The classic appearance of this finding is caused by the combination of the following features: huge right atrium that may fill the entire right hemithorax shelved appearance of th...
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Brachytherapy seed migration to the lung

Brachytherapy seed migration to the lung is a known complication of radioactive seed therapy. These seeds are used for localized treatment of malignancies, most commonly prostate cancer. Regarding staging, nearly 79% of the cases are localized, 12% are regional and 5% present with distant disea...
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Bronchial cut-off sign

The bronchial cut-off sign refers to the abrupt truncation of a bronchus from obstruction, which may be due to cancer, mucus plugging, trauma or foreign bodies. Typically, there is associated distal lobar collapse. 
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Bronchorrhea

Bronchorrhea is the expectoration of copious amounts of mucus from the lungs. It has been defined as production of more than 100 mL of mucus in 24 hours, which is more than is usually seen in chronic lung disease (e.g. chronic bronchitis typically produces 25 mL/24 hrs) 2. It may be a feature of...
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Bubbly consolidation

Bubbly consolidation describes internal or central lucencies which represent normal aerated lung lobule within infarcted, consolidated, lung parenchyma. It is one of the highly specific imaging appearances of focal pulmonary hemorrhage or possibly pulmonary infarct secondary to pulmonary embolis...
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Bulging fissure sign (lobar consolidation)

The bulging fissure sign refers to lobar consolidation where the affected portion of the lung is expanded causing displacement of the adjacent fissure. Any type of pneumonia or space-occupying process can lead to bulging (sagging) fissure sign. Classically, it has been described in right upper l...
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Bunch of grapes sign (bronchiectasis)

The bunch of grapes sign, a.k.a. cluster of grapes sign, is a characteristic imaging finding on CT seen in bronchiectasis. Closely apposed dilated bronchi may look like multiple adjacent thin walled cysts which mimic the appearance of a bunch of grapes.
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Bunch of grapes sign (disambiguation)

Bunch of grapes sign refers to the imaging appearance of multiple cystic spaces or lesions and it has been described for multiple pathologies: bunch of grapes sign (hydatidiform mole) 7 bunch of grapes sign (bronchiectasis) 3 bunch of grapes sign (IPMN) 6 bunch of grapes sign (botryoid rhabd...
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Cannonball metastases (lungs)

Cannonball metastases refer to multiple large, well-circumscribed, round pulmonary metastases that appear not unsurprisingly like cannonballs. The French terms "envolée de ballons" and "lâcher de ballons",  which translate to "balloons release", are also used to describe this same appearance. M...
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Centrilobular micronodules

Centrilobular micronodules are an image descripter which refer to centrilobular nodules when the nodules are very small and present in a centrilobular distribution in the lungs. They are usually seen with a bronchiolitis and can blend into tree-in-bud opacities.  Image interpretation Postproce...
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Cervicothoracic sign

The cervicothoracic sign is a variation of the silhouette sign on frontal chest radiography used to determine whether a superior (para)mediastinal soft tissue mass is anterior or posterior to the trachea. A positive cervicothoracic sign occurs when a thoracic lesion contacts the neck or extends...
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Chang sign (pulmonary embolism)

The Chang sign refers to the dilatation and abrupt change in caliber of the main pulmonary artery due to pulmonary embolism 1. It is one of several described signs of pulmonary embolus on chest radiographs. History and etymology It is named after C H Joseph Chang, (July 7 1929 - November 15 20...
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Cheerio sign (disambiguation)

The Cheerio sign has been described in two different scenarios: Cheerio sign (pulmonary nodule) Cheerio sign (shoulder)
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Cheerio sign (pulmonary nodule)

Cheerio sign in thoracic imaging relates to pulmonary nodules with a central lucent cavity supplied by a patent bronchus as seen on CT 3. It is due to proliferation of (malignant or non-malignant) cells around an airway. They are so named because of their resemblance to the breakfast cereal, Che...
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Chen sign

Chen sign on chest radiography is the prominence of the left basal pulmonary vasculature, compared to the right, seen in valvular pulmonary stenosis. It is due to the asymmetric increase in pulmonary blood flow to the left lung due to preferential blood flow into the left pulmonary artery after ...
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Cluster of black pearls sign

The "cluster of black pearls" sign refers to a finding on contrast-enhanced CT useful in differentiating sarcoidosis from other causes of lymphadenopathy such as tuberculosis, lymphoma and metastatic adenocarcinoma. The sign is depicted by the presence of multiple tiny round nodules (1-2 mm) di...
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Coin lesion (lung)

A coin lesion refers to a round or oval, well-circumscribed solitary pulmonary lesion. It is usually 1-5 cm in diameter and calcification may or may not be present 1,3. Typically but not always the patient is asymptomatic 1.  Differential diagnosis The differential diagnosis for such lesions i...
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Collar sign in diaphragmatic rupture

The collar sign, also called the hourglass sign, is a helpful sign for diagnosis of diaphragmatic rupture on coronal or sagittal CT/ MR images and barium studies. It refers to a waist-like or collar-like appearance of herniated organs at the level of the diaphragm. Small tear on the right side ...
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Comet tail sign (chest)

The comet tail sign is a finding that can be seen on CT scans of the chest. It consists of a curvilinear opacity that extends from a subpleural "mass" toward the ipsilateral hilum. The comet tail sign is produced by the distortion of vessels and bronchi that lead to an adjacent area of round ate...
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Continuous diaphragm sign

The continuous diaphragm sign is a chest radiograph sign of pneumomediastinum or pneumopericardium if lucency is above the diaphragm, or of pneumoperitoneum if lucency is below the diaphragm.  Normally the central portion of the diaphragm is not discretely visualized on chest radiographs as it ...
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Costal hook sign (flail chest)

The costal hook sign is a chest x-ray feature seen in some cases of flail chest. It represents the rotation of a fractured rib along its long axis, something that is only possible if a second fracture is present along its length, even if the second fracture is not visible 1. 
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COVID-19

For a quick reference guide, please see our COVID-19 summary article. COVID-19 (coronavirus disease 2019) is an infectious disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a strain of coronavirus. The first cases were seen in Wuhan, China, in December 2019 before ...
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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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Crescent sign - inverted crescent sign (hydatid disease)

The crescent sign is described in hydatid disease.  When the hydatid cyst erodes the adjacent bronchus or bronchiole, the trapped air between the pericyst and the laminated membrane of the endocyst give a crescent-shaped rim of air around the cyst, thus is termed the crescent sign 1, 2. It can b...
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Crow feet sign (round atelectasis)

Crow feet sign is a characteristic, but uncommon, feature seen in round atelectasis. On CT, this is seen as linear bands radiating from a mass into adjacent lung tissue resembling the feet of a crow. This sign should not be confused with fibrotic changes occurring in the lung.
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CT angiogram sign (lungs)

The CT angiogram sign refers to vessels appearing prominent during a contrast enhanced CT as they traverse an airless low attenuation portion of consolidated lung. Although initially thought to be specific for bronchoalveolar carcinoma, it has now been recognized as a generic appearance provided...
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Dark bronchus sign

The dark bronchus sign is the appearance of a relatively darker bronchus as compared to adjacent ground glass opacity. Normally, the density of lung parenchyma and the bronchiolar lumen is similar. In cases of ground glass opacity, the bronchiolar lumen within the affected lung parenchyma appear...
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Deep sulcus sign (chest)

The deep sulcus sign on a supine chest radiograph raises suspicion of a pneumothorax. On a supine plain chest film (common in intensive care units or as part of a trauma radiograph series), it may be the only suggestion of a pneumothorax because air collects anteriorly and basally, within the n...
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Deep sulcus sign (disambiguation)

The deep sulcus sign can refer to two different radiographic signs but is best known in the chest: deep sulcus sign (chest): of pneumothorax on supine CXR: deep sulcus sign (knee): better known as the lateral femoral notch sign of ACL injury
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Dense hilum sign

The dense hilum sign suggests a pathological process at the hilum or in the lung anterior or posterior to the hilum. Malignancy, especially lung cancer, should be suspected. Radiographic features On a well-centered chest posteroanterior (PA) radiograph the density of the hilum is comparable on...
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Dependent viscera sign

The dependent viscera sign is one of the signs of diaphragmatic rupture on axial CT or MR images, where herniated viscera lie against the posterior thoracic wall in a dependent position, as they are no longer supported by the diaphragm. See also  collar sign (or hourglass sign)
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Dot in box appearance

A "dot in box" appearance is a pattern that has been described with pulmonary lymphangitis carcinomatosis.  The interlobular septal thickening from lymphangitis forms polygonal arcades accounting for the box while the prominence of the centrilobular bronchovascular bundle is thought to represent...
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Double artery sign

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.
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Double diaphragm sign

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...
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Double lung point sign (Ultrasound)

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 ...
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Doughnut sign (chest)

The doughnut sign can be appreciated on the lateral chest radiograph of patients with mediastinal adenopathy, most commonly seen in pediatric patients with pulmonary tuberculosis infection1. The sign is made up of precarinal, subcarinal and retrocarinal lymph nodes which surround the radiolucen...
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Doughnut sign (disambiguation)

The doughnut sign can refer to a variety of different signs: doughnut sign (bone scan) doughnut sign (bowel) crescent in a doughnut sign (bowel) doughnut sign (chest) doughnut sign (orbit)
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Egg and banana sign (pulmonary hypertension)

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 ...
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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). In 1967 Jacobsen and Felson published criteria to help "avoid over-reading of t...
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Empty cyst sign

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.
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Extrapleural air sign (pneumomediastinum)

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...
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Extrapleural fat sign

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...
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Extrapleural sign

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...
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Fallen lung sign

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 ...
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Fat stranding (CT)

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, neck and subcutaneous tissues. It can be helpful in localizing both acute and chronic pathology. Radiographic features CT Fat stran...
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Feeding vessel sign

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...
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Figure 3 sign (aortic coarctation)

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...
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Finger clubbing

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.  Clinical Presentation Finger clubbing presen...
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Finger in glove sign (lung)

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 toothpaste-shaped opacities Y-shaped opacities V-shaped opac...
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Flat waist sign

The flat waist sign refers to flattening of the left heart border, specifically 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. It is different to the straight left hear...
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Fleischner sign (disambiguation)

Fleischner sign can refer to two distinctly separate signs: Fleischner sign (enlarged pulmonary artery) Fleischner sign (tuberculosis of ileocecal junction)
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Fleischner sign (enlarged pulmonary artery)

The Fleischner sign refers to a prominent central pulmonary artery that can be commonly caused either by pulmonary hypertension or by distension of the vessel by a large pulmonary embolus. It can be seen on chest radiographs, CT pulmonary angiography (CTPA), and MR pulmonary angiography (MRPA). ...
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Fluid bronchogram sign

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/...
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Fluid color sign

The fluid color sign is a diagnostic sign to differentiate a pleural effusion from pleural thickening by means of color Doppler ultrasound. In the case of pleural effusion a color signal is seen in the pleural fluid during respiratory and cardiac movement, whereas this color signal is not seen i...
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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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Galaxy sign (lungs)

The so-called galaxy sign, initially described as the sarcoid galaxy, represents a coalescent granuloma seen in a minority of patients with pulmonary sarcoidosis 1. The same appearance can be seen in tuberculosis 2,3. In other words, it represents a mass-like region composed of numerous smaller ...
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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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Ghon lesion

A Ghon lesion, sometimes called a Ghon focus, represents a tuberculous caseating granuloma (tuberculoma) and represents a sequela of primary pulmonary tuberculosis infection. Terminology Radiologically, this term is used quite loosely to refer to a calcified granuloma; technically, the Ghon le...
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Ginkgo leaf sign (disambiguation)

The ginkgo leaf sign can refer to: ginkgo leaf sign (chest) of chest wall surgical emphysema ginkgo leaf sign (spine) of spinal meningioma
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Ginkgo leaf sign (subcutaneous emphysema)

The ginkgo leaf sign of the chest, also referred as the ginkgo leaf sign of subcutaneous emphysema, is a radiographic appearance seen with extensive subcutaneous emphysema of the chest wall. Gas outlines the fibers of the pectoralis major muscle and creates a branching pattern that resembles the...
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Golden S-sign (lung lobe collapse)

The Golden S-sign is seen on both PA chest radiographs and on CT scans. It is named because this sign resembles a reverse S shape, and is therefore sometimes referred to as the reverse S-sign of Golden. Although typically seen with right upper lobe collapse, the S-sign can also be seen with the...
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Hairy pleural plaque

Hairy pleural plaques are a manifestation of asbestos-related disease. They arise from the visceral pleura, typically from an interlobar fissure. The hairiness stems from short radially-oriented linear regions of fibrosis extending from the plaque into the adjacent lung parenchyma. Compared to ...
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Halo sign (chest)

The halo sign in chest imaging is a feature seen on lung window settings, ground glass opacity surrounding a pulmonary nodule or mass and represents hemorrhage. It is typically seen in angioinvasive aspergillosis. Pathology Histopathologically, it represents a focus of pulmonary infarction sur...
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Hampton hump

Hampton hump refers to a dome-shaped, pleural-based opacification in the lung most commonly due to pulmonary embolism and lung infarction (it can also result from other causes of pulmonary infarction (e.g. vascular occlusion due to angioinvasive aspergillosis). While a pulmonary embolism is expe...
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Haystack sign (pneumomediastinum)

The haystack sign on chest radiographs in pediatric patients is indicative of pneumomediastinum. The pediatric heart is surrounded above and below with gas, giving it an appearance of a haystack from Monet's paintings. 
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Head cheese sign (lungs)

The head cheese sign refers to a juxtaposition of regions with three (or sometimes more) different densities/regions of different attenuation within the lungs: ground-glass opacities (high attenuation) mosaic attenuation pattern (low attenuation) normal lung tissue (normal attenuation) A mix...
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Hemithorax white-out (differential)

Complete white-out of a hemithorax on the chest x-ray has a limited number of causes. The differential diagnosis can be shortened further with one simple observation: the position of the trachea. Is it central, pulled or pushed from the side of opacification? Is there pulmonary volume loss or vo...
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Hilum convergence sign

The hilum convergence sign is a useful chest radiograph sign to distinguish the cause of a bulky hilum as due to pulmonary artery dilatation or to a juxtahilar mass, including nodal enlargement.  If pulmonary vessels appear to converge centrally towards the lateral margin of the abnormal 'bump'...
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Hilum overlay sign

The hilum overlay sign is useful in differentiating whether an opacity on a frontal chest radiograph in the region of the lung hilum is located within the hilum versus anterior or posterior to it. The sign refers to preserved visualization of the hilar vessels, excluding abnormalities that local...
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Hoffman-Rigler sign (heart)

The Hoffman-Rigler sign is a sign of left ventricular enlargement inferred from the distance between the inferior vena cava (IVC) and left ventricle (LV).​ Radiographic features On a lateral chest radiograph, if the distance between the left ventricular border and the posterior border of IVC e...
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Holly leaf sign

The holly leaf sign refers to the appearance of pleural plaques on chest radiographs. Their irregular thickened nodular edges are likened to the appearance of a holly leaf.
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Honeycombing (lungs)

Honeycombing is a CT imaging descriptor referring to clustered cystic air spaces (between 3-10 mm in diameter, but occasionally as large as 2.5 cm) that are usually subpleural, peripheral and basal in distribution. They can be subdivided into: microcystic honeycombing macrocystic honeycombing ...
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Hydatid cyst signs

There are numerous named imaging signs of hydatid cysts in echinococcal infection. There is considerable variability in the naming and definition of many of the signs in the literature. In general, the signs demonstrate the presence of laminated cyst membranes in various morphologies within a la...
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Hypercontracting (nutcracker) esophagus

Hypercontracting (nutcracker) esophagus is a motility disorder of the esophagus. This condition is primarily diagnosed with manometry with high intra-esophageal pressure and normal peristalsis. Most patients will have a normal barium swallow.  Hypercontracting esophagus ("nutcracker esophagus")...
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Incomplete border sign (chest)

The incomplete border sign is useful to depict an extrapulmonary mass on chest radiograph. An extrapulmonary mass will often have an inner well-defined border and an ill-defined outer margin 1-3. This can be attributed to the inner margin being tangential to the x-ray beam and has good inherent...
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Interface sign (HRCT chest)

The interface sign is a feature seen on HRCT chest imaging and refers to the presence of irregular interfaces at the margins of pulmonary parenchymal structures or the pleural surface of the lung. It suggests interstitial thickening.
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Jellyfish sign (ultrasound)

The jellyfish sign refers to the sonographic appearance of atelectatic lung "swimming" within a large pleural effusion. The mobility of the lung within pleural fluid implies an absence of lung consolidation and the absence of pleural adhesions 1. It is also suggestive of a transudative pleural e...
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Juxtaphrenic peak sign

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 or post Lobectomy (lung). It is caused by retraction of the lower end of diaphragm at an inferior accessor...
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Kirklin sign

The Kirklin sign refers to a deformity of the normal gastric bubble on an upright chest radiograph due to a mass lesion of the gastric cardia or fundus. The Kirklin sign is different from the Kirklin complex, a gastric finding on upper GI fluoroscopy. History and etymology Byrl Raymond Kirkli...
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Knuckle sign (pulmonary embolism)

The knuckle sign refers to the abrupt tapering or cutoff of a pulmonary artery secondary to an embolus. It is better visualized on CT pulmonary angiography (CTPA) than chest x-ray. This is an important ancillary finding in pulmonary embolism (PE), and often associated with the Fleischner sign of...
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Lambda sign (disambiguation)

There are two described lambda signs: lambda sign (twin pregnancy) lambda sign (sarcoidosis)
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Lambda sign (sarcoidosis)

The lambda sign is seen on gallium-67 scans in the setting of thoracic sarcoidosis. Bilateral hilar and right paratracheal lymph nodes are typically involved which can resemble the Greek letter lambda (λ). See also lambda sign of twin pregnancy

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