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.

765 results found
Article

Mount Fuji sign

Mount Fuji sign is seen on cross sectional imaging and is indicative of a tension pneumocephalus.  The sign refers to the presence of air (pneumocephalus) between the tips of the frontal lobes with a heaped-up appearance giving the silhouette like appearance of Mount Fuji 1-3. It suggests that ...
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Scottie dog sign (spine)

The Scottie dog sign refers to the normal appearance of the lumbar spine when seen on oblique radiographic projection. On oblique views, the posterior elements of the vertebra form the figure of a Scottie dog with: the transverse process being the nose the pedicle forming the eye the inferior...
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Garland triad

Garland triad, also known as the 1-2-3 sign or Pawnbrokers 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-ca...
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Thrombus fissuration

Thrombus fissuration is a sign of impending rupture of an aortic aneurysm. It reflects blood dissecting into the intramural thrombus. This sign is observed on contrast-enhanced CT as linear contrast infiltrations from the aneurysm lumen through the intramural thrombus. Thrombus fissurations exte...
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Swirl sign (intracranial haemorrhage)

The swirl sign refers to the non-contrast CT appearance of acute extravasation of blood into a haematoma, for example an extradural haematoma or subdural haematoma. It represents unclotted fresh blood which is of lower attenuation than the clotted blood which surrounds it 1. It is the corollary...
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Rim sign in pulmonary infarction

The rim sign in pulmonary infarction is seen on PET-CT with very mild peripheral continuous FDG uptake and the complete absence of central uptake. This is a different appearance to that seen in lung abscesses or necrotic tumours, whereby the peripheral FDG-avidity is marked. History and etymolo...
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Pronator quadratus sign

The pronator quadratus sign can be an indirect sign of distal forearm trauma. It relies on displacement of the fat pad that lies superficial to the pronator quadratus muscle. Radiographic features Plain radiograph On lateral wrist radiographs, the pronator fat pad normally appears as a thin r...
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Septal lines in lung

Septal lines, also known as Kerley lines, are seen when the interlobular septa in the pulmonary interstitium become prominent. This may be because of lymphatic engorgement or oedema of the connective tissues of the interlobular septa. They usually occur when pulmonary capillary wedge pressure re...
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Tramp-stamp oedema

Tramp-stamp oedema is a colloquial term used by some radiologists to denote posterior lumbar subcutaneous oedema. The term is used to describe oedema in the distribution seen with lower back tattoos, usually in young women, which are known pejoratively as tramp-stamps.  This oedema is thought t...
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Sandwich vertebral body

Sandwich vertebral body is a radiologic appearance in which the endplates are densely sclerotic, giving the appearance of a sandwich. This term and pattern are distinctive for osteopetrosis. Differential diagnosis the sandwich vertebrae appearance resembles rugger-jersey spine but can be diffe...
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Papilloedema

Papilloedema is an ophthalmoscopic diagnosis and refers to swelling of the optic disc. The MRI appearance relates to the dural anatomy of the optic nerve, which is continuous with the subarachnoid space, thereby allowing increased intracranial pressure (ICP) to be transmitted to the optic disc. ...
Article

Grey cortex sign (stress fracture)

The grey cortex sign was described as an early sign of stress (fatigue) fractures on conventional radiographs and refers to subtle ill-definition of the cortex. However, conventional radiography is insensitive for the detection of early-stage fatigue fractures. CT is much more sensitive for det...
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Anterior tibial translocation sign

The anterior tibial translocation sign or anterior drawer sign (a.k.a. anterior translation of tibia) is seen in cases of complete rupture of the anterior cruciate ligament, and refers to anterior translocation (anterior tibial subluxation) of the tibia relative to the femur of >7 mm 1. 
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Empty notch sign

Empty notch sign is a direct sign of avulsion of the anterior cruciate ligament (ACL) tear at its femoral attachment. It denotes a fluid signal at the expected ACL attachment site at the intercondylar notch (fossa) on axial and coronal fluid-sensitive MR images. The proximal ACL is the second m...
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Whirlpool sign (ovarian torsion)

The whirlpool sign or whirl sign of ovarian torsion is characterised by the appearances of a twisted ovarian pedicle seen on US or even on CT.  Terminology The term whirlpool sign is used in other contexts: see whirlpool sign (disambiguation).
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Positive PCL line sign

The positive PCL line sign is an indirect sign of anterior cruciate ligament (ACL) tear based on secondary changes of the posterior cruciate ligament (PCL) on MRI images. A line tangent to the upper border of the PCL should normally intersect the medullary cavity of the distal femur, if it does ...
Article

Bird beak sign (right colon)

The bird beak sign of the right colon is tapering obstruction of the inferior part of right colon seen on contrast enema or CT scan with rectal contrast indicating caecal volvulus. This sign can help to differentiate caecal volvulus from caecal bascule, in particular on a contrast/barium enema ...
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Bird beak sign (sigmoid colon)

Bird's beak sign of the sigmoid is one of the signs of sigmoid volvulus. It represents gradual narrowing/tapering of sigmoid colon up to the level of obstruction during contrast/barium insertion to the rectum or on CT. When located in the sigmoid colon, it suggests the diagnosis of sigmoid volv...
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Whirlpool sign (mesentery)

The whirlpool sign of the mesentery, also known as the whirl sign, is seen when the bowel rotates around its mesentery leading to whirls of the mesenteric vessels.  Terminology The term whirlpool sign is used in other contexts: see whirlpool sign (disambiguation). Radiographic features It is...
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Lateral femoral notch sign (knee)

The (deep) lateral femoral notch sign describes a depression on the lateral femoral condyle at the terminal sulcus, a junction between the weight-bearing tibial articular surface and the patellar articular surface of the femoral condyle. Pathology The likely mechanism is a hyperextension or im...
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Tattoo sign (mammogram)

The tattoo sign is a feature given to describe dermal calcifications seen on mammography 1. The basis of this sign is that dermal calcifications maintain fixed relationships to one another which are reproducible with similar projections at different times. This is in contrast to intramammary cal...
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Comb sign (mesentery)

The comb sign refers to the hypervascular appearance of the mesentery in active Crohn disease. Fibrofatty proliferation and perivascular inflammatory infiltration outline the distended intestinal arcades. This forms linear densities on the mesenteric side of the affected segments of small bowel,...
Article

Hide-bound sign (bowel)

The hide-bound bowel sign refers to an appearance on a barium study of the small bowel in patients with scleroderma. The sign describes the narrow separation between the valvulae conniventes which are of normal thickness despite dilatation of the bowel lumen.   Although the term hide-bound is u...
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Thumbprinting

Thumbprinting is a radiographic sign of large bowel wall thickening, usually caused by oedema, related to an infective or inflammatory process (colitis). The normal haustra become thickened at regular intervals appearing like thumbprints projecting into the aerated lumen. Pathology Aetiology ...
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Copper beaten skull

Copper beaten skull, also known as beaten silver skull or beaten brass skull, refers to the prominence of convolutional markings (gyral impressions on the inner table of the skull) seen throughout the skull vault. Clinical presentation The appearance of copper beaten skull is associated with r...
Article

Phrygian cap

Phrygian caps are the most common congenital anatomic variant of the gallbladder. It denotes folding of the fundus back upon the gallbladder body and is asymptomatic with no pathological significance. Radiographic findings A Phrygian cap may be identified on ultrasound, multiphase CT/MRI or ch...
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Picture frame vertebral body

Picture frame vertebral body is a radiologic appearance in which the cortex of the vertebral body is thickened. This sign can be seen in patients with Paget disease.  It is a result of disorganised new cortical bone formation after excessive osteoclastic activity causes the resorption of normal...
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Piece of pie sign (wrist)

The piece of pie sign refers to an abnormal triangular appearance of the lunate on a PA image of the wrist representing either lunate dislocation or perilunate dislocation 1,2. A lateral image will help differentiate whether there is lunate or perilunate dislocation, with lunate dislocation demo...
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Spilled teacup sign (wrist)

The spilled teacup sign describes abnormal volar displacement and tilt of a dislocated lunate on lateral radiographs of the wrist 1,2. The convexity of the lunate is no longer in articulation with the distal radius while the concavity is no longer in articulation with the capitate. It is an impo...
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Oesophageal intubation

Oesophageal intubation refers to the incorrect placement of an endotracheal tube in the oesophagus. Within minutes its consequences can be catastrophic with the seriousness of its outcome depending largely on the timeliness of its diagnosis. Epidemiology Accidental oesophageal intubation can h...
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Shading sign (endometrioma)

Shading sign is an MRI finding typically seen in an endometrioma. It may also be seen with some endometrioid tumours (e.g endometrioid carcinoma of the ovary) It helps to distinguish endometriomas from other blood-containing lesions (e.g. haemorrhagic corpus luteum cysts), with a sensitivity of...
Article

Baastrup syndrome

Baastrup syndrome (also referred to as kissing spines) results from adjacent spinous processes in the lumbar spine rubbing against each other and resulting in hypertrophy and sclerosis with focal midline pain and tenderness relieved by flexion and aggravated by extension.  Epidemiology It tend...
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Hot cross bun sign (pons)

The hot cross bun sign refers to the MRI appearance of the pons in a variety of neurodegenerative diseases.  T2 hyperintensity forms a cross on axial images through the pons, representing selective degeneration of pontocerebellar tracts. It has been described in 1: multiple system atrophy (MSA...
Article

Yin-yang sign

The yin-yang sign (also known as Pepsi sign) is a radiological sign described in both true and false aneurysms on various imaging modalities.  Radiographic features Ultrasound On Doppler ultrasound, the yin-yang sign indicates bidirectional flow due to the swirling of blood within the true or...
Article

Salt and pepper sign (skull)

Salt and pepper sign or pepper pot skull refers to multiple tiny well-defined lucencies in the calvaria caused by resorption of trabecular bone in hyperparathyroidism. There is a loss of definition between the inner and outer tables of the skull and a ground-glass appearance as well as spotty de...
Article

Rokitansky nodule

A Rokitansky nodule or dermoid plug refers to a solid protuberance projecting from an ovarian cyst in the context of a mature cystic teratoma. It often contains calcific, dental, adipose, hair, and/or sebaceous components 1. This region has the highest propensity to undergo malignant transformat...
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Sunburst appearance (bone)

Sunburst appearance is a type of periosteal reaction giving the appearance of a sunburst secondary to an aggressive periostitis. It should not be confused with the sunburst sign of meningioma vascularity.  The sunburst appearance occurs when the lesion grows too fast and the periosteum does not...
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Split hand sign

The split hand sign is a clinical sign classically seen in amyotrophic lateral sclerosis (ALS) and refers to loss of pincer grasp due to preferential wasting of the thenar eminence (abductor pollicis brevis and first dorsal interosseous muscle) with relative preservation of the the hypothenar em...
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Tram-track sign (chest)

Tram-track sign may be used in chest radiography or CT to denote the thickened non-tapering (parallel) walls of cylindrical bronchiectasis. It should not be confused with other tram-track signs elsewhere in the body. 
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Lemon sign

The lemon sign, noted on antenatal imaging, is one of the many notable fruit-inspired signs. It is a feature when there appears to be an indentation of the frontal bone (depicting that of a lemon). It is classically seen as a sign of a Chiari II malformation and also seen in the majority (90-98%...
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Cannonball metastases (lungs)

Cannonball metastases refer to large, well circumscribed, round pulmonary metastases that appear, well, like cannonballs. The French term "envolée de ballons" which translates to "balloons release" is also used to describe this same appearance. Metastases with such an appearance are classically...
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Small bowel faeces sign

The small bowel faeces sign can be observed on abdominal CT scans. The sign has been described as a finding specific for small bowel obstruction or another severe small bowel abnormality (e.g. metabolic or infectious disease). While the reported prevalence of the sign in small bowel obstruction ...
Article

Cobra head sign (ureter)

The cobra head sign (or spring onion sign) refers to dilatation of the distal ureter, surrounded by a thin lucent line, which is seen in patients with an adult-type ureterocoele. The cobra head appearance indicates an uncomplicated ureterocele. The lucent "hood" of the cobra represents the comb...
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Mosaic attenuation pattern in lung

Mosaic attenuation is a descriptive term used in describing a patchwork of regions of differing pulmonary attenuation on CT imaging.  It is a non-specific finding, although is associated with the following: obstructive small airways disease: low attenuation regions are abnormal and reflect decr...
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Bamboo spine

Bamboo spine is a radiographic feature seen in ankylosing spondylitis that occurs as a result of vertebral body fusion by marginal syndesmophytes. It is often accompanied by fusion of the posterior vertebral elements as well.  A bamboo spine typically involves the thoracolumbar and/or lumbosacr...
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Bridging vessel sign

The bridging vessel sign refers to an appearance of vessels coursing from the uterus into an adjoining pelvic mass (a vascular bridge). This sign helps to differentiate a pedunculated subserosal uterine leiomyoma from other juxtauterine masses of ovarian, adnexal or bowel origin. Colour and pow...
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Echogenic fetal bowel

Echogenic fetal bowel is an observation in antenatal ultrasound imaging, in which fetal bowel appears to be brighter than it is supposed to be. It is a soft marker for trisomy 21 and has several other associations. When observed, it needs to be interpreted in the context of other associated abno...
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Striated nephrogram

Striated nephrogram is a descriptive term indicating an appearance of alternating linear bands of high and low attenuation in a radial pattern extending through the corticomedullary layers of the kidney on iodine-based intravenous contrast enhanced imaging. It is important to know that a simila...
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Periportal halo

Periportal halo or periportal collar sign is a zone of low attenuation seen around the portal veins on contrast-enhanced CT or hypoechogenicity on liver US. Periportal halos may occur around the central portal veins or their peripheral branches and occurs on both sides of the portal triads. Pat...
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Water-lily sign (hydatid cyst)

The water-lily sign is seen in hydatid infections when there is detachment of the endocyst membrane which results in floating membranes within the pericyst that mimic the appearance of a water lily. It is classically described on plain radiographs (mainly chest X-ray) when the collapsed membran...
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Intrabiliary rupture of hepatic hydatid cyst

Intrabiliary rupture of hepatic hydatid cyst is a common complication associated with hepatic hydatid cysts. It is important to appreciate the direct and indirect signs of this condition. Radiographic features The radiological features of intrabiliary rupture of a hepatic hydatid cyst can be c...
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Signs article structure

Signs are numerous in radiology and typically relate to a specific appearance or feature that is reminiscent of an object. The aim of a named sign is to help recognise or understand a specific imaging appearance (e.g. racing car sign of corpus callosal dysgenesis). The most important signs are t...
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Drooping lily sign (ureter)

The drooping lily sign is a urographic sign in some patients with a duplicated collecting system. It refers to the inferolateral displacement of the opacified lower pole moiety due to an obstructed (and unopacified) upper pole moiety. The similarity to a lily is further strengthened by the smal...
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Spalding sign (fetal demise)

The Spalding sign refers to the overlapping of the fetal skull bones caused by collapse of the fetal brain. It appears usually a week or more after fetal death in utero.  This finding was originally described by Alfred Baker Spalding (1874-1942), an American obstetrician 2, on abdominal radiogr...
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Coca-Cola bottle sign (thyroid eye disease)

The Coca-Cola bottle sign refers to the appearance of the muscles of the orbit in thyroid eye disease.  The belly of the muscle enlarges with sparing of the tendinous insertion, giving the appearance of the traditional Coca-Cola bottle. The enlargement of the muscles follows the I'M SLOW format...
Article

Teardrop sign (ankle)

The ankle teardrop sign is one of the radiological signs of an ankle joint effusion. It represents the presence of excess fluid in the inferior part of the anterior compartment of the ankle. Pathology Aetiology trauma gout rheumatoid arthritis synovitis septic arthritis Radiographic feat...
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Silhouette sign (x-rays)

Silhouette sign is somewhat of a misnomer and in the true sense actually denotes the loss of a silhouette, thus, it is sometimes also known as loss of silhouette sign or loss of outline sign 4.  The differential attenuation of x-ray photons by two adjacent structures defines the silhouette, e.g...
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Double duct sign

The double duct sign refers to the presence of simultaneous dilatation of the common bile and pancreatic ducts. Being an anatomical sign it can be seen on all modalities that can visualise the region, including: MRI, CT, ultrasound and endoscopic retrograde cholangiopancreatography (ERCP).  The...
Article

Wimberger sign

The Wimberger sign, also called Wimberger corner sign, refers to localised bilateral metaphyseal destruction of the medial proximal tibias. It is a pathognomonic sign for congenital syphilis. It must not be mixed up with Wimberger ring sign seen in scurvy, which is sometimes also confusingly re...
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Perilymphatic fistula

A perilymphatic fistula (also known as a labyrinthine fistula) is a pathologic communication between the fluid-filled space of the inner ear and the air-filled space of the middle ear, most commonly occurring at either the round or oval window. The primary manifestations of perilymphatic fistu...
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Wimberger ring sign

Wimberger ring sign , often simply just called Wimberger ring, refers to a circular calcification surrounding the osteoporotic epiphyseal centre of ossification in scurvy, which may result from bleeding. It must not be confused with Wimberger sign, pathognomonic for congenital syphilis. Histor...
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Sandwich sign (Marchiafava-Bignami disease)

Sandwich sign of Marchiafava-Bignami disease is described as the appearance due to the involvement of central layers of the corpus callosum. T2 and FLAIR hyperintensities are seen in the central region of body and splenium of corpus callosum with sparing of peripheral dorsal and ventral layers ...
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Salt and pepper sign

The salt and pepper sign is used to refer to a speckled appearance of tissue. It is used in many instances, but most commonly on MRI. Please note that pathologists also use the term. Differential diagnosis Vascular tumours Used to describe some highly vascular tumours which contain foci of ha...
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Penumbra sign (bones)

The penumbra sign represents a rim of vascularized granulation tissue around a bone abscess cavity that has a higher T1 signal intensity than the cavity itself 1.  It should not be confused with the ischaemic penumbra of cerebral infarction.  The penumbra is isointense to muscle on T1, enhance...
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Salad oil sign

Salad oil sign, also referred to as the droplet sign, is characterised by small rounded high T2 signal foci within a breast implant on MRI studies and represents water droplets or small amounts of gas within the silicone. It also can be characterised as hypointense foci on the water-suppressed s...
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Saddle pulmonary embolism

Saddle pulmonary embolism commonly refers to a large pulmonary embolism that straddles the bifurcation of the pulmonary trunk, extending into the left and right pulmonary arteries. If large enough, it can completely obstruct both left and right pulmonary arteries resulting in right heart failur...
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Sonographic Murphy sign

Sonographic Murphy sign is defined as maximal abdominal tenderness from pressure of the ultrasound probe over the visualised gallbladder 1,2. It is a sign of local inflammation around the gallbladder along with right upper quadrant pain, tenderness and/or a mass 2. It is one of the most importa...
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Pulmonary plethora

Pulmonary plethora is a term used to describe the appearances of increased pulmonary perfusion on chest radiographs. It is commonly used in paediatric radiology.  Pathology Usually a left-to-right shunt of 2:1 is required for pulmonary plethora to occur 2,3. Increased pulmonary perfusion occur...
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Crescent sign of avascular necrosis

The crescent sign of avascular necrosis is seen on conventional radiographs and refers to a linear area of subchondral lucency seen most frequently in the anterolateral aspect of the proximal femoral head (which is optimally depicted on the frog-leg radiographic view). It indicates imminent arti...
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Fat halo sign (inflammatory bowel disease)

The fat halo sign refers to a feature seen on CT examination of the abdomen, and represents infiltration of the submucosa with fat, between the muscularis propria and the mucosa. It is characterised by an inner (mucosa) and outer (muscularis propria and serosa) ring of enhancing bowel wall along...
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Pseudosubarachnoid haemorrhage

Pseudosubarachnoid haemorrhage describes apparent increased attenuation within the basal cisterns simulating true subarachnoid haemorrhage. It is usually due to cerebral oedema. Pathology Causes and associations The most common cause is cerebral oedema where there is a decrease in parenchymal...
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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 oedema) 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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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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Rat-tail sign (oesophagus)

The rat-tail sign is used to refer to the tapering of the inferior oesophagus in achalasia. The same appearance (although it is difficult to see the similarity) is also referred to as the ​bird beak sign (oesophagus). 
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Ice cream cone sign (disambiguation)

The ice cream cone sign may refer to: the appearance of the head of malleus and the body and short process of the incus on axial CT scan: failure of this normal configuration suggests incudomalleolar dysarticulation the ball of the ice cream is formed by the head of the malleus and cone is for...
Article

Raindrop skull

The appearance of multiple, well-defined lytic lesions (punched out lesions) of various size scattered throughout the skull constitutes the raindrop skull appearance of multiple myeloma. This term is applied as an analogy to rain hitting a surface and splashing, where it leaves a random pattern ...
Article

Arcuate sign (knee)

The arcuate sign is often a subtle but important finding on knee x-rays and represents an avulsion fracture of the proximal fibula at the site of insertion of the arcuate ligament complex, and is usually associated with cruciate ligament injury (~90% of cases) 2. The fracture fragment is attache...
Article

Cockade sign (intraosseous lipoma)

The cockade sign describes the classic appearance of a calcaneal intraosseous lipoma seen as a well-defined lytic lesion with a central calcification. History and etymology It is named after a cockade, which is a badge, usually in the form of a rosette or knot, generally worn on the hat.
Article

Dawson fingers

Dawson fingers are a radiographic feature of demyelination characterised by periventricular demyelinating plaques distributed along the axis of medullary veins, perpendicular to the body of the lateral ventricles and/or callosal junction. This is thought to reflect perivenular inflammation. They...
Article

White pyramid sign (kidney)

The white pyramid sign refers to the CT appearance of the medullary pyramids of the kidney which can be seen normally on unenhanced CT scans as high-attenuation triangular structures.  Bilateral high-attenuation renal pyramids are an occasional incidental normal finding. Additionally, the unila...
Article

Keyhole sign (intracapsular breast implant rupture)

The keyhole or noose sign indicates an uncollapsed intracapsular breast implant rupture seen as the focal invagination of the implant shell caused by a small concealed leak of silicone outside shell where the two membranes do not contact each other. It is best appreciated by MRI. Differential d...
Article

Tombstone iliac wings

Tombstone iliac wings, also referred to as Mickey Mouse ears pelvis 1, are an imaging descriptor for the iliac wings of individuals with achondroplasia. These are seen to be small and squared and have been likened to the appearance of tombstones or the ears of Mickey Mouse.
Article

Falciform ligament sign

The falciform ligament sign, also called the Silver sign, is characterised by the falciform ligament being outlined with free abdominal gas in cases of pneumoperitoneum of a large amount.  It is almost never seen in isolation as, if there is enough free gas to outline the falciform ligament, th...
Article

Racing car sign (callosal dysgnesis)

The racing car sign refers to widely spaced lateral ventricles due to agenesis of the corpus callosum with intervening Probst bundles. Appearances on axial MRI or CT are reminiscent of a Formula One car seen from above, with the tyres represented by the widely-spaced frontal horns, and the dilat...
Article

Chilaiditi sign (pseudopneumoperitoneum)

Chilaiditi sign refers to the interposition of bowel, usually colon, between the inferior surface of the right hemidiaphragm and the superior surface of the liver. It may be misinterpreted as a true pneumoperitoneum resulting in unnecessary further investigations and/or therapy. The presence of ...
Article

Rings and arcs calcification

Rings and arcs calcification is characteristic of chondroid lesions, such as enchondromas and chondrosarcomas. It is due to endochondral mineralisation of multiple hyaline cartilage nodules and is similar to popcorn calcification, which has rings and arcs on the background of more amorphous calc...
Article

Cardiac chamber enlargement

Cardiac chamber enlargement can be recognised by cardiac contour changes, new or different interfaces with adjacent lung, and/or displacement of adjacent mediastinal structures. These are discussed separately: right atrial enlargement right ventricular enlargement left atrial enlargement lef...
Article

Pneumothorax (ultrasound)

Pneumothorax is a serious potential consequence of blunt thoracic trauma and, if misdiagnosed, it may quickly become life-threatening. For a discussion on epidemiology, clinical presentation, pathology, and treatment and prognosis please see the main pneumothorax article.  Radiographic feature...
Article

Luftsichel sign (lungs)

The luftsichel sign is seen in some cases of left upper lobe collapse and refers to the frontal chest radiographic appearance due to hyperinflation of the superior segment of the left lower lobe interposing itself between the mediastinum and the collapsed left upper lobe.   Radiographic feature...
Article

Polka-dot sign (vertebral haemangioma)

The polka-dot sign is the result of the replacement of the normal cancellous bone by thickened vertical trabeculae surrounded by fat marrow or vascular lacunae in vertebral intraosseous haemangiomas 2. It is the axial equivalent of the corduroy sign seen on sagittal and coronal images. On CT the...
Article

Corduroy sign (vertebral haemangioma)

The corduroy sign refers to vertically-oriented, thickened trabeculae seen in intraosseous haemangiomas of the spine. It is the sagittal/coronal equivalent of the polka-dot sign seen on axial imaging.  It is caused by the replacement of the normal cancellous bone by thickened vertical trabecula...
Article

Bird beak sign (oesophagus)

The bird's beak sign of the oesophagus is used to refer to the tapering of the inferior oesophagus in achalasia. The same appearance (although it is difficult to see the similarity) is also referred to as the rat-tail sign. The appearance, although classically occurring in primary achalasia, ca...
Article

Moguls of the heart

The 'moguls of the heart' refer to the bulges of the cardiomediastinal contour on frontal chest radiographs. The cardiomediastinal bulges are likened to skiing moguls (bumps of packed snow on a mountainside sculptured by turning skis). Awareness of their usual locations and aetiologies is helpfu...

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