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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.

972 results found
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Pseudocavitation (lung)

Pseudocavitation has been described as a well-recognized feature of adenocarcinoma in situ, minimally invasive adenocarcinoma, and invasive adenocarcinomas of the lung. It refers to the central bubble-like low-density region seen within a pulmonary nodule on CT.
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Pseudodysraphism

A pseudodysraphism refers to the splayed appearance of a normal spine created due to excessive craniocaudal angulation during sonographic evaluation. This can erroneously lead to the diagnosis of a spinal neural tube defect.
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Pseudogallbladder sign

Pseudogallbladder sign is a sonographic feature that can be seen in some children with biliary atresia. Radiographic features Ultrasound Appears as a cystic structure seen in the liver which is confused with gallbladder in a few cases of biliary atresia. In these patients it is an important f...
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Pseudogestational sac

A pseudogestational sac, also known as a pseudosac or intra-cavitary fluid, is the concept that a small amount of intrauterine fluid in the setting of a positive pregnancy test and abdominal pain could be erroneously interpreted as a true gestational sac in ectopic pregnancy. The sign was origi...
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Pseudokidney (intussusception)

The pseudokidney of intussusception is an ultrasound finding in some cases of intestinal intussusception. It refers to the longitudinal ultrasound appearance of the intussuscepted segment of bowel which mimics a kidney. The fat-containing mesentery which is dragged into the intussusception, con...
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Pseudo-omphalocele

Pseudo-omphalocele is a spurious sonographic appearance giving an impression of an anterior abdominal wall defect. Radiographic features Antenatal ultrasound Pseudo-omphalocele may be seen in: scanning errors where there is a deformation of the fetal abdomen by transducer pressure and the im...
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Pseudopneumomediastinum

Pseudopneumomediastinum is the false impression, usually on a chest x-ray, of pneumomediastinum. Correctly identifying pneumomediastinum is important, but making the diagnosis in error may lead to further unnecessary investigation and possible treatment. Causes include: Mach band superimposed...
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Pseudo-Rigler sign

The pseudo-Rigler sign is an important form of pseudopneumoperitoneum, and a mimicker of the classic Rigler (double wall) sign, that can be encountered normally on abdominal radiographs. Radiographic features The pseudo-Rigler sign can result from omental or mesenteric fat, or oral contrast me...
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Pseudosubarachnoid hemorrhage

Pseudosubarachnoid hemorrhage describes an apparent increased attenuation within the basal cisterns simulating true subarachnoid hemorrhage. It is usually due to cerebral edema. Pathology Etiology The most common cause is cerebral edema where there is a decrease in parenchymal attenuation and...
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Pseudovein sign (bowel)

The pseudovein sign can occur with active gastrointestinal bleeding where contrast extravasation during angiography may have a curvilinear appearance as it pools in the gastric rugae or mucosal folds of bowel, mimicking the appearance of a vein. However, contrast in the “pseudovein” persists bey...
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Psoas sign (abdominal x-ray)

The psoas sign is a classic non-specific finding on the abdominal radiograph, potentially representing retroperitoneal pathology. Normally on an abdominal radiograph, the lateral margins of both the psoas muscles are clearly visible due to adjacent fat. When the lateral edge of one, or both, ps...
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Ptosis

Ptosis (or blepharoptosis) is a drooping or falling of the upper eyelid. Complete ptosis is due to complete oculomotor nerve palsy. Partial ptosis is due to a dysfunction of the sympathetic pathway leading to paralysis of Muller muscle.  Note that facial nerve paralysis prevents screwing of the...
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Puff of smoke sign

The puff of smoke sign describes the characteristic angiographic appearance of tiny abnormal intracranial collateral vessel networks in moyamoya disease. Progressive narrowing of the supraclinoid internal carotid arteries and circle of Willis vessels results in extensive small collateral arteria...
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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 pediatric radiology.  Pathology Usually a left-to-right shunt of 2:1 is required for pulmonary plethora to occur 2,3. Increased pulmonary perfusion occurs...
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Pulmonary target sign

The pulmonary target sign has been described in the lung parenchyma as a central high attenuation focus surrounded by one or more dense complete or incomplete ring-like consolidation, forming one or more circles. This sign has been predominantly reported on non-contrast chest CT in patients with...
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Pulvinar sign (Creutzfeldt-Jakob disease)

The pulvinar sign refers to bilateral FLAIR hyperintensities involving the pulvinar thalamic nuclei. It is classically described in variant Creutzfeldt-Jakob disease. It is also described in other neurological conditions: Fabry disease: the hyperintense signal is seen on T1 rather than T2 bila...
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Punctate microcalcification within the breast

Punctate microcalcifications in the breast are defined as calcific opacities <0.5 mm in diameter seen within the acini of a terminal duct lobular unit. Pathology Associations fibrocystic changes skin calcification skin talc rarely in DCIS: punctate, clustered, segmentally distributed Radi...
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Putaminal rim sign

The putaminal rim sign, also known as the putaminal slit sign, is a relatively specific sign of multiple system atrophy - parkinsonism (MSA-P), and refers to a linear region of high signal surrounding the lateral aspect of the putamen at 1.5 T MRI on T2 weighted images or ADC map. Importantly th...
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Putty kidney

A putty kidney refers to a pattern of renal calcification associated with renal tuberculosis conventionally described on plain radiography. The calcification is characteristically very homogeneous and ground glass-like, representing calcified caseous tissue 3,4. Premkumar et al. labeled calcific...
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Pyrexia

Pyrexia (or fever) is a clinical sign, indicated by an abnormally elevated core body temperature, which is defined by several medical societies as ≥38.3°C (≥≈101°F). The temperature elevation may be persistent or episodic. If the body temperature is greater than 41.5°C - a rare phenomenon - it i...
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Quad sign

The quad sign is a static sonographic sign observed in pleural effusion. It consists of four lines representing the pleura, rib, fluid, and lung. Similar to the sinusoid sign, this sign has a high sensitivity and specificity for pleural effusion, which - when simple - is itself anechoic.
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Raccoon eyes sign (base of skull fracture)

Raccoon eyes sign (or panda eyes in the UK and Ireland) refers to periorbital ecchymosis with sparing of the tarsal plate 3 and is a physical examination finding indicative of a base of skull fracture of the anterior cranial fossa. However it is not pathognomonic for trauma, and there are sever...
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Rachitic rosary

Rachitic rosary refers to expansion of the anterior rib ends at the costochondral junctions and is most frequently seen in rickets as nodularity at the costochondral junctions. Differential diagnosis Other causes of this appearance include:  scurvy the costochondral junction is more angular ...
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Racing car sign (callosal dysgenesis)

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...
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Radial bands sign (tuberous sclerosis)

The radial bands sign, also known as radial migration bands, refers to linear bands seen on MRI, radiating from the periventricular white matter to the subcortical region, thought to be specific for tuberous sclerosis 1,2. Pathology The exact pathogenesis of radial bands is uncertain, but they...
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Radiocapitellar line

The radiocapitellar line is one of the key lines used to assess alignment on the elbow radiograph. It is particularly useful in the pediatric setting. The rule A line drawn down the neck of the radius should intersect the capitellum. It is important to ensure that you draw the line down the ra...
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Raindrop skull

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

Ranke complex is seen in 'healed' primary pulmonary tuberculosis and is a later manifestation of the Ghon complex. It consists of two components: a Ghon lesion that has undergone calcification an ipsilateral calcified mediastinal node It is important to note that a Ranke complex is not specif...
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Rat bite erosions (gout)

Rat (or mouse) bite erosions are seen in gout and refer to punched out erosions with sclerotic and overhanging margins. 
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Rat-tail sign (esophagus)

The rat-tail sign is used to refer to the tapering of the inferior esophagus in achalasia. The same appearance (although it is difficult to see the similarity) is also referred to as the ​bird beak sign (esophagus). 
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Renal arterial cut-off sign

Renal arterial cut-off sign, as the name suggests, is an abrupt termination of the contrast-opacified lumen of the renal artery. It may or may not be associated with contrast extravasation. It is seen in a vascular injury, e.g. segmental or main renal artery thrombosis or occlusion.
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Retrocardiac sail sign

The retrocardiac sail sign represents the characteristic and highly specific appearance of left lower lobe collapse on a frontal chest x-ray. Radiographic appearance The collapsed, medially displaced left lower lobe is represented by a triangular area of increased density with sharp margins, s...
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Reverse bat wing pulmonary opacities

Reverse bat wing pulmonary opacities refer to peripheral opacities of the lungs, sparing the perihilar region. It is a relatively unusual appearance with a fairly narrow differential: chronic eosinophilic pneumonia organizing pneumonia (formerly bronchiolitis obliterans with organizing pneumon...
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Reversed halo sign (lungs)

Reversed halo sign, also known as the atoll sign, is defined as central ground-glass opacity surrounded by denser consolidation of crescentic shape (forming more than three-fourths of a circle) or complete ring of at least 2 mm in thickness 8. It was initially described on high-resolution CT. T...
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Reverse figure 3 sign (esophagus)

The reverse figure 3 sign (also known as the E sign) is seen on barium swallows in patients with coarctation of the aorta and is the medial equivalent of the figure 3 sign seen on plain chest radiographs. It is formed by prestenotic dilatation of the ascending aorta, indentation of the coarctati...
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Reverse rim sign (kidney)

The reverse rim sign describes relative hypoenhancement of the renal cortex and normal enhancement of the renal medulla on contrast-enhanced CT and MRI. This enhancement pattern can also be visualized using CEUS 2. It is a typical finding of renal cortical necrosis that may occur in the setting...
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Reverse target sign (cirrhotic nodules)

A reverse target sign is a potential ultrasound marker for cirrhotic nodules on ultrasound.It represents central iso-hyperechogenicity with surrounding hyperechoic rim. This sign is useful to differentiate metastases from cirrhotic nodules, conversely the target sign is seen with liver metastases.
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Ribbon ribs deformity

Ribbon ribs deformity refers to the presence of thinned ribs on image studies. Such findings could be present in patients with neurofibromatosis type 1 due to the presence of multiple neurofibromas of intercostal nerves.  This deformity is also described in osteogenesis imperfecta 1 Edwards s...
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Rice grain calcification

Rice grain calcification is characteristic of infection with Taenia solium (cysticercosis); when the inflammatory response of the host kills the larval cysts (cysticerci), they undergo granulomatous change and become calcified. Radiographic features Ovoid flecks of calcification resembling gra...
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Right posterior hepatic notch sign

The right posterior hepatic notch sign is a sharp indentation of the normally smooth posterior right hepatic lobe margin. It is associated with cirrhosis, although the mechanism is not entirely clear. It has been suggested that this may be an indication of relative caudate lobe hypertrophy and d...
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Rigler notch sign (lungs)

The Rigler notch sign refers to an indentation in the border of a solid lung mass, which is thought to represents a feeding vessel, thus suggesting the presence of a bronchial carcinoma 1. However, this sign is also observed in other conditions, including granulomatous infections, and its differ...
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Rigler sign (bowel)

The Rigler sign, also known as the double-wall sign, is a sign of pneumoperitoneum seen on an abdominal radiograph when gas is outlining both sides of the bowel wall, i.e. gas within the bowel's lumen and gas within the peritoneal cavity. It is seen with large amounts of pneumoperitoneum (>1000 ...
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Rigler triad (gallstone ileus)

Rigler triad consists of three findings seen in gallstone ileus: pneumobilia small bowel obstruction ectopic calcified gallstone, usually in the right iliac fossa History and etymology It is named after Leo George Rigler, American radiologist (1896-1979) 1. Practical points Rigler triad s...
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Rim sign (avascular necrosis)

A rim sign can be seen in avascular necrosis and comprises a high T2 or intermediate T1 signal line sandwiched between two low signal lines, and represents fluid between the sclerotic borders of an osteochondral fragment, and implies instability (stage III). This rim sign should not be confused...
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Rim sign (chronic hydronephrosis)

The rim sign can be seen in association with chronic hydronephrosis.  In patients with chronic hydronephrosis, in all forms of contrast-enhanced imaging of the obstructed kidney, enhancement may occur in the residual, but markedly atrophic, renal parenchyma, surrounding the dilated calyces and ...
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Rim sign (pulmonary infarction)

The rim sign can be seen in cases of pulmonary infarction 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 tumors, whereby the peripheral FDG-avidity is marked. History...
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Rim sign (spinal cord metastasis)

The rim sign has been described as a helpful MRI sign of spinal cord metastases, enabling them to be distinguished from other enhancing spinal cord lesions (e.g. ependymoma and astrocytoma).  Radiographic features MRI The rim sign is seen on sagittal post contrast T1 weighted imaging of the s...
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Rind sign (bones)

The rind sign is used when a lesion is surrounded by a layer of thick, sclerotic reactive bone (i.e. a rind) and is suggestive of fibrous dysplasia. The classic rind sign is most commonly seen in the proximal femur.
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Ring around artery sign

The ring around artery sign refers to a (semi-) circular radiolucency surrounding the right pulmonary artery caused by mediastinal air in case of pneumomediastinum 1-3. The sign was originally described on lateral chest radiographs 1-4 but can be equally appreciated on sagittal multiplanar reco...
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Ring of fire sign (adnexa)

The ring of fire sign, also known as ring of vascularity, signifies a hypervascular lesion with peripheral vascularity on color or pulsed Doppler examination of the adnexa due to low impedance high diastolic flow 1. This sign can be seen in: corpus luteum cyst (more commonly) ectopic pregnancy
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Rings and arcs calcification

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

Ring shadows on chest x-ray are classically associated with cystic bronchiectasis 1,2 but the term has also been used to describe a normal bronchus imaged end-on 3. 
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Ring shadow (disambiguation)

Ring shadows are radiographic signs seen on either chest x-rays or on upper gastrointestinal fluoroscopy: ring shadow (chest) ring shadow (abdomen)
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Roberts sign (fetal demise)

Roberts sign refers to the presence of a gas shadow within the heart or the greater vessels, in cases of fetal death in utero. It is a rare sign caused by postmortem blood degeneration, usually seen 1-2 days after death; and may be seen as early as 12 hours. History and etymology First describ...
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Rokitansky nodule

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

The rolling stone sign refers to the presence of gallstones within the gallbladder that are mobile when the patient moves. Small gallstones can sometimes be difficult to diagnose due to the absence of posterior shadow artefact but the presence of a rolling stone sign increases the confidence of...
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Romaña sign (Chagas disease)

Romaña sign, also known as the periorbital swelling syndrome, refers to periorbital swelling, palpebral edema and conjunctivitis seen 1-2 weeks following infection with Trypanosoma cruzi (causative agent in Chagas disease). When present it is diagnostic of acute Chagas disease. Romaña sign is a...
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Romanus lesion (vertebral bodies)

The Romanus lesion represents an early finding in inflammatory spondyloarthropathies, such as ankylosing spondylitis and enteropathic arthritis, and appears as irregularity and erosion involving the anterior and posterior edges of the vertebral endplates 1. Healing response to these inflammatory...
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Rosary sign (gallbladder)

The rosary sign is a CT finding in adenomyomatosis of the gallbladder. It is formed by the enhanced proliferative mucosal epithelium, with the intramural diverticula surrounded by the unenhanced hypertrophied muscle coat of the gallbladder. The rosary sign is similar to the pearl necklace sign.
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Rose-thorn ulcers (terminal ilium)

Rose-thorn ulcers or rose-thorn appearance refers to deep penetrating linear ulcers or fissuring typically seen within stenosed terminal ileum with a thickened wall. They appear as thorn-like extraluminal projections on barium studies and this appearance is one of the typical signs of Crohn dise...
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Round belly sign (abdominal compartment syndrome)

Round belly sign is a sign of increased abdominal pressure of greater than 20 mmHg in abdominal compartment syndrome where the abdomen has a rounded appearance of transverse section on CT, rather than its typical oval shape. The sign is positive when the AP to transverse diameter of the abdomen...
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Rugger jersey spine (hyperparathyroidism)

Rugger jersey spine describes the prominent endplate densities at multiple contiguous vertebral levels to produce an alternating sclerotic-lucent-sclerotic appearance. This mimics the horizontal stripes of a rugby jersey. This term and pattern are distinctive for hyperparathyroidism. Pathology ...
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Saber-sheath trachea

Saber-sheath trachea refers to diffuse coronal narrowing of the intrathoracic portion of the trachea with the concomitant widening of the sagittal diameter. It is not uncommon and is pathognomonic for chronic obstructive pulmonary disease (COPD) 1.  The sagittal:coronal diameter is over 2:1 2 a...
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Saber sign (pneumobilia)

The saber sign refers to a pattern of gas distribution seen in supine abdominal radiographs of patients with pneumobilia.  A sword-shaped lucency is apparent in the right paraspinal region of the upper abdomen representing arching gas extending from the common bile duct into the left hepatic duc...
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Sack of marbles sign (dermoid cyst)

The sack of marbles sign, also known as the marbles in a bag sign, refers to aggregations of multiple small globules of fat within a cyst mimicking marble spheres within a sack. They appear hyperechoic on ultrasound, fat attenuation on CT, and high signal on T1WI and T2WI on MRI. It is considere...
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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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Sagging rope sign (Perthes disease)

The sagging rope sign is a thin sclerotic line that crosses the femoral neck and resembles a hanging or sagging rope that is suspended on both ends. This sign is seen in late stage of Perthes disease on plain radiographs of the hip or pelvis. This sign is thought to indicate damage to the growt...
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Sail sign (disambiguation)

There are numerous sail signs in radiology, where a normal structure is displaced or a pathology creates the appearance of a sail: elbow sail sign: the raised anterior fat pad on an elbow radiograph thymic sail sign: normal thymus on a pediatric chest radiograph spinnaker-sail sign (angel win...
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Sail sign (elbow)

The sail sign on an elbow radiograph, also known as the anterior fat pad sign, describes the elevation of the anterior fat pad to create a silhouette similar to a billowing spinnaker sail from a boat. It indicates the presence of an elbow joint effusion. The anterior fat pad is usually conceale...
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Sail sign (larynx)

The sail sign of the larynx refers to the axial appearance of unilateral dilatation of the laryngeal ventricle due to vocal cord/fold paralysis. It should not be confused with the several other sail signs in radiology. Radiographic features CT Axial images at the level of the glottis show the...
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Salad oil sign

The salad oil sign also referred to as the droplet sign, is characterized 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 characterized as hypointense foci on the water-suppresse...
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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. NB: pathologists also use the term. Differential diagnosis Vascular tumors Used to describe some highly vascular tumors which contain foci of hemorrhage, typic...
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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...
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Salted pretzel sign (CT head)

The salted pretzel sign is an uncommon sign of the presence of numerous small (<3 mm) calcific foci in the distal branches of a cerebral artery on non-contrast CT head that represent a shower of calcified cerebral emboli 1. Cerebral calcified emboli may be the initial manifestation of significan...
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Sandwich sign (disambiguation)

The sandwich sign is used for two different imaging appearances: sandwich sign (Marchiafava-Bignami disease) sandwich sign (mesentery) Sandwich sign has also been coined for the appearance of: primary pleural lymphoma 1,2 mediastinal lymphoma 3 marrow edema and hemorrhage on MRI of flexion...
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Sandwich sign (Marchiafava-Bignami disease)

The sandwich sign of Marchiafava-Bignami disease has been described for the appearance of the central layers of the corpus callosum which are preferentially involved by this disease. T2 and FLAIR hyperintensities are seen in the central region of body and splenium of corpus callosum with sparin...
Article

Sandwich sign (mesentery)

A sandwich sign, sometimes known as a hamburger sign, refers to a mesenteric nodal mass, either para-aortic or not, giving an appearance of a hamburger. Confluent lymphadenopathy on both sides of the mesenteric vessels gives rise to an appearance described as the sandwich sign 2. The sign is sp...
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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 benign adult autosomal dominant osteopetrosis. Differential diagnosis rugger jersey spine: sandwich vertebrae appears ...
Article

Scallop sign

The scallop sign is a radiological sign initially described in rheumatoid arthritis of the wrist. It refers to the appearance of the ulnar aspect of the distal radius on plain radiograph of the wrist, where it has a scalloped shape with a sclerotic border 1,2. It occurs due to progressive erosi...
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Scalpel sign (spinal cord)

The scalpel sign has been recently described in dorsal thoracic arachnoid web on sagittal MRI spine studies. It relates to focal distortion of the thoracic cord, appearing anteriorly displaced. The enlarged dorsal CSF space mimics the profile of a surgical scalpel. It is helpful in distinguishi...
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Scaphoid fat pad sign

The scaphoid fat pad or stripe sign is defined as obliteration or lateral displacement of the normal scaphoid fat pad. A positive sign usually indicates a scaphoid fracture, although it may also be associated with a radial styloid or proximal first metacarpal fracture. Is it best visualized on p...
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Schwartze sign

Schwartze sign also known as Flemingo's flush sign or Rising sun sign is a characteristic reddish discolouration of the promontory seen during an otoscopic examination. It is seen in cases with otospongiosis in the active phase of the disease 3. History and Etymology Named after German otologi...
Article

Scimitar (disambiguation)

The term scimitar, referring to the characteristic shape of the Middle Eastern sword, may refer to the following: scimitar syndrome (lungs) scimitar sign (cystic adventitial disease) scimitar sacrum (bones)
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Scimitar sign (cystic adventitial disease)

Scimitar sign traditionally referred to a catheter angiographic appearance, although it can also be seen on MRA and CTA. It denotes lateral displacement and stenosis of the popliteal artery in patients with cystic adventitial disease. 
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Scottie dog sign (spine)

The Scottie dog sign (often seen spelled Scotty but Scottie is the correct spelling) 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 p...
Article

Seatbelt sign (abdomen)

The seatbelt sign is both a clinical and radiological sign. It is simply the presence of bruising/abrasions in the distribution of a seatbelt (i.e. horizontal and/or diagonal) across the abdomen, chest and sometimes neck.  A positive seatbelt sign, in combination with abdominal pain or tenderne...
Article

Segond fracture

Segond fracture is an avulsion fracture of the knee that involves the lateral aspect of the tibial plateau and is very frequently (~75% of cases) associated with disruption of the anterior cruciate ligament (ACL). On the frontal knee radiograph, it may be referred to as the lateral capsular sign...
Article

Sentinel clot sign

The sentinel clot sign is a useful CT finding for the evaluation of probable anatomic sites of hemorrhage. On CT, acute clotted hemorrhage typically has high attenuation (45 to 70 HU), whereas surrounding areas of acute non-clotted hemorrhage or more chronic hemorrhage have either lower attenua...
Article

Sentinel loop

A sentinel loop is a short segment of adynamic ileus close to an intra-abdominal inflammatory process. The sentinel loop sign may aid in localizing the source of inflammation. For example, a sentinel loop in the upper abdomen may indicate pancreatitis, while one in the right lower quadrant may ...
Article

Septal bounce

Septal bounce is a sign of ventricular interdependence on echocardiography, cardiac CT, and cardiac MRI, manifested by paradoxical interventricular septal movement during early diastole (i.e. initial septal movement towards and then away from the left ventricle) seen mainly in constrictive peric...
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Septal flash

Septal flash, also known as septal beaking, is a sign of interventricular dyssynchrony seen on echocardiography or cinematographic cardiac CT/MRI. It represents an abnormal rapid movement pattern of the interventricular septum during pre-ejection systole (i.e. isovolumic contraction): septal mo...
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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 edema of the connective tissues of the interlobular septa. They usually occur when pulmonary capillary wedge pressure rea...
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Sergeant stripes sign (cerebellum)

The sergeant stripes sign refers to the oblique direction of the cerebellar tonsillar folia a feature sometimes visible in cases of Chiari I malformation on sagittal imaging. It is unclear which insignia this is meant to represent as the direction of the chevrons depends on nationality. For exam...

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