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Panda sign (disambiguation)

The humble panda has a few signs to its name: panda sign of the midbrain double panda sign panda sign of sarcoidosis panda eyes (base of skull fracture) See also animal and animal produce inspired signs

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

Panda sign (sarcoidosis)

The panda sign of sarcoidosis is a gallium-67 citrate scan finding. It is due to bilateral involvement of parotid and lacrimal glands in sarcoidosis, superimposed on the normal uptake in the nasopharyngeal mucosa. The presence of perihilar adenopathy adds the lambda distribution of increased up...

Lyre sign (carotid artery)

The lyre sign refers to the splaying of the internal and external carotid by a carotid body tumor. Classically described on angiography it is also visible on CT angiography.

Cobblestone appearance (hollow viscera)

Cobblestoning (having a cobblestone appearance) can occur in a number of hollow organs with mucosa, most commonly the bowel, in the setting of Crohn disease. Longitudinal and circumferential fissures and ulcers separate islands of mucosa, giving it an appearance reminiscent of cobblestones. ...

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,...

Glenoid labrum ovoid mass sign

The glenoid labrum ovoid mass (GLOM) sign (seen on MRI) is useful when a torn anterior glenoid labrum retracts superiorly. Seen typically on a T2 axial image through the glenohumeral joint as a low signal ovoid mass anterior to the glenoid labrum. Sometimes this can be the only sign of a torn la...

Shading sign (endometrioma)

Shading sign is an MRI finding typically seen in an endometrioma. It may also be seen with some endometrioid tumors (e.g. endometrioid carcinoma of the ovary) and uncommonly other blood-containing lesions (e.g. hemorrhagic corpus luteum cysts). The sign is seen on T2-weighted sequences of lesio...

Crescent sign of arterial dissection

The crescent sign refers to the high signal crescent seen in the wall of a vessel when dissected. This may be seen both on T1 or T2 sequences depending on the age of the blood (see aging blood on MRI). It is classically referred to in internal carotid artery dissection. It should not be confuse...

Tram-track sign (orbit)

Tram-track sign refers to the parallel thickening and enhancement around the optic nerve, and is most frequently seen in the setting of optic nerve meningioma. It may, however, also be seen in 1: orbital pseudotumor perioptic neuritis orbital sarcoidosis orbital leukemia orbital lymphoma o...

Sunburst appearance (bone)

Sunburst or sunray appearance describes two separate findings in the bone: a periosteal reaction and a trabeculation pattern. It should not be confused with the sunburst sign of meningioma vascularity. Sunburst periosteal reaction Sunburst periosteal reaction reflects aggressive periostitis. ...

Swirl sign (intracranial hemorrhage)

The swirl sign refers to the non-contrast CT appearance of acute extravasation of blood into a hematoma, for example an intracerebral hemorrhage, extradural hematoma or subdural hematoma. It represents unclotted fresh blood which is of lower attenuation than the clotted blood which surrounds it ...

Calyceal crescent sign (intravenous pyelogram)

The calyceal crescent sign (of Dunbar and Nogrady) refers to the early intravenous pyelogram (IVP) appearance of markedly dilated renal calyces. It is formed by early contrast opacification of the dilated collecting ducts and ducts of Bellini with the characteristic shape as a result of the asso...

Shepherd crook deformity

A shepherd crook deformity refers to a coxa varus angulation of the proximal femur, classically seen in femoral involvement by fibrous dysplasia, although may be seen in other disorders such as Paget disease of bone and osteogenesis imperfecta. History and etymology The shape of the proximal f...

Caput medusae sign - developmental venous anomalies

The caput medusae sign refers to developmental venous anomalies of the brain, where a number of veins converge centrally into a single draining vein. The sign is seen on both CT and MRI when contrast medium is administered. Angiographically the caput medusae appearance is seen only in the veno...

Funneling of the internal cervical os

Cervical funnelling is a sign of cervical incompetence and represents the dilatation of the internal part of the cervical canal and reduction of the cervical length. Greater than 50% funnelling before 25 weeks is associated with ~80% risk of preterm delivery. Radiographic features Good scanni...

Crescent in a doughnut sign (intestinal intussusception)

The crescent in a doughnut sign refers to the transverse ultrasound appearance of intestinal intussusception, and is a variation of the target sign (which is also known as the doughnut sign) The doughnut is formed by concentric alternating echogenic and hypoechogenic bands. The echogenic bands ...

Pseudokidney sign (intussusception)

The pseudokidney sign is a characteristic ultrasound appearance 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, containing vessels, which is dragged into ...

Moulage sign (bowel)

The moulage sign is related to sprue, in particular celiac disease. It occurs where there is a dilated jejunal loop with complete loss of jejunal folds 1. It is said to appear like a tube into which wax has been poured. History and etymology Moulage (French: casting/molding) is the art of appl...

Cupola sign

The cupola sign is seen on a supine chest or abdominal radiograph in the presence of pneumoperitoneum. It refers to non-dependent gas that rises within the abdominal cavity of the supine patient to accumulate underneath the central tendon of the diaphragm in the midline. It is seen as lucency ...

Pelvic teardrop

The pelvic teardrop, also known as U-figure or Köhler teardrop, is a radiographic feature seen on pelvic x-rays and results from the end-on projection of a bony ridge running along the floor of the acetabular fossa. This was shown to be the case by demonstrating that sawing away this bony plat...

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...

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...

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...

Popcorn calcification (disambiguation)

Popcorn calcification refers to amorphous calcifications often with rings and arcs that resemble popped corn kernels. This type of calcification may be seen in many radiological settings including 1: chondroid lesions (e.g. enchondroma, chondrosarcoma) fibrous dysplasia pulmonary hamartomas ...

Lead pipe sign (colon)

The lead pipe appearance of colon is the classical barium enema finding in chronic ulcerative colitis, and is also seen with other modalities such as CT, MRI or a plain radiograph. There is a complete loss of the haustral markings in the diseased segment of the colon, appearing smooth-walled and...

Intramural bowel gas

Intramural bowel gas, also known as pneumatosis intestinalis, refers to the clinical or radiological finding of gas within the wall of the bowel. Terminology There are different terminologies in the medical literature, such as pneumatosis intestinalis, pneumatosis coli, and pneumatosis cystoid...

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...

Kirner deformity

A Kirner deformity, also known as dystelephalangy, is characterized by a curvature of the distal phalanx of the 5th digit in both a palmar and radial direction. Epidemiology The deformity typically presents in late childhood to early adolescence, although a mild deformity may be present at bir...

Zebra stripe sign (bones)

The zebra stripe sign occurs where children with osteogenesis imperfecta have been treated with cyclical bisphosphonate therapy, e.g. pamidronate. When the drug is delivered in cycles, dense bone is formed while treatment is being given. This results in dense stripes across the metaphyses of bon...

Rat's tail sign (esophagus)

The rat's tail sign refers to tapering of the inferior esophagus on barium swallow study. Many sources use this sign synonymously with the bird beak sign (esophagus) and indicate that it is characteristic of achalasia 1. It is important to remember that if a "rat tail" involves more than just t...

Bird beak sign (esophagus)

The bird's beak sign of the esophagus is used to refer to the tapering of the inferior esophagus in achalasia. The same appearance is also referred to as the rat's tail sign. The appearance, although classically occurring in primary achalasia, can also occur in pseudoachalasia due to a gastric ...

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 There are no clinical features specific and unique to a co...

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...

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 bronchocele. Terminology The same appearance has also been referred to as: Mickey Mouse appearance rabbit ear appearance toothpaste-shaped opacity V-shaped opacities Y...

Harlequin eye deformity

The harlequin eye deformity is characterized by elevation of the superolateral corner of the orbit. It may be seen in unilateral (plagiocephaly) or bilateral (brachycephaly) coronal suture synostosis. History and etymology The term harlequin eye derives from the appearance of the eyes on a har...

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...

Flat floor of fourth ventricle sign

The flat floor of fourth ventricle sign is useful in detecting a pontine mass and is a sign of mass effect. The normal floor of the fourth ventricle (remember that the floor is anterior) normally slopes upwards towards the midline, with the facial colliculi visible on either side. It is a non-...

Lhermitte sign (spinal cord)

Lhermitte sign or the barber chair phenomenon is an electrical shock sensation running down the spine and into the limb on neck flexion. It suggests compression of the upper cervical spinal cord and/or brainstem. Pathology It is typically seen with multiple sclerosis but is also associated wit...

Hutchinson teeth

Hutchinson teeth are smaller and more widely spaced than normal and are notched on their biting surfaces. It is a sign of congenital syphilis and should not be confused with: Hutchinson triad Hutchinson pupil Hutchinson freckle Hutchinson sign Hutchinson syndrome History and etymology Na...

Hutchinson pupil

Hutchinson pupil is a fixed and dilated pupil caused by compression of the oculomotor nerve (CN III) as a result of uncal herniation. It should not be confused with any of the following: Hutchinson triad Hutchinson freckle Hutchinson teeth Hutchinson sign Hutchinson syndrome History and e...

Steeple sign (trachea)

The steeple sign (also called the wine bottle sign, and inverted V sign), refers to the tapering of the upper trachea on a frontal chest radiograph reminiscent of a church steeple, suggestive of croup. A corresponding lateral x-ray would show narrowing of the subglottic trachea and ballooning of...

Hutchinson sign (disambiguation)

The Hutchinson sign can refer to two clinical signs. Hutchinson sign (ophthalmology) Relates to involvement of the tip of the nose from facial herpes zoster. It implies involvement of the external nasal branch of the nasociliary nerve (branch of the ophthalmic division of the trigeminal nerve...

Prévost sign (eyes)

The Prévost sign, also known as the Vulpian sign, refers to conjugate ocular deviation in patients with acute cortical hemiparetic stroke. The direction is variable, depending on the location of the stroke 3. In a hemispheric stroke, the eyes usually deviate towards the lesion (away from the h...

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...

Hutchinson triad

The Hutchinson triad of congenital syphilis consists of: dental abnormalities interstitial keratosis deafness The Hutchinson triad should not be confused with: Hutchinson pupil Hutchinson freckle Hutchinson teeth Hutchinson sign Hutchinson syndrome History and etymology Named after Si...

Stuck temporomandibular joint disc

A stuck disc, also called anchored disc phenomenon, refers to a temporomandibular joint (TMJ) disc which does not translate anteriorly out of the mandibular fossa onto the articular eminence but rather remains (thus "stuck") in the fossa. It is a form of TMJ dysfunction. Clinical presentation ...

Double disc sign

Thickening of the insertion of the lateral pterygoid muscle can mimic an anterior displaced temporomandibular disc. When both thickening of the inferior belly insertion and an anteriorly displaced disc are present, as in temporomandibular joint dysfunction, the two structures parallel each other...

Hyperdense MCA sign (brain)

The hyperdense MCA sign, also known as Gács sign, refers to focal hyperdensity of the middle cerebral artery (MCA) on non-contrast brain CT and is the direct visualization of thromboembolic material within the lumen. It is thus the earliest visible sign of MCA infarction as it is seen within 90 ...

Tree-in-bud sign (lung)

Tree-in-bud sign or pattern describes the CT appearance of multiple areas of centrilobular nodules with a linear branching pattern. Although initially described in patients with endobronchial tuberculosis, it is now recognized in a large number of conditions. Pathology Pathogenesis Simply put...

Pneumothorax in supine projection

A pneumothorax does not display classical signs when a patient is positioned supine for a chest radiograph as commonly occurs in acute trauma or the critical care setting. Of course, pneumothoraces are common in both these scenarios and even relatively small pneumothoraces may be significant due...

CT angiogram sign (lungs)

The CT angiogram sign refers to vessels appearing prominent on contrast-enhanced CT as they traverse an airless low attenuation portion of consolidated lung 1,2. This sign has been associated with 1,2: lung adenocarcinoma 3 pulmonary lymphoma metastasis from gastrointestinal carcinom...

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...

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 ...

Cyst with dot sign (neurocysticercosis)

The cyst with dot sign is seen in neurocysticercosis and represents the parasitic cyst with, usually eccentric, scolex. It can be seen on both MRI and CT at: the vesicular stage (CSF density / intensity cyst - denser / hyperintense scolex) and colloidal vesicular stage (enhancement of wall an...

Salt and pepper sign (disambiguation)

The salt and pepper sign is used to refer to a speckled appearance of tissue on imaging. It is used in many contexts, but most commonly for the appearance of certain lesions on MRI, especially paragangliomas. salt and pepper noise (MRI artifact) 9 salt and pepper sign (ARPCKD) 8 salt and pepp...

Thumb sign (chordoma)

The thumb sign or thumbing of the pons is described in chordomas as is meant to be relatively specific. It is seen in midline sagittal projection as a projection of the tumor indenting the pons 1,2. See also thumb sign (disambiguation)

Empty delta sign (dural venous sinus thrombosis)

The empty delta sign is a CT sign of dural venous sinus thrombosis of the superior sagittal sinus, where contrast outlines a triangular filling defect, which represents thrombus. It is only described in contrast-enhanced CT, not in unenhanced scans. An equivalent appearance can be noted in the ...

Face of the giant panda sign (midbrain)

The face of the giant panda sign in neuroimaging refers to the appearance of the midbrain, when the red nucleus and substantia nigra are surrounded by high T2 signal in the tegmentum. It is classically seen in Wilson disease, although whenever the white matter is diffusely abnormal in the regio...

Target sign (intussusception)

The target sign of intestinal intussusception, also known as the doughnut sign or bull's eye sign. The appearance is generated by concentric alternating echogenic and hypoechoic bands. The echogenic bands are formed by mucosa and muscularis whereas the submucosa is responsible fo the hypoechoi...

Blade of grass sign (Paget disease)

The blade of grass sign, also called the candle flame sign, refers to the lucent leading edge in a long bone seen during the lytic phase of Paget disease of bone. The blade of grass sign is characteristic of Paget disease of bone. This is akin to osteoporosis circumscripta cranii seen in the sk...

Celery stalk sign (anterior cruciate ligament)

The celery stalk sign is a term given to the appearance of the anterior cruciate ligament which has undergone mucoid degeneration and has been likened to that of a celery stalk. Its low signal longitudinal fibers are separated from each other by higher signal mucinous material, best appreciated ...

Inverted Napoleon hat sign

The inverted Napoleon hat sign is a radiologic sign seen on the frontal pelvic or lumbar radiograph at the level of the 5th lumbar vertebra and the sacrum. It is seen when there is bilateral spondylolysis with marked anterolisthesis of L5 on S1 or marked exaggeration of the normal lordosis at t...

Water-lily sign (hydatid cyst)

The water-lily sign, also known as the camalote 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...

Vertebral body squaring (differential)

Vertebral body squaring refers to the loss of normal concavity of the anterior border of the vertebral body. It is seen in a variety of conditions, some of which are listed below. Differential diagnosis Ankylosing spondylitis Ankylosing spondylitis is the most common cause of vertebral body ...

Vertebral scalloping

Vertebral scalloping is a concavity to the posterior (or less commonly anterior) aspect of the vertebral body when viewed in a lateral projection. A small amount of concavity is normal, as is concavity of the anterior vertebral body (see vertebral body squaring). Posterior scalloping Causes of...

Vegetable and plant inspired signs

There are many signs in radiology which are vegetable- and plant-inspired, they include: Unprocessed produce bamboo spine celery stalk (disambiguation): celery stalk sign anterior cruciate ligament celery stalk metaphysis Christmas tree intestinal atresia coconut left atrium coffee bean...

Vacuum phenomenon in shoulder

Vacuum phenomenon in the shoulder refers to the presence of intra-articular gas in the shoulder joint. It is a very common occurrence, particularly in external rotation. This can cause circular or linear areas of low signal intensity on GRE MR images of the shoulder obtained with external rotati...

Twin-peak sign (twin pregnancy)

The twin peak sign (also known as the lambda (λ) sign) is a triangular appearance of the chorion insinuating between the layers of the intertwin membrane and strongly suggests a dichorionic twin pregnancy. It is best seen in the first trimester (between 10-14 weeks) 5. While the presence of a tw...

Tubal ring sign

Tubal ring sign also referred to as bagel sign or blob sign, one of the ultrasound signs of a tubal ectopic. It comprises an echogenic ring that surrounds an unruptured ectopic pregnancy. It is said to have a 95% positive predictive value (PPV) for ectopic pregnancy. Differential diagnosis It ...

Trumpeted internal acoustic meatus sign

A trumpeted internal acoustic meatus (IAM) is an indirect sign of a vestibular schwannoma and is useful in helping to differentiate between one and other cerebellopontine angle entities, especially from a meningioma which typically does not extend into the meatus and is more often associated wit...

Toothpaste sign

The toothpaste sign in spinal imaging represents an extrusion of an intervertebral disc into the epidural space. It is called after the shape of extruded material relatively to the parent disc in a sagittal plane.

Target sign (pyloric stenosis)

The target sign of pyloric stenosis is a sign seen due to hypertrophied hypoechoic muscle surrounding echogenic mucosa, seen in pyloric stenosis. This is likened to a target. See also antral nipple sign (pyloric stenosis) cervix sign (pyloric stenosis) shoulder sign (pyloric stenosis)

Tam o' Shanter sign (skull)

This imaging sign is named after the Tam o' Shanter, a Scottish hat, named after the character in Robert Burns's 1 poem of the same name. The appearances of advanced Paget disease of the skull are similar in appearance to the hat. Paget involvement of the skull, with widening of the diploic sp...

T sign (obstetrics)

The "T sign" is really the absence of a twin-peak sign (or lambda (λ) sign) and is used in ultrasound assessment of a multifetal pregnancy. It refers to the lack of chorion extending between the layers of the intertwin membrane, denoting a monochorionic pregnancy. The intertwin membrane comes t...

Sugar coating

So-called "sugar coating" or zuckerguss (German for sugar icing) refers to the appearance of diffuse linear/sheetlike leptomeningeal contrast enhancement in the brain or spinal cord due to drop metastases or leptomeningeal carcinomatosis. It is seen both as a result of CNS involvement from dista...

String sign (bones)

The string sign of parosteal osteosarcoma refers to the plain radiographic/CT appearance of a radiolucent cleavage plane between portions of the tumor and cortex of the affected bone. The tumor stalk becomes more broad-based with time, obliterating the string sign in later stages. The string si...

String of pearls sign (gastrointestinal)

The string of pearls (or beads) sign can be seen on upright or decubitus abdominal radiographs as well as on CT in patients with small bowel obstruction, increased intraluminal fluid, and slow resorption of intraluminal gas. It consists of an obliquely or horizontally oriented row of small gas ...

String of pearls sign (disambiguation)

String of pearls sign can refer to: string of pearls sign on an abdominal radiograph of fluid-filled dilated small bowel loops string of pearls sign on cerebral MRI in deep border zone infarction string of pearls sign on ultrasound in polycystic ovarian syndrome string of pearls sign for ang...

String sign (disambiguation)

The string sign may refer to: angiographic string sign gastrointestinal string sign string sign of parosteal osteosarcoma myositis ossificans string sign

Strawberry skull

Strawberry skull refers to the shape of the head on an antenatal ultrasound. Epidemiology Associations In general, strawberry skull is considered one of the non-specific 'soft markers' for abnormal fetal development. It is considered more closely associated with trisomy 18 (Edward syndrome). ...

Strawberry gallbladder

Strawberry gallbladder refers to the surface appearance (not shape) of the mucosa of the gallbladder due to multiple small collections of triglycerides and cholesterol esters within the lamina propria of the gallbladder wall (gallbladder wall cholesterolosis). Strawberry gallbladder represents...

Stipple sign (transitional cell carcinoma)

The stipple sign refers to the pointillistic end-on appearance on intravenous pyelography or retrograde pyelography of contrast material tracking into the interstices of a papillary lesion. Because the majority of transitional cell carcinomas (TCC) have a papillary configuration, the presence of...

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...

Signet ring sign (bronchiectasis)

The signet ring sign is seen in bronchiectasis when the dilated bronchus and accompanying pulmonary artery branch are seen in cross-section. The bronchus and artery should be the same size, whereas in bronchiectasis, the bronchus is markedly dilated. The signet ring analogy has also been applie...

Shiny corner sign (ankylosing spondylitis)

The shiny corner sign is a spinal finding in ankylosing spondylitis, representing reactive sclerosis secondary to inflammatory erosions at the superior and inferior endplates (corners on lateral radiograph) of the vertebral bodies which are known as Romanus lesions. Eventually, the vertebral bod...

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...

Sentinel loop

A sentinel loop is a short segment of adynamic ileus close to an intra-abdominal inflammatory process. When seen, it is usually identified on abdominal radiography. The sentinel loop sign may aid in localizing the source of inflammation. For example, a sentinel loop in the upper abdomen may ind...

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...

Saber-sheath trachea

Saber-sheath trachea refers to a 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...

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 1. However ...

Rim sign (osteonecrosis)

A rim sign can be seen in osteonecrosis 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 with...

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 1: chronic eosinophilic pneumonia organizing pneumonia (formerly bronchiolitis obliterans with organizing pneum...

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