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Low attenuation lymphadenopathy

Low attenuation lymphadenopathy refers to abnormal lymph nodes that on CT appear to have lower attenuation than other soft tissues. This category can be split into two types: cystic (necrotic) lymph nodes metastatic carcinoma (or lymphoma) infection (tuberculous or fungal) inflammatory necro...

Bright dot sign (atypical liver hemangioma)

The bright dot sign refers to the presence of a bright dot within a lesion which remains hypoattenuating on arterial and portal venous phase CT, corresponding to early nodular enhancement seen on dynamic MRI of liver hemangioma. This can be used as an indicator that the lesion in question is a...

Humpback deformity of the scaphoid

Humpback deformity of the scaphoid results from volar angulation of the proximal and distal poles of the scaphoid in the setting of scaphoid fracture through the waist 1. The dorsal component forms a 'humpback' which can be palpated. It is important to identify as it can result in a progressive...

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...

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...

Hawkins sign (talus)

The Hawkins sign describes subchondral lucency of the talar dome seen in AP view that occurs secondary to subchondral atrophy 6-8 weeks after a talar neck fracture 1. This indicates that there is sufficient vascularity in the talus, and is therefore unlikely to develop avascular necrosis of the...

Upper lobe pulmonary venous diversion

Upper lobe pulmonary venous diversion (also described as cephalisation of the pulmonary veins) reflects elevation of left atrial pressure and is an early sign of pulmonary edema. Clinical presentation The normal left atrial pressure is 5-10 mmHg. An elevation of left atrial pressure to 10-15 m...

Dinner fork deformity (wrist)

A dinner fork deformity, also known as a bayonet deformity, occurs as the result of a malunited distal radial fracture, usually a Colles fracture. The distal fragment is dorsally angulated, displaced and often also impacted. The term is descriptive, as the lateral view of the wrist is similar to...

Breast within a breast sign

The breast within a breast sign refers to the common mammographic appearance of breast hamartomas (fibroadenolipomas). Since these benign lesions are well-circumscribed and contain a mixture of fibrous, glandular and fatty tissue (just like normal breast), it is not surprising that they appear v...

Loss of the insular ribbon sign

The loss of the insular ribbon sign refers to a loss of definition of the gray-white interface in the lateral margin of the insular cortex ("insular ribbon") and is considered an early CT sign of MCA infarction. The insular cortex is more susceptible to ischemia following MCA occlusion than oth...

Infundibulum sign (pituitary)

The infundibulum sign is helpful in distinguishing an empty pituitary sella from a cystic lesion of the pituitary region 1. In the former, although the sella is enlarged, there is no mass as such and the pituitary infundibulum traverses the enlarged sella to its floor where residual pituitary ...

Continuous diaphragm sign

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

Tau sign

The tau sign represents the appearance of a persistent primitive trigeminal artery on the sagittal plane of an angiogram or on sagittal MRI images. It resembles the Greek letter τ, pronounced 'tau', and is equivalent to the modern day 'T' in the Latin alphabet. The persistent trigeminal artery ...

Leopard skin sign (white matter)

The leopard skin sign (also known as tigroid pattern or stripe sign) results from dark spots or stripes (spared perivascular white matter) within bright demyelinated periventricular white matter on T2W images. It is characteristically seen in: metachromatic leukodystrophy Krabbe disease 2 Pel...

Bare orbit sign (sphenoid wing)

The bare orbit sign, is described as a characteristic appearance of the orbit, seen when the innominate line is absent. The innominate line is a projection of the greater wing of the sphenoid, and its absence or destruction is responsible for this appearance. It is the classical frontal radiogr...

White cerebellum sign

White cerebellum sign, also called reversal sign or dense cerebellum sign, is encountered when there is a diffuse decrease in density of the supratentorial brain parenchyma, with relatively increased attenuation of the thalami, brainstem and cerebellum. This sign indicates irreversible brain dam...

Pancake brain

Pancake brain is the classical sign of alobar holoprosencephaly. It is due to fusion of the cerebral hemispheres leaving a single ventricle in its center. It is the most severe form of holoprosencephaly. It is associated with multiple facial abnormalities. See also pancake vertebra vegetable ...

Sonographic halo sign (disambiguation)

Sonographic halo sign can be useful in a number of situations: hypoechoic halo sign (also known as target or bull's eye sign) in liver metastases: used in hepatobiliary imaging, is a concerning feature for malignant lesion if the lesion is a hyperechoic liver lesion 1,2 ultrasound halo i...

Venous distension sign

The venous distension sign is a finding that may be identified on sagittal imaging of the dural venous sinuses which is said to have a diagnostic sensitivity and specificity of 94% for intracranial hypotension. The sign is positive when there is a convex inferior margin of the midportion of the...

Peribronchial cuffing

Peribronchial cuffing refers to a radiographic term used to describe haziness or increased density around the walls of a bronchus or large bronchiole seen end-on, both on plain radiographs and on CT. It is sometimes described as a "doughnut sign". When viewed tangentially, it can give the appear...

Yin-yang sign (vascular)

The yin-yang sign, also known as the 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...

Mickey Mouse sign (disambiguation)

In medical imaging, a Mickey Mouse sign or appearance has been given to imaging features that mimic Mickey Mouse when viewed from the front. It has been described in the following: anencephaly 2 progressive supranuclear palsy 1 synonymously with a finger in glove sign the flared shape of the...

Periportal halo (CT/US)

Periportal halo or periportal collar sign refers to a zone of low attenuation seen around the intrahepatic portal veins on contrast-enhanced CT or hypoechogenicity on liver ultrasound. It likely represents periportal edema, which is often used as a synonymous term. Periportal haloes may occur ar...

Coxa valga

Coxa valga describes a deformity of the hip where there is an increased angle between the femoral neck and femoral shaft. Pathology Coxa valga is often associated with shallow acetabular angles and femoral head subluxation. Etiology bilateral neuromuscular disorders, e.g. cerebral palsy ...

Endosteal scalloping

Endosteal scalloping refers to the focal resorption of the inner layer of the cortex (i.e. the endosteum) of bones, most typically long bones, due to slow-growing medullary lesions 1. It is important to note that although it is evidence of a slow non-infiltrative lesion, it does not equate to b...

Wheel within a wheel sign (hepatic candidiasis)

The wheel within a wheel sign describes one of several possible ultrasound findings of hepatic candidiasis. The finding consists of a round lesion with three layers corresponding to the following histopathological changes 2: peripheral hypoechoic area (fibrosis) middle hyperechoic area (inflam...

Sunset eye sign

The sunset eye sign (also known as the setting sun phenomenon) is a clinical phenomenon encountered in infants and young children with raised intracranial pressure (seen in up to 40% of children with obstructive hydrocephalus and 13% of children with shunt dysfunction 1). It consists of an up-...

Platyspondyly

Platyspondyly is a radiographic sign and refers to flattened vertebral bodies throughout the axial skeleton. Pathology Associations Platyspondyly can be feature of many conditions which include: severe Gaucher disease 1 metatrophic dysplasia Morquio syndrome osteogenesis imperfecta Rober...

Cloverleaf skull (craniosynostosis)

Cloverleaf skull, also known as kleeblattschädel syndrome or deformity, refers to a type of severe craniosynostosis which gives the skull a cloverleaf shape. It is very rare, with less than 130 case reports globally. It typically results from intrauterine premature closure of the sagittal, coron...

Oreo cookie sign (heart)

The Oreo cookie sign refers to the appearance of pericardial effusion on lateral radiographs of the chest. A vertical opaque line (pericardial fluid) separating a vertical lucent line directly behind the sternum (paracardial fat) anteriorly from a similar lucent vertical lucent line (epicardial ...

Water bottle sign (heart)

The water bottle sign or configuration refers to the shape of the cardiac silhouette on erect frontal chest x-rays in patients who have a very large pericardial effusion. Typically the effusion has accumulated over many weeks to months (e.g. in patients with malignancy) and the pericardium has g...

Hilum overlay sign

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

Stepladder sign (intracapsular breast implant rupture)

The stepladder sign is a sonographic sign indicating an intracapsular breast implant rupture. It is considered the most reliable ultrasonographic finding in silicone gel breast implant intracapsular rupture. It is identified as multiple, discontinuous, parallel, linear echoes in the lumen, and i...

Shortening of the cervical canal

Shortening of the uterine cervical canal as the name implies refers to an abnormal shortening of the uterine cervical length. It is considered a sign of cervical incompetence during pregnancy and can lead to premature delivery. Pathology Etiology primary (i.e. congenital/idiopathic) secondar...

Tent sign (breast)

The tent sign is a term referring to a characteristic appearance of the posterior edge of the breast parenchyma when a mass (usually an infiltrating lesion) causes its retraction and forms an inverted "V" that resembles the tip of a circus tent. The detection of a "tent sign" is facilitated by ...

Empty amnion sign

The empty amnion sign is a sonographic observation where there is the visualization of an amniotic sac without concomitant visualization of an embryo. It is an indicator of pregnancy failure regardless of the mean sac diameter and is considered to have a sufficiently high positive predictive val...

Doge cap sign (pneumoperitoneum)

The doge cap sign, also referred to as Morison pouch sign, is a radiographic sign of pneumoperitoneum. It presents as a triangular-shaped (although may also be crescentic or semicircular) gas lucency, usually bound by the 11th rib in the right upper quadrant on abdominal radiographs due to air i...

Winking owl sign (spine)

The (absent) pedicle sign, also called the winking owl sign, occurs on plain radiograph of the spine when a pedicle is absent 5. The term, winking owl sign, where the missing pedicle corresponds to the closed eye, the contralateral pedicle to the other round open eye, and the spinous process to...

Polka dot sign (vertebral hemangioma)

The polka dot sign, also known as the salt and pepper 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 hemangiomas 2. It is the axial equivalent of the corduroy sign or the...

Andersson lesion

An Andersson lesion, also known as rheumatic spondylodiscitis, refer to an inflammatory involvement of the intervertebral discs by spondyloarthritis. Epidemiology Rheumatic spondylodiscitis is a non-infectious condition that has been shown to occur in about 8% of patients with ankylosing spond...

Hummingbird sign (midbrain)

The hummingbird sign, also known as the penguin sign, refers to the appearance of the brainstem in patients with progressive supranuclear palsy (PSP). The atrophy of the midbrain results in a profile of the brainstem (in the sagittal plane) in which the preserved pons forms the body of the bir...

Cartilage interface sign

Cartilage interface sign, also referred to as double cortex sign, refers to the sonographic presence of a thin markedly hyperechoic line at the interface between the normally hypoechoic hyaline articular cartilage of the humeral head and an abnormally hypoechoic supraspinatus tendon. This arises...

Empty thecal sac sign

The empty thecal sac sign or empty sac sign is when the thecal sac appears empty on MRI of the lumbar spine, best seen on T2-weighted images. If the empty thecal sac sign is present, a diagnosis of adhesive arachnoiditis can be made. Radiographic features MRI There is usually no gadolinium c...

Claw sign (mass)

The claw sign is useful in determining that a mass arises from a solid structure rather than is located adjacent to it and distorts the outline. It refers to the sharp angles on either side of the mass, which the surrounding normal parenchyma forms when the mass has arisen from the parenchyma. ...

Viking helmet appearance

The Viking helmet appearance refers to the morphology of the lateral ventricles in the coronal plane in patients with dysgenesis of the corpus callosum. The cingulate gyrus is everted into narrowed and elongated frontal horns. An alternative name is moose head appearance. Other names include st...

Moose head appearance

The moose head appearance refers to the lateral ventricles in coronal projection in patients with dysgenesis of the corpus callosum. The cingulate gyrus is everted into narrowed and elongated frontal horns. An alternative name is the viking helmet sign. Other names include steer-horn, Texas lon...

Mother in law sign

The mother in law sign is perhaps uncharitably (depends on the mother in law I suppose) used to describe lesions that enhance early during the arterial phase and remain opacified well after the venous phase. The joke is that a mother in law comes early and stays late. It is most frequently equ...

Deep sulcus sign (chest)

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

Wasp-waist sign (spine)

The wasp-waist sign is a radiographic appearance seen in patients with Klippel Feil syndrome. It results from fusion of the vertebral bodies such that the anteroposterior diameter at the level of the affected discovertebral joint is smaller than the diameter at the superior and inferior limits o...

Hot cross bun sign (pons)

The hot cross bun sign refers to the MRI appearance of the pons when T2 hyperintensity forms a cross on axial images, representing selective degeneration of transverse pontocerebellar tracts and median pontine raphe nuclei 1. It has been described in a variety of neurodegenerative and other con...

Lambda sign (disambiguation)

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

Antral pad sign

The antral pad sign is a feature seen on a spot radiograph of the upper gastrointestinal tract obtained with orally-administered contrast material. It refers to the extrinsic impression or indentation on the posteroinferior aspect of the antrum. The impression is generally arcuate and smooth, an...

Fat ring sign (mesenteric panniculitis)

The fat ring sign (also known as a fat halo sign) describes preservation of fat around the mesenteric vessels and around soft tissue nodules on the background of diffuse fat stranding in patients with mesenteric panniculitis or mesenteric lipomas. This finding may help distinguish mesenteric p...

Kissing carotids

The term kissing carotids refers to tortuous and elongated carotid arteries which touch in the midline. They can be found in: retropharynx 2 intrasphenoid 1 within the pituitary fossa within sphenoid sinuses within sphenoid bones The significance of kissing ca...

Foamy esophagus sign

Foamy esophagus is an appearance seen on a single contrast barium study in Candida esophagitis with associated scleroderma/achalasia (stasis). Pathology Pathophysiologic basis of the foamy esophagus is uncertain. Stasis is a predisposing factor. Foam is produced directly by the fungal organism...

Melting ice cube sign (lungs)

The melting ice cube sign describes the resolution of pulmonary hemorrhage following pulmonary embolism (PE). When there is pulmonary hemorrhage without infarction following PE, the typical wedge-shaped, pleural-based opacification (Hampton's hump) resolves within a week while preserving its t...

Hampton hump

Hampton hump refers to a dome-shaped, pleural-based opacification in the lung most commonly due to pulmonary embolism and lung infarction (it can also result from other causes of pulmonary infarction (e.g. vascular occlusion due to angioinvasive aspergillosis). Although uncommon, it can be seen...

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.

Putty kidney

A putty kidney refers to a pattern of renal calcification associated with renal tuberculosis conventionally described on plain radiography. The calcification can be large, round or oval, dense or very homogeneous and ground glass-like, representing calcified caseous tissue within dilated calyces...

Trident hand

A trident hand is a description where the hands are short with stubby fingers, with a separation between the middle and ring fingers. It may be used for the clinical appearance of the hand or the appearance on imaging, particularly reminiscent of a trident on fetal ultrasound 5. It can be seen ...

Celery stalk metaphysis

Celery stalk metaphysis refers to a plain film appearance of the metaphyses in a number of conditions characterized by longitudinally aligned linear bands of sclerosis. They are seen in: congenital infections congenital rubella congenital syphilis congenital cytomegalovirus (CMV) osteopathi...

Absent nasal bone

In a fetal sonographic assessment, an absent nasal bone is a feature that can sometimes be used as a surrogate marker for fetal aneuploidy. Radiographic assessment Antenatal ultrasound It is assessed on a midline sagittal view. In this section, the nasal bone is often seen as a bright echogen...

Keyhole sign (posterior urethral valves)

The keyhole sign is an ultrasonographic sign seen in boys with posterior urethral valves. It refers to the appearance of the proximal urethra (which is dilated) and an associated thick walled distended bladder which on ultrasound may resemble a keyhole.

Hypercontracting (nutcracker) esophagus

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

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...

Subcoracoid triangle sign

The subcoracoid triangle sign refers to the obliteration of the fat triangle between the coracohumeral ligament (superiorly), coracoid process / coracobrachialis (anterosuperiorly) and glenohumeral joint capsule (posteroinferiorly). It is considered a specific but not sensitive sign for adhesive...

Floating aorta sign

The floating aorta sign refers to displacing the abdominal aorta away from the vertebral column. It is a radiographic sign of retroperitoneal masses and most commonly suggests a lymphoma diagnosis. Rarely, other diseases with diffuse retroperitoneal mass, such as Castleman's disease, primary re...

Butterfly vertebra

Butterfly vertebra (also sometimes known as a sagittal cleft vertebra or anterior rachischisis) is a type of vertebral anomaly that results from the failure of fusion of the lateral halves of the vertebral body because of persistent notochordal tissue between them. Pathology Butterfly vertebra...

Cobra head sign (ureter)

The cobra head sign, also known as the 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 ureterocele. The cobra head appearance indicates an uncomplicated ureterocele. During an excretory phase of an intr...

Cone-shaped cecum (differential)

A cone-shaped cecum refers to a loss of the normal rounded appearance of the cecum, which instead becomes narrow and cone-shaped with the apex pointing towards the base of the appendix. It is encountered in a number of conditions including: inflammatory infective blastomycosis amoebiasis Ye...

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 visualize the region, including: MRI, CT, ultrasound and endoscopic retrograde cholangiopancreatography (ERCP). In ge...

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 gas (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 ...

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. It is mea...

High-attenuation crescent sign

The high-attenuation crescent sign, also called the hyperdense crescent sign, represents an acute hematoma within either the mural thrombus or the aneurysm wall, especially when detected on unenhanced CT scans. It is a specific sign of impending abdominal aortic aneurysm (AAA) rupture or so-call...

Swischuk line

The Swischuk line is helpful in differentiating pathological anterior displacement of the cervical spine from physiological displacement, termed pseudosubluxation. Measurement the line is drawn from anterior aspect of posterior arch of C1 to anterior aspect of posterior arch of C3 the anterio...

Ivory vertebra

The ivory vertebra (also known as ivory vertebra sign) sign refers to the diffuse and homogeneous increase in opacity of a vertebral body that otherwise retains its size and contours and with no change in the opacity and size of adjacent intervertebral discs. Pathology Etiology The cause for ...

J-shaped sella

A J-shaped sella is a variant morphology of the sella turcica, whereby the tuberculum sellae is flattened, thus forming the straight edge of the "J". The dorsum sellae remains rounded and forms the loop of the "J". Differential diagnosis Differential diagnosis for a J-shaped sella includes 1,2...

Porcelain gallbladder

Porcelain gallbladder refers to extensive calcium encrustation of the gallbladder wall. The term has been used to emphasize the blue discolouration and brittle consistency of the gallbladder wall at surgery but is often an incidental finding on multiple different imaging modalities. Clinical p...

Holly leaf sign

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

Thymic wave sign

Thymic wave sign refers to the indentation of the normal thymus in young children by the ribs, resulting in a wavy border on chest radiograph. There are at least 3 described signs relating to a normal thymus in infants; thymic sail sign, thymic notch sign and thymic wave sign. Being able to id...

Small bowel feces sign

The small bowel feces sign can be observed on abdominal CT. 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 is low...

Fallen fragment sign

The fallen fragment sign refers to the presence of a bone fracture fragment resting dependently in a cystic bone lesion. This finding was once thought to be pathognomonic for a simple (unicameral) bone cyst following a pathological fracture, although it has occasionally been reported with other ...

Misty mesentery sign

Misty mesentery sign is a sign on CT in which mesenteric fat with increased attenuation mimics mistiness. Just as with fat stranding elsewhere, a number of processes can lead to the appearance including infiltration by inflammatory cells, edema, lymphatic accumulation, hemorrhage, tumor infiltra...

Throckmorton sign (pelvis)

Throckmorton sign, also known as John Thomas sign, refers to when the penis points in the direction of unilateral disease, typically of the pelvis or hip. Throckmorton sign is a slang term used humorously by medical students and residents. According to the first serious study of the sign publ...

Cecal bar sign (acute appendicitis)

The cecal bar sign is a secondary sign in acute appendicitis. It refers to the appearance of inflammatory soft tissue at the base of the appendix, separating the appendix from the contrast-filled cecum. See also arrowhead sign

Arrowhead sign (cecum)

The arrowhead sign refers to the focal cecal thickening centered on the appendiceal orifice, seen as a secondary sign in acute appendicitis. The contrast material in the cecal lumen assumes an arrowhead configuration, pointing at the appendix. The arrowhead sign is applicable only when enteri...

Loss of normal half-moon overlap sign (shoulder)

Loss of half-moon overlap sign, which does not really roll off the tongue, is a sign of posterior shoulder dislocation on AP radiographs. On a normal true anteroposterior image, there is a half-moon overlap between the humeral head and the glenoid. In a posteriorly dislocated shoulder, there i...

Trough line sign

The trough line sign is a sign of posterior shoulder dislocation on AP shoulder radiograph. Pathology In a posterior dislocation, the anterior aspect of the humeral head becomes impacted against the posterior glenoid rim. With sufficient force, this causes a compression fracture on the anteri...

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.

Comet tail sign (chest)

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

Thumbprinting

Thumbprinting is a radiographic sign of large bowel wall thickening, usually caused by edema, 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 Etiology Th...

Reversed halo sign (lungs)

The reversed halo sign, also known as the atoll sign, on chest CT 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. The consolidation should be at least 2 mm in thickness 8. The sign ...

MCA dot sign (brain)

The middle cerebral artery (MCA) dot sign, also known as the Sylvian fissure sign, is seen on non-contrast brain CT and represents the cross-sectional M2 equivalent of the hyperdense MCA sign. Rather than imaging a length of middle cerebral artery (typically the M1 segment), the dot sign represe...

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