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.

903 results found
Article

Hemithorax white-out (differential)

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

Hennebert sign (inner ear)

The Hennebert sign describes a positive fistula test without clinical evidence of middle ear or mastoid disease. It is associated with congenital syphilis and may also be present in Ménière disease. It has been postulated that the vestibular stimulation is mediated by fibrous bands between foot...
Article

Hepatic edge sign

The hepatic edge sign is a radiographic sign of pneumoperitoneum seen on a supine plain abdominal radiograph. It is represented by a cigar-shaped pocket of free air in the subhepatic region, which tracks superomedial following the contour of the liver.
Article

Hide-bound sign (bowel)

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

High-attenuation crescent sign

The high attenuating 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-called contained rupture. Pathology The hyper...
Article

Higoumenakis sign (clavicle)

The Higoumenakis sign is the unilateral enlargement of the sternal end of the clavicle in patients with late congenital syphilis. It was originally described as a clinical sign on physical examination but can also be recognized on chest radiograph 5. Pathology Treponema pallidum becomes readil...
Article

Hilum convergence sign

The hilum convergence sign is a useful chest radiograph sign to help distinguish a bulky hilum due to pulmonary artery dilatation from a juxtahilar mass/nodal enlargement.  If pulmonary artery branches are visible through the opacity and converge towards the waist of the heart (positive hilum c...
Article

Hilum overlay sign

The hilum overlay sign is useful in differentiating cardiac enlargement from a mediastinal mass. It refers to an abnormally dense hilum on frontal chest radiograph with preserved visualization of the hilar vessels.   If a mass arises from the hilum, the normal pulmonary vessels (interlobar arte...
Article

Hitchhiker thumb deformity

Hitchhiker thumb deformity, also known as Z-thumb or duckbill thumb, refers to: flexion of the metacarpophalangeal joint and extension of the distal interphalangeal joint of the thumb It is used to both describe the appearance of the thumb on physical examination and also the corresponding ra...
Article

Hockey stick sign (Creutzfeldt-Jakob disease)

The hockey stick sign refers to the hyperintense signal involving the pulvinar and dorsomedial thalamic nuclei bilaterally on FLAIR, in cases of variant Creutzfeldt-Jakob disease, which has the shape of a hockey stick. See also pulvinar sign (Creutzfeldt-Jakob disease) hockey stick sign (thyr...
Article

Hockey stick sign (disambiguation)

The hockey stick sign can refer to a variety of different signs and appearances: hockey stick sign (thyroid hemiagenesis) hockey stick sign (Creutzfeldt-Jakob disease) hockey stick sign (ureters)
Article

Hockey stick sign (thyroid hemiagenesis)

Hockey stick sign has been used to describe the appearance of the thyroid gland in cases of thyroid hemiagenesis when investigated with thyroid scan (Tc-99m)​ 1. The unilateral lobe and isthmus make a shape reminiscent of a hockey stick.  See also hockey stick sign (Creutzfeldt-Jakob disease)
Article

Hoffman-Rigler sign (heart)

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

Hole within a hole sign

The hole within a hole sign or bevelled edge sign describes one classic appearance of lytic skull lesions in patients with eosinophilic granuloma. The bevelled edge of the defects indicates asymmetrical destruction of both inner and outer tables of the skull, giving the appearance of two overlap...
Article

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.
Article

Holman-Miller sign (maxillary sinus)

The Holman-Miller sign (also called the antral sign) is seen in juvenile nasopharyngeal angiofibroma; it refers to the anterior bowing of the posterior wall of the maxillary antrum as seen on a lateral skull radiograph or cross-sectional imaging 1,2. This is a non-specific sign that can be prod...
Article

Honda sign (sacrum)

The Honda sign (H sign / H pattern) is a term used to describe the appearances of bilateral sacral insufficiency fractures on a radioisotope bone scan. Radiographic features Sacral insufficiency fractures are usually vertically through the sacral alae, paralleling the sacroiliac joint, often w...
Article

Honeycombing (lungs)

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

Hot cross bun sign (pons)

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

Hot nose sign

The hot nose sign refers to increased perfusion in the nasal region on nuclear medicine cerebral perfusion studies in the setting of brain death. The absent or reduced flow in the internal carotid arteries is thought to lead to increased flow within the external carotid arteries and subsequent i...
Article

Howship-Romberg sign

The Howship-Romberg sign refers to obturator nerve neuropathy due to compression of the obturator nerve by an obturator hernia. Patients present with pain and paraesthesia along the inner aspect of the thigh, down to the knee. History and etymology Named after Moritz Heinrich Romberg (1795-187...
Article

H-shaped vertebra

H-shaped vertebrae, also known as Lincoln log vertebrae, are a characteristic finding of sharply delimited central endplate depression, classically seen in approximately 10% of patients with sickle-cell anemia, and results from microvascular endplate infarction (figure 1) 3. It may occasionally...
Article

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...
Article

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...
Article

Hurley stick ureters

Hurley stick ureters refers to the widening of the distal ureters with abnormal lateral and upward curvature instead of normal oblique intramural course in excretory urogram. The appearance of distal ureter resembles hurley stick used in the traditional Iris game of hurling. This is seen in blad...
Article

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...
Article

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...
Article

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...
Article

Hutchinson triad

Hutchinson triad of congenital syphilis consists of: dental abnormalities interstitial keratosis deafness History and etymology Named after Sir Johnathan Hutchinson, English surgeon, ophthalmologist and pathologist (1828 - 1913). Hutchinson triad should not be confused with: Hutchinson pu...
Article

Hydatid cyst signs

There are several signs of hydatid cysts seen associated with hydatid disease: cumbo sign: air is seen between the pericyst and the laminated membrane of the cyst  serpent sign: internal rupture of the cyst with collapse of membranes of the parasite into the cyst water lily sign: endocyst flo...
Article

Hyoid elevation

Hyoid elevation on a modified barium swallow study indicates that the pharyngeal muscles are contracting appropriately. Radiographic features Modified barium swallow With real time fluoroscopy (or videofluoroscopy) during the act of swallowing, the larynx moves upward and forward when there i...
Article

Hyperattenuating ring sign in epiploic appandagitis

The hyperattenuating ring sign is a sign that has been described with epiploic appendagitis and refers to a hyperattenuating ring of visceral peritoneum surrounding an inflamed epiploic appendage 1. On CT it can be seen as a ring of soft tissue surrounding a region of fat attenuation adjacent to...
Article

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")...
Article

Hyperdense MCA sign (brain)

The hyperdense MCA 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 minutes after the event 1....
Article

Hypomelanotic macules

Hypomelanotic macules are otherwise known as ash-leaf spots due to their resemblance to Sorbus aucuparia, or mountain-ash, leaves. These macules have a strong association with tuberous sclerosis and are often multiple and present in the vast majority of individuals with the condition (up to 97% ...
Article

Ice cream cone sign (disambiguation)

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

Ice pick sign

The ice pick sign is a smooth tapered narrowing of the upstream pancreatic duct distal to the pancreatic lesion seen frequently in benign pancreatic lesions such as a focal autoimmune pancreatitis, this is due to the extrinsic narrowing of the duct secondary to periductal fibrosis and inflammati...
Article

Imaging psoas sign (spondylodiskitis)

The imaging psoas sign is an MRI finding specific for spondylodiskitis and is seen as T2 hyperintensity in the psoas major muscle. The sign has a high sensitivity (92%) and specificity (92%) for spondylodiskitis and in the clinical context of a suspected infective process of the spine supports c...
Article

Inanimate object inspired signs

Inanimate object inspired signs are numerous with many radiographic appearances likened to bottles, hooks, items of clothing, weapons etc.  They are listed below in the 'related articles' section. 
Article

Incomplete border sign (chest)

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

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 ...
Article

Interface sign (HRCT chest)

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

Interstitial line sign

The interstitial line sign is an ultrasound finding in interstitial ectopic pregnancy. It is an echogenic line from the mass to the endometrial echo complex. Reportedly it has high sensitivity (80%) and specificity (98%).
Article

Intrabiliary rupture of hepatic hydatid cyst

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

Intracranial arterial beading

Intracranial arterial beading represents alternating areas of constriction in the intracranial arteries that gives the appearance of beads strung together. Differential diagnosis The various conditions where this may be seen are: cerebral vasculitis radiation therapy cerebral vasospasm post...
Article

Intradecidual sac sign

Intradecidual sac sign (IDSS) is a useful feature in identifying an early intrauterine pregnancy (IUP) as early as 25 days of gestation 1. The threshold level (earliest one can see the sign) is 24 days of gestation and the discriminatory level (one should always see the sac) is 47 days. As per t...
Article

Intrahepatic arterioportal shunt

Intrahepatic arterioportal shunts represent abnormal flow between the portal venous system and a hepatic arterial system within the liver. They can be a reversible cause of portal hypertension. Clinical presentation Clinical features will depend on the size and other underlying pathology. Smal...
Article

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...
Article

Intramural fat of the urinary bladder

Intramural fat of the urinary bladder is an occasional benign finding on CT/MRI.  Epidemiology Incidence of this finding on histopathological studies is up to 4%. Published radiological and pathological cohorts both report a male predominance. Clinical presentation Incidental asymptomatic fi...
Article

Inverted Mercedes-Benz sign

The inverted Mercedes-Benz sign refers to the shape taken on by a spinal subdural hematoma on axial imaging at the level of the denticulate ligaments, best visualized on MRI. A pair of denticulate ligaments and the dorsal septum constitute the three radiating spikes of the sign, while blood expa...
Article

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...
Article

Inverted "V" sign (pneumoperitoneum)

The inverted "V" sign, also known as the lateral umbilical ligament sign, is a sign of pneumoperitoneum manifested by the visualization of an inverted "V"  shape in the pelvis on supine view of abdominal radiographs. It represent free gas outlining the lateral umbilical ligaments. In infants, th...
Article

Inverted "V" sign (spinal cord)

The inverted "V" sign, also known as the inverted rabbit ears sign, is a radiological sign described in subacute combined degeneration of the spinal cord​. It refers to the appearance of the spinal cord on axial MRI slices 1-3. On these slices in a patient with subacute combined degeneration of...
Article

Ivory phalanx

Ivory phalanx is a finding of increased radiodensity of an entire phalanx as a result of periosteal and endosteal bone formation. This sign is a unique and specific radiographic manifestation of psoriatic arthritis, yet it is uncommon and thus of low sensitivity. Nevertheless, it is of particul...
Article

Ivory vertebra sign

The ivory vertebra sign refers to 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 an ivory vertebra depends on the age of...
Article

Ivy sign (brain)

The ivy sign refers to the MRI appearance of patients with moyamoya disease or moyamoya syndrome. Prominent leptomeningeal collaterals result in vivid contrast enhancement and high signal on FLAIR due to slow flow. The appearance is reminiscent of the brain having been covered with ivy. Differe...
Article

Jack and Jill lesion

The Jack and Jill lesion refers to simultaneous bucket handle tears of the medial and lateral menisci with intercondylar notch displacement of the fragments which appear as the quadruple sign on coronal MRI images.
Article

Jejunoileal fold pattern reversal

Jejunoileal fold pattern reversal (a.k.a. jejunisation of the ileum) is one of the signs of celiac disease, and is seen on small bowel follow-through studies as well as CT. The pattern is one of increased number of ileal folds and reduced number of jejunal folds 1,2, and is considered positive w...
Article

Jellyfish sign (ultrasound)

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

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...
Article

J sign (shoulder)

The J sign refers to the appearance of the inferior glenohumeral ligament in the presence of humeral avulsion of the glenohumeral ligament (HAGL lesion) as well as in the less common glenoid avulsion of the glenohumeral ligament (GAGL lesion). Radiographic features MRI The normal U-shaped inf...
Article

Juxtaphrenic peak sign

The juxtaphrenic peak sign, also known as diaphragmatic tenting or Kattan sign, refers to the peaked or tented appearance of a hemidiaphragm which can occur in the setting of lobar collapse. It is caused by retraction of the lower end of diaphragm at an inferior accessory fissure (most common 1)...
Article

Kayser-Fleischer rings

Kayser-Fleischer rings, sometimes shortened to K-F rings, are caused by copper deposition in the cornea and are a specific, clinical sign of Wilson disease. Clinical presentation They are usually brown or dark reddish in color. Early on they may need a slit lamp to be visible before they becom...
Article

Kernohan phenomenon

Kernohan notch phenomenon is an imaging finding resulting from extensive midline shift due to mass effect, resulting in indentation in the contralateral cerebral crus by the tentorium cerebelli. This has also been referred to as Kernohan-Woltman notch phenomenon and false localizing sign. Clini...
Article

Kerr kink

The Kerr kink is a sign of renal tuberculosis. Scarring in the adjacent tissues due to chronic inflammation leads to a sharp kink at the pelviureteric junction (PUJ). History and etymology William "Bill" K Kerr, a Canadian urologist, described his eponymous sign in 1967 3.
Article

Keyhole sign (intracapsular breast implant rupture)

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

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.
Article

Kidney sweat sign

The kidney sweat sign refers to the presence of thin, hypoechoic, extracapsular fluid collections around kidneys in renal failure patients. This fluid is thought to represent perirenal edema. It can be appreciated on ultrasound, CT and MRI.  Differential diagnosis perirenal hematoma perirenal...
Article

Kirklin complex

The Kirklin complex is a combination of the Carman meniscus sign associated with a radiolucent semicircular zone surrounding the elevated ridge of the ulcer. This complex is seen in cases of gastric adenocarcinoma on barium studies. History and etymology Byrl Raymond Kirklin, (1888-1957 2) an ...
Article

Kirklin sign

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

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...
Article

Kissing carotids

The term kissing carotids refers to tortuous and elongated vessels 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 carotids is two-fold: may mimic intrase...
Article

Kissing ovaries sign

The kissing ovaries sign refers to the appearance seen when both ovaries are located in close proximity or are touching each other in the pouch of Douglas, usually due to pelvic adhesions, and may be seen on ultrasound, CT or MRI. This sign is most frequently associated with the severe form of ...
Article

Knuckle sign (pulmonary embolism)

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

Lambda sign (disambiguation)

There are a number of lambda signs: lambda sign of twin pregnancy lambda sign of sarcoidosis
Article

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
Article

Lateral crescent sign (inguinal hernia)

The lateral crescent sign is a useful diagnostic sign of a direct inguinal hernia on CT scan, the hernia causing compression and lateral displacement of the inguinal canal contents (ductus deferens, testicular vessels, fat, etc.) to form a semicircle of tissue that resembles a moon crescent seen...
Article

Lateral femoral notch sign (knee)

The (deep) lateral femoral notch sign describes a depression on the lateral femoral condyle at the terminal sulcus, a junction between the weight-bearing tibial articular surface and the patellar articular surface of the femoral condyle. It is occasionally referred to as a deep sulcus sign, not ...
Article

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 or MRI. There is a complete loss of the haustral markings in the diseased segment of the colon, appearing smooth-walled and cylindrical.  This...
Article

Leaping dolphin sign

The leaping dolphin sign (also known as the diaphragm muscle slip sign) may be seen in pneumoperitoneum on a supine abdominal radiograph. It represents the outlining of the diaphragmatic muscle slips by free intraperitoneal gas and usually requires a moderate to large volume of pneumoperitoneum ...
Article

Lemon sign

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

Lentiform fork sign (basal ganglia)

The lentiform fork sign has been described on MRI and is seen as bilateral symmetrical hyperintensities in the basal ganglia surrounded by a hyperintense rim delineating the lentiform nucleus. It has been postulated to result from metabolic acidosis due to any cause 1, e.g. end stage renal dise...
Article

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 Pelizaeus-Merzbacher ...
Article

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...
Article

Licked candy stick appearance (bones)

The term licked candy stick appearance refers to tapering of the tips of the metacarpal bones, metatarsal bones, phalanges or clavicles and is usually associated with: psoriatic arthropathy rheumatoid arthritis leprosy neuropathic joint
Article

Light bulb sign (hepatic hemangioma)

The light bulb sign of a hepatic hemangioma is a feature than can be seen on MRI imaging with a classic hepatic hemangioma. This refers to marked hyperintensity seen on heavily T2 weighted sequences that has been likened to a glowing light bulb. See also light bulb sign - shoulder light bulb ...
Article

Light bulb sign (pheochromocytoma)

The light bulb sign of an adrenal pheochromocytoma is an MRI feature of this tumor. It refers to marked hyperintensity on T2 weighted sequences, however, this finding is neither sensitive nor specific and pheochromocytomas are more often heterogeneous with intermediate or high T2 signal intensit...
Article

Lightbulb sign (shoulder dislocation)

The lightbulb sign refers to the abnormal AP radiograph appearance of the humeral head in posterior shoulder dislocation. When the humerus dislocates it also internally rotates such that the head contour projects like a lightbulb when viewed from the front 1. See also light bulb sign (hepatic...
Article

Lincoln sign on bone scintigraphy

Lincoln sign on bone scintigraphy (also known as black beard sign) is one of the signs of Paget disease on the radionuclide bone scan when the disease involves the mandible. The sign might be seen when the extensive mandibular involvement with Paget disease results in the uptake of the radiotrac...
Article

Linguine sign (breast)

Linguine sign is one of the imaging signs of intracapsular rupture of a breast implant. After implantation of a silicone or saline breast implant, a fibrous capsule (scar) forms around the implant shell. In an intracapsular rupture, the contents of the implant are contained by the fibrous scar,...
Article

Lipohemarthrosis

Lipohemarthrosis results from an intra-articular fracture with escape of fat and blood from the bone marrow into the joint, and is most frequently seen in the knee, associated with a tibial plateau fracture or distal femoral fracture; rarely a patellar fracture. They have also been described in ...
Article

Liver overlap sign

The liver overlap sign can be seen in sigmoid volvulus wherein the sigmoid loop is seen, usually on an abdominal radiograph, ascending to the right upper quadrant and projecting over the liver shadow. In one study of 21 patients with confirmed sigmoid volvulus, the sign was present in 9 patient...
Article

Locked facet joint

Locked facet joint is a type of facet joint dislocation that results from jumping of the inferior articular process over the superior articular process of the vertebra below and becomes locked in the position. It can be unilateral or bilateral. Radiographic features Plain radiograph The tip ...

Updating… Please wait.

 Unable to process the form. Check for errors and try again.

 Thank you for updating your details.