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.

975 results found
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Girdlestone procedure

The Girdlestone procedure (also known as a femoral head ostectomy or Girdlestone resection arthroplasty) is an excision arthroplasty of the hip. The procedure inevitably results in limb shortening. Indications  peri-prosthetic infection aseptic loosening recurrent dislocation failed interna...
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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...
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Goblet sign (ureter)

The goblet sign, also known as the champagne glass sign, refers to the appearance of the ureter when it is focally dilated by an intraluminal mass. It is best seen when the ureter is opacified by retrograde contrast (retrograde ureterogram). Presence of this sign indicates the pathology to be ch...
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Golden arches sign (knees)

The Golden arches sign is a nuclear medicine sign often seen on bone scan in patients with total knee prosthesis. The femoral condylar prosthesis results in two central photopenic regions with two 'hot' arches formed around the periprosthetic region. This finding is non-specific and may sugges...
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Golden S-sign (lung lobe collapse)

The Golden S-sign is seen on both PA chest radiographs and on CT scans. It is named because this sign resembles a reverse S shape, and is therefore sometimes referred to as the reverse S-sign of Golden. Although typically seen with right upper lobe collapse, the S-sign can also be seen with the...
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Grey cortex sign (stress fracture)

The grey cortex sign was described as an early sign of stress (fatigue) fractures on plain radiographs and refers to subtle ill-definition/lucency of the cortex at the site of microfracture. However, plain radiography is insensitive (~25%, range 15-25%) for the detection of early-stage injuries....
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Grey Turner sign

The Grey Turner sign refers to the clinical finding of atraumatic flank ecchymosis, which is occasionally associated with retroperitoneal hemorrhage, classically due to hemorrhagic pancreatitis 2. It is thought to occur when blood extravasates from the posterior pararenal space and crosses throu...
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Griesinger sign (mastoid)

The Griesinger sign refers to edema of the postauricular soft tissues overlying the mastoid process as a result of thrombosis of the mastoid emissary vein. It is a complication of acute otomastoiditis and may be associated with dural sinus occlusive disease (DSOD). It is said to be a pathognomon...
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Gull-wing appearance (phalanges)

The gull-wing appearance, also known as seagull erosions or sawtooth appearance, is classically seen in erosive osteoarthritis, typically on posteroanterior radiographs of the hands, although has also been reported in psoriatic and rheumatoid arthritis. These erosions more commonly occur at the ...
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Gut signature sign

The gut signature sign is an ultrasound term used to describe the appearance of the gastrointestinal wall. Radiographic features  Ultrasound The bowel wall has five layers, composed of alternating hyperechoic and hypoechoic appearances. Anatomically these layers are as follows (innermost to o...
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Guttman test (larynx)

The Guttman test is a clinical test relating to the function of the larynx. In normal subjects, frontal pressure on the thyroid cartilage lowers the tone of voice produced and lateral pressure produces a higher tone of voice. The opposite is true with paralysis of the cricothyroid muscle.
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Hematocrit effect

The hematocrit effect with fluid-fluid levels is the result by layering of heavier cellular elements of blood located dependent to a liquid supernatant. It can be seen on CT or MRI. It is most frequently seen in the setting of anticoagulation therapy or coagulopathy. See also signal flare phen...
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Hemorrhage exclusion sign (prostate)

The hemorrhage exclusion sign can be a useful MRI finding following prostate biopsy. Pathology The normal prostate produces high concentrations of citrate, which among other properties, acts as an anticoagulant 1. As tumor cells are dysfunctional, they will produce lower levels of citrate than...
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Hemosiderin cap sign

The hemosiderin cap sign refers to an MR imaging feature in some spinal tumors where a cap of T2 hypointense hemosiderin is above and/or below the tumor due to previous hemorrhage.  It is most often associated with spinal cord ependymomas (20-33% of cases) 1. It may also be seen in hemangioblas...
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Hair on end sign (mnemonic)

The hair on end sign refers to a radiographic appearance of the diploic space of the skull vault which results from a thickening of trabeculae as the diploic space expands. These trabeculae are perpendicular in orientation, interspersed by radiolucent marrow hyperplasia along with skull vault. ...
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Hairy kidney sign (Erdheim-Chester disease)

The hairy kidney sign refers to the soft tissue ring of perirenal infiltration seen on cross-sectional imaging studies in Erdheim-Chester disease, and is considered to be pathognomonic of this disease. The ‘‘hairy’’ description refers to the associated thickening of the bridging perirenal septa ...
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Hairy pleural plaque

Hairy pleural plaques are a manifestation of asbestos-related disease. They arise from the visceral pleura, typically from an interlobar fissure. The hairiness stems from short radially-oriented linear regions of fibrosis extending from the plaque into the adjacent lung parenchyma. Compared to ...
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Halberd pelvis

A halberd pelvis refers to a pathognomonic appearance of the pelvis seen in metatropic dysplasia, a rare form of spondyloepimetaphyseal dysplasia. hypoplastic ilia with narrow sacrosciatic notches horizontal acetabular roofs with small associated notches superior to their lateral borders prom...
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Halo sign (chest)

The halo sign in chest imaging is a feature seen on lung window settings, ground glass opacity surrounding a pulmonary nodule or mass and represents hemorrhage. It is typically seen in angioinvasive aspergillosis. Pathology Histopathologically, it represents a focus of pulmonary infarction sur...
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Halo sign (osseous)

The Halo sign in bone imaging refers to the presence of a hyperintense rim around an osseous lesion on T2-weighted MRI, which is an indicator of a metastatic lesion 1.
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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). While a pulmonary embolism is expe...
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Hampton line

The Hampton line is a thin millimetric radiolucent line seen at the neck of a gastric ulcer in barium studies (profile view), indicating its benign nature. It is caused by a thin line of mucosa overhanging the ulcer's crater. History and etymology It was originally described by Aubrey Otis Ham...
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Hanging noose sign

Hanging noose sign in obstetric imaging is a rarely described but classical finding of a true umbilical cord knot. It demonstrates a transverse section of the umbilical cord surrounded by a loop of umbilical cord and changes in the pressure of the knot can be demonstrated with the fetal movement...
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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...
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Harrison sulcus

The Harrison sulcus or Harrison groove refers to a groove at the lower end of the rib cage seen in young children/infants with abnormally weak bones (e.g. rickets) or chronic respiratory disease (e.g. severe asthma). The lower chest is drawn in with flaring of the rib margin. The exact cause is ...
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Hatchet sign (ankylosing spondylitis)

Hatchet sign refers to the limited erosion of the lateral aspect of the humeral head that produces a hatchet-shaped deformity. This finding is typically associated with ankylosing spondylitis. In the absence of osteoporosis and the presence of sclerosis, this sign helps to differentiate it from...
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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...
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Haystack sign (pneumomediastinum)

The haystack sign on chest radiographs in pediatric patients is indicative of pneumomediastinum. The pediatric heart is surrounded above and below with gas, giving it an appearance of a haystack from Monet's paintings. 
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Head cheese sign (lungs)

The head cheese sign refers to a juxtaposition of regions with three (or sometimes more) different densities/regions of different attenuation within the lungs: ground-glass opacities (high attenuation) mosaic attenuation pattern (low attenuation) normal lung tissue (normal attenuation) A mix...
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Heel pad sign

Increased heel pad thickness, also known as the heel pad sign, is seen in a number of conditions and relates to an increase in the soft-tissue thickness of the heel pad on lateral ankle radiographs.   The heel pad should normally be <25 mm 1,2. However, in certain pathological situations, this ...
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Hellmer sign

Hellmer sign is a radiographic finding depicting medial displacement of the lateral edge of the liver from the peritoneal wall. It was originally described as a pathognomonic sign of ascites. However, this displacement can also be caused by intraperitoneal fat, extraperitoneal free fluid or a ma...
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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...
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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...
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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.
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Hide-bound sign (bowel)

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

Hildreth sign describes pain relief with application of a proximal tourniquet in patients with a glomus tumor 1. The rationale is that ischemia will decrease the size of the tumor, as these tumors are highly vascular. The sign is reportedly very sensitive and specific for glomus tumor, with a se...
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Hilum convergence sign

The hilum convergence sign is a useful chest radiograph sign to distinguish the cause of a bulky hilum as due to pulmonary artery dilatation or to a juxtahilar mass, including nodal enlargement.  If pulmonary vessels appear to converge centrally towards the lateral margin of the abnormal 'bump'...
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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...
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Hitchhiker thumb deformity

Hitchhiker thumb deformity is a musculoskeletal manifestation of rheumatoid arthritis presenting in the thumb, with the combination of: flexion of the metacarpophalangeal (MCP) joint hyperextension of the interphalangeal (IP) joint Terminology Hitchhiker thumb deformity, also known as Z-thum...
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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...
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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)
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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)
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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...
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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...
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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.
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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...
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Honda sign (sacrum)

The Honda sign (H sign / H pattern) is a term used to describe the appearance 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 wi...
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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, peripheral and basal in distribution. They can be subdivided into: microcystic honeycombing macrocystic honeycombing ...
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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 pontocerebellar tracts. It has been described in a variety of neurodegenerative diseases 1: multiple system atrophy (MSA) spinocerebellar...
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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...
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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 paresthesia along the inner aspect of the thigh, down to the knee. History and etymology Named after Moritz Heinrich Romberg (1795-1873...
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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 disease, and results from microvascular endplate infarction (figure 1) 3. It may occasionall...
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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...
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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...
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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...
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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...
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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...
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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...
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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...
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Hydatid cyst signs

There are numerous named imaging signs of hydatid cysts in echinococcal infection. There is considerable variability in the naming and definition of many of the signs in the literature. In general, the signs demonstrate the presence of laminated cyst membranes in various morphologies within a la...
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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...
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Hyperattenuating ring sign (epiploic appendagitis)

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")...
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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....
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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% ...
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Ice cream cone sign (disambiguation)

The ice cream cone sign may refer to: ice cream cone sign (middle ear ossicles) ice cream cone sign (vestibular schwannoma)
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Ice cream cone sign (vestibular schwannoma)

The ice cream cone sign refers to the appearance of a medium-sized (1.5 to 3.0 cm) vestibular schwannoma. The intracanalicular component represents the cone and the cerebellopontine angle (CPA) (cisternal) component representing the ice cream ball. See also ice cream cone sign (middle ear ossi...
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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...
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Ilioischial line

The ilioischial line, also known as the Köhler line, is a radiologic feature seen in the AP pelvis view and serves to assess the posterior acetabular column 1-4. Measurement The ilioischial line takes its course along the lateral border of the obturator foramen to the medial border of the ilia...
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Iliopectineal line

The iliopectineal line is seen in the AP view of the pelvis and serves to evaluate the anterior acetabular column 1,2. Measurement The iliopectineal line is a curvilinear line running from the iliosacral joint along the medial border of the iliac wing and the superior border of the superior pu...
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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...
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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. 
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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...
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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.
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Interpeduncular angle

The interpeduncular angle is defined as the angle formed by the posterior half of the cerebral peduncles on axial images. The interpeduncular angle has been proposed as a sensitive and specific measure of intracranial hypotension (reduced) and progressive supranuclear palsy (PSP) (increased)1,2....
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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%).
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Intrabiliary rupture of hepatic hydatid cyst

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

The inverted V sign has been described in several different pathologies: inverted V sign (pneumoperitoneum) inverted V sign (spinal cord)
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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 represents free gas outlining the lateral umbilical ligaments. In infants, t...
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

Ischial spine sign

The ischial spine sign is a radiographic sign on the AP view of the pelvis, for the diagnosis of acetabular retroversion, which poses a form of pincer morphology and predisposes to femoroacetabular impingement. Acetabular retroversion seems to be a result of a rotation of the entire acetabular ...
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...
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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...

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