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.

16 results found
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

Ice-cream cone sign

The ice cream cone sign may refer to: the appearance of the malleus head and the incus body on axial CT scan: failure of this normal configuration suggests incudomalleolar dysarticulation. Ball of the icecream is formed by head of malleus and cone is formed by body of incus. Space between ice c...
Article

Inanimate object inspired signs

Inanimate object inspired signs are numerous: champagne glass pelvis: achondroplasia dinner fork deformity: poorly set Colles' fracture fishhook ureters: seen in BPH apple core (napkin ring) sign: colorectal carcinoma or synovial osteochondromatosis of the hip joint H-shaped / Lincoln log v...
Article

Incidental lung nodules

Incidental lung nodules are encountered commonly in routine cross sectional imaging. The risk of developing cancer in very small nodules (<5mm) is very low. However, clear-cut recommendations are still not in place with high variation in practice amongst reporting radiologists 1. As a result,...
Article

Incomplete border sign

The incomplete border sign is useful to depict an extrapulmonary mass on chest radiograph. An extrapulmonary mass will often have a 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

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 lung. It suggest 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

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 is seen are: cerebral vasculitis radiation therapy cerebral vasospasm post sub...
Article

Intradecidual sac sign

Intradecidual sac sign (IDSS) is a useful feature in identifying an early intrauterine pregnancy as early as 25 days of gestation 1. As per this sign, site of implantation is seen as an early gestational sac or an intrauterine fluid collection or an echogenic area in a markedly thickened decidua...
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 size and other underlying pathology. Small sh...
Article

Intramural gas

Intramural gas, also known as pneumatosis intestinalis, refers to gas within the wall of the bowel. Terminology There are different terminologies in the medical literature, such as pneumatosis intestinalis, pneumatosis coli, and pneumatosis cystoides intestinalis, that seem to describe the sam...
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

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 Aetiology The cause for an ivory vertebra depends on the age o...
Article

Ivy sign

The ivy sign refers to the MRI appearance of patients with moya moya disease or moya moya 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. Diffe...

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