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 continuously improved upon by countless contributing members. Our dedicated editors oversee each edit for accuracy and style. Find out more about articles.
1,141 results found
Article
Patellotrochlear index
Patellotrochlear index is one of the methods to determine patellar height.
Measurement
The patellotrochlear index is measured on a sagittal MR image with the maximal patellar cartilage thickness and the maximal craniocaudal diameter of the patella.
Two measurements are made:
A: the length o...
Article
Caton-Deschamps index (knee)
The Caton-Deschamps index is used to measure patellar height and identify patella alta and patella baja. The Caton-Deschamps index relies upon the length of the patellar articular surface and its distance from the tibia, reducing erroneous measurements in those with long patella bodies, as measu...
Article
Flat tyre sign (globe rupture)
The flat tyre sign, also known as the mushroom sign, is one of the most specific signs of ruptured eye globe, due to the similarity between the abnormal contour of injured globe and the appearance of a flat tyre 1. It is classically described on CT but may be seen on ultrasound or MRI 2.
The mo...
Article
Scalpel sign (spinal cord)
The scalpel sign is described in dorsal thoracic arachnoid web on sagittal MRI spine studies. It relates to focal distortion of the thoracic cord, appearing anteriorly displaced. The enlarged dorsal CSF space mimics the profile of a surgical scalpel.
It is helpful in distinguishing cases where ...
Article
Straight left heart border sign
Straight left heart border sign is a described finding on chest radiograph in cases of hemopericardium. It is a fairly specific (84%) sign of hemopericardium after a penetrating chest trauma, although sensitivity at 40% is relatively poor. Positive predictive value (PPV) was found to be 89% 1.
...
Article
Skeletal muscle edema on MRI (differential)
The presence of skeletal muscle edema (increased high T2/STIR signal) on MRI carries an extremely broad differential.
Potential diagnoses include:
trauma
effects of direct injury or tear
denervation injury: denervation changes in muscles
early myositis ossificans
inflammatory myopathies
i...
Article
Garland triad
Garland triad, also known as the 1-2-3 sign or pawnbroker's sign, is a lymph node enlargement pattern on chest radiographs which has been described in sarcoidosis:
right paratracheal nodes
right hilar nodes
left hilar nodes
Hilar lymphadenopathy is symmetrical and usually massive. These so-c...
Article
Pumice stone sign
The pumice stone sign describes the distinctive imaging appearance of emphysematous osteomyelitis on CT described as clusters of greater than 3 distinct foci of intramedullary gas with irregularly irregular sizes ranging between 2 and 5 mm with resemblance to surface appearance of pumice stone. ...
Article
Floating balls sign
The floating balls sign refers to the appearance of multiple mobile globules/spherules of solid, usually fatty, tissue within an adnexal cyst. It is pathognomonic for ovarian mature cystic teratoma 1,2.
Terminology
Alternative names include the meatballs 3, truffle sign 4, and boba sign 13.
...
Article
Barbell sign (progressive multifocal leukoencephalopathy)
The barbell sign is a radiological sign present in progressive multifocal leukoencephalopathy (PML) on MRI brain.
This describes confluent T2/FLAIR parieto-occipital abnormalities with a thin continuation of signal abnormality across the splenium 1,2. Given the lack of mass effect typically exh...
Article
Cloverleaf sign (deep infiltrating endometriosis)
The cloverleaf sign is an MRI sign of deep infiltrating endometriosis described in one case series 1. It is detectable on T2W sequences in sagittal, coronal, and axial planes when at least three organs (uterus, ovaries, rectum, bowel loops, etc.) are brought closer by constrictive adhesions and ...
Article
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....
Article
Diaphragmatic slips
Diaphragmatic slips are the muscular bundles that attach the central tendon of the diaphragm to the inside of the bones and cartilage of the lower 6-7 ribs, xiphoid process, lumbar vertebrae 1. They can mimic or help identify pathology when seen on imaging modalities.
Mimics
Diaphragmatic slip...
Article
Starry sky appearance (ultrasound)
A starry sky appearance, also known as a centrilobular pattern 7, refers to a sonographic appearance of the liver parenchyma with bright echogenic dots throughout a background of decreased liver parenchymal echogenicity. Although usually associated with acute hepatitis, this sign has been found ...
Article
Crescent sign (lung hydatid)
The crescent sign is described in hydatid disease. When the hydatid cyst erodes the adjacent bronchus or bronchiole, the trapped air between the pericyst and the laminated membrane of the endocyst gives a crescent-shaped rim of air around the cyst, thus is termed the crescent sign 1,2. It can be...
Article
Phrygian cap
Phrygian caps are the most common congenital anatomic variant of the gallbladder. It denotes folding of the fundus back upon the gallbladder body and is asymptomatic with no pathological significance.
Radiographic findings
A Phrygian cap may be identified on ultrasound, multiphase CT/MRI, or c...
Article
Steinstrasse
Steinstrasse [stīn′shtra-se] is the German word for "stone street", describing a possible complication of extracorporeal shock wave lithotripsy (ESWL) for urinary tract calculi, wherein a column of stone fragments forms that blocks the ureter.
Terminology
The term steinstrasse can equally, alb...
Article
Split pleura sign (empyema)
The split pleura sign is seen with pleural empyemas and is considered the most reliable CT sign helping to distinguish an empyema from a peripheral pulmonary abscess (see empyema vs pulmonary abscess) 1,2.
The sign results from fibrin coating both the parietal and visceral surfaces of the pleu...
Article
Notch of Harty
The notch of Harty or the anteromedial tibial notch is a pseudodefect and an anatomic variant of the ankle joint 1-4.
Gross anatomy
The notch of Harty is a groove located in the anteromedial region of the tibial plafond. Based on a previous anatomical study, this defect measures 5-10 mm in med...
Article
Shepherd crook deformity
A shepherd crook deformity refers to a coxa varus angulation of the proximal femur, classically seen in femoral involvement by fibrous dysplasia, although may be seen in other disorders such as Paget disease of bone and osteogenesis imperfecta.
History and etymology
The shape of the proximal f...
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