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.
More than 200 results
Article
X-marks-the-spot sign (large bowel volvulus)
The X-marks-the-spot sign of large bowel volvulus refers to the crossing loops of the bowel at the site of the transition. It has been reported to improve diagnostic confidence in detecting cecal and sigmoid volvulus. This is in contrast to the split-wall sign which indicates partial obstruction...
Article
Egyptian eye sign
"Egyptian eye sign" or "sonographic eye sign" refers to the normal appearance of great saphenous vein on ultrasound, in transverse view 1,2.
Ultrasound examination of the great saphenous vein shows echogenic fascia surrounding it, with the saphenous fascia superiorly and the muscular fascia inf...
Article
Coandă effect (physics)
The Coanda effect refers to the phenomenon by which a narrow jet of liquid (or air) passing through an orifice directly in sequence with a solid (especially convex) surface will deviate from its path and adhere to this curved surface, following its shape in parallel.
The mechanism is thought to...
Article
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...
Article
Tulip sign
The tulip sign is a sonographic clue for in utero diagnosis of severe hypospadias.
The configuration of a tulip is given by the severe curvature of the penis in association with the penoscrotal transposition of a bifid scrotum.
History and etymology
The tulip sign was first described in 2002 ...
Article
Powers ratio
The Powers ratio is a measurement of the relationship of the foramen magnum to the atlas, used in the diagnosis of atlanto-occipital dissociation injuries.
The ratio, AB/CD, is measured as the ratio of the distance in the median (midsagittal) plane between the:
basion (A) and the posterior spi...
Article
Medial breast margin sign
The medial breast margin sign is a sign of pectus excavatum seen on the frontal chest radiographs of women. It is one of several described signs of pectus excavatum on frontal chest radiographs.
Radiographic features
Plain radiograph
Women with pectus excavatum may have a more vertically ori...
Article
Zebra sign (disambiguation)
The evocative appearance of the coat of a zebra has been used for several distinctive signs in radiology:
zebra sign: cerebellar hemorrhage 1
zebra sign: amyotrophic lateral sclerosis 2
zebra spleen: arterial phase appearance of normal spleen 4,5
zebra stripe sign: treated osteogenesis imper...
Article
Wimberger sign
The Wimberger sign, also called Wimberger corner sign, refers to localized bilateral metaphyseal destruction of the medial proximal tibias. It is a pathognomonic sign of congenital syphilis.
The term must not be mistaken for the Wimberger ring sign seen in scurvy, as both entities are often con...
Article
Saber-sheath trachea
Saber-sheath trachea refers to a diffuse coronal narrowing of the intrathoracic portion of the trachea with the concomitant widening of the sagittal diameter. It is not uncommon and is pathognomonic for chronic obstructive pulmonary disease (COPD) 1.
The sagittal:coronal diameter is over 2:1 2...
Article
Saber sign (pneumobilia)
The saber sign refers to a pattern of gas distribution seen in supine abdominal radiographs of patients with pneumobilia. A sword-shaped lucency is apparent in the right paraspinal region of the upper abdomen representing arching gas extending from the common bile duct into the left hepatic duc...
Article
Coin lesion (lung)
A coin lesion refers to a round or oval, well-circumscribed solitary pulmonary lesion. It is usually 1-5 cm in diameter and calcification may or may not be present 1,3. Typically but not always the patient is asymptomatic 1.
Differential diagnosis
The differential diagnosis for such lesions i...
Article
Signet ring sign (scaphoid)
The signet ring sign, cortical ring sign, or just ring sign refers to the rounded cortex of the scaphoid tubercle on an AP or PA wrist radiograph due to rotatory subluxation from flexion of the scaphoid. It is seen in injuries of the scapholunate ligament (scapholunate dissociation) and the rela...
Article
Fothergill sign
The Fothergill sign describes an examination finding that is used to help distinguish an abdominal wall mass from an intra-abdominal mass.
The sign is said to be present if a mass remains palpable and fixed even when the rectus muscles are contracted, such as when the patient lifts their head f...
Article
Flat floor of fourth ventricle sign
The flat floor of fourth ventricle sign is useful in detecting a pontine mass and is a sign of mass effect. The normal floor of the fourth ventricle (remember that the floor is anterior) normally slopes upwards towards the midline, with the facial colliculi visible on either side.
It is a non-...
Article
Cookie bite bone metastases
Cookie bite bone metastases are characterized by small focal eccentric lytic external cortical destruction in long tubular bones. This type of destruction is typically described for metastases from lung cancer, however, they can also occur with other tumors.
Article
Flip-flop renal enhancement
Flip-flop renal enhancement describes when an infarcted renal parenchyma alternates between hypoattenuation during the arterial phase, and hyperattenuation on the delayed phase of a contrast enhanced CT 1,2.
Terminology
Flip-flop renal enhancement should not be confused with the flip-flop eff...
Article
Bright rim sign (anterior talofibular ligament injury)
The bright rim sign in anterior talofibular ligament injury refers to a sign seen on MRI. A cortical defect with a bright dot-like or curvilinear high-signal-intensity, usually at the fibular attachment site, is seen on MRI. It has been described as an indicator of ATFL injury 1.
See also
brig...
Article
Mosaic attenuation pattern in lung
Mosaic attenuation is a descriptive term used in describing a patchwork of regions of differing pulmonary attenuation on CT imaging. It is a non-specific finding, although is associated with the following:
obstructive small airways disease: low attenuation regions are abnormal and reflect two p...
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...
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