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.

51 results found
Article

T sign

The "T sign" is really the absence of a twin-peak sign (or lambda sign) and is used in ultrasound assessment of a mulifetal pregnancy. It refers to the lack of chorion extending between the layers of the intertwin membrane, denoting a monochorionic pregnancy. The intertwin membrane co...
Article

T1 black holes

T1 black holes are hypointense lesions commonly seen on T1WI in patients with multiple sclerosis, and indicates the chronic stage with white matter destruction, axonal loss and irreversible clinical outcome. There is a correlation between the number of black holes and patient positive outcome3.
Article

T2 dark spot sign

T2 dark spot sign is an MRI appearance of endometriomas seen as a result of chronic haemorrhage. The sign is useful in differentiating a solitary endometrioma from a functional haemorrhagic ovarian cyst, as both might show high T1 signal with T2 shading.  The T2 dark spot, described in the sign...
Article

Talar beak sign

The talar beak sign is seen in cases of tarsal coalition, and refers to a superior projection of the distal aspect of the talus. It is most frequently encountered in talocalcaneal coalition 1-2. It is thought to result from abnormal biomechanic stresses at the talonavicular joint.  Differential...
Article

Tam o' shanter sign

The "tam o' shanter" is a Scottish hat, named after the character in Robert Burn's 1 poem of the same name. The appearances of advanced Paget disease of the skull are similar in appearance to the hat.  Paget involvement of the skull, with widening of the diploic space and an overall e...
Article

Target sign of choledocholithiasis

The target sign of choledocholithiasis is a finding seen on contrast enhanced CT and comprises: central density within the bile duct: stone surrounding low density: bile or mucosa
Article

Target sign of intussusception

There are many target signs, one of which the the appearance of intestinal intussusception, also known as the doughnut sign. The appearance is generated by concentric alternating echogenic and hypoechogenic bands. The echogenic bands are formed by mucosa and muscularis whereas the submucosa is ...
Article

Target sign of pyloric stenosis

The target sign of pyloric stenosis is a sign seen due to hypertrophied hypoechoic muscle surrounding echogenic mucosa, seen in pyloric stenosis. This is likened to that of a target. See also antral nipple sign cervix sign of pyloric stenosis shoulder sign of pyloric stenosis
Article

Target sign of tuberculosis

The target sign of tuberculosis refers to the bull's-eye appearance of some parenchymal tuberculomas involving the brain (see: CNS tuberculosis) and solid abdominal organs (see: hepatic and splenic tuberculosis) on cross-sectional imaging.  Radiographic features CT central nidus of calcificat...
Article

Tattoo sign - mammogram

The tattoo sign is a feature given to describe dermal calcifications seen on mammography 1. The basis of this sign is that dermal calcifications maintain fixed relationships to one another which are reproducible with similar projections at different times. This is in contrast to intramammary cal...
Article

Tau sign

The tau sign represents the appearance of a persistent trigeminal artery on the sagittal plane of an angiogram or on sagittal MRI images. It resembles the greek letter 'tau'. Persistent trigeminal artery arising from the junction between the petrous and cavernous ICA and runs posterolaterally al...
Article

Tear drop sign of the superior mesenteric vein

Tear drop sign of the superior mesenteric vein  is one of the important signs in the staging of pancreatic adenocarcinoma . Its importance lies in its diagnosis as well as prognostic significance . This sign is used in assessing the resectability of pancreatic cancer. Radiographic appearance C...
Article

Tectal beaking

Tectal beaking refers to fusion of midbrain colliculi into a single beak pointing posteriorly and invaginating into cerebellum. It is seen with a Chiari type II malformation.
Article

Tensile gallbladder fundus sign

The tensile gallbladder fundus sign is positive when the gallbladder fundus is seen to bulge into, and distort, the anterior abdominal wall and is a feature of acute cholecystitis. It is particularly useful as an early sign of the condition on CT as it has around a 75% sensitivity and 95% speci...
Article

Tent sign

The tent sign is a term referred to a characteristic of the posterior edge of the breast parenchyma  when a mass (usually an infiltrating lesion) causes its retraction and forms a "V" that resembles the tip of a circus tent. The detection of a "tent-sign" is facilitated by t...
Article

Terry Thomas sign

The Terry Thomas sign refers to an increase in the scapholunate space on an AP radiograph of the wrist (or coronal CT). The increased distance indicates scapholunate dissociation (often with rotary subluxation of the scaphoid) due to ligamentous injury. There is no consensus as to what measureme...
Article

Third mogul sign

The third mogul sign can be seen on frontal chest radiograph in the presence of left atrial enlargement. It refers to an extra mogul or bump along the upper left cardiac silhouette just below the left main bronchus. The third mogul sign commonly represents the enlarged left atrial appendage, pa...
Article

Thoracoabdominal sign

Thoracoabdominal sign is a chest x-ray sign probably coined by Benjamin Felson. It defines the location of a thoracic lesion based on the fact that the posterior costophrenic sulcus extends caudally than the anterior lung. Thus a thoracic lesion which has its caudal end visible below the dome o...
Article

Threads and streaks sign

The threads and streaks sign refers to an angiographic appearance of a vascularised tumour thrombus extending into the ipsilateral renal vein or the inferior vena cava from a renal cell carcinoma. This gives an appearance of linear, thread like or string like appearance of the involved vessel.  ...
Article

Three line sign

The three line sign refers to an MRI term that describes the appearance of roundworm Ascaris lumbricoides within the CBD lumen which appears as two hypointense lines representing the worm walls and hyperintense center which represents the worm gut. See also biliary ascariasis
Article

Throckmorton sign

Throckmorton sign, also known as John Thomas sign, refers to when the penis points in the direction of unilateral disease, typically of the pelvis or hip.  Throckmorton sign is a slang term used jokingly by medical students and residents. History and etymology It is named after Tom Bentley Th...
Article

Thrombus fissuration

Thrombus fissuration is a sign of impending rupture of an aortic aneurysm. It reflects blood dissecting into the intramural thrombus. This sign is observed on contrast-enhanced CT as linear contrast infiltrations from the aneurysm lumen through the intramural thrombus. Thrombus fissurations exte...
Article

Thumb sign of chordoma

The thumb sign or thumbing of the pons is described in chordomas as is meant to be relatively specific. It is seen in midline sagittal projection as a projection of the tumour indenting the pons 1.  Terminology Thumb sign is a term also used in other conditions such as: the thumb sign of Marf...
Article

Thumb sign of epiglottitis

The thumb sign is a manifestation of an oedematous and enlarged epiglottis which is seen on lateral soft-tissue radiograph of the neck, and it suggests a diagnosis of acute infectious epiglottitis. This is the radiographic corollary of the omega sign 1-3.  Terminology Thumb sign is a term also...
Article

Thumbprinting

Thumbprinting is a radiographic sign of large bowel wall thickening, usually caused by oedema, related to an infective or inflammatory process (colitis). The normal haustra become thickened at regular intervals appearing like thumbprints projecting into the aerated lumen. Pathology Aetiology ...
Article

Thymic notch sign

The thymic notch sign represents normal thymus in newborn on a frontal chest radiograph. Interruption of the cardiac silhouette forms a notch, which may be seen on either side, but more frequently seen on left side. 
Article

Thymic sail sign

The thymic sail sign represents a triangular-shaped inferior margin of the normal thymus seen on neonatal frontal chest radiograph. It is more commonly seen on the right side, and can also be bilateral. It is seen in 3-15% of all cases. This sign should not be confused with the spinnaker sail si...
Article

Thyroid inferno

Thyroid inferno refers to the colour Doppler appearance of the thyroid gland in active Graves disease (inclusive of variants such as Marine Lenhart syndrome), and consists of multiple small areas of colour flow seen diffusely throughout the gland representing increased vascularity and arterioven...
Article

Tiger stripe appearance

The tiger stripe appearance refers to the characteristic distinctive alternating hypo and hyperintense bands on MRI in Lhermitte-Duclos disease. This rare cerebellar tumour appearing like the coat of a tiger. See also tigroid pattern - in brain
Article

Tip of the iceberg sign

The tip of the iceberg sign refers to one of the characteristic appearances of an ovarian dermoid cyst.  The highly echogenic cyst contents of sebum and hair cause posterior attenuation of sound, so that only the superficial part of the cyst is seen.    The intense acoustic shadowing in a...
Article

Tombstone iliac wings

Tombstone iliac wings are an imaging descriptor for the iliac wings of individuals with achondroplasia. These are seen to be small and squared and have been likened to the appearance of tombstones.
Article

Toothpaste sign

The toothpaste sign in spinal imaging represents an extrusion of an intervertebral disc into the epidural space. It is called after the shape of extruded material relatively to the parent disc in a sagittal plane.
Article

Tram-track sign

Tram-track sign may refer to: tram-track sign - orbit tram-track sign - chest
Article

Tram-track sign - chest

Tram-track sign may be used in chest radiography to denote the thickened non-tapering (parallel) walls of cylindrical bronchiectasis.
Article

Tram-track sign - orbit

Tram-track sign refers to the parallel thickening and enhancement around the optic nerve, and is most frequently seen in the setting of optic nerve meningioma. It may however also be seen in 1: orbital pseudotumour perioptic neuritis sarcoidosis leukemia lymph...
Article

Tramp-stamp oedema

Tramp-stamp oedema is a colloquial term used by some radiologists to denote posterior lumbar subcutaneous oedema. The term is used to describe oedema in the distribution seen with lower back tattoos, usually in young women, which are known as tramp-stamps.  This oedema is thought be related to ...
Article

Transient ischaemic dilatation

Transient ischaemic dilatation is a paradoxical phenomenon seen in myocardial perfusion SPECT imaging.   With severe balanced coronary artery disease, myocardial ischaemia may result in apparent enlargement of the left ventricular cavity during stress. The cause of this is not entirely clear, b...
Article

Transmantle sign

The transmantle sign is an MRI feature of focal cortical dysplasia, almost exclusively seen in type II focal cortical dysplasia (Taylor dysplasia - also known as transmantle cortical dysplasia for this reason). However, it is not always present, seen in ~45% (range 21-72%) of patients with type ...
Article

Tree-in-bud sign

Tree-in-bud sign or pattern describes the CT appearance of multiple areas of centrilobular nodules with a linear branching pattern. Although initially described in patients with endobronchial tuberculosis, it is now recognised in a large number of conditions. Pathology Pathogenesis The tree-i...
Article

Trethowan sign

The Trethowan sign is used to diagnose slipped capital femoral epiphysis (also called slipped upper femoral epiphysis). In this sign, the line of Klein passes above the femoral head. It is best done on both AP and true lateral projections. On the AP view of a normal hip, the Klein line intersec...
Article

Triangular cord sign

The triangular cord sign is a triangular or tubular echogenic cord of fibrous tissue seen in the porta hepatis at ultrasonography and is relatively specific in the diagnosis of  biliary atresia1,2. This sign is useful in the evaluation of infants with cholestatic jaundice, helping for the diffe...
Article

Troisier sign

Troisier sign is the clinical finding of a hard and enlarged left supraclavicular node (Virchow node), and is considered a sign of metastatic abdominal malignancy. Terminology It is sometimes referred to as Virchow node, which is the name given by Dr Rudolf Virchow (1821-1902), a German pathol...
Article

Trough line sign

The trough line sign is a sign of posterior shoulder dislocation on AP films.  In posterior dislocation, the anterior aspect of the humeral head becomes impacted against the posterior glenoid rim. With sufficient force, this causes a compression fracture on the anterior aspect of the humeral he...
Article

Trumpeted internal acoustic meatus sign

A trumpeted internal acoustic meatus (IAM) is an indirect sign of an acoustic schwannoma and is useful in helping differentiating between one and other cerebellopontine angle entities, especially from a meningioma which typically does not extend into the meatus 1. It is characterized by widenin...
Article

Tubal ring sign

Tubal ring sign is one of the ultrasound signs of a tubal ectopic. It comprises of an echogenic ring which surrounds an unruptured ectopic pregnancy. It is said to have a 95% positive predictive value (PPV) for ectopic pregnancy. Differential diagnosis It can be mimicked by a normal corpus lut...
Article

Tuberculous dactylitis

Tuberculous dactylitis, also known as spina ventosa, is a rare skeletal manifestation of tuberculosis where the short tubular bones (i.e. phalanges, metacarpals, metatarsals) are affected. Epidemiology Tuberculous osteitis is one of the commonest bacterial osteitis. Typically the dactylitis fo...
Article

Tulip bulb sign

Tulip bulb sign refers to characteristic appearance due to dilatation of sinuses of Valsalva slightly extending into the ascending aorta as seen on CT scan of chest.  It is seen especially in Marfan's syndrome. On CT angiography, aneurysm of the aortic root with effacement of sinotubular junct...
Article

Tullio phenomenon

The Tullio phenomenon describes the precipitation of vertigo and nystagmus by a loud noise. Aetiology The tympanic membrane and ossicular chain must be intact with a mobile footplate. It can be present in may situations congenital syphilis, with a semicircular canal fistula post-fenestratio...
Article

Turtle back sign

Turtle back sign, also referred as tortoise shell appearance, represents a very characteristic pattern of the schistosomiasis cirrhotic liver in which calcified fibrotic septa are seen aligned perpendicular to the liver capsule resembling the turtle's carapace. 
Article

Twin-peak sign

The twin peak sign (also known as the lambda (λ) sign) is a triangular appearance of the chorion insinuating between the layers of the inter twin membrane and strongly suggests a dichorionic twin pregnancy. It is best seen in the first trimester (between 10-14 weeks). 5 While the presence of a t...
Article

Two-slice-touch rule

The two-slice-touch rule is a sign on MRI of the knee to increase the sensitivity of diagnosing meniscal tears. This rule states a meniscal tear is present if abnormal findings are present on two or more images - these do not have to be contiguous, e.g. can occur on sagittal and coronal slices ...

Updating… Please wait.
Loadinganimation

Alert_accept

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

Alert_accept Thank you for updating your details.