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.

42 results found
Article

Faceless kidney

A faceless kidney refers to one in which the normal appearance of the renal sinus on cross-sectional imaging is absent. It was initially described as a sign of duplication of the collecting system 1 (a slice obtained between the two collecting systems will not demonstrate the normal components o...
Article

Falciform ligament sign

The falciform ligament sign (also called the Silver's sign) is a sign seen with a pneumoperitoneum. It is almost never seen in isolation. If there is enough free air to outline the falciform ligament, there is usually enough air to also provide at least a Rigler's sign.  The falciform ligamen...
Article

Fallen fragment sign

The fallen fragment sign refers to the presence of a bone fracture fragment resting dependently in a cystic bone lesion. This finding is said to be pathognomonic for a simple (unicameral) bone cyst following a pathological fracture. The finding exists because a simple bone cyst is fluid filled,...
Article

Fallen lung sign

The fallen lung sign (also known as CT fallen lung sign) describes the appearance of collapsed lung away from the mediastinum encountered with tracheobronchial injury (in particular those > 2 cm away from the carina). It is helpful to look for this rare but specific sign, in cases of unexplai...
Article

Fascial tail sign

The fascial tail sign is the linear extension along the fascia/muscular aponeurosis from a deeper tumor. Radiographic features It appears as a tail and is best appreciated on MRI, classically seen in desmoid tumours as T2 hypointense bands that progressively enhance particularly on delayed pha...
Article

Fascicular sign

Fascicular sign is a finding on T2-weighted MRI images that suggests a lesion of neurogenic origin. It is characterised by multiple small ring-like structures with peripheral hyperintensity representing the fascicular bundles within the nerves. It is found in various neurogenic tumours, includi...
Article

Fat halo sign of inflammatory bowel disease

The fat halo sign refers to a feature seen on CT examination of the abdomen, and represents infiltration of the submucosa with fat, between the muscularis propria and the mucosa. It is characterised by an inner (mucosa) and outer (muscularis propria and serosa) ring of enhancing bowel wall along...
Article

Fat ring sign

The fat ring sign (also known as a  fat halo sign) describes preservation of fat around the mesenteric vessels and around soft tissue nodules on back ground of diffuse fat stranding in patients with mesenteric panniculitis or mesenteric lipomas.  This finding may help distinguish mesenteric pan...
Article

Fat stranding on CT

Fat stranding is a common sign on CT seen anywhere fat can be found but is most commonly seen in the abdomen/pelvis, but also in the retroperitoneum, thorax and subcutaneous tissues. It can be helpful in localising both acute and chronic pathology. Radiographic features CT Fat stranding can a...
Article

Fat-stranding (summary)

Fat stranding is a sign that is seen on CT. It describes the change in attenuation of fat around an inflamed structure and is a very helpful signpost for intra-abdominal pathology. Summary relatively high sensitivity for intra-abdominal inflammatory pathology many inflammatory processes will ...
Article

FBI sign

The FBI sign is an acronym referring to the components that form a lipohaemarthrosis. It stands for: 
 fat 
 
 blood 
 
 interface 
Article

Feeding vessel sign

Feeding vessel sign consists of a distinct vessel leading directly to a nodule or a mass. This sign indicates either that the lesion has a hematogenous origin or that the disease process occurs near small pulmonary vessels.  A number of vessel-related non-neoplastic disorders of the lung produc...
Article

Feline oesophagus

Feline oesophagus also known as oesophageal shiver, refers to the transient transverse bands seen in the mid and lower oesophagus on a double contrast barium swallow. The appearance is almost always associated with active gastro-oesophageal reflux 2,3 and is thought to be due to contraction of ...
Article

Female prostate sign

Female prostate sign is a characteristic imaging sign seen in patients with a large urethral diverticulum.  A large urethral diverticulum in females surrounds the urethra, and elevates the base of the bladder, mimicking the typical appearance of enlarged prostate in males. 
Article

Fetal cardio thoracic circumference ratio

Fetal cardio-thoracic (C/T) circumference ratio is parameter than can be used in assessment of fetal cardiac and thoracic/chest wall anomalies. It is essentially the ratio of the cardiac circumference of the thoracic circumference and may be easily measured on ultrasound/fetal echocardiography. ...
Article

Fetal maceration

Fetal maceration is one of the signs of fetal death. It is a destructive aseptic process that appears between 12 to 24 hours after fetal death. It may not be seen in a pregnancy earlier than 6 months. In this a separation of the skin from head and trunk occurs giving a bubble like appearance.
Article

Figure 3 sign

The figure 3 sign is seen in aortic coarctation and is formed by prestenotic dilatation of the aortic arch and left subclavian artery, indentation at the coarctation site (also known as the "tuck"), and poststenotic dilatation of the descending aorta. On barium studies of the oesopha...
Article

Figure of eight appearance

Following lesions may resemble a figure of eight (sometimes referred to as snowman shaped): supracardiac variety of total anomalous pulmonary venous return (TAPVR) 1 pituitary macroadenoma with suprasellar extension2 intraspinal neurofibroma with extraspinal extension through neural foramina ...
Article

Finger clubbing

Finger clubbing, also called "drumstick fingers", is a common clinical sign in patients with heart or lung disease. The term is used to describe an enlargement of the distal phalanges of the fingers, giving them a drumstick or club-like appearance.  Pathology The underlying pathogene...
Article

Finger in glove sign

The finger in glove sign can be seen on either chest radiograph or CT chest and refers to the characteristic sign of a bronchocoele. The same appearance has also been referred to as: rabbit ear appearance mickey mouse appearance toothpaste shaped opacities Y-shaped opacities V-shaped opacit...
Article

Fishhook ureters

Fishhook ureters, also known as "J-shaped ureters" or "hockey stick ureter" describe the course of the distal ureter in patients with significant Benign prostatic hypertrophy. It has also been used to describe the appearance of a retrocaval ureter further up, as the right ure...
Article

Fistula test

The fistula test is used when examining patient with recurrent
 vertigo. A finger is abruptly applied to the external meatus which causes a pulse of air-transmitted pressure. If 
 nystagmus is induced in association with vertigo, it indicates bony
 destruction within the inner ear e...
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

Flat waist sign

The flat waist sign refers to flattening of the contours of the aortic arch and adjacent pulmonary trunk. It is seen in severe left lower lobe collapse and is caused by leftward displacement and rotation of the heart.
Article

Fleck sign

The fleck sign is a small bony fragment seen in the Lisfranc space (between the base of the 1st and 2nd metatarsal) associated with avulsion of Lisfranc's ligament (at the base of the 2nd metatarsal). It is a very subtle, but important finding, since it predisposes to Lisfranc injury.
Article

Fleischner sign

Fleischner sign is a prominent central artery that can be caused either by pulmonary hypertension that develops or by distension of the vessel by a large pulmonary embolus. It can be seen on chest radiographs and CT pulmonary angiography. It is seen most commonly in the setting of massive pulmo...
Article

Fleischner sign of tuberculosis

The Fleischner sign refers to a widely gaping, thickened,patulous ileocaecal valve and narrowed ulcerated terminal ileum associated with tuberculous involvement of the ileocaecum. See also gastrointestinal tuberculosis stierlin sign fleishner's sign
Article

Floating aorta sign

The floating aorta sign refers to displacement of the abdominal aorta away from the vertebral column. It is a radiographic/ CT sign of retroperitoneal masses. Radiographic findings On lateral lumbar spine radiographs, the expected location of posterior aortic wall is expected to be <= 10mm...
Article

Floating head appearance

A floating head appearance refers to imaging features observed typically on antenatal ultrasound with certain skeletal dysplasias such as achondrogenesis.   Against the background of poorly mineralized spine, a normal ossified skull is seen giving an impression of a floating head.
Article

Floating viscera sign

The floating viscera sign is an angiographic sign that occurs when there is visualisation of branches of the abdominal aorta (e.g. coeliac axis, superior mesenteric artery, and renal arteries) during aortography with little or no visualisation of the aortic lumen. it indicates the presence of a...
Article

Fluid colour sign

The fluid colour sign is a diagnostic sign to differentiate a pleural effusion from pleural thickening by means of colour Doppler ultrasound. In the case of pleural effusion a colour signal is seen in the pleural fluid during respiratory and cardiac movement, whereas this colour signal is not se...
Article

Fluid sign in acute vertebral collapse

The fluid sign is one of the radiological features of osteoporotic fractures, and can be helpful in distinguishing them from metastatic vertebral fractures, as it is seen more often in osteoporotic fractures and is rarely seen in metastatic fractures 1. It is not as helpful as identifying a para...
Article

Foamy oesophagus sign

Foamy oesophagus is an appearence seen on a single contrast barium study in Candida oesophagitis with associated scleroderma/achalasia (stasis). Pathophysiology Pathophysiologic basis of the foamy esophagus is uncertain. Stasis is a predisposing factor.  Foam is produced directly by the fungal...
Article

Focal hepatic hot spot sign

The focal hepatic hot spot sign can be seen on technetium 99m sulfur colloid scans of the liver and spleen. Radiographic features It occurs as a focal area of increased radiopharmaceutical uptake in the medial segment of the left hepatic lobe (segment IV) due to superior vena cava obstruction ...
Article

Fogging phenomenon

Fogging phenomenon is seen on non contrast CT of the brain and represents a transient phase of the evolution of cerebral infarct where the region of cortical infarction regains a near normal appearance.  {{youtube:http://www.youtube.com/watch?v=LuX3VV__2w0}} During the first week following a c...
Article

Football sign

The football sign is seen in cases of massive pneumoperitoneum, where the abdominal cavity is outlined by gas from a perforated viscus. The median umbilical ligament and falciform ligament are sometimes included in the description of this sign, as representing the sutures. Which football is use...
Article

Fragment-in-notch sign

The fragment-in-notch sign is closely related to, can be thought of as a failed, double PCL sign, in so far as it represents a meniscal fragment lying in the intercondylar notch, but not paralleling the posterior cruciate ligament (PCL).  Although both signs are most frequently seen in the sett...
Article

Frimann-Dahl sign

Frimann-Dahl sign is a diagnostic sign demonstrated when three dense lines representing the sigmoid walls seen converging to the site of obstruction in sigmoid volvulus and associated with empty rectal gas.
Article

Frostburg inverted 3 sign

Frostburg inverted 3 sign is a sign seen on a barium examination where there is  effacement and distortion of the mucosal pattern on the medial wall of the second part of the duodenum due to focal mass and local oedema. It is most commonly asssociated with carcinoma of the head of the pancreas b...
Article

Fruit inspired signs

There are many fruit-inspired signs in radiology: apple core sign: colorectal carcinoma and synovial osteochondromatosis apple-peel intestinal atresia banana sign: Chiari II malformation banana fracture of Paget disease berry aneurysm bunch of grapes sign hydropic swelling of trophoblastic...
Article

Funnel trachea

Funnel trachea is a colloquialism for congenital long-segment intrathoracic tracheal stenosis.  The diameter of the trachea immediately below the cricoid is normal, and becomes becomes progressively more stenotic caudally. The posterior, membranous portion of the trachea may be partially or com...
Article

Funneling of the internal cervical os

Cervical funneling is a sign of cervical incompetence and represents the dilatation of the internal part of the cervical canal and reduction of the cervical length. Greater than 50% funneling before 25 weeks is associated with approximately 80% risk of preterm delivery. Radiographic assessment...

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.