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.

46 results found
Article

Baastrup syndrome

Baastrup syndrome (also referred to as kissing spines) results from adjacent spinous processes in the lumbar spine rubbing against each other and resulting in hypertrophy and sclerosis with focal midline pain and tenderness relieved by flexion and aggravated by extension.  Epidemiology It tend...
Article

Backwash ileitis

Backwash ileitis is seen in patients with ulcerative colitis (UC), where the entire colon is involved. In such cases the terminal ileum is oedematous. Backwash ileitis extends contiguously backward from the cecum without skip regions. One source estimates it to occur in 6% of patients with UC, ...
Article

Ballet sign

The Ballet sign refers paralysis of voluntary movements of the eyeball with preservation of the automatic movements. Sometimes this sign is present with exophthalmic goitre and hysteria.
Article

Balloon on a string sign - IVU

In renal imaging, the balloon on a string sign refers to the appearance on IVU in ureteropelvic junction obstruction. It is seen due to the high and eccentric point of exit of ureter from a dilated renal pelvis. 
Article

Bamboo spine

Bamboo spine is a radiographic feature seen in ankylosing spondylitis that occurs as a result of vertebral body fusion by marginal syndesmophytes. It is often accompanied by fusion of the posterior vertebral elements as well.  A bamboo spine typically involves the thoracolumbar and or lumbosacr...
Article

Banana sign

The banana sign is one of the many notable fruit inspired signs. It is seen on axial imaging through the posterior fossa of fetus and is associated with the Chiari II malformation. It describes the way the cerebellum is wrapped tightly around the brain stem as a result of spinal cord tethering ...
Article

Bare orbit sign

Bare orbit sign, is described as a characteristic appearance of orbit, where the innominate line is absent. The innominate line is a projection of the greater wing of the sphenoid, and its absence or destruction is responsible for this appearance. It is the classical frontal radiograph sign of ...
Article

Bat wing 4th ventricle

Bat wing 4th ventricle sign refers to the morphology of the fourth ventricle in the Joubert anomaly and related syndromes. The absence of a vermis with apposed cerebellar hemispheres give the fourth ventricle an appearance reminiscent of a bat with its wings outstretched. It is best demonstrate...
Article

Bat wing pulmonary opacities

Bat's wing or butterfly pulmonary opacities refer to a pattern of bilateral perihilar shadowing. It is classically described on a frontal chest radiograph but can also refer to appearances on chest CT 3-4. Differential diagnosis Bat's wing pulmonary opacities can be caused by: pulmonary oedem...
Article

Bayonet deformity

Bayonet deformity is a term used to describe the shape of wrist in certain conditions: Madelung deformity hereditary multiple exostosis with pseudo-Madelung deformity retarded bone growth of the distal ulna with outward bowing of radius with distal radioulnar joint subluxation Colles fracture
Article

Beak sign in pyloric stenosis

Beak sign in pyloric stenosis is one of the fluoroscopic (Barium meal) findings which is useful in the diagnosis of congenital hypertrophic pyloric stenosis.  Radiographic features Barium meal Peak of Barium is seen entering into the narrowed and compressed pyloric channel with distal taperin...
Article

Beak sign of arterial dissection

The beak sign of arterial dissection represents a wedge of haematoma at the distal end of the false lumen. It is here that false lumen propagation is occurring. It manifests as an acute angle between the dissection flap and the outer wall. It may be filled with contrast enhanced blood (high atte...
Article

Bear paw sign

The bear paw sign is seen in xanthogranulomatous pyelonephritis and refers to the cross-sectional appearance of the kidney which is said to resemble the paw of a bear. The renal pelvis is contracted whereas the calyces are dilated, mimicking the toe-pads of the paw.
Article

Beck triad

Beck triad is a collection of three clinical signs associated with pericardial tamponade which is due to excess accumulation of fluid within the pericardial sac. The three signs are: low blood pressure (weak pulse or narrow pulse pressure) muffled heart sounds  raised jugular venous pressure ...
Article

Big rib sign

The big rib sign is a sign to differentiate right and left ribs on lateral chest radiographs.  It exploits a technique of magnification differences on lateral projections between right and left ribs. For example, on right lateral projections the left ribs appear larger than right ribs.  This s...
Article

Bilateral adrenal gland hyperenhancement

Bilateral adrenal gland hyperenhancement or intense adrenal enhancement may be a feature of hypotension and forms part of the CT hypoperfusion complex. It has has been described in paediatric and small adult series or individual cases of haemorrhagic shock, pancreatitis, sepsis and trauma 1-3 b...
Article

Bird-beak sign

The bird-beak sign is used to refer to the tapering of the inferior oesophagus in achalasia. The same appearance (although it is difficult to see the similarity) is also referred to as the rat-tail sign. The appearances although classically occurring in primary achalasia, can also occur in pseu...
Article

Black turbinate sign

The black turbinate sign refers to an area of non-enhancing mucosa on MRI in a patient with angioinvasive fungal sinus infection / rhinocerebral mucormycosis. Mucormycosis is caused by fungi that include Mucor, Rhizopus, and Absidia species.  It is seen in diabetic and immunocompromised patient...
Article

Blade of grass sign

The blade of grass sign (also called the candle flame sign) refers to the lucent leading edge in a long bone seen during the lytic phase of Paget disease of bone.  The blade of grass sign is characteristic of Paget disease of bone. This is akin to osteoporosis circumscripta cranii seen in the s...
Article

Blend sign

Early haematoma growth is not uncommon in patients with intracerebral haemorrhage and is an independent predictor of poor functional outcome. In nonenhanced cranial CT the blend sign is defined as blending of a hypoattenuating area and a hyperattenuating region with a well-defined margin.
Article

Bone within a bone appearance

Bone within a bone is a descriptive term applied to bones that appear to have another bone within them. There are numerous causes including: normal thoracic and lumbar vertebrae (in infants) growth recovery lines (after infancy) sickle cell disease / thalassaemia autosomal dominant osteopet...
Article

Boomerang sign

The boomerang sign refers to boomerang shaped splenial lesion (splenium of corpus callosum) which is seen as hyperintense lesion on T2-WI, FLAIR and DWI 1. This sign can be seen in: transient lesion in splenium ischemia posterior reversible encephalopathy syndrome diffuse axonal injury mul...
Article

Boomerang sign: in horizontal meniscal flap tear

The boomerang sign is defined as a small displaced flap from longitudinal horizontal type medial meniscal tear which is displaced inferiorly into the medial meniscotibial recess. The imaging diagnosis of this type of tear is crucial because it is normally hidden from surgeons eye during routine ...
Article

Bouchard nodes

Bouchard nodes are a clinical sign relating to bony nodules of the the proximal interphalangeal joints, and are much less common than Heberden nodes. They generally (but not always) correspond to palpable osteophytes. Clinical presentation They are sometimes painful, and are typically associat...
Article

Bouquet of flowers appearance

A bouquet of flowers appearance is a description given to the appearances of medullary sponge kidney on a traditional intravenous pyelogram (IVP) study. The ectatic distal collecting ducts contain the microcalcification typical of the disease. This is also known as a 'bunch of grapes' appearance...
Article

Boutonniere deformity

Boutonniere deformity is one of the musculoskeletal manifestations of rheumatoid arthritis in the hand with: flexion contracture of the proximal interphalangeal (PIP) joints extension of the distal interphalangeal (DIP) joints  The buttonhole appears in the tendon which splays open. The appea...
Article

Box-shaped heart

A 'box-shaped' heart is a radiographic description given to the cardiac silhouette in some cases of Ebstein anomaly. The classic appearance of this finding is caused by the combination of the following features: huge right atrium that may fill the entire right hemithorax shelved appearance of ...
Article

Bracket sign

The bracket sign refers to a radiographic appearance seen with the tubulonodular variety of pericallosal lipoma. It reflects calcification seen at the periphery of the midline lipoma. It is best seen on coronal imaging, and historically was identified on frontal radiographs.
Article

Breast within a breast sign

The breast within a breast sign refers to the common mammographic appearance of breast hamartomas (fibroadenolipomas). Since these benign lesions are well-circumscribed and contain a mixture of fibrous, glandular and fatty tissue (just like normal breast), it is not surprising that they appear v...
Article

Bridging vessel sign

The bridging vessel sign refers to an appearance of vessels coursing from the uterus into an adjoining pelvic mass (a vascular bridge). This sign helps to differentiate a pedunculated subserosal uterine leiomyoma from other juxtauterine masses of ovarian, adnexal or bowel origin. Colour and pow...
Article

Bright dot sign - atypical liver haemangioma

The bright dot sign refers to presence of a bright dot within a lesion which remains hyper-attenuating on arterial and portal venous phase CT, corresponding to early nodular enhancement seen on dynamic MRI of liver haemangioma.  This can be used as an indicator that the lesion in question is a ...
Article

Bright rim sign in 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 in fibular attachment site, is seen on MRI. It has been described an indicator of ATFL injury 1. See also bright rim ...
Article

Bright rim sign in DNETs

The bright rim sign has been described in DNETs and is seen, as the name so aptly describes, as a rim of high signal around the DNET on FLAIR sequences.
Article

Bronchial cut off sign

The bronchial cut off sign refers to the abrupt truncation of a bronchus from obstruction, which may be due to cancer, mucous plugging, trauma or foreign bodies. Typically, there is associated distal lobar collapse. 
Article

Bronchorrhoea

Bronchorrhoea is the expectoration of copious amounts of mucus from the lungs. It has been defined as production of more than 100ml of mucus in 24 hours, which is more than is usually seen in chronic lung disease (e.g. chronic bronchitis typically produces 25ml/24hrs) 2. It may be a feature of: ...
Article

Brudzinski sign

Brudzinski sign occurs in meningitis, where passive flexion of one leg causes flexion in the opposite leg. Passive flexion of the neck brings about flexion of the legs as well. Historical context First described by Jósef Brudziñski (1874-1917), Paediatrician from Warsaw, Poland 2.
Article

Bubbly consolidation

Bubbly consolidation describes internal or central lucencies which represent normal aerated lung lobule within infrarcted, consolidated, lung parenchyma. It is one of the unique imaging appearances of focal pulmonary haemorrhage or possibly pulmonary infarct secondary to pulmonary embolism.  Ra...
Article

Bulging fissure sign

The bulging fissure sign refers to lobar consolidation where the affected portion of the lung is expanded. It is now rarely seen due to the widespread use of antibiotics. The most common infective causative agents are 1: Klebsiella pneumoniae: Klebsiella pneumonia Streptococcus pneumoniae Ps...
Article

Bull's eye sign: general

There are many bull's eye signs, also referred to as target signs: red bone marrow located in shaft of long bone with central yellow marrow on MRI peripheral plexiform neurofibromas on MRI intussusception: see target sign of intussusception choledocholithiasis: see target sign of choledochol...
Article

Bullet and bodkin sign

Bullet and bodkin sign is the appearance of the ureter when there is an abrupt transition in the ureteral caliber. Bullet in the name is represented by the dilated proximal ureteric segment which appears to be perched on the constricted / non dilated encased ureter which gives an appearance of a...
Article

Bullet shaped vertebra

Bullet shaped vertebra refers to the anterior beaking of the vertebral body. It is seen in the following conditions: mucopolysaccharidosis (Morquio disease, Hurler disease) achondroplasia  congenital hypothyroidism  See also weapons and munitions inspired signs
Article

Bunch of grapes sign

Bunch-of-grapes sign refers to the ultrasound appearance of multiple cystic spaces within the uterus as the result of hydropic swelling of trophoblastic villi within a hydatidiform mole. This sign is also described in bronchiectasis where on plain radiograph, the dilated bronchi in approximatio...
Article

Butterfly glioma

Butterfly gliomas are a high grade astrocytoma, usually a glioblastoma (WHO grade IV), which crosses the midline via the corpus callosum. Other white matter commissures are also occasionally involved. The term butterfly refers to the symmetric wing like extensions across the midline.  Most freq...
Article

Butterfly sign

Butterfly sign refers to the normal appearance of bilateral choroid plexuses on axial imaging of the fetal brain, commonly observed on the antenatal ultrasound. Its absence may suggest holoprosencephaly 1. In the CNS, the term should not be mistaken by butterfly glioma, which is a glioblastoma ...
Article

Butterfly vertebra

Butterfly vertebra is a type of vertebral anomaly that results from the failure of fusion of the lateral halves of the vertebral body because of persistent notochordal tissue between them. Pathology Associations an anterior spina bifida, with or without an anterior meninogocoele can be part ...
Article

Button sequestrum

A button sequestrum is a small sequestrum of devascularised bone surrounded by lucency. Although classically described in osteomyelitis and eosinophilic granuloma it is also occasionally seen in fibrosarcoma and lymphoma. Differential diagnoses osteoid osteoma tuberculous osteitis radiatio...

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.