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
Atoll sign (lungs)
The atoll sign or reversed halo sign refers to focal ground-glass opacity with a peripheral ring of consolidation which may be complete or incomplete. The sign was originally described in organizing pneumonia but can also occur in infections, infarction, granulomatous disease, inflammation and t...
Article
Rat's tail sign (esophagus)
The rat's tail sign refers to tapering of the inferior esophagus on barium swallow study. Many sources use this sign synonymously with the bird beak sign (esophagus) and indicate that it is characteristic of achalasia 1. It is important to remember that if a "rat tail" involves more than just t...
Article
Elfin facies
Elfin facies refers to a characteristic facial appearance seen in certain rare congenital syndromes.
Terminology
Elfin facies is sometimes used synonymously with Williams syndrome and the latter is occasionally called elfin facies syndrome. However elfin facies is seen with other rare genetic ...
Article
Juxtaphrenic peak sign
The juxtaphrenic peak sign, also known as diaphragmatic tenting or Kattan sign, refers to the peaked or tented appearance of a hemidiaphragm which can occur in the setting of lobar collapse or post lobectomy (lung). It is caused by retraction of the lower end of diaphragm at an inferior accessor...
Article
Double contour sign (knee)
The double contour sign is a helpful radiologic sign of trochlear dysplasia and is seen on true lateral knee radiographs as a double line at the anterior aspect of condyles that occurs if the medial femoral condyle is hypoplastic.
Article
Kissing carotids
The term kissing carotids refers to tortuous and elongated carotid arteries which touch in the midline. They can be found in:
retropharynx 2
intrasphenoid 1
within the pituitary fossa
within sphenoid sinuses
within sphenoid bones
The significance of kissing carotids is two-fold:
may mimi...
Article
Cloverleaf skull (craniosynostosis)
Cloverleaf skull, also known as kleeblattschädel syndrome or deformity, refers to a type of severe craniosynostosis that gives the skull a cloverleaf shape. It is very rare, with less than 130 case reports globally. It typically results from intrauterine premature closure of the sagittal, corona...
Article
Shagreen patch
A shagreen patch is a subepidermal collagenous connective tissue nevus, also known as a collagenoma, associated with tuberous sclerosis. The overlying skin may be discoloured with obvious pores, giving the appearance of orange peel. These lesions are most commonly found in the lumbosacral region...
Article
Lambda sign (disambiguation)
There are two described lambda (λ) signs:
lambda sign (twin pregnancy)
lambda sign (sarcoidosis)
Article
Black turbinate sign (nasal cavity)
The black turbinate sign refers to the non-enhancement of nasal turbinates in a patient with acute invasive fungal rhinosinusitis.
Angioinvasive fungal infection (e.g. mucormycosis or aspergillosis) involves the nasal mucosa and causes infarction of the surrounding tissue. The infarcted tissue ...
Article
Fleck sign (foot)
The fleck sign in the foot is a small bony fragment seen in the Lisfranc space (between the base of the 1st and 2nd metatarsal) associated with avulsion of the Lisfranc ligament (at the base of the 2nd metatarsal or the medial cuneiform). It is a very subtle, but important finding since it predi...
Article
Cervicothoracic sign
The cervicothoracic sign is a variation of the silhouette sign on frontal chest radiography used to determine whether a superior (para)mediastinal soft tissue mass is anterior or posterior to the trachea.
A positive cervicothoracic sign occurs when a thoracic lesion contacts the neck or extends...
Article
Comma sign of subscapularis tear
The comma sign of subscapularis tear was first described on arthroscopy but recognized later on MRI. The comma sign represents a full thickness partial width superior subscapularis tear along with torn superior glenohumeral and coracohumeral ligament insertional fibers vertically retracted via a...
Article
Hydatid cyst signs
There are numerous named imaging signs of hydatid cysts in echinococcal infection. There is considerable variability in the naming and definition of many of the signs in the literature. In general, the signs demonstrate the presence of laminated cyst membranes in various morphologies within a la...
Article
Gasless abdomen
A gasless abdomen refers to a paucity of gas on abdominal radiography, and the specific cause can usually be identified when the patient's history is known. Common causes include:
proximal obstruction: gastric outlet obstruction, esophageal atresia
small bowel obstruction
bowel ischemia
asci...
Article
Accordion sign (colon)
The accordion sign (also known as concertina sign) is seen on CT of the abdomen and refers to the similarity between the thickened edematous wall of pseudomembranous colitis and the folds of an accordion. This appearance is the result of hyperemic enhancing mucosa stretched over markedly thicken...
Article
Strawberry skull
Strawberry skull refers to the shape of the head on an antenatal ultrasound.
Epidemiology
Associations
In general, strawberry skull is considered one of the non-specific 'soft markers' for abnormal fetal development. It is considered more closely associated with trisomy 18 (Edward syndrome).
...
Article
Signs of pulmonary embolus on chest radiography
There are several described signs of pulmonary embolus on chest radiography which are suggestive of this diagnosis. None are pathognomonic and need to be interpreted with caution with close regard to the clinical presentation.
Chang sign
Fleischner sign
Hampton hump (strictly a sign of pulmon...
Article
Aubergine sign (penis)
The aubergine sign (also known as egg-plant sign or deformity) is a clinical sign of a fractured penis. Hemorrhage beyond the tunica albuginea produces swelling and bruising of the penis simulating the appearance of an aubergine.
Article
Pretzel sign (serpentine aneurysm)
The pretzel sign is seen on DSA and is indicative of a serpentine aneurysm 1.
The sign refers to the sinusoid configuration of the intra-aneurysmal vascular channel seen in serpentine aneurysms, giving it the appearance of a pretzel.
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