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.

21 results found
Article

Earth-heart sign

The earth-heart sign is a newly recognised sign of cardiac compromise that may be seen on chest radiographs of patients with tension pneumomediastinum. The substantial pressure exerted on the heart by the air trapped in mediastinum with subsequent impairment of central venous return and obstruc...
Article

Eccentric target sign

The eccentric target sign is considered pathognomonic for cerebral toxoplasmosis. It is seen on postcontrast MRI/CT as a ring enhancing lesion with an eccentrically located enhancing mural nodule. It is believed that this mural nodule is an extension from the abscess wall itself with inflamed ve...
Article

Echogenic fetal bowel

Echogenic fetal bowel is an observation in antenatal ultrasound imaging, in which fetal bowel appears to be brighter than it is supposed to be. It is a soft marker for trisomy 21 and has several other associations. When observed, it needs to be interpreted in the context of other associated abno...
Article

Egg shell calcification within the breast

Egg shell calcifications in the breast are benign peripheral rim like calcifications Pathology They represent calcifications secondary to fat necrosis, calcification of oil cysts. Radiographic features thin rim like calcification (< 1mm in thickness) lucent centres small to several cent...
Article

Egg-on-a-string sign

Egg-on-a-string sign, also referred as egg on its side, refers to the cardiomediastinal silhouette seen in transposition of the great arteries (TGA). The heart appears globular due to an abnormal convexity of the right atrial border and left atrial enlargement and therefore appears like an egg...
Article

Eggshell calcification

Eggshell calcification refers to fine calcification seen at the periphery of a mass, and usually relates to lymph node calcification. In 1967 Jacobsen and Felson published criteria to help "avoid over-reading of the incidental circumferential concentrations of calcium and to eliminate conf...
Article

Elbow joint effusion

Recognising an elbow joint effusion on lateral radiographs is an essential radiology skill. While the fluid itself is not discretely seen because it is the same density as the surrounding muscles, an effusion can be inferred by observing displacement of the anterior and / or posterior fat pads s...
Article

Empty amnion sign

The empty amnion sign is a sonographic observation where there is visualization of an amniotic sac without concomitant visualization of an embryo. It is an indicator pregnancy failure regardless of the mean sac diameter and is considered to have a sufficiently high positive predictive value 2.  ...
Article

Empty delta sign

The empty delta sign is CT sign of dural venous sinus thrombosis of the superior sagittal sinus, where contrast outlines a triangular filling defect (clot). It is only described with CECT-scan or MRI, not with NECT nor non-contrast MRI. Pathology The exact mechanism for this appearance is unce...
Article

Empty light bulb sign in brain death

In brain death, on HMPAO-Tc99m imaging there is absent or reduced flow in the internal carotid arteries and increased flow within the external carotid arteries. This leads to absent uptake in the brain with subsequent increased perfusion in the nasal region. This appearance has been called the '...
Article

Empty thecal sac sign

The empty thecal sac sign or empty sac sign is when the thecal sac appears empty on MRI of the lumbar spine, best seen on T2-weighted images. If the empty thecal sac sign is present, a diagnosis of adhesive arachnoiditis can be made.​ Radiographic features MRI There is usually no Gadolinium c...
Article

Endosteal scalloping

Endosteal scalloping refers to the focal resorption of the inner margin of cortical bones, typically seen in long bones, due to slow growing medullary lesions. It is important to note that although it is evidence of a slow non-infiltrative lesion, it does not equate to benign aetiology. In fact...
Article

Erlenmeyer flask deformity

An Erlenmeyer flask deformity refers to a radiographic appearance typically on a femoral radiograph where there is relative constriction of the diaphysis and flaring of the metaphysis. Causes include marrow infiltration/expansion Gaucher disease associated osteopenia with avascular necrosis ...
Article

État criblé

État criblé, also known as status cribrosum, is a term that describes the diffusely widened perivascular spaces (Virchow-Robin spaces) in the basal ganglia, especially in the corpus striatum. It is usually symmetrical, with the perivascular spaces showing CSF signal and without diffusion restric...
Article

État lacunaire

État lacunaire is a term describing the presence of multiple lacunar infarcts, which are ischemic strokes due to occlusion of penetrating cerebral arterioles, especially in the basal ganglia. The term has been strongly described as a pathological substrate for a multi-infarct vascular dementia 4...
Article

Expanded amnion sign

The expanded amnion sign has been described as a poor prognostic sign in early pregnancy, suspicious though not diagnostic of failed early pregnancy. An abnormal embryo will have an abnormally large amniotic cavity. Gestational sac diameter is usually found to be correct for age. See also empt...
Article

Extracranial brain herniation

Extracranial brain herniation refers to herniation of brain tissue outside the calvarium through a skull bone defect, which may be post traumatic or post surgery. Unlike encephalocoeles, brain herniation is surrounded by the meninges.  The herniated brain tissue requires surgical reduction as i...
Article

Extrapleural air sign

The extrapleural air sign is one of the many signs of pneumomediastinum, and was first described by Lillard and Allen in 1965. It is defined as the presence the air between the parietal pleura and the diaphragm. On a lateral projection the air forms a radiolucent pocket of air posterior to the d...
Article

Extrapleural fat sign

The extrapleural fat sign is an imaging feature which can be seen on CT under certain circumstances. It occurs from the inward displacement of an extrapleural fat stripe by an extrapleural fluid collection, extrapleural haematoma or extra pleural mass. The presence of the extrapleural fat sign i...
Article

Extrapleural sign

The extrapleural sign, described by Felson in 1973 1, refers to the appearance of a pulmonary opacity with oblique margins that taper slowly to the chest wall when the lesion is viewed tangentially to the x-ray beam. This appearance suggests that the lesion is extrapleural in nature, as opposed ...
Article

Eye of tiger sign

The eye of the tiger sign refers to abnormal low T2 signal on MRI (due to abnormal accumulation of iron) in the globus pallidus with a longitudinal stripe of high signal (due to gliosis and spongiosis) that can be seen in: Hallervorden-Spatz syndrome: classical but not 100% pathognomonic progr...

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