Archive | November 2012

Cord sign – refers to cord-like hyperattenuation with a dural…

Cord sign refers to cord-like hyperattenuation with a dural venous sinus on non-contrast enhanced CT of the brain due to dural venous sinus thrombosis. The sign is most commonly seen with the transverse sinus (as in this case, red arrow) because it runs along the origin of the tentorium approximately in the axial plane such that it is visible on one image. CT venogram in this case confirmed thrombosis (blue arrow).

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Puff of smoke sign – describes the characteristic angiographic…

Puff of smoke sign – describes the characteristic angiographic appearance of tiny abnormal intracranial collateral vessel networks in moyamoya disease. Progressive narrowing of the supraclinoid internal carotid arteries and circle of Willis vessels results in extensive small collateral arterial networks evolving from the lenticulostriate and choroidal arteries. When viewed angiographically, the abnormal collaterals simulate smoke emanating away from the major arteries.    

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Shepherd’s crook deformity – refers to a distinctive…

Shepherd’s crook deformity – refers to a distinctive abnormal contour of the proximal femur in the setting of fibrous dysplasia.  As the bone deforms the angle made between the neck of the femur and the femoral shaft decreases (coxa vara) and the bone becomes rounded simulating the appearance of a shepherd’s crook, a stick with a C-shaped end carried by shepherd’s particularly common in biblical times.

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Left atrial enlargement – while echocardiography has emerged as…

Left atrial enlargement – while echocardiography has emerged as the preferred tool for assessing cardiac chamber size, recognising the features of left atrial enlargement on chest radiography remains worthwhile.

Direct signs

  • The double density sign (left image) occurs when the right side of the dilated left atrium is visible next to the normal right heart border (right atrium). It may even extend out beyond the right heart border, an appearance known as atrial escape
  • Oblique measurement of greater than 7cm (right image, blue arrow).
  • Convex left atrial appendage – normally it is flat or concave.
Indirect signs
  • Splaying of the carina to greater than a 90 degree angle (right image, yellow lines).
  • Posterior displacement of the left main stem bronchus on lateral radiographs forming an upside down ‘V’ known as the walking man sign. 

from our tumblr blog

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Acute appendicitis – a quick video tutorial demonstrating the…

Acute appendicitis – a quick video tutorial demonstrating the key features to help you diagnose appendicitis on CT. Video courtesy of RadiologyChannel.  

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Corkscrew sign – describes the spiral appearance of the distal…

Corkscrew sign – describes the spiral appearance of the distal duodenum and proximal jejunum in the setting of midgut volvulus on contrast studies. In patients with congenital malrotation of the midgut, the distal duodenum and proximal jejunum do not cross the midline and instead pass inferiorly. These loops are predisposed to twist on their shortened mesentery creating the classic corkscrew appearance of midgut volvulus.

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QUIZ: Can you spot the two potentially deadly diagnoses on this…

QUIZ: Can you spot the two potentially deadly diagnoses on this abdominal CT? Click here for ANSWER

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