Football sign – of massive pneumoperitoneum on a supine abdominal radiograph. Normally the margins of the abdominal cavity are only faintly visible due to the density difference between intraperitoneal fat and the abdominal wall. However in the setting of pneumoperitoneum, air makes the outline of the distended abdominal cavity extremely distinct and somewhat football-shaped. Sometimes the falciform ligament is outlined centrally like the football’s seam. The sign is most frequently seen in infants with advanced necrotising enterocolitis (as was the case above) but may be seen with any cause of free gas.
Note: Radiopaedia.org was founded in Australia hence the Aussie rules football!
from our tumblr blog: http://radiologysigns.tumblr.com/post/24041716382
Finger in glove sign – refers to the characteristic finger-like appearance of mucous plugs within dilated bronchiectatic central bronchi in allergic bronchopulmonary aspergillosis (ABPA). Seen here in the right upper lobe, this condition almost exclusively occurs as the result of chronic asthma. The sign can be observed on CXR and CT.
from our tumblr blog: http://radiologysigns.tumblr.com/post/23895539803
Segmental renal infarct
Lobar nephronia (pyelonephritis)
Cortical rim sign – useful in distinguishing renal infarct from lobar nephronia on contrast enhanced CT or MRI. Both pathologies appear as wedge-shaped regions of reduced enhancement, however in approximately 50% of segmental infarcts the very outer few millimetres of cortex enhances as perfusion is maintained by the renal capsular artery (left image ‘cortical rim sign’). In contradistinction the oedema and hypoperfusion of pyelonephritis involves the entire cortex (right image).
from our tumblr blog: http://radiologysigns.tumblr.com/post/23729422999
Steeple sign – tapering of the upper trachea on a frontal chest or neck radiograph reminiscent of a church steeple. The appearance is suggestive of croup (which should be obvious clinically!). A corresponding lateral image would show narrowing of the sub-glottic trachea and ballooning of the hypopharynx.
from our tumblr blog: http://radiologysigns.tumblr.com/post/23588723084
Comb sign – seen in active Crohn’s disease. It describes prominent mesenteric vessels extending towards inflamed segments of small bowel like the teeth of a comb. The appearance is due to a combination of vascular distension and mesenteric fibrofatty proliferation. It can be seen on both CT and MRI.
from our tumblr blog: http://radiologysigns.tumblr.com/post/23471336368
Normal = more black sign
Lower lobe pneumomia
More black sign – an important normal lateral chest x-ray finding (left image). It refers to the gradual increase in radiolucency (blackness) of the vertebral bodies when proceeding from upper to lower chest due to an increasing proportion of air. When air is replaced by higher attenuation material, such as in lower lobe consolidation (right image), then the lower vertebral bodies become abnormally radiodense (white).
from our tumblr blog: http://radiologysigns.tumblr.com/post/23274370027
Infundibulum sign – helpful in distinguishing an empty pituitary sella from a cystic lesion of the pituitary region. In the former, although the sella is enlarged, there is no mass and the pituitary infundibulum continues to traverse the enlarged sella to the residual pituitary at the floor. When a cystic mass is present however the infundibulum is displaced away.
from our tumblr blog: http://radiologysigns.tumblr.com/post/23146212972