In chest radiography, the<unk>  is a sign that represents a focus of oligemia (hypovolemia) (leading to collapse of vessel) seen distal to a pulmonary embolism (PE). While the chest x-ray is normal in the majority of PE cases, the<unk>  is seen in 2% of patients. Essentially, this is a plain X-ray version of a filling defect as seen on computed tomography pulmonary arteriogram. The sign results from a combination of: # the dilation of the pulmonary arteries proximal to the embolus and # the collapse of the distal vasculature creating the appearance of a sharp cut off on chest radiography.
Westermark sign
Amsler sign
Claybrook sign
Lincoln sign
Blumberg sign
Markle sign
Froment's sign
Gorlin sign