Acute MCA infarct – dot sign

This case illustrates the ‘dot’ sign of an acute MCA infarct. A cross section through thrombus in a segmental branch of the MCA in the Sylvian fissure results in a high attenuation dot (left image, arrow). The image on the right shows abnormal low attenuation with loss of the normal grey-white matter differentiation throughout the left MCA territory (arrows), indicating a massive infarct.