"Doughnut" sign in brain scanning.

The significance of the "doughnut" sign at present is relegated to characterizing the morphology of a lesion. The use of the "doughnut" sign in differential diagnosis should not be attempted except in specific clinical contexts, and never excluding other evidence. The "doughnut" sign in scanning together with other studies such as angiography and computerized axial tomography gives additional characterizing data in the neuroradiologic evaluation of a patient.