<prompt> Delta-sign is seen inPetrositisAcute mastoiditisSigmoid sinus thrombosisGlomus tumor  <response>: Delta-sign is seen in sigmoid sinus thrombosis. Contrast-enhanced CT scan can show sinus thrombosis by typical delta sign. It is a triangular area with rim enhancement, and the central low-density area is seen in a posterior cranial fossa on axial cuts. Delta sign may also be seen on contrast-enhanced MRI. Ref: Textbook of diseases of ENT, PL Dhingra, 7th edition, pg no. 92,93 