<prompt> Delta-sign is seen in-PetrositisAcute mastoiditissigmoid sinus thrombosisGlomus tumor  <response>: Refer: PL Dhingra, Diseases of Ear, Nose Throat, 7th edition, pg no. 92Contrast-enhanced CT scan can show sinus thrombosis by typical delta-sign. It is a triangular area with rim enhancement, and central low density area is seen in posterior cranial fossa on axial cutsDelta-sign may also be seen on contrast enhanced MRI 