Delta-sign is seen in-
(Refer: PL Dhingra, Diseases of Ear, Nose & Throat, 7th edition, pg no. 92)

Contrast-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 cuts
Delta-sign may also be seen on contrast enhanced MRI
Petrositis
Acute mastoiditis
sigmoid sinus thrombosis
Glomus tumor