Dilated Intercavernous Sinuses: An MR Sign of Carotid-Cavernous and Carotid-

Dilated venous channels traversing the sella and connecting the two cavernous sinuses were seen on contrast-enhanced MR images in four patients with angiographi-cally proved carotid fistulas. The anatomy and variations of these so-called intercaver-nous sinuses are discussed and are demonstrated in Latex-injected anatomic speci-mens. Direct visualization of the intercavernous sinuses on contrast-enhanced MR images may serve as an ancillary sign for the diagnosis of carotid-cavernous or carotid-dural fistulas near the sella