Section Editor: Sandy Cheng-Yu Chen, M.D.
Taipei Medical University Hospital, Taipei, Taiwan
Figure Caption
The lateralized petrous internal carotid artery is an anatomic variant consisting of a more lateral position of the genu of the vertical and horizontal petrous segments of the internal carotid artery, often with associated lateral wall dehiscence. The classic CT findings include a lateralized internal carotid artery that passes under the cochlea (yellow arrows) in the hypotympanum (blue arrows), where the inferior tympanic canaliculus (red arrows) is normal. The main differential diagnosis is aberrant internal carotid artery, which typically courses across the middle ear along the cochlear promontory and is characterized by enlargement of the inferior tympanic canaliculus.