title: The anatomical classification of AICA/PICA branching and configurations in the cerebellopontine angle area on 3D-drive thin slice T2WI MRI.
abstract: BACKGROUND
  With the technical advance of magnetic resonance imaging (MRI), we have been able to observe not only the small cranial nerves arising from the brain stem but also the branches of vertebrobasilar artery in the cerebellopontine angle (CPA) cistern.
  
  
  OBJECTIVE
  The purpose was to demonstrate the courses and configurations of the anterior inferior cerebellar artery (AICA) or posterior inferior cerebellar artery (PICA) branch including the internal auditory artery in the CPA cistern and evaluate the relationship between the facial-vestibulocochlear (VIIth-VIIIth) nerves and AICA/PICA on high-resolution, thin-slice, three-dimensional T2-weighted MRI using driven equilibrium pulse.
  
  
  METHODS
  Thirty-three men and 27 women aged 8-85 years old with sensory hearing loss or vertigo, and/or tinnitus were evaluated by thin-slice (0.75 mm) T2-weighted MRI. Five subjects (3 men, 2 women) without any auditory symptoms were also examined.
  
  
  RESULTS
  Thin-slice T2WI drive MRI revealed several variations of the AICA/PICA coursing, such as a loop formation (n=30, 48 sides) or the IAC extension (n=19, 30 sides). Contact with the vestibulocochlear nerve was seen in 31.7% subjects (n=19, 27 sides). The AICA/PICA branching and shape patterns relative to the CPA and IAC were classified into four major types: type 1A, nonloop AICA/PICA in the CPA cistern; type 1 B, nonloop AICA/PICA (internal auditory artery) entering the IAC; type 2A, loop-type AICA/PICA in the CPA cistern; and type 2B, loop-type AICA/PICA entering the IAC.
  
  
  CONCLUSIONS
  There was statistically significant association between types 1A and 2A (P<.01) regarding the existence of any auditory 3 symptoms. The results of our study suggest that this classification is simple and very useful for the elucidation of the mechanism of auditory symptoms and deciding the therapeutic strategies.
authors.affiliation: Department of Radiology, Kyoto University Hospital, Kyoto-City, Kyoto 606-8507, Japan. Electronic address: nk1207@kuhp.kyoto-u.ac.jp.
authors.forename: Nobukata
authors.initials: N
authors.lastname: Kazawa
authors.forename: Kaori
authors.initials: K
authors.lastname: Togashi
authors.forename: Juichi
authors.initials: J
authors.lastname: Ito
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001488:Basilar Artery / Q000473:pathology*; D002530:Cerebellopontine Angle / Q000098:blood supply* / Q000473:pathology; D002536:Cerebral Arteries / Q000473:pathology*; D002648:Child; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D014012:Tinnitus / Q000473:pathology; D014711:Vertebral Artery / Q000473:pathology*; D014717:Vertigo / Q000473:pathology; D000159:Vestibulocochlear Nerve / Q000473:pathology; D055815:Young Adult
keywords: 3D-drive-T2WI Anterior inferior cerebellar artery (AICA) Posterior inferior cerebellar artery (PICA) Vestibulocochlear (VIIIth) cranial nerve Nerve–vascular compression syndrome; Anatomical topics; Head and neck; MR imaging