title: Use of cranial surface anatomic fiducials for interactive image-guided navigation in the temporal bone: a cadaveric study.
abstract: OBJECTIVE
  Because of the intricate anatomy of the temporal bone, we examined the feasibility and reliability of cranial surface anatomic fiducials to register computed tomographic images of the temporal bone by using a frameless image-guided system.
  
  
  METHODS
  One-millimeter thick computed tomographic slices and the smallest possible field of view were used to register 10 dry and 10 fresh temporal bones from cadavers. The fiducials used for registration included the umbo of the tympanic membrane, emissary foramina, the asterion, various sutures, the tip of the mastoid process, and Henle's spine.
  
  
  RESULTS
  Mean initial fiducial registration error ranged from 0.6 to 0.7 mm, and was reduced to 0.5 and 0.4 mm for the dry cranial and cadaveric studies, respectively, by eliminating or reregistering inexact fiducials. Mean target localization error ranged from 0.91 to 2.44 mm for superficial structures of the temporal bone in the dry cranial specimens and from 0.71 to 1.52 mm for deep structures such as the facial nerve, semicircular canals and ossicles in the cadaveric study.
  
  
  CONCLUSIONS
  Interactive image-guided navigation in the temporal bone is possible with registration of cranial surface anatomic fiducials. It may be useful to the neurosurgeon and otologist in identifying critical anatomic structures of the temporal bone encountered during the translabyrinthine, retrolabyrinthine presigmoid, and suboccipital approaches.
authors.affiliation: Department of Neurosurgery, The University of Tennessee College of Medicine, Memphis, USA.
authors.forename: F D
authors.initials: FD
authors.lastname: Vrionis
authors.forename: K T
authors.initials: KT
authors.lastname: Foley
authors.forename: J H
authors.initials: JH
authors.lastname: Robertson
authors.forename: J J
authors.initials: JJ
authors.lastname: Shea
mesh_terms: D002508:Cephalometry / Q000379:methods*; D003051:Cochlea / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D005154:Facial Nerve / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D005240:Feasibility Studies; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D007431:Intraoperative Complications / Q000517:prevention & control; D008416:Mastoid / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D016343:Monitoring, Intraoperative / Q000379:methods*; D013701:Temporal Bone / Q000033:anatomy & histology / Q000000981:diagnostic imaging* / Q000601:surgery; D014057:Tomography, X-Ray Computed / Q000379:methods*; D014432:Tympanic Membrane / Q000033:anatomy & histology / Q000000981:diagnostic imaging