title: Surgical planning for retrosigmoid craniotomies improved by 3D computed tomography venography.
abstract: OBJECTIVE
  It is impossible to precisely anticipate the crooked course of the transverse and sigmoid sinuses and their individual relationship to superficial landmarks such as the asterion during retrosigmoid approaches. This study was designed to evaluate this anatomical relationship with the help of a surgical planning system and to analyze the impact of these in vivo findings on trepanation placement in retrosigmoid craniotomies.
  
  
  METHODS
  In a consecutive series of 123 patients with pathologies located in the cerebellopontine angle, 72 patients underwent surgical planning for retrosigmoid craniotomies based on 3D volumetric renderings of computed tomography venography. By opacity modulation of surfaces in 3D images the position of the asterion was assessed in relationship to the transverse-sigmoid sinus transition (TST) and compared to its intraoperative localization. We evaluated the impact of this additional information on trepanation placement.
  
  
  RESULTS
  The spatial relationship of the asterion and the underlying TST complex could be identified and recorded in 66 out of 72 cases. In the remaining 6 cases the sutures were ossified and not visible in the 3D CT reconstructions. The asterion was located on top of the TST in 51 cases, above the TST in 4 cases, and below the TST in 11 cases. The location of the trepanation was modified in 27 cases due to the preoperative imaging findings with major and minor modifications in 10 and 17 cases, respectively.
  
  
  CONCLUSIONS
  Volume-rendered images provide reliable 3D visualization of complex and hidden anatomical structures in the posterior fossa and thereby increase the precision in retrosigmoid approaches.
authors: Eberhard Karls University, Tübingen, Germany. alireza.gharabaghi@uni-tuebingen.de
authors: A
authors: A
authors: Gharabaghi
authors: S K
authors: SK
authors: Rosahl
authors: G C
authors: GC
authors: Feigl
authors: A
authors: A
authors: Samii
authors: T
authors: T
authors: Liebig
authors: S
authors: S
authors: Heckl
authors: J M
authors: JM
authors: Mirzayan
authors: S
authors: S
authors: Safavi-Abbasi
authors: A
authors: A
authors: Koerbel
authors: H
authors: H
authors: Löwenheim
authors: T
authors: T
authors: Nägele
authors: R
authors: R
authors: Shahidi
authors: M
authors: M
authors: Samii
authors: M
authors: M
authors: Tatagiba
mesh_terms: D001932:Brain Neoplasms / Q000000981:diagnostic imaging / Q000601:surgery; D015331:Cohort Studies; D003399:Craniotomy / Q000379:methods*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional; D008297:Male; D016343:Monitoring, Intraoperative / Q000379:methods; D010690:Phlebography / Q000379:methods*; D012680:Sensitivity and Specificity; D019291:Skull Base / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000601:surgery; D014057:Tomography, X-Ray Computed / Q000379:methods*; D054064:Transverse Sinuses / Q000000981:diagnostic imaging* / Q000601:surgery