title: Value of 3-dimensional high-resolution magnetic resonance imaging in detecting the offending vessel in hemifacial spasm: comparison with intraoperative high definition endoscopic visualization.
abstract: BACKGROUND
  High-resolution 3-dimensional (3-D) magnetic resonance imaging (MRI) is widely used to predict the neurovascular anatomy within the cerebellopontine angle.
  
  
  OBJECTIVE
  To assess the value of 3-D steady-state free precession imaging (SSFP) and time-of-flight magnetic resonance angiography (TOF MRA) in detecting the offending vessels in hemifacial spasm in comparison to intraoperative endoscopic visualization.
  
  
  METHODS
  42 patients underwent endoscope-assisted microvascular decompression (MVD). All available preoperative 3-D SSFP and TOF MRA images were checked. Intraoperative videos were captured by a high-definition endoscopic camera attached to endoscopes while exploring the area of facial nerve root exit zone (REZ). Evaluation of the 3-D images was performed by 2 independent groups of observers and compared with the operative findings.
  
  
  RESULTS
  Three-D MRI had an average positive predictive value (PPV) of 89.1% in differentiating between simple and complex compression. Mean accuracy of the images in detection of the offending vessels was 83.3% and 77% according to the first and second groups of observers, respectively. Averaged inter-observer agreement between the 2 groups of observers was substantial, with an averaged Kappa coefficient (K) of 0.56. In the simple compression group, mean accuracy was 97% and 89.4% according to the first and second groups of observers, respectively. Averaged K for agreement was substantial (K = 0.65).
  
  
  CONCLUSIONS
  According to endoscopic visualization, 3-D SSFP and TOF MRA images are accurate in detecting the offending vessels in simple compression of the facial nerve, and in predicting presence of a complex compression with variable sensitivity in identifying all offending vessels.
authors.affiliation: Department of Neurosurgery, University Medicine Greifswald, Germany. e.elrefaee@googlemail.com
authors.forename: Ehab
authors.initials: E
authors.lastname: El Refaee
authors.forename: Soenke
authors.initials: S
authors.lastname: Langner
authors.forename: Joerg
authors.initials: J
authors.lastname: Baldauf
authors.forename: Marc
authors.initials: M
authors.lastname: Matthes
authors.forename: Michael
authors.initials: M
authors.lastname: Kirsch
authors.forename: Henry W S
authors.initials: HW
authors.lastname: Schroeder
mesh_terms: D000328:Adult; D000368:Aged; D002536:Cerebral Arteries / Q000473:pathology* / Q000601:surgery*; D004724:Endoscopy / Q000379:methods*; D005260:Female; D019569:Hemifacial Spasm / Q000175:diagnosis* / Q000601:surgery*; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods; D007430:Intraoperative Care / Q000379:methods; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D061145:Microvascular Decompression Surgery / Q000379:methods*; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D016896:Treatment Outcome