title: Targeting the subthalamic nucleus for deep brain stimulation--a comparative study between magnetic resonance images alone and fusion with computed tomographic images.
abstract: BACKGROUND
  The aim of this study is to determine whether stereotactic computed tomographic (CT) images fused with magnetic resonance images (MRI) is superior to stereotactic MRI alone in accuracy for targeting the subthalamic nucleus (STN) in deep brain stimulation (DBS).
  
  
  METHODS
  During 2006 to 2007, 21 consecutive patients with Parkinson's disease were enrolled in this retrospective cohort study. CT Fusion group included 10 patients who underwent 20 procedures of STN-DBS under MRI-directed targeting in which the MRIs were fused to stereotactic CT images for surgical coordinates. MRI group included 11 patients who underwent 20 procedures under MRI-directed targeting alone.
  
  
  RESULTS
  After DBS surgery, in comparison to baseline levodopa (L-dopa) OFF, Unified Parkinson Disease Rating Scale, Part III scores improved by 43.6% ± 20.3% and 39.0% ± 15.6% (P = 0.60) in CT Fusion group and MRI group, respectively (L-dopa OFF/DBS ON). The mean decrease in L-dopa equivalent daily dose was 38.9% ± 26.3% and 36.7% ± 30.5% (P = 0.87), respectively. Single microelectrode recording (MER) trajectory procedure was experienced in 65% of patients in the CT Fusion group (13/20) and 45% of patients in the MRI group (9/20). The mean recorded STN length from initial to final MER trajectory in the CT Fusion and MRI groups was 4.3 mm (standard deviation [SD] = 1.8 mm)/5.1 mm (SD = 0.5 mm) and 3.6 mm (SD = 1.7 mm) (P = 0.214)/4.5 mm (SD = 0.7 mm) (P = 0.006), respectively. The final recorded STN length was significantly longer in the CT Fusion group.
  
  
  CONCLUSIONS
  In-frame-based stereotactic STN targeting, an image fusion technique between stereotactic CT and MRI, can record a significantly longer STN length through limited MER compared with MRI alone. Whether this could translate into better clinical outcome and less morbidity still need a large and randomized trial.
authors.affiliation: Department of Neurosurgery, Tzu Chi General Hospital/Tzu Chi University, Hualien, Taiwan.
authors.forename: Shin-Yuan
authors.initials: SY
authors.lastname: Chen
authors.forename: Sheng-Tzung
authors.initials: ST
authors.lastname: Tsai
authors.forename: Hsiang-Yi
authors.initials: HY
authors.lastname: Hung
authors.forename: Sheng-Huang
authors.initials: SH
authors.lastname: Lin
authors.forename: Yan-Hong
authors.initials: YH
authors.lastname: Pan
authors.forename: Shinn-Zong
authors.initials: SZ
authors.lastname: Lin
mesh_terms: D000328:Adult; D000368:Aged; D015331:Cohort Studies; D046690:Deep Brain Stimulation / Q000009:adverse effects / Q000379:methods*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000009:adverse effects / Q000379:methods*; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D020531:Subthalamic Nucleus / Q000033:anatomy & histology* / Q000000981:diagnostic imaging* / Q000601:surgery; D025321:Surgery, Computer-Assisted / Q000009:adverse effects / Q000379:methods*; D014057:Tomography, X-Ray Computed / Q000009:adverse effects / Q000379:methods*; D016896:Treatment Outcome