title: Assessment of the variability in the anatomical position and size of the subthalamic nucleus among patients with advanced Parkinson's disease using magnetic resonance imaging.
abstract: OBJECTIVE
  Targeting of the subthalamic nucleus (STN) during deep brain stimulation (DBS) surgery using standard atlas coordinates is used in some centers. Such coordinates are accurate for only a subgroup of patients, and subgroup size depends on the extent of inter-individual variation in STN position/size and degree to which atlas represents average anatomical relations. Few studies have addressed this issue.
  
  
  METHODS
  Sixty-two axial T(2)-weighted magnetic resonance (MR) images of the brain (1.5 T) were obtained before STN-DBS in 62 patients (37 males) with Parkinson's disease using a protocol optimized for STN visualization. Image distortion was within sub-millimeter range. Midcommissural point (MCP)-derived coordinates of STN borders, STN center, and other brain landmarks were obtained using stereotactic software. MR-derived measurements were compared to Schaltenbrand and Wahren Atlas.
  
  
  RESULTS
  We evaluated 117 best-visualized STNs. STN dimensions and coordinates of its center were highly variable. STN lateral coordinate ranged 8.7 mm-14.5 mm from MCP, A-P coordinate 3.5 mm posterior to 0.5 mm anterior to MCP, and vertical coordinate 1.3 mm-6 mm below MCP. The antero-posterior nucleus dimension varied by 8 mm and lateral-medial dimension by 5.8 mm. Differences between mean values of MR-derived data sets and Atlas values were statistically significant but moderate, excluding AC-PC length, for which the Atlas value was below the 1st percentile of the MR data set. The STN lateral coordinate strongly correlated with the width of the third ventricle (r = 0.73, p < 0.001).
  
  
  CONCLUSIONS
  It is now possible to directly evaluate STNs at 1.5 T with minimal image distortion, which reveals variation in STN position and dimensions in the range of nucleus size. This puts under question the rationale of use of standard STN coordinates during DBS surgery.
authors.affiliation: Department of Neurosurgery, Boston University School of Medicine, 88 East Newton St., Robinson 4, Boston, MA 02118, USA. sdaniluk@bu.edu
authors.forename: Slawomir
authors.initials: S
authors.lastname: Daniluk
authors.forename: Keith
authors.initials: K
authors.lastname: G Davies
authors.forename: Samuel A
authors.initials: SA
authors.lastname: Ellias
authors.forename: Peter
authors.initials: P
authors.lastname: Novak
authors.forename: Jules M
authors.initials: JM
authors.lastname: Nazzaro
mesh_terms: D000328:Adult; D000368:Aged; D001271:Atlases as Topic; D001931:Brain Mapping / Q000379:methods*; D004599:Electric Stimulation Therapy / Q000379:methods*; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D038361:Neuronavigation / Q000379:methods; D009929:Organ Size; D010300:Parkinson Disease / Q000503:physiopathology / Q000628:therapy*; D011183:Postoperative Complications / Q000517:prevention & control; D011300:Preoperative Care / Q000379:methods*; D012727:Sex Characteristics; D013238:Stereotaxic Techniques; D020531:Subthalamic Nucleus / Q000033:anatomy & histology* / Q000502:physiology / Q000601:surgery