title: The role of the supramammillary commissure in MR localization of the subthalamic nucleus.
abstract: OBJECTIVE
  We have discovered a method for localization of the subthalamic nucleus (STN) utilizing the supramammillary commissure (SMC) as reference point. It is our purpose to present our experience and compare our methods with others.
  
  
  METHODS
  Sixteen patients targeted for bilateral DBS for 32 total STN targets were studied by 1 mm MP-RAGE images with coronal T2W images. A modified red nucleus and mustache method was applied. The predicted target points were then confirmed with electronic calipers measuring the differences in methods.
  
  
  RESULTS
  Modified red nucleus method using Surgiplan, and EBAL and BAGM electronic brain map atlas matched the target loci of 12 mm, -3 mm, -4 mm on an X-, Y-, and Z-coordinate system with zero at the mid-commissural point. From the coronal view Y is fixed at -3 mm. The mustache method was in error with values of X-axis at 14.25 (+/- 1.41 SD) (p = 0.69), and of Z-axis at -5.0 (+/- 1.60 SD) (p = 0.55). Three-fourths had moderate to marked ventricular enlargement of the III, but only 3 had enlargement of the frontal horns.
  
  
  CONCLUSIONS
  The mustache method erred in the X-axis because the thalamocaudate groove was located lateral to the target point of the STN, and in the Z-axis because of varying thicknesses of the SMC. The top of the SMC is directly lateral from the STN target by 12 mm from the anterior and posterior commissures line. The SMC being a recognizable structure with constant relation to the STN should be the target structure.
authors.affiliation: Department of Neuroradiology, University of Kentucky, Lexington, KY 40536-0084, USA. clee02@uky.edu
authors.forename: Charles
authors.initials: C
authors.lastname: Lee
authors.forename: Byron
authors.initials: B
authors.lastname: Young
authors.forename: Michael F
authors.initials: MF
authors.lastname: Sanders
mesh_terms: D001931:Brain Mapping; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D010300:Parkinson Disease / Q000473:pathology*; D013238:Stereotaxic Techniques; D020531:Subthalamic Nucleus / Q000033:anatomy & histology / Q000473:pathology* / Q000502:physiology*