title: Is the subthalamic nucleus hypointense on T2-weighted images? A correlation study using MR imaging and stereotactic atlas data.
abstract: OBJECTIVE
  Although the subthalamic nucleus is the most frequently used target for surgical treatment of Parkinson's disease, the criteria on which it can be identified on T2-weighted images have never been clearly defined. This study was conducted to characterize the precise anatomic distribution of T2-weighted hyposignal in the subthalamic region and to correlate this hyposignal with iron content in the subthalamic nucleus.
  
  
  METHODS
  The T2-weighted MR imaging acquisitions of 15 patients with Parkinson's disease were fused with a digitized version of the Schaltenbrand and Wahren anatomic atlas. The MR signal intensity within the anatomic limits of the subthalamic nucleus was evaluated. An anatomic specimen obtained at autopsy was used to evaluate iron content.
  
  
  RESULTS
  In all patients, the subthalamic nucleus was hypointense on both sides in the anterior half of the nucleus. At more posterior levels of the nucleus, hypointensity was less frequently observed (20-80%). Hypointensity was never observed at the most posterior pole. Iron was present in the anteromedial part of the nucleus but absent at the most posterior levels.
  
  
  CONCLUSIONS
  The hypointense signal intensity located lateral to the red nucleus and dorsolateral to the substantia nigra correlates with the presence of iron and corresponds anatomically to the subthalamic nucleus. It can therefore be used as a landmark for electrode implantation in patients with Parkinson's disease. It should, however, be emphasized that although hypointensity was always present in the anterior half of the subthalamic nucleus, the posterior part of the nucleus was not visible in most cases.
authors.affiliation: Department of Neuroradiology, Pitié-Salpêtrière Hospital, Paris, France.
authors.forename: Didier
authors.initials: D
authors.lastname: Dormont
authors.forename: Kenneth G
authors.initials: KG
authors.lastname: Ricciardi
authors.forename: Dominique
authors.initials: D
authors.lastname: Tandé
authors.forename: Karine
authors.initials: K
authors.lastname: Parain
authors.forename: Carole
authors.initials: C
authors.lastname: Menuel
authors.forename: Damien
authors.initials: D
authors.lastname: Galanaud
authors.forename: Soledad
authors.initials: S
authors.lastname: Navarro
authors.forename: Philippe
authors.initials: P
authors.lastname: Cornu
authors.forename: Yves
authors.initials: Y
authors.lastname: Agid
authors.forename: Jérôme
authors.initials: J
authors.lastname: Yelnik
mesh_terms: D000328:Adult; D000368:Aged; D001931:Brain Mapping; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D007501:Iron / Q000378:metabolism; D008279:Magnetic Resonance Imaging / Q000706:statistics & numerical data*; D008297:Male; D008875:Middle Aged; D009474:Neurons / Q000473:pathology; D010300:Parkinson Disease / Q000175:diagnosis / Q000473:pathology / Q000601:surgery*; D012680:Sensitivity and Specificity; D013223:Statistics as Topic; D013238:Stereotaxic Techniques / Q000706:statistics & numerical data*; D020531:Subthalamic Nucleus / Q000473:pathology*
chemical_list: D007501:Iron