title: The subthalamic nucleus at 7.0 Tesla: evaluation of sequence and orientation for deep-brain stimulation.
abstract: BACKGROUND
  Deep-brain stimulation (DBS) of the subthalamic nucleus (STN) is an accepted neurosurgical technique for the treatment of medication-resistant Parkinson's disease and other neurological disorders. The accurate targeting of the STN is facilitated by precise and reliable identification in pre-stereotactic magnetic resonance imaging (MRI).                 The aim of the study was to compare and evaluate different promising MRI methods at 7.0 T for the pre-stereotactic visualisation of the STN                                METHODS:                  MRI (T2-turbo spin-echo [TSE], T1-gradient echo [GRE], fast low-angle shot [FLASH] two-dimensional [2D] T2* and susceptibility-weighted imaging [SWI]) was performed in nine healthy volunteers. Delineation and image quality for the STN were independently evaluated by two neuroradiologists using a six-point grading system. Inter-rater reliability, contrast-to-noise ratios (CNRs) and signal-to-noise ratios (SNRs) for the STN were calculated. For the anatomical validation, the coronal FLASH 2D T2* images were co-registered with a stereotactic atlas (Schaltenbrand-Wahren).
  
  
  RESULTS
  The STN was clearly and reliably visualised in FLASH 2D T2* imaging (particularly coronal view), with a sharp delineation between the STN, the substantia nigra and the zona incerta. No major artefacts in the STN were observed in any of the sequences. FLASH 2D T2* and SWI images offered significantly higher CNR for the STN compared with T2-TSE. The co-registration of the coronal FLASH 2D T2* images with the stereotactic atlas affirmed the correct localisation of the STN in all cases.
  
  
  CONCLUSIONS
  The STN is best and reliably visualised in FLASH 2D T2* imaging (particularly coronal orientation) at 7.0-T MRI.
authors.affiliation: Department of Neuroradiology, Medical Faculty Mannheim, University of Heidelberg, Theodor-Kutzer-Ufer 1-3, 68167, Mannheim, Germany.
authors.forename: Hans U
authors.initials: HU
authors.lastname: Kerl
authors.forename: Lars
authors.initials: L
authors.lastname: Gerigk
authors.forename: Ioannis
authors.initials: I
authors.lastname: Pechlivanis
authors.forename: Mansour
authors.initials: M
authors.lastname: Al-Zghloul
authors.forename: Christoph
authors.initials: C
authors.lastname: Groden
authors.forename: Ingo S
authors.initials: IS
authors.lastname: Nölte
mesh_terms: D000328:Adult; D001921:Brain / Q000473:pathology; D001931:Brain Mapping / Q000379:methods; D046690:Deep Brain Stimulation / Q000379:methods*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D059906:Neuroimaging / Q000379:methods; D059629:Signal-To-Noise Ratio; D020531:Subthalamic Nucleus / Q000502:physiology*; D016896:Treatment Outcome; D055815:Young Adult