title: Advanced MR Imaging of the Human Nucleus Accumbens--Additional Guiding Tool for Deep Brain Stimulation.
abstract: OBJECTIVE
  The human nucleus accumbens (Acc) has become a target for deep brain stimulation (DBS) in some neuropsychiatric disorders. Nonetheless, even with the most recent advances in neuroimaging it remains difficult to accurately delineate the Acc and closely related subcortical structures, by conventional MRI sequences. It is our purpose to perform a MRI study of the human Acc and to determine whether there are reliable anatomical landmarks that enable the precise location and identification of the nucleus and its core/shell division.
  
  
  METHODS
  For the Acc identification and delineation, based on anatomical landmarks, T1WI, T1IR and STIR 3T-MR images were acquired in 10 healthy volunteers. Additionally, 32-direction DTI was obtained for Acc segmentation. Seed masks for the Acc were generated with FreeSurfer and probabilistic tractography was performed using FSL. The probability of connectivity between the seed voxels and distinct brain areas was determined and subjected to k-means clustering analysis, defining 2 different regions.
  
  
  RESULTS
  With conventional T1WI, the Acc borders are better defined through its surrounding anatomical structures. The DTI color-coded vector maps and IR sequences add further detail in the Acc identification and delineation. Additionally, using probabilistic tractography it is possible to segment the Acc into a core and shell division and establish its structural connectivity with different brain areas.
  
  
  CONCLUSIONS
  Advanced MRI techniques allow in vivo delineation and segmentation of the human Acc and represent an additional guiding tool in the precise and safe target definition for DBS.
authors: Anatomy Department, Lisbon Medical School, Lisboa, Portugal.|Neuroradiology Department, North Lisbon Medical Center, Lisboa, Portugal.
authors: Lia
authors: L
authors: Lucas-Neto
authors: Neuroradiology Department, North Lisbon Medical Center, Lisboa, Portugal.
authors: Sofia
authors: S
authors: Reimão
authors: Anatomy Department, Lisbon Medical School, Lisboa, Portugal.|Neurosurgery Department, North Lisbon Medical Center, Lisboa, Portugal.
authors: Edson
authors: E
authors: Oliveira
authors: Anatomy Department, Lisbon Medical School, Lisboa, Portugal.|Neurosurgery Department, North Lisbon Medical Center, Lisboa, Portugal.
authors: Alexandre
authors: A
authors: Rainha-Campos
authors: Instituto de Biofísica e Engenharia Biomédica, Faculdade de Ciências, University of Lisbon, Lisboa, Portugal.
authors: João
authors: J
authors: Sousa
authors: Instituto de Biofísica e Engenharia Biomédica, Faculdade de Ciências, University of Lisbon, Lisboa, Portugal.
authors: Rita G
authors: RG
authors: Nunes
authors: Anatomy Department, Lisbon Medical School, Lisboa, Portugal.|Neurosurgery Department, North Lisbon Medical Center, Lisboa, Portugal.
authors: António
authors: A
authors: Gonçalves-Ferreira
authors: Neuroradiology Department, North Lisbon Medical Center, Lisboa, Portugal.
authors: Jorge G
authors: JG
authors: Campos
mesh_terms: D000368:Aged; D046690:Deep Brain Stimulation / Q000379:methods*; D056324:Diffusion Tensor Imaging / Q000379:methods* / Q000592:standards; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D008875:Middle Aged; D009714:Nucleus Accumbens / Q000033:anatomy & histology* / Q000502:physiology*
keywords: Deep brain stimulation; diffusion tensor imaging; magnetic resonance imaging; nucleus accumbens; probabilistic tractography