title: Tract identification by novel MRI signal changes following stereotactic anterior capsulotomy.
abstract: BACKGROUND
  Five patients underwent magnetic resonance imaging (MRI) following MRI-guided stereotactic bilateral anterior capsulotomy to detect lesion-related anatomic changes.
  
  
  METHODS
  Five disabled and treatment-resistant patients with major depression (n = 4) and obsessive-compulsive disorder (n = 1) underwent stereotactic bilateral anterior capsulotomy. All patients had postoperative MRI at 2 months and at 1-4 years after surgery. An additional patient who had a pure motor deficit following a spontaneous basal ganglia hemorrhagic stroke was imaged as a comparator.
  
  
  RESULTS
  The 2-month postcapsulotomy MRI showed a previously undescribed increase in T1-weighted signal within similar neural pathways for each patient. These pathways showed no changes in T2-weighted or fluid-attenuated inversion recovery sequences. The signal changes are different from the expected changes associated with anterograde Wallerian degeneration and identify retrograde changes in the proximal segment of the interrupted axon.
  
  
  CONCLUSIONS
  Previously undescribed T1-weighted signal alterations following stereotactic surgery identify retrograde non-Wallerian changes in interrupted axons and provide a new method in identifying and tracing lesioned pathways.
authors.affiliation: Department of Psychiatry, University of British Columbia, Vancouver, Canada. t.hurwitz@ubc.ca
authors.forename: T A
authors.initials: TA
authors.lastname: Hurwitz
authors.forename: T
authors.initials: T
authors.lastname: Mandat
authors.forename: B
authors.initials: B
authors.lastname: Forster
authors.forename: C
authors.initials: C
authors.lastname: Honey
mesh_terms: D000328:Adult; D003866:Depressive Disorder / Q000473:pathology* / Q000601:surgery*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D020644:Midline Thalamic Nuclei / Q000033:anatomy & histology; D009771:Obsessive-Compulsive Disorder / Q000473:pathology* / Q000601:surgery*; D013238:Stereotaxic Techniques; D016896:Treatment Outcome