title: Comparison of diffusion tensor imaging tractography of language tracts and intraoperative subcortical stimulations.
abstract: OBJECTIVE
  Diffusion tensor (DT) imaging tractography is increasingly used to map fiber tracts in patients with surgical brain lesions to reduce the risk of postoperative functional deficit. There are few validation studies of DT imaging tractography in these patients. The aim of this study was to compare DT imaging tractography of language fiber tracts by using intraoperative subcortical electrical stimulations.
  
  
  METHODS
  The authors included 10 patients with low-grade gliomas or dysplasia located in language areas. The MR imaging examination included 3D T1-weighted images for anatomical coregistration, FLAIR, and DT images. Diffusion tensors and fiber tracts were calculated using in-house software. Four tracts were reconstructed in each patient including the arcuate fasciculus, the inferior occipitofrontal fasciculus, and 2 premotor fasciculi (the subcallosal medialis fiber tract and cortical fibers originating from the medial and lateral premotor areas). The authors compared fiber tracts reconstructed using DT imaging with those evidenced using intraoperative subcortical language mapping.
  
  
  RESULTS
  Seventeen (81%) of 21 positive stimulations were concordant with DT imaging fiber bundles (located within 6 mm of a fiber tract). Four positive stimulations were not located in the vicinity of a DT imaging fiber tract. Stimulations of the arcuate fasciculus mostly induced articulatory and phonemic/syntactic disorders and less frequently semantic paraphasias. Stimulations of the inferior occipitofrontal fasciculus induced semantic paraphasias. Stimulations of the premotor-related fasciculi induced dysarthria and articulatory planning deficit.
  
  
  CONCLUSIONS
  There was a good correspondence between positive stimulation sites and fiber tracts, suggesting that DT imaging fiber tracking is a reliable technique but not yet optimal to map language tracts in patients with brain lesions. Negative tractography does not rule out the persistence of a fiber tract, especially when invaded by the tumor. Stimulations of the different tracts induced variable language disorders that were specific to each fiber tract.
authors.affiliation: Department of Neuroradiology, Groupe Hospitalier Pitié-Salpêtrière, Université Pierre et Marie Curie, Paris, France. dlecl_99@yahoo.fr
authors.forename: Delphine
authors.initials: D
authors.lastname: Leclercq
authors.forename: Hugues
authors.initials: H
authors.lastname: Duffau
authors.forename: Christine
authors.initials: C
authors.lastname: Delmaire
authors.forename: Laurent
authors.initials: L
authors.lastname: Capelle
authors.forename: Peggy
authors.initials: P
authors.lastname: Gatignol
authors.forename: Mathieu
authors.initials: M
authors.lastname: Ducros
authors.forename: Jacques
authors.initials: J
authors.lastname: Chiras
authors.forename: Stéphane
authors.initials: S
authors.lastname: Lehéricy
mesh_terms: D000328:Adult; D001921:Brain / Q000473:pathology* / Q000503:physiopathology* / Q000601:surgery; D001932:Brain Neoplasms / Q000473:pathology / Q000503:physiopathology / Q000601:surgery; D056324:Diffusion Tensor Imaging / Q000379:methods*; D004558:Electric Stimulation / Q000379:methods*; D005260:Female; D005910:Glioma / Q000473:pathology / Q000503:physiopathology / Q000601:surgery; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods; D007802:Language; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D054220:Malformations of Cortical Development / Q000473:pathology / Q000503:physiopathology / Q000601:surgery; D008875:Middle Aged; D009434:Neural Pathways / Q000473:pathology / Q000503:physiopathology; D019635:Neurosurgical Procedures / Q000379:methods*; D012984:Software; D055815:Young Adult