title: Diffusion tensor imaging (DTI) and tractography of the brachial plexus: feasibility and initial experience in neoplastic conditions.
abstract: BACKGROUND
  The objective of this study was to assess the feasibility and potential clinical applications of diffusion tensor imaging (DTI) and tractography in the normal and pathologic brachial plexus prospectively.
  
  
  METHODS
  Six asymptomatic volunteers and 12 patients with symptoms related to the brachial plexus underwent DTI on a 1.5T system in addition to the routine anatomic plexus imaging protocol. Maps of the apparent diffusion coefficient (ADC) and of fractional anisotropy (FA), as well as tractography of the brachial plexus were obtained. Images were evaluated by two experienced neuroradiologists in a prospective fashion. Three patients underwent surgery, and nine patients underwent conservative medical treatment.
  
  
  RESULTS
  Reconstructed DTI (17/18) were of good quality (one case could not be reconstructed due to artifacts). In all volunteers and in 11 patients, the roots and the trunks were clearly delineated with tractography. Mean FA and mean ADC values were as follows: 0.30+/-0.079 and 1.70+/-0.35 mm2/s in normal fibers, 0.22+/-0.04 and 1.49+/-0.49 mm2/s in benign neurogenic tumors, and 0.24+/-0.08 and 1.51+/-0.52 mm2/s in malignant tumors, respectively. Although there was no statistically significant difference in FA and ADC values of normal fibers and fibers at the level of pathology, tractography revealed major differences regarding fiber architecture. In benign neurogenic tumors (n=4), tractography revealed fiber displacement alone (n=2) or fiber displacement and encasement by the tumor (n=2), whereas in the malignant tumors, either fiber disruption/destruction with complete disorganization (n=6) or fiber displacement (n=1) were seen. In patients with fiber displacement alone, surgery confirmed the tractography findings, and excision was successful without sequelae.
  
  
  CONCLUSIONS
  Our preliminary data suggest that DTI with tractography is feasible in a clinical routine setting. DTI may demonstrate normal tracts, tract displacement, deformation, infiltration, disruption, and disorganization of fibers due to tumors located within or along the brachial plexus, therefore, yielding additional information to the current standard anatomic imaging protocols.
authors.affiliation: Department of Neuroradiology, DISIM, Geneva University Hospital, 4 Rue Gabrielle-Perret-Gentil, 1211 Genève 14, Switzerland. maria.i.vargas@hcuge.ch
authors.forename: Maria Isabel
authors.initials: MI
authors.lastname: Vargas
authors.forename: Magalie
authors.initials: M
authors.lastname: Viallon
authors.forename: Duy
authors.initials: D
authors.lastname: Nguyen
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Delavelle
authors.forename: Minerva
authors.initials: M
authors.lastname: Becker
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016880:Anisotropy; D001917:Brachial Plexus / Q000473:pathology*; D056324:Diffusion Tensor Imaging / Q000379:methods*; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D008875:Middle Aged; D009369:Neoplasms / Q000473:pathology / Q000601:surgery; D011446:Prospective Studies