title: Acute radial nerve entrapment at the spiral groove: detection by DTI-based neurography.
abstract: OBJECTIVE
  This study evaluated the potential of three-tesla diffusion tensor imaging (DTI) and tractography to detect changes of the radial (RN) and median (MN) nerves during transient upper arm compression by a silicon ring tourniquet.
  
  
  METHODS
  Axial T2-weighted and DTI sequences (b = 700 s/mm(2), 16 gradient encoding directions) of 13 healthy volunteers were obtained. Fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values of the MN and RN were measured at the spiral groove and further visualized in 3D by deterministic tractography (thresholds: FA = .15, angle change = 27°).
  
  
  RESULTS
  Local/lesional RN FA values increased (p = 0.001) and ADC values decreased (p = 0.02) during a 20-min upper arm compression, whereas no significant FA (p = 0.49) or ADC (p = 0.73) changes of the MN were detected. There were no T2-w nerve signal changes or alterations of nerve trajectories in 3D.
  
  
  CONCLUSIONS
  Acute nerve compression of the RN leads to changes of its three-tesla DTI metrics. Peripheral nerve DTI provides non-invasive insights into the "selective" vulnerability of the RN at the spiral groove.
  
  
  CONCLUSIONS
  • DTI-based neurography detects nerve changes during acute nerve compression. • Compression leads to a transient increase in local radial nerve FA values. • DTI provides insights into radial nerve vulnerability at the spiral groove.
authors.affiliation: Department of Biomedical Imaging and Image-guided Therapy, Division of Neuro- and Musculosceletal Radiology, Medical University of Vienna, Währinger Gürtel 18-20, 1090, Vienna, Austria.
authors.forename: Suren
authors.initials: S
authors.lastname: Jengojan
authors.forename: Florian
authors.initials: F
authors.lastname: Kovar
authors.forename: Julia
authors.initials: J
authors.lastname: Breitenseher
authors.forename: Michael
authors.initials: M
authors.lastname: Weber
authors.forename: Daniela
authors.initials: D
authors.lastname: Prayer
authors.forename: Gregor
authors.initials: G
authors.lastname: Kasprian
mesh_terms: D000208:Acute Disease; D000328:Adult; D016880:Anisotropy; D056324:Diffusion Tensor Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008475:Median Nerve / Q000473:pathology; D009408:Nerve Compression Syndromes / Q000175:diagnosis*; D011446:Prospective Studies; D011826:Radial Nerve / Q000473:pathology*; D015203:Reproducibility of Results; D055815:Young Adult