title: NMR properties of human median nerve at 3 T: proton density, T1, T2, and magnetization transfer.
abstract: OBJECTIVE
  To measure the proton density (PD), the T1 and T2 relaxation time, and magnetization transfer (MT) effects in human median nerve at 3 T and to compare them with the corresponding values in muscle.
  
  
  METHODS
  Measurements of the T1 and T2 relaxation time were performed with an inversion recovery and a Carr-Purcell-Meiboom-Gill (CPMG) imaging sequence, respectively. The MT ratio was measured by acquiring two sets of 3D spoiled gradient-echo images, with and without a Gaussian saturation pulse.
  
  
  RESULTS
  The median nerve T1 was 1410 +/- 70 msec. The T2 decay consisted of two components, with average T2 values of 26 +/- 2 msec and 96 +/- 3 msec and normalized amplitudes of 78 +/- 4% and 22 +/- 4%, respectively. The dominant component is likely to reflect myelin water and connective tissue, and the less abundant component originates possibly from intra-axonal water protons. The value of proton density of MRI-visible protons in median nerve was 81 +/- 3% that of muscle. The MT ratio in median nerve (40.3 +/- 2.0%) was smaller than in muscle (45.4 +/- 0.5%).
  
  
  CONCLUSIONS
  MRI-relevant properties, such as PD, T1 and T2 relaxation time, and MT ratio were measured in human median nerve at 3 T and were in many respects similar to those of muscle.
authors.affiliation: Laboratory of Functional and Metabolic Imaging , Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland. giulio.gambarota@epfl.ch
authors.forename: Giulio
authors.initials: G
authors.lastname: Gambarota
authors.forename: Ralf
authors.initials: R
authors.lastname: Mekle
authors.forename: Vladimír
authors.initials: V
authors.lastname: Mlynárik
authors.forename: Gunnar
authors.initials: G
authors.lastname: Krueger
mesh_terms: D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008475:Median Nerve / Q000033:anatomy & histology*; D018482:Muscle, Skeletal / Q000033:anatomy & histology; D011522:Protons
chemical_list: D011522:Protons