title: Rapid isotropic 3D-sodium MRI of the knee joint in vivo at 7T.
abstract: OBJECTIVE
  To demonstrate the feasibility of acquiring high-resolution, isotropic 3D-sodium magnetic resonance (MR) images of the whole knee joint in vivo at ultrahigh field strength (7.0T) via a 3D-radial acquisition with ultrashort echo times and clinically acceptable acquisition times.
  
  
  METHODS
  Five healthy controls (four males, one female; mean +/- standard deviation [SD] age 28.7 +/- 4.8 years) and five patients with osteoarthritis (OA) (three males, two females; mean +/- SD age 52.4 +/- 5.6 years) underwent (23)Na MRI on a 7T, multinuclei equipped whole-body scanner. A quadrature (23)Na knee coil and a 3D-gradient echo (GRE) imaging sequence with a radial acquisition were utilized. Cartilage sodium concentration was measured and compared between the healthy controls and OA patients.
  
  
  RESULTS
  The average signal-to-noise ratio (SNR) for different spatial resolutions (1.2-4 mm) varied from approximately 14-120, respectively. The mean sodium concentration of healthy subjects ranged from approximately 240 +/- 28 mM/L to 280 +/- 22 mM/L. However, in OA patients the sodium concentrations were reduced significantly by approximately 30%-60%, depending on the degree of cartilage degeneration.
  
  
  CONCLUSIONS
  The preliminary results suggest that sodium imaging at 7T may be a feasible potential alternative for physiologic OA imaging and clinical diagnosis.
authors.affiliation: Center for Biomedical Imaging, New York University Langone Medical Center, New York, NY, USA. Ligong.Wang@nyumc.org
authors.forename: Ligong
authors.initials: L
authors.lastname: Wang
authors.forename: Yan
authors.initials: Y
authors.lastname: Wu
authors.forename: Gregory
authors.initials: G
authors.lastname: Chang
authors.forename: Niels
authors.initials: N
authors.lastname: Oesingmann
authors.forename: Mark E
authors.initials: ME
authors.lastname: Schweitzer
authors.forename: Alexej
authors.initials: A
authors.lastname: Jerschow
authors.forename: Ravinder R
authors.initials: RR
authors.lastname: Regatte
mesh_terms: D000328:Adult; D003198:Computer Simulation; D005240:Feasibility Studies; D005260:Female; D005583:Fourier Analysis; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D021621:Imaging, Three-Dimensional / Q000379:methods*; D007719:Knee Joint / Q000033:anatomy & histology / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008280:Magnetics; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000175:diagnosis*; D019047:Phantoms, Imaging; D012975:Sodium Isotopes
chemical_list: D012975:Sodium Isotopes