title: Quantitative (23) Na MRI of human knee cartilage using dual-tuned (1) H/(23) Na transceiver array radiofrequency coil at 7 tesla.
abstract: OBJECTIVE
  To develop quantitative dual-tuned (DT) (1) H/(23) Na MRI of human knee cartilage in vivo at 7 Tesla (T).
  
  
  METHODS
  A sensitive (23) Na transceiver array RF coil was developed at 7T. B1 fields generated by the transceiver array coil were characterized and corrected in the (23) Na images. Point spread function (PSF) of the (23) Na images was measured, and the signal decrease due to partial-volume-effect was compensated in [(23) Na] quantification of knee cartilage. SNR and [(23) Na] in anterior femoral cartilage were measured from seven healthy subjects.
  
  
  RESULTS
  SNR of (23) Na image with the transceiver array coil was higher than that of birdcage coil. SNR in the cartilage at 2-mm isotropic resolution was 26.80 ± 3.69 (n = 7). B1 transmission and reception fields produced by the DT coil at 7T were similar to each other. Effective full-width-half-maximum of (23) Na image was ∼5 mm at 2-mm resolution. Mean [(23) Na] was 288.13 ± 29.50 mM (n = 7) in the anterior femoral cartilage of normal subjects.
  
  
  CONCLUSIONS
  We developed a new high-sensitivity (23) Na RF coil for knee MRI at 7T. Our (1) H/(23) Na MRI allowed quantitative measurement of [(23) Na] in knee cartilage by measuring PSF and cartilage thickness from (23) Na and (1) H image, respectively.
authors.affiliation: Department of Radiology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA.
authors.forename: Chan Hong
authors.initials: CH
authors.lastname: Moon
authors.forename: Jung-Hwan
authors.initials: JH
authors.lastname: Kim
authors.forename: Tiejun
authors.initials: T
authors.lastname: Zhao
authors.forename: Kyongtae Ty
authors.initials: KT
authors.lastname: Bae
mesh_terms: D000328:Adult; D002358:Cartilage, Articular / Q000378:metabolism* / Q000473:pathology; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000378:metabolism* / Q000473:pathology; D008279:Magnetic Resonance Imaging / Q000295:instrumentation*; D008297:Male; D008875:Middle Aged; D011522:Protons; D011846:Radio Waves; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012964:Sodium / Q000378:metabolism*; D012979:Sodium Radioisotopes / Q000493:pharmacokinetics; D014159:Transducers
chemical_list: D011522:Protons; D019275:Radiopharmaceuticals; D012979:Sodium Radioisotopes; D012964:Sodium
keywords: dual-tuned 1H/23Na MRI; knee cartilage; transceiver array RF coil