title: Bilateral kidney sodium-MRI: Enabling accurate quantification of renal sodium concentration through a two-element phased array system.
abstract: OBJECTIVE
  To develop a sodium-MRI ((23) Na-MRI) method for bilateral renal sodium concentration (RSC) measurements in rat kidneys at 9.4 Tesla (T).
  
  
  METHODS
  To simultaneously achieve high B1 -field homogeneity and high receive sensitivity a dual resonator system composed of a double-tuned linearly polarized (1) H/(23) Na volume resonator and a newly developed two-element (23) Na receive array was used. In conjunction with three-dimensional (3D) ultra-short Time-to-Echo sequence a quantification accuracy of ± 10% was achieved for a nominal spatial resolution of (1 × 1 × 4) mm(3) in 10 min acquisition time. The technique was applied to study the RSC in six kidneys before and after furosemide-induced diuresis.
  
  
  RESULTS
  The loop diuretic agent induced an increase of cortical RSC by 22% from 86 ± 16 mM to 105 ± 18 mM (P = 0.02), whereas the RSC in the inner medulla decreased by 38% from 213 ± 24 mM to 132 ± 25 mM (P = 0.8×10(-4) ). The RSC changes measured in this study agreed well with the qualitative sodium signal intensity variations reported elsewhere.
  
  
  CONCLUSIONS
  Furosemide-induced diuresis has been investigated accurately with herein presented quantitative (23) Na-MRI technique. In the future, RSC quantification could allow for defining pathological and nonpathological RSC ranges to assess sodium concentration changes, e.g., induced by drugs.
authors: Computer Assisted Clinical Medicine, Heidelberg University, Mannheim, Germany. raffi.kalayciyan@medma.uni-heidelberg.de
authors: Raffi
authors: R
authors: Kalayciyan
authors: Friedrich
authors: F
authors: Wetterling
authors: Sabine
authors: S
authors: Neudecker
authors: Stefan
authors: S
authors: Haneder
authors: Norbert
authors: N
authors: Gretz
authors: Lothar R
authors: LR
authors: Schad
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000032:analysis; D004232:Diuretics / Q000494:pharmacology; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005260:Female; D005665:Furosemide / Q000494:pharmacology*; D007668:Kidney / Q000033:anatomy & histology / Q000187:drug effects / Q000378:metabolism*; D007677:Kidney Function Tests / Q000295:instrumentation*; D008279:Magnetic Resonance Imaging / Q000295:instrumentation*; D057054:Molecular Imaging / Q000295:instrumentation*; D051381:Rats; D017207:Rats, Sprague-Dawley; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012964:Sodium / Q000493:pharmacokinetics*; D014018:Tissue Distribution
chemical_list: D015415:Biomarkers; D004232:Diuretics; D005665:Furosemide; D012964:Sodium
keywords: diuresis; dual resonator system; furosemide; kidney; quantification of sodium concentration; renal 23Na-MRI