In vivo sodium (23Na) imaging of the human kidneys at 7 T: Preliminary results

Stefan Haneder, Vladimir Juras, Henrik J. Michaely, Xeni Deligianni, Oliver Bieri, Stefan O. Schoenberg, Siegfried Trattnig, Štefan Zbýň

Research output: Contribution to journalArticlepeer-review

26 Scopus citations

Abstract

Objective: To evaluate the feasibility of in vivo 23Na imaging of the corticomedullary 23Na gradient and to measure 23Na transverse relaxation times (T2*) in human kidneys. Methods: In this prospective, IRB-approved study, eight healthy volunteers (4 female, 4 male; mean age 29.4 ± 3.6 years) were examined on a 7-T whole-body MR system using a 23Na-only spine-array coil. For morphological 23Na-MRI, a 3D gradient echo (GRE) sequence with a variable echo time scheme (vTE) was used. T2*times were calculated using a multiecho 3D vTE-GRE approach. 23Na signal-to-noise ratios (SNR) were given on a pixel-by-pixel basis for a 20-mm section from the cortex in the direction of the medulla. T2*maps were calculated by fitting the 23Na signal decay monoexponentially on a pixel-by-pixel basis, using least squares fit. Results: Mean corticomedullary 23Na-SNR increased from the cortex (32.2 ± 5.6) towards the medulla (85.7 ± 16.0). The SNR increase ranged interindividually from 57.2 % to 66.3 %. Mean 23Na- T2*relaxation times differed statistically significantly (P < 0.001) between the cortex (17.9 ± 0.8 ms) and medulla (20.6 ± 1.0 ms). Conclusion: The aim of this study was to evaluate the feasibility of in vivo 23Na MRI of the corticomedullary 23Na gradient and to measure the 23Na T2*relaxation times of human kidneys at 7 T. Key Points: • High field MR offers new insights into renal anatomy and physiology. • 23 Na MRI of healthy human kidneys is feasible at ultra-high field. • Renal 23 Na concentration increases from the cortex in the medullary pyramid direction. • In vivo measurements of renal 23 Na-T2*times are demonstrated at 7.0 T.

Original languageEnglish (US)
Pages (from-to)494-501
Number of pages8
JournalEuropean Radiology
Volume24
Issue number2
DOIs
StatePublished - Feb 1 2014
Externally publishedYes

Keywords

  • Corticomedullary Na gradient
  • Human kidney 7 Tesla
  • Na imaging
  • T2
  • relaxation times

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