Skin sodium measured with 23Na MRI at 7.0 T. (18th October 2014)

• Record Type: Journal Article
• Authors: Linz, Peter; Santoro, Davide; Renz, Wolfgang; Rieger, Jan; Ruehle, Anjuli; Ruff, Jan; Deimling, Michael; Rakova, Natalia; Muller, Dominik N.; Luft, Friedrich C.; Titze, Jens; Niendorf, Thoralf
• Is Part Of: NMR in biomedicine. Volume 28:Number 1(2015:Jan.)
• Page Start: 54
• Page End: 62
• Publication Date: 2014-10-18
• Subjects: Nuclear magnetic resonance -- Periodicals; Magnetic Resonance Spectroscopy -- Periodicals; 574
• DOI: 10.1002/nbm.3224
• Languages: English
• ISSNs: 0952-3480

Abstract

<abstract abstract-type="main"> <title> <x xml:space="preserve">Abstract</x> </title> <p>Skin sodium (Na<sup>+</sup>) storage, as a physiologically important regulatory mechanism for blood pressure, volume regulation and, indeed, survival, has recently been rediscovered. This has prompted the development of MRI methods to assess Na<sup>+</sup> storage in humans (<sup>23</sup>Na MRI) at 3.0 T. This work examines the feasibility of high in‐plane spatial resolution <sup>23</sup>Na MRI in skin at 7.0 T. A two‐channel transceiver radiofrequency (RF) coil array tailored for skin MRI at 7.0 T (<italic>f</italic> = 78.5 MHz) is proposed. Specific absorption rate (SAR) simulations and a thorough assessment of RF power deposition were performed to meet the safety requirements. Human skin was examined in an <italic>in vivo</italic> feasibility study using two‐dimensional gradient echo imaging. Normal male adult volunteers (<italic>n</italic> = 17; mean ± standard deviation, 46 ± 18 years; range, 20–79 years) were investigated. Transverse slices of the calf were imaged with <sup>23</sup>Na MRI using a high in‐plane resolution of 0.9 × 0.9 mm<sup>2</sup>. Skin Na<sup>+</sup> content was determined using external agarose standards covering a physiological range of Na<sup>+</sup> concentrations. To assess the intra‐subject reproducibility, each volunteer was examined three to five times with each session including a 5‐min walk and repositioning/preparation of the subject. The age dependence of skin Na<sup>+</sup> content was investigated. The <sup>23</sup>Na RF coil provides improved sensitivity within a range of 1 cm from its surface <italic>versus</italic> a volume RF coil which facilitates high in‐plane spatial resolution imaging of human skin. Intra‐subject variability of human skin Na<sup>+</sup> content in the volunteer population was <10.3%. An age‐dependent increase in skin Na<sup>+</sup> content was observed (<italic>r</italic> = 0.78). The assignment of Na<sup>+</sup> stores with <sup>23</sup>Na MRI techniques could be improved at 7.0 T compared with current 3.0 T technology. The benefits of such improvements may have the potential to aid basic research and clinical applications designed to unlock questions regarding the Na<sup>+</sup> balance and Na<sup>+</sup> storage function of skin. Copyright © 2014 John Wiley & Sons, Ltd.</p> </abstract>