Abstract: FR-PO985

Sodium MRI Identifies Differences of Sodium Concentration with Age, Gender, and Race in Muscle and Skin of Healthy Subjects from the US

Session Information

Category: Bioengineering and Informatics

  • 101 Bioengineering and Informatics

Authors

  • Dyke, Jonathan, Weill Cornell Medical College, NY, New York, United States
  • Meyring-Wosten, Anna, Renal Research Institute, New York, New York, United States
  • Zhao, Yize, Weill Cornell Medical College, NY, New York, United States
  • Thijssen, Stephan, Renal Research Institute, New York, New York, United States
  • Linz, Peter, University Hospital Erlangen,, Erlangen, Germany
  • Kotanko, Peter, Renal Research Institute, New York, New York, United States
Background

Sodium (Na+) balance is important in managing hemodialysis patients; however, its assessment is difficult and incomplete. Experimental studies show that Na+ is stored without commensurate water accumulation in muscle and skin and may exceed levels measured in the serum. Our study implemented quantitative 23Na MRI imaging of the calf muscle and skin of healthy subjects compared with ex-vivo reference standards. Contributions from age, gender and race were examined.

Methods

A total of 30 subjects were enrolled for the study [(15M/15F), 46.4±14.8 yrs, (10 White/20 African-American)]. Studies were performed on a 3.0 Tesla Siemens MRI using a 23Na coil (Helmut Stark;Germany)[Fig 1]. Scan-rescan reproducibility was assessed the same day and 1 week later for a total of 4 time points/subject. Regions of interest were defined in the skin and following muscles: lateral gastrocnemius (LGM), medial gastrocnemius (MGM), soleus, tibialis anterior and peroneus. A mixed effects model was used based on repeated measures to determine the marginal multivariate effects of age, gender and race versus sodium MRI concentrations. A Bland-Altman plot assessed scan-rescan variability with the smallest real difference (SRD) calculated as 2.77*SEM.

Results

The Bland-Altman plots indicated high agreement between runs in all regions.The SRD was 9.7% and 4.1% within the same day and 10.9% and 12.2% comparing runs a week apart. Sodium increased in all muscles and skin with age. An association in muscle sodium was seen in the LGM (p=0.03), anterior (p=0.04) and peroneus (p=0.01) muscles with gender. No significant association was seen between sodium levels and race.

Conclusion

Tissue Na+ content was confirmed to increase with age in both muscle and skin of healthy controls. Differences in muscle sodium levels were also found with gender but not race. Reproducibility of 23Na MRI in the muscle and skin resulted in an SRD that shows promise to assess serial changes in patients with renal insufficiency.

Funding

  • Private Foundation Support