Kidney Week

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

• Bioengineering and Informatics
  November 03, 2017 | Location: Hall H, Morial Convention Center
  Abstract Time: 10:00 AM - 10:00 AM

Category: Bioengineering and Informatics

• 101 Bioengineering and Informatics

Authors

• Dyke, Jonathan, Weill Cornell Medical College, NY, New York, United States

Jonathan Dyke,

• Meyring-Wosten, Anna, Renal Research Institute, New York, New York, United States

Anna Meyring-Wosten,

• Zhao, Yize, Weill Cornell Medical College, NY, New York, United States

Yize Zhao,

• Thijssen, Stephan, Renal Research Institute, New York, New York, United States

Stephan Thijssen,

• Linz, Peter, University Hospital Erlangen,, Erlangen, Germany

Peter Linz,

• Kotanko, Peter, Renal Research Institute, New York, New York, United States

Peter Kotanko,

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