Reliability and agreement of sodium (<sup>23</sup>Na) MRI in calf muscle and skin of healthy subjects from the US.

Overview

PURPOSE: To quantify the reliability and agreement of sodium (²³Na) MRI in calf muscle and skin of healthy subjects and to measure the smallest real difference (SRD) in each. SUBJECTS AND METHODS: Thirty healthy subjects underwent ²³Na MRI studies of the calf. A scan-rescan protocol was performed the same day and 1 week later. Relative sodium concentration was measured in the calf muscle and skin and compared between studies. RESULTS: A high degree of reliability was confirmed between the scan and rescan tests using linear regression analysis. The Bland-Altman plots indicated high agreement between runs in all regions. The SRD was measured between scans taken the same day and one week later. Correlations were also reported with age, gender and race. CONCLUSIONS: Reliability and agreement of ²³Na MRI in the calf muscle and skin show promise for accurately assessing serial changes in patients.