Table 1.

Studies of CKD or cardiovascular disease evaluated using ²³Na MRI.

Year	Study Design	Subjects	Findings	Refs
2012	Cross-sectional	Normotensive subjects (17 men, 13 women) and 5 patients with primary aldosteronism	29% increase in muscle sodium content in patients with aldosteronism compared with normal subjects.	[30]
2013	Cross-sectional	56 healthy control men and women, 57 men and women with essential hypertension	Age-dependent increases in sodium content was observed in calf muscle in men. Patients with refractory hypertension showed increased tissue sodium content compared with normotensive controls.	[31]
2015	Cross-sectional	24 HD patients and 27 age-matched healthy controls, 20 HD patients before and shortly after HD	Age was associated with higher tissue sodium content in controls. Older HD patients showed increased sodium and water in skin and muscle compared with age-matched controls. After HD, patients with low circulating VEGF-C levels showed higher skin sodium content compared with HD patients with high VEGF-C levels.	[32]
2017	Cross-sectional	99 patients with mild to moderate CKD (42 women)	Skin sodium content, but not total overhydration, correlated with systolic blood pressure. Skin sodium content was closely linked to left ventricular mass in CKD patients.	[33]
2019	Cross-sectional	23 patients with CKD5, 11 healthy controls	CKD patients had fluid overload when compared to controls. Tissue sodium concentrations were higher in the subcutaneous compartment, but not in the muscle. Tissue sodium content was correlated with fluid overload. Fluid overload in CKD was linked to higher IL-8 and inversely associated with E-selectin. Higher subcutaneous sodium concentration was linked to higher ICAM.	[34]
2020	Cross-sectional	10 healthy controls, 20 patients with CKD5 (not on dialysis)	CKD patients had higher sodium and lower extracellular resistance. Tissue sodium concentration has an inverse linear relationship with extracellular resistance.	[35]
2020	Cross-sectional	10 healthy controls, 12 CKD3-5, 13 HD, 10 PD patients	Tissue sodium in the skin, sleus, and tibia was higher in HD and PD patients compared with controls. Serum albumin showed a negative correlation with soleus sodium in HD patients. Estimated GFR showed a negative correlation with tissue sodium in merged control-CKD patients. Hemoglobin was negatively correlated with tissue sodium concentration in CKD and HD patients.	[36]
2021	Cross-sectional	162 subjects (10 PD, 33 HD patients, 119 controls)	Patients on PD and HD showed higher muscle and skin sodium accumulation compared with controls. African American patients, older age, and male sex were associated with increased sodium content. Greater ultrafiltration was associated with lower skin sodium content in PD patients. Higher plasma IL-6 and hsCRP levels correlated with increased muscle and skin sodium content in the subjects.	[37]
2021	Prospective	18 patients with HF, 34 HD patients, 31 patients with CKD (GFR matched to the HF patients)	HF patients showed higher skin sodium content than matched CKD patients, which was indistinguishable from skin sodium content in HD patients.	[38]
2022	Cross-sectional	52 HD patients divided into groups with (23 subjects) or without (29 subjects) a positive history of cardiovascular events	HD patients with previous CVD events showed an increased sodium content in skin and muscle tissue compared to HD patients without CVD events. Fluid amount was not different between groups. Tissue sodium accumulation in HD-CVD patients was paralleled by higher plasma IL-6 levels.	[39]
2022	Cross-sectional	36 pediatric participants (17 healthy, 19 CKD) and 19 healthy adults	Healthy adults had higher tissue sodium content compared with pediatric groups. No differences in tissue sodium content were found between healthy children and CKD patients. CKD patients with glomerular disease showed increased sodium content; however, CKD patients with tubular disorders showed reduced sodium content.	[40]
2022	Prospective	52 subjects (10 PD, 42 HD patients)	Higher skin sodium accumulation was associated with worse clinical outcomes. Skin sodium concentration could be a predictor of survival.	[41]