Upper and Lower Extremity Measurement of Tissue Sodium and Fat Content in Patients with Lipedema.

Objective: The aim of this study is to compare tissue sodium and fat content in the upper and lower extremities of participants with lipedema versus controls using magnetic resonance imaging (MRI).
Methods: MRI was performed at 3.0 T in females with lipedema (n = 15, age = 43.2 ± 10.0 years, BMI = 30.3 ± 4.4 kg/m ² ) and controls without lipedema (n = 14, age = 42.8 ± 13.2 years, BMI = 28.8 ± 4.4 kg/m ² ). Participants were assessed for pain and disease stage. Sodium MRI was performed in the forearm and calf to quantify regional tissue sodium content (TSC, mmol/L). Chemical-shift-encoded water-fat MRI was performed in identical regions for measurement of fat/water (ratio).
Results: In the calf, skin TSC (16.3 ± 2.6 vs. 14.4 ± 2.2 mmol/L, P = 0.04), muscle TSC (20.3 ± 3.0 vs. 18.3 ± 1.7 mmol/L, P = 0.03), and fat/water (1.03 ± 0.37 vs. 0.56 ± 0.21 ratio, P < 0.001) were significantly higher in participants with lipedema versus control participants. In the forearm, skin TSC (13.4 ± 3.3 vs. 12.0 ± 2.3 mmol/L, P = 0.2, Cohen's d = 0.50) and fat/water (0.65 ± 0.24 vs. 0.48 ± 0.24 ratio, P = 0.07, Cohen's d = 0.68) demonstrated moderate effect sizes in participants with lipedema versus control participants. Calf skin TSC was significantly correlated with pain (Spearman's rho = 0.55, P = 0.03) and disease stage (Spearman's rho = 0.82, P < 0.001) among participants with lipedema.
Conclusions: MRI-measured tissue sodium and fat content are significantly higher in the lower extremities, but not upper extremities, of patients with lipedema compared with BMI-matched controls.
(© 2020 The Obesity Society.)