Tissue Sodium Response to Complete Decongestive Therapy in Lower Extremity Lymphedema

Lower extremity lymphedema affects a growing number of cancer survivors. Standard-of-care therapy for lymphedema is complete decongestive therapy (CDT), yet the primary outcome measurement of therapeutic efficacy is limb volume, which is relatively insensitive to both well-managed and severe disease. The primary goal of this study was to examine whether physiological sodium magnetic resonance imaging (²³Na-MRI) is sensitive to the effect of CDT on leg lymphedema, and how this effect compares with the measurement reproducibility limits.

Participants with lymphedema (n = 11) underwent ≥5 sessions of CDT per participant in their affected leg(s) (n = 12) over 9.2 ± 5.6 weeks, following individual treatment plans with a licensed therapist. At the baseline visit and intervention visit, at least one leg was scanned with ²³Na-MRI to measure tissue sodium content (TSC) in the skin, muscle, and adipose tissue. Control subjects (n = 16) were scanned at two visits separated by a similar timeframe with no treatment to establish measurement reproducibility. Skin TSC significantly reduced by 4.32 mmol/L (p = 0.027) in affected legs treated by CDT, a change greater than the reproducibility coefficient (RPC) (3.82 mmol/L) in controls. Adipose TSC decreased in treated legs (2.27 mmol/L; p = 0.046), a change less than the RPC (5.83 mmol/L). Muscle TSC (p = 0.171) and leg circumference (p = 0.764) did not decrease in treated legs.

TSC is reduced in the skin of affected legs with lymphedema treated by CDT, which is observable within the reproducibility limits of ²³Na-MRI. Results provide a basis for applying sodium MRI to observe the physiological effects of emerging lymphedema therapies.