We applied a novel application of T2 mapping in a longitudinal study to evaluate whether MRI relaxometry may hold more potential than current measures for portending breast-cancer-treatment-related-lymphedema (BCRL) progression. Baseline biophysical and T2 measurements were performed in patients following lymph node removal. Patients were then monitored for BCRL progression (duration=two years). Baseline descriptive (age, BMI, number of nodes removed) and biophysical (bioimpedance, tissue dielectric, and arm volume) measures did not discriminate between patients who did vs. did not progress, yet baseline T2 was regionally elevated in those who progressed. MRI relaxometry may serve as a tool to identify BCRL risk.