MRI staging of upper extremity secondary lymphedema: correlation with clinical measurements.

OBJECTIVES

Staging of upper extremity lymphedema is needed to guide surgical management, but is not standardized due to lack of accessible, quantitative, or precise measures. Here, we established an MRI-based staging system for lymphedema and validate it against existing clinical measures.

METHODS

Bilateral upper extremity MRI and lymphoscintigraphy were performed on 45 patients with unilateral secondary lymphedema, due to surgical intervention, who were referred to our multidisciplinary lymphedema clinic between March 2017 and October 2018. MRI short-tau inversion recovery (STIR) images were retrospectively reviewed. A grading system was established based on the cross-sectional circumferential extent of subcutaneous fluid infiltration at three locations, labeled MRI stage 0-3, and was compared to L-Dex®, ICG lymphography, volume, lymphedema quality of life (LYMQOL), International Society of Lymphology (ISL) stage, and lymphoscintigraphy. Linear weighted Cohen's kappa was calculated to compare MRI staging by two readers.

RESULTS

STIR images on MRI revealed a predictable pattern of fluid infiltration centered on the elbow and extending along the posterior aspect of the upper arm and the ulnar side of the forearm. Patients with higher MRI stage were more likely to be in ISL stage 2 (p = 0.002) or to demonstrate dermal backflow on lymphoscintigraphy (p = 0.0002). No correlation was found between MRI stages and LYMQOL. Higher MRI stage correlated with abnormal ICG lymphography pattern (rs = 0.63, p < 0.0001), larger % difference in limb volume (rs = 0.68, p < 0.0001), and higher L-Dex® ratio (rs = 0.84, p < 0.0001). Cohen's kappa was 0.92 (95% CI, 0.85-1.00).

CONCLUSION

An MRI staging system for upper extremity lymphedema offers an improved non-invasive precision marker for lymphedema for therapeutic planning.

KEY POINTS: • Diagnosis and staging of patients with secondary upper extremity lymphedema may be performed with non-contrast MRI, which is non-invasive and more readily accessible compared to lymphoscintigraphy and evaluation by lymphedema specialists. • MRI-based staging of secondary upper extremity lymphedema is highly reproducible and could be used for long-term follow-up of patients. • In patients with borderline clinical measurements, MRI can be used to identify patients with early-stage lymphedema.