Analysis of ICG Arrival Time in Relation to ICG Lymphography Stage and Lymphoscintigraphy severity stage for Upper limb Lymphedema Diagnosis; retrospective observational study

Background: Indocyanine green lymphography (ICG L) and lymphoscintigraphy (LS) are widely used to stage breast cancer–related upper limb lymphedema (BCRL); however, both are primarily read qualitatively. We evaluated whether a pragmatic ICG time to axilla metric (elapsed time from hand injection to axillary visualization) correlates with MD Anderson (MDACC) ICG L stage and LS severity. Methods: In this retrospective observational study at a tertiary center (March 2018–May 2023), unilateral BCRL patients who underwent both ICG L and LS were included. ICG L was performed at 1, 2, and 3 hours after web space injections, and time to axilla was categorized as ≤1 h, ≤2 h, ≤3 h, and >3 h/not reached (T grades 1–4). Outcomes were associations of T grade with MDACC stage, LS stage, and maximal circumference difference (MCD). Ordinal trends were tested by Jonckheere–Terpstra. Results: Eighty nine women were analyzed. T grades: 1 (n=37), 2 (n=7), 3 (n=6), 4 (n=39). MCD increased across T grades (medians 2.5, 2.3, 3.9, and 3.5 cm; P = 0.009). MDACC stage distribution shifted rightward with higher T grade (median 3.00 at T1 to 4.00 at T4; P < 0.001). LS stage also trended higher with T grade (medians 3.00, 5.00, 5.00, and 4.00; P = 0.003). Conclusions: A simple, categorical ICG time to axilla measure correlates with both MDACC morphology and LS severity and tracks clinical limb size difference. Time to axilla may complement qualitative ICG L patterns and LS findings by providing an objective transport capacity signal for BCRL stratification.