Abstract No. 518 Renal Angiomyolipoma Embolization: Does Lipid Content or Embolic Agent Predict Tumor Shrinkage?

The primary objective is to determine if there is a difference in volume reduction in lipid rich vs lipid poor angiomyolipomas (AMLs) following embolization. The secondary objective is to assess whether there is a difference in volume reduction based on embolic used (alcohol/ethiodized oil vs calibrated microspheres). Retrospective review from 2005-2023 of renal AMLs treated electively with embolization from a single enterprise. Patient demographics, technical embolization details (including embolic agent used), complications and pre/post cross sectional imaging were reviewed. Pre procedure 3D volume calculations and Hounsfield unit density histograms were performed on each AML, placing them into lipid rich ( >50% lipid) or lipid poor (< 50% lipid) groups. 3D volume calculations were performed of the first cross sectional imaging study following embolization to assess volume change. Fisher's exact tests, unequal variance t-tests, Spearman's correlation, and linear regression were used to assess associations. 45 patients with 50 AMLs (6 male, mean age 53.0) were included. 20 AMLs were lipid poor and had a mean volume decrease of 55.7% (23.8) compared to volume decrease of 36.0% (24.5) in 30 lipid rich AMLs (p=0.007). Fat composition, evaluated as a continuous variable, was moderately correlated with percent volume change (rs=0.45). 23 AMLs were treated with alcohol/ethiodized oil only, 13 with calibrated microspheres only. The remainder had multiple embolics and were excluded from the comparison. The AMLs treated with alcohol/ethiodized oil had a mean volume decrease of 49.8% (24.2) compared to 37.9% (29.7) in the microspheres (p=.231). Subgroup analysis showed in lipid rich AMLs, there was a 47.4% (23.6) reduction with alcohol/ethiodized oil and a 32.1% (29.9) reduction with microspheres (p=.219). Lipid poor AMLs demonstrate greater volume reduction compared to lipid rich AMLs following embolization. The embolic agent (alcohol/ethiodized oil vs calibrated microspheres) did not demonstrate a statistically significant difference in volume reduction. Further study with a larger sample size may be warranted.