E5112. Utility of Total Lesional Glycolysis in Characterizing Liver Metastases in Patients Undergoing Ablation
  1. Fereshteh Yazdanpanah; University of Pennsylvania
  2. Omar Aldaoud; University of Pennsylvania
  3. Moein Moradpour; University of Pennsylvania
  4. Mamduh Alatout; University of Pennsylvania
  5. Thomas Werner; University of Pennsylvania
  6. Abass Alavi; University of Pennsylvania
  7. Stephen Hunt; University of Pennsylvania
Total lesion glycolysis (TLG) is a quantitative FDG PET-CT measure incorporating both metabolic activity and volume assessment of tumor burden. This study examines the utility of TLG as a quantitative marker of disease burden and treatment response in the setting of percutaneous ablation of liver metastases.

Materials and Methods:
An IRB-approved retrospective analysis of patients undergoing liver ablation for metastatic disease at a single academic medical center from January 2014 to January 2022 identified from an IR quality database (Hi-IQ), and having both pre and postablation PET-CT within 1 year of ablation. TLG in the ablated tumor was determined using an automated adaptive contrast-oriented thresholding method (ROVER, ABX GmbH). Two-tailed paired t-tests were conducted to compare FDG-PET/CT scan parameters before and after ablation. Kaplan-Meier analysis was used to compare outcome data.

During the study interval, 447 patients underwent liver mass ablation. Among these patients, FDG-PET imaging was performed for 59 patients, and 20 patients had both baseline and follow-up PET-CT (12 men; eight women). Median age was 61 (54.2–72) years with a median follow up of 22.5 months (14.2–54.7). Five patients underwent multiple ablations. Origin of metastases included colorectal cancer (10), lung cancer (7), tonsilar squamous cell carcinoma (1), cholangiocarcinoma (1), and pancreatic adenocarcinoma (1). Seventeen patients experienced intrahepatic recurrence during follow up, with a mean interval of 6 months (range: 1–27 months). Pre and postablation TLG of the lesions were significantly different (p < 0.01). Eighteen out of 20 patients demonstrated decrease in TLG consistent with response to ablation, and two patients demonstrated increase in tumor TLG, consistent with ablation mistargeting. Complete response to ablation was defined as postablation TLG < 2, with 11 patients meeting criteria for complete ablation with a mean TLG of 0.2 (range 0.1–1.6). Complete responders had a decrease of 98% or greater between pre- and post-TLG. The remaining 10 patients had postablation TLG of > 2, with a mean postablation TLG of 30 and TLG decrease of 59% (range 25–83%). Postablation survival (mean ± SE) differed significantly between complete ablation responders (37 ± 7 months) and incomplete responders (27 ± 7 months; p < 0.1).

TLG provides a quantitative assessment of disease burden and response to liver metastasis ablation, and postablation TLG of > 2 is associated with poorer survival outcomes.