Utilizing Cone-Beam CT Densities as an Alternative to Lung Shunt Fraction Measurement in Yttrium-90 Radioembolization

Wednesday, April 2, 2025

10:39 AM – 10:48 AM CT

Location: Music City Center, 209 ABC

Presenting Author(s)

Marisela Neff (she/her/hers)

Medical Student
University of Miami, United States

Author/Co-author(s)

Konrad Kozlowski, BA

Medical Student
University of Miami, United States
KB

Kaethan Bysani, MD

Medical Resident
University of Miami, United States
JZ

Joseph Zikria, MD

Assistant Professor of Clinical Radiology
University of Miami, United States

Purpose: 99mTc-macroaggregated albumin (99mTc-MAA) scintigraphy is used in Yttrium-90 (Y90) radioembolization planning to evaluate hepatopulmonary shunting via the lung shunt fraction (LSF). This study investigates the association between cone-beam CT (CBCT) enhancement densities during Y90 radioembolization and mapping angiogram, evaluating the use of CBCT enhancement as an alternative method to predict LSF.

Materials and Methods: 81 patients who underwent Y90 radioembolization mapping were retrospectively analyzed. LSF was calculated using pre-treatment 99mTc-MAA scans, and enhancement at the hepatic/IVC confluence in Hounsfield units (HU) was assessed using intra-procedural CBCT by a board-certified radiologist. To account for variability in CBCT scans, the enhancement difference was calculated between the sub-hepatic IVC and hepatic/IVC confluence. Correlations between CBCT enhancement, LSF, liver/tumor volume, liver function, and MELD scores were analyzed.

Results: The mean patient age was 66 years, 61.7% were male, and 59% diagnosed hepatocellular carcinoma. Microcatheter placement was in a segmental branch for 26 patients (32%) and non-segmental branch for 55 patients (68%). LSF was ≥20% in 6 patients (7%), between 15% and 20% in 6 patients (7%), and < 15% in 69 patients (85.2%). The average LSF for patients with LSF ≥20% was 28.9%, with average CBCT enhancement of 107 HU. For patients with LSF between 20% and 15%, the average LSF was 18.6%, with average CBCT enhancement of 62.7 HU. The average LSF for patients with LSF <15% was 7.8, with average CBCT enhancement of 59.9 HU. Average liver volume for patients with LSF ≥ 20 was 1603 cc and 1889 cc for LSF < 20. Average MELD score for patients with LSF ≥ 20 was 6.8 and 9.1 for LSF < 20. A significant difference was found in CBCT enhancement in patients with LSF ≥ 20 compared to LSF < 20 (p=0.00076). Regression analysis demonstrated greater CBCT enhancement at the hepatic/IVC confluence was associated with higher LSF values, with each unit increase in HU corresponding to a 0.071 increase in LSF (p=0.000081). Liver volumes, tumor volumes and MELD scores did not significantly correlate with LSF.

Conclusion: CBCT enhancement patterns during Y90 radioembolization appear to correlate with LSF, offering a predictive tool for assessing lung shunt fraction. CBCT analysis of the hepatic/IVC confluence may provide an alternative method to 99mTc-MAA scintigraphy in evaluating pulmonary risk from Y90 therapy.