Purpose: To identify liver tumor characteristics associated with low (<10%), intermediate (10%-20%), and high (>20%) lung shunt fraction (LSF) at technetium 99m ((99m)Tc) macroaggregated albumin (MAA) imaging performed before yttrium 90 ((90)Y) radioembolization (RE).
Materials and methods: In this single-center retrospective study, 141 patients (70 with hepatocellular carcinoma [HCC], 71 with other tumors; 95 men, 45 women; median age, 61 years) underwent mapping arteriography with (99m)Tc-MAA LSF calculation before (90)Y RE from 2006 to 2012. Tumor characteristics, including tumor type, index lesion size and morphologic structure (circumscribed, infiltrative), focality (solitary oligonodular, multinodular), disease distribution (unilobar, bilobar), tumor burden (≤50%, 50%), portal vein invasion (present, absent), and arterioportal shunting (present, absent) were correlated with (99m)Tc-MAA imaging-calculated LSFs at univariate and multivariate analysis.
Results: Median LSF was 8.4% (HCC, 9.0%; other tumors, 8.3%). LSF greater than 20% occurred in 14% of HCCs, but only in 3% of other tumors (P = .004). For HCC, tumor morphologic structure (P = .022), tumor burden (P < .001), main portal vein invasion (P = .033), and arterioportal shunting (P < .001) were significantly associated with different LSF categories at univariate analysis; infiltrative morphologic structure, tumor burden greater than 50%, portal vein invasion, and shunting had confirmed association with high LSF at multivariate analysis. For other liver tumors, tumor size (P = .001) and tumor burden (P = .003) were significantly associated with different LSF categories at univariate analysis. Multivariate confirmation was precluded by small sample size. Patients underwent a median of one (90)Y RE session (range, one to six), with median per-treatment and cumulative lung doses of 6.0 Gy and 8.5 Gy, respectively.
Conclusion: LSF greater than 20% periodically occurs in HCC but is uncommon in other liver tumors. Specific tumor characteristics are associated with LSF greater than 20% and may indicate need for interventions to reduce LSF.