Abstract Background Estimation of the lung shunt fraction (LSF) is an integral part of liver radioembolization treatment planning to prevent excessive lung irradiation from arterio-venous shunting in the liver. 99ᵐTc macro-aggregated albumin (99ᵐTc-MAA) nuclear imaging is the standard method. Recent literature suggests that 99ᵐTc-MAA nuclear imaging may be omitted in selected patient populations. Purpose This study investigates the potential of contrast-enhanced computed tomography (CECT) as a non-invasive method for estimating LSF as an alternative for 99ᵐTc-MAA nuclear imaging. Methods This single-center retrospective study included 30 consecutive patients who underwent 90Y radioembolization between January 2015 and December 2024 where both four-phase CECT and 99ᵐTc-MAA planar imaging were performed within one month of each other. Hypervascular tumor enhancement was identified on the CECT by subtracting the portal venous phase from the arterial phase and applying an intensity threshold. Additional perfusion characteristics were captured. Statistical analysis assessed the agreement between the CECT-derived volume ratios and the LSF values derived from 99ᵐTc-MAA imaging. Results The cohort consisted of 23 male and 7 female patients with a median age of 66 years (interquartile range IQR: 58–71), diagnosed with hepatocellular carcinoma (n = 24), intrahepatic cholangiocarcinoma (n = 2), pancreatic neuroendocrine tumors (n = 2), metastatic colorectal cancer (n = 1), and lymphocyte carcinoma (n = 1). Regression of the hypervascular-tumor-to-perfused volume ratio on CECT against LSF from 99ᵐTc-MAA imaging showed R2 = 0.95 (p 0.001). In contrast, the correlation between tumor volume and LSF was R2 = 0.38 (p = 0.001). The root mean square error between the LSF estimated from CECT and that measured using 99ᵐTc-MAA planar imaging was 3%. Conclusion Hypervascular-tumor-to-perfused volume ratio computed from CECT may offer a suitable alternative to 99ᵐTc-MAA nuclear imaging for LSF estimation in patients undergoing transarterial radioembolization.
Mehadji et al. (Mon,) studied this question.