Purpose: To investigate a possible correlation between relative tumor enhancement by intraprocedural direct contrast injection into the targeted hepatic vessels in a 4DCT (hybrid angio-CT system) suite and radiographic tumor response evaluated by mRECIST and overall survival (OS) following radioembolization treatment with Y90-labelled glass microspheres in patients with hepatocellular carcinoma (HCC).
Materials and Methods: This single institution retrospective study includes 51 consecutive patients with HCC who underwent work-up angiography using intraprocedural 4DCT system followed by Y90 radioembolization treatment between July 1, 2017 and June 30, 2019. Images were evaluated using mRECIST. Enhancement values were measured in Hounsfield units on the native and post-contrast intraprocedural 4DCT datasets. HCC delta enhancement (postcontrast density-native density), and HCC delta enhancement ratio (postcontrast density/native density×100-100) were calculated and correlated with OS, liver progression-free survival (LPFS) and toxicity.
Results: Thirty-eight men (74.5%) and 13 women (25.5%) underwent Y90 radioembolization. Median age was 71 years (range, 22-87). Median OS was 13.7 (95% CI: 6.63-24.7) months and LPFS was 9.3 (95% CI: 5.1-16.8) months in our patient group. Median MELD score was 7 (IQR: 6-9) on pretreatment and 7 (IQR: 6-10) on the 3-month follow-up without any significant difference (P=.072). 43 patients had laboratory testing on the 3-month follow-up, 25 of it (58%) had mild (grade 1-2) biochemical toxicity. One patient (2.3%) had grade 3 elevation of bilirubin level. The correlation between OS and HCC enhancement (P=.091; 95% CI 0.997-1.0), and HCC delta enhancement ratio (P=.083; 95% CI: 0.997-1.0) did not meet the significance level. The correlation between LPFS and HCC enhancement (P=.166; 95% CI 0.994-1.0), and HCC delta enhancement ratio (P=.244; 95% CI: 0.998-1.0) were also not significant.
Conclusion: There is no significant correlation between intraprocedural contrast enhancement and median OS or imaging response following Y90 radioembolization in patients with HCC. Based on these results transarterial radioembolization treatment of liver tumors is not or less dependent on tumor vascularity.