Influencing Factors of Lung Shunt Fraction in Transarterial Radioembolization Treatment

Abstract

Abstract Purpose We aimed to evaluate the influencing factors of lung shunt fraction(LSF) in patients who underwent transarterial radioembolization treatment. Methods We enrolled 105 patients who had either primary or metastatic liver disease. Planar and SPECT/CT images were obtained after intraarterial injection of 99mTc-MAA to measure LSF. Planar-based LSFs(LSFplanar), calculated as the arythmetic mean(LSFAM) and geometric mean(LSFGM), were compared to LSFSPECT/CT. Subgroup analyses were conducted to assess the impact of scattering and spillover effects in patients with target lesions located near lung. Both lungs were segmented into lower, middle and upper sections(RL,RM,RU,LL,LM,LU). For control group, ten patients with normal lung perfusion scintigraphy were included. Results The mean of LSFSPECT/CT was significantly lower than the mean of LSFGM(6.5 ± 4.1 vs 13.9 ± 8.4, p = < 0.001) and the mean of LSFAM(13.5 ± 8.4%, p = < 0.001). LSFplanar methods overestimated LSF compared to LSFSPECT/CT. LSFGM divided by 2.3 can provide more accurate estimated LSF similar to LSFSPECT/CT. In subgroup analyses, we found that mean values of RL/RU, RM/RU, LL/LU and LM/LU were 9.3 ± 7.4, 2.2 ± 1.2; 1.2 ± 0.4, and 1.2 ± 0.2, respectively. In control group, mean values of RL/RU, RM/RU, LL/LU and LM/LU were within a range of 0.9–1.1. Conclusion LSFSPECT/CT with attenuation correction can provide more accurate results compared to LSFplanar before TARE treatment. In patients who had liver lesions located adjacent to lung, the possible miscalculation of LSFSPECT/CT from scattering and spillover effect could be eliminated by exclusion of 3 cm diameter from inferior border of the right lung.