Application of energy-spectrum CT monoenergetic imaging and metal-artifact reduction system in congenital funnel chest children after thoracoscopic minimally invasive funnel chest correction

Objective To evaluate the ability of monoenergy imaging technique and metal-artifact reduction system (MARs) in improving the CT image quality of thoracoscopic minimally invasive funnel chest correction for children with congenital funnel chest.Methods A total of 114 children with congenital funnel chest who underwent thoracoscopic minimally invasive funnel chest correction in Xuzhou Children's Hospital from January 2022 to August 2023 were selected, and their chest CT plain scan images after metal plate implantation were collected for retrospective analysis. We measured the CT value and SD value of the dark area of stent edge artifact, the soft tissue of chest wall around the dark area and the erector spine area of the back in the images of 120 kVp-like, 110 keV and 110 keV+MARs, 50 keV and 50 keV+MARs, which were indicated as CT₁, CT₂, CT₃ and SD₁, SD₂, SD₃, respectively, and calculate |ΔCT| and artifact index (AI). The quality of these images were compared.Results The values of CT₂, CT₃, SD₂, SD₃, |ΔCT| and AI in 120 kVp-like images were higher than those in 110 keV images and lower than those in 50 keV images, with statistical differences (P＜0.05). The CT₁ value of 120 kVp-like image was lower than that of 110 keV image and higher than that of 50 keV image, with statistical differences (P＜0.05). The CT₂, CT₃, SD₂, SD₃, |ΔCT| and AI values of 50 keV and 110 keV images were higher than those of 50 keV+MARs and 110 keV+MARs images, respectively. The CT₁ values of 50 keV image were lower than those of 50 keV+MARs image. The CT₁ values of 110 keV image were lower than those of 110 keV+MARs image. There were no statistical differences in CT₃ and |ΔCT| values between 110 keV image and 110 keV+MARs image (P＞0.05), while statistical differences were seen in other values (P＜0.05). The subjective reading scores of the two physicians were consistent.Conclusions High-energy mono-energenic image (110 keV) of the energy-spectrum CT is effective in suppressing metal artifacts, and the combined use of MARs can further improve the quality of images.