Reduced-dose deep learning iterative reconstruction for abdominal computed tomography with low tube-voltage and tube-current

Abstract

Abstract Background: Low tube-voltage technique (e.g., 80 kV) could efficiently reduce the radiation dose and increase the contrast enhancement of vascular and parenchymal structures in abdominal CT. However, a high tube current is always required in this setting and limits the dose reduction potential. By using a deep learning iterative reconstruction algorithm (Deep IR), this paper aims to investigate the feasibility of a Deep IR in reducing radiation dose while improving the image quality for abdominal computed tomography (CT) with low tube-voltage and tube-current. Methods: Sixty patients (Male/female, 36/24; Age, 57.72±10.19 years) undergoing the abdominal portal venous phase CT were randomly divided into groups A (100 kV, automatic exposure control [AEC] with reference tube-current of 213 mAs) and B (80 kV, AEC with reference of 130 mAs). Images were reconstructed by hybrid iterative reconstruction (HIR) and Deep IR (levels 1-5). The mean CT and standard deviation (SD) values of four regions of interest (ROI), i.e. liver, spleen, main portal vein and erector spinae at the porta hepatis level in each image serial were measured, and signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated. The image quality was subjectively scored by two radiologists using a 5-point criterion. Results: A significant reduction of radiation dose by 69.94% (5.09±0.9 mSv vs. 1.53±0.37 mSv) were detected in group B when compared to group A. With regard to Deep IR algorithm at various levels, there was no significant change in CT value, but SD gradually increased. Group B had higher CT values than group A, and the portal vein CT values significantly differed between groups (P<0.003). The SNR and CNR in group B with Deep IR at levels 1-5 were higher than those in group A and significantly differed when HIR and Deep IR were applied at levels 1-3 of HIR and Deep IR (P<0.003). The subjective scores (distortion, clarity of the portal vein, visibility of small structures and overall image quality) with Deep IR at levels 4-5 in group B were significantly higher than those in group A with HIR (P<0.003). Conclusion: Deep IR algorithm can reduce radiation dose and improve the image quality of parenchymal organs and portal vein clarity in portal venous phase abdominal CT with low tube-voltage and tube-current.