Image Quality Improvement of Low-dose Abdominal CT using Deep Learning Image Reconstruction Compared with the Second Generation Iterative Reconstruction

Background: Whether deep learning-based CT reconstruction could improve lesion conspicuity on abdominal CT when the radiation dose is reduced is controversial. Objectives: To determine whether DLIR can provide better image quality and reduce radiation dose in contrast-enhanced abdominal CT compared with the second generation of adaptive statistical iterative reconstruction [ASiR-V]. Aims: This study aims to determine whether deep-learning image reconstruction [DLIR] can improve image quality. Methods: In this retrospective study, a total of 102 patients were included, who underwent abdominal CT using a DLIR-equipped 256-row scanner and routine CT of the same protocol on the same vendor's 64-row scanner within four months. The CT data from the 256-row scanner were reconstructed into ASiR-V with three blending levels [AV30, AV60, and AV100], and DLIR images with three strength levels [DLIR-L, DLIR-M, and DLIR-H]. The routine CT data were reconstructed into AV30, AV60, and AV100. The contrast-to-noise ratio [CNR] of the liver, overall image quality, subjective noise, lesion conspicuity, and plasticity in the portal venous phase [PVP] of ASiR-V from both scanners and DLIR were compared. Results: The mean effective radiation dose of PVP of the 256-row scanner was significantly lower than that of the routine CT [6.3±2.0 mSv vs. 2.4±0.6 mSv; p< 0.001]. The mean CNR, image quality, subjective noise, and lesion conspicuity of ASiR-V images of the 256-row scanner were significantly lower than those of ASiR-V images at the same blending factor of routine CT, but significantly improved with DLIR algorithms. DLIR-H showed higher CNR, better image quality, and subjective noise than AV30 from routine CT, whereas plasticity was significantly better for AV30. Conclusion: DLIR can be used for improving image quality and reducing radiation dose in abdominal CT, compared with ASIR-V.