Algorithm

Lumbar

Radon transform

Computed tomography

Image noise

Computer science

Radiology

Hounsfield scale

Image (mathematics)

Sharpening

Artificial intelligence

Medicine

Nuclear medicine

Noise reduction

Korean Journal of Radiology

Objective:The purpose of this study was to assess whether a deep learning (DL) algorithm could enable simultaneous noise reduction and edge sharpening in low-dose lumbar spine CT. Materials and Methods: This retrospective study included 52 patients (26 male and 26 female; median age, 60.5 years) who had undergone CT-guided lumbar bone biopsy between October 2015 and April 2020.Initial 100-mAs survey images and 50-mAs intraprocedural images were reconstructed by filtered back projection.Denoising was performed using a vendor-agnostic DL model (ClariCT.AI TM , ClariPI) for the 50-mAS images, and the 50-mAs, denoised 50-mAs, and 100-mAs CT images were compared.Noise, signal-to-noise ratio (SNR), and edge rise distance (ERD) for image sharpness were measured.The data were summarized as the mean ± standard deviation for these parameters.Two musculoskeletal radiologists assessed the visibility of the normal anatomical structures.Results: Noise was lower in the denoised 50-mAs images (36.38 ± 7.03 Hounsfield unit [HU]) than the 50-mAs (93.33 ± 25.36 HU) and 100-mAs (63.33 ± 16.09 HU) images (p < 0.001).The SNRs for the images in descending order were as follows: denoised 50-mAs (1.46 ± 0.54), 100-mAs (0.99 ± 0.34), and 50-mAs (0.58 ± 0.18) images (p < 0.001).The denoised 50-mAs images had better edge sharpness than the 100-mAs images at the vertebral body (ERD; 0.94 ± 0.2 mm vs. 1.05 ± 0.24 mm, p = 0.036) and the psoas (ERD; 0.42 ± 0.09 mm vs. 0.50 ± 0.12 mm, p = 0.002).The denoised 50-mAs images significantly improved the visualization of the normal anatomical structures (p < 0.001).Conclusion: DL-based reconstruction may enable simultaneous noise reduction and improvement in image quality with the preservation of edge sharpness on low-dose lumbar spine CT.Investigations on further radiation dose reduction and the clinical applicability of this technique are warranted.

Deep Learning Algorithm for Simultaneous Noise Reduction and Edge Sharpening in Low-Dose CT Images: A Pilot Study Using Lumbar Spine CT