Performance of a Deep Learning Reconstruction Method on Clinical Chest-Abdomen-Pelvis Scans from a Dual-Layer Detector CT System.

Objective

The objective of this study was to compare the performance and robustness of a deep learning reconstruction method against established alternatives for soft tissue CT image reconstruction. Materials and

Methods

Images were generated from portal venous phase chest-abdomen-pelvis CT scans (n = 99) acquired on a dual-layer spectral detector CT using filtered back projection, iterative model reconstruction (IMR), and deep learning reconstruction (DLR) with three parameter settings, namely 'standard', 'sharper', and 'smoother'. Experienced raters performed a quantitative assessment by considering attenuation stability and image noise levels in ten representative structures across all reconstruction methods, as well as a qualitative assessment using a four-point Likert scale (1 = poor, 2 = fair, 3 = good, 4 = excellent) for their overall perception of 'smoother' DLR and IMR images. One scan was excluded due to cachexia, which limited the quantitative measurements.

Results

The inter-rater reliability for quantitative measurements ranged from moderate to excellent (r = 0.63-0.96). Attenuation values did not differ significantly between reconstruction methods except for DLR against IMR in the psoas muscle (mean + 3.0 HU, p < 0.001). Image noise levels differed significantly between reconstruction methods for all structures (all p < 0.001) and were lower than FBP with any DLR parameter setting. Image noise levels with 'smoother' DLR were predominantly lower than or equal to IMR, while they were higher with 'standard' DLR and 'sharper' DLR. The 'smoother' DLR images received a higher mean rating for overall image quality than the IMR images (3.7 vs. 2.3, p < 0.001).

Conclusions

'Smoother' DLR images were perceived by experienced readers as having improved quality compared to FBP and IMR while also exhibiting objectively lower or equivalent noise levels.