Next generation spectral AI-based reconstruction for abdominal spectral detector dual energy CT: superior quality for liver imaging
Author Block: L. Fortmann1, J. Lueckel1, L. Hieronymi1, S. Skornitzke2, D. Maintz1, N. Große Hokamp1; 1Cologne/DE, 2Hamburg/DE
Purpose: Spectral detector DECT (sdDECT) offers advantages in liver imaging, like virtual monoenergetic images. A new prototype deep learning–based spectral reconstruction algorithm (SAI, Philips) was evaluated for conventional reconstructions (SAI) and virtual monoenergetic images (SAI-VMI) to optimize reconstruction settings for abdominal image quality compared to existing fully-iterative reconstruction (FI-R) and hybrid-iterative reconstruction (HI-R/HI-VMI).
Methods or Background: For 20 patients undergoing abdominal sdDECT, conventional images were reconstructed with FI-R, HI-R, and five SAI settings: SAI-Sharper, SAI-Sharp, SAI-Standard, SAI-Smooth, and SAI-Smother. For 55keV-VMI, we compared HI-VMI with the five SAI-VMI settings. Quantitative analysis with eight liver ROIs included signal-to-noise (SNR) and contrast-to-noise ratio (CNR). Image quality was assessed by two radiologists using a two-alternative forced-choice design.
Results or Findings: For conventional images, mean attenuation was comparable between FI-R, HI-R, and SAI (103.31HU18.93HU;p>.05). Noise was lowest for FI-R and SAI-Smoother (4.12HU0.85HU and 5.05HU1.11HU;p≤.05 vs. remaining; HI-R:15.08HU3.91HU). FI-R achieved highest SNR (25.726.64;p≤.05) and CNR (51.917.59;p≤.05) followed by SAI-Smoother (SNR: 21.135.79, CNR: 43.828.19; both p≤.05 vs. remaining; HI-R SNR:7.232.33 and CNR:15.293.31). Regarding subjective quality, radiologists showed a significant preference for SAI-Smoother (81.67%9.60%) and SAI-Smooth (75.83%7.60%) compared to FI-R (65.00%13.13%), HI-R (19.58%8.67%), and other reconstructions (p≤.05). For 55keV-VMI, there was no significant difference in mean attenuation between HI-VMI and SAI-VMI (146.94HU28.14HU). Noise was significantly lower with SAI-VMI-Smoother (4.97HU2.68HU, HI-VMI:12.68HU3.27HU;p≤.05), resulting in significantly higher SNR (30.407.04, HI-VMI:12.103.88;p≤.05) and CNR (55.1610.43, HI-VMI:23.354.92;p≤.05). Radiologists significantly preferred SAI-VMI-Smooth (81.50%7.45%) and SAI-VMI-Smoother (81.00%15.53%) compared to HI-VMI (38.50%7.45%) and other reconstructions (p≤.05).
Conclusion: For conventional sdDECT, novel SAI-Smooth and SAI-Smoother are preferred by radiologists, despite having lower quantitative SNR and CNR than FI-R. Additionally, SAI-VMI-Smooth and SAI-VMI-Smoother also yield better quantitative and qualitative results than HI-VMI.
Limitations: The study is limited by its retrospective design.
Funding for this study: This work was funded by Philips Healthcare. The funding source had no involvement in study design, collection or interpretation of data.
Has your study been approved by an ethics committee? Yes
Ethics committee - additional information: IRB-approved