Image quality evaluation of dual-layer spectral detector CT of the chest and comparison with conventional CT imaging

Objectives: To evaluate image quality parameters of virtual mono-energetic (MonoE) and conventional (CR) imaging derived from a dual-layer spectral detector CT (DLCT) in oncological follow-up venous phase imaging of the chest and comparison with conventional multi-detector CT (CRMDCT) imaging. Materials and methods: A total of 55 patients who had oncologic staging with conventional CT and DLCT of the chest in venous phase were included in this study. Established image quality parameters were derived from all datasets in defined thoracic landmarks. Attenuation, image noise, and signal-/ contrast-to noise ratios (SNR, CNR) were compared between CRDLCT and MonoE as well as CRMDCT imaging. Two readers performed subjective image analysis. Results: CRMDCT showed significant lower attenuation values compared to CRDLCT and MonoE at 40-70 keV (p 0.99). SNR values were significantly increased for MonoE at 40-80 keV compared to CRMDCT and CRDLCT (p < 0.001). CRDLCT and MonoE (40-70 keV) from DLCT revealed significantly higher CNR values than CRMDCT (p < 0.001). In subjective analysis, MonoE at 40 keV surpassed all other image reconstructions except for noise in MonoE at 70 keV. Conclusion: In dual-layer spectral detector CT, MonoE at low keV showed superior image quality compared to conventional images derived from the same system and may therefore be added to clinical routine imaging protocols. Whether MonoE reconstructions yield additional diagnostic information is still unknown