Comparative study on the image quality of partial solid nodules in the lungs based on energy spectrum CT virtual plain scan and conventional plain scan

HONG Jingjing; WEN Ge; ZHANG Fei; ZHANG Lianlian; LIU Disi; HUANG Weikang

doi:10.12122/j.issn.1674-4500.2024.05.13

Abstract：Objective To investigate the feasibility of utilizing virtual non-contrast enhanced(VNC)images derived from dual-energy computed tomography(DECT)for the assessment of part-solid nodules(PSN)within the lung,and compare the image quality with that of true non-enhanced(TNC)images.Methods A retrospective analysis was conducted on 46 patients with solitary pulmonary nodules at our institution from January 2022 to January 2023.Patients underwent both TNC scanning and contrast-enhanced DECT scanning during the arterial and venous phases,with dual-phase VNC images reconstructed from the dual-phase DECT data.CT values,noise(standard deviation),and lesion diameters of PSN and the ipsilateral erector spinae muscle were measured on both dual-phase VNC and TNC images.The signal-to-noise ratio and contrast-to-noise ratio for PSN were calculated.Effective radiation doses in TNC and VNC modes were recorded.Subjective scoring was performed by two experienced radiologists using a 5-point scale.Non-parametric tests were employed to compare the subjective and objective parameters,as well as the effective radiation doses,of images obtained at different scanning phases.Kappa tests were utilized to evaluate the inter-rater agreement of the subjective scores provided by the two radiologists.Results The objective evaluation metrics(diameter,CT value,standard deviation,signal-to-noise ratio,contrast-to-noise ratio)between arterial and venous phase VNC and TNC images were not statistically significant(P>0.05).The mean subjective score for TNC images was the highest,followed by venous phase VNC images,with arterial phase scores being the lowest.There was a statistically significant difference in the scores among the three groups(P<0.001),yet both phases of VNC met diagnostic requirements.The inter-rater agreement for the subjective scores between the two radiologists was strong,with a range of 0.63 to 0.73.The use of VNC in place of TNC resulted in an approximate 30%reduction in radiation dose.Conclusion The dual-phase spectral CT with virtual non-contrast venous phase imaging provides image quality comparable to conventional non-contrast imaging and significantly reduces patient radiation exposure,making it particularly suitable for patients requiring multiple follow-up examinations.