The Application Value Of Virtual Non-Contrast CT Of Energy Sprctrual CT In The Chest Imging

Part 1:A Feasibility study for comparative study of virtual non-contrast CT to true non-contrast CT images of the chest Purpose:To investigate the value of different VNC for spectral CT imaging of the chest by comparisons of virtual non-contrast CT(VNC)and true non-contrast CT(TNC).Materials and methods:Forty-six cases with clinical suspected lung disease received CT scans,including a conventional plain scan and dual-phasic contrast-enhanced dual-energy spectral scans.Six types of VNC were reconstructed for analysis using a GSI viewer.Water-iodine,140 kev-monochromatic,and material suppressed-iodine images from the arterial(WI-A,140MI-A,and MSI-A,respectively)and venous phases(WI-V,140MI-V,and MSI-V,respectively)were compared with TNC in terms of subjective scoring,noise,the contrast-noise ratio(CNR),CT value,effective radiation dose(ED)and the detectability of lesions.Results::The mean score of each VNC was greater than 3 in a 5-point scale and satisfied the basic requirements for diagnosis,and the VNC score during the venous phase was higher than 4,which were much better.The noise associated with the WI-A,140MI-V,MSI-V and WI-V either did not differ(P>0.05)or was less than that of TNC(P<0.05).Each VNC did not differ from TNC in terms of the CNR(P>0.05).MSI-A and MSI-V did not differ from TNC in terms of the CT value(P>0.05).VNC and TNC showed similar performances with regard to the detection of lesions,except for the small calcifications and lymph nodes near the vena cava;The ED was reduced by approximately 31.2%using VNC.Conclusion:MSI-A and MSI-V,which not only can satisfy the requirements for diagnosis and supply the accurate CT value,but also can detect the lesions perfectly,especially the MSI-V,may have the potential value to substitute for the conventional plain scan,thus reducing the radiation dose.Part 2:The application value of Energy spectrum CT in the evaluation of pulmonary nodules and masses by virtual non-contrast imagespurpose:To investigate the effect of MSI(material suppressed iodine)of spectral CT in the diagnosis of pulmonary nodules or massesMaterials and methods:26 cases with either lung cancer or clinical suspected lung cancer underwent CT scans including conventional plain scan and dual-phasic contrast-enhanced dual energy spectral scans.2 types of VNCs were reconstructed for analysis with GSI viewer:Artery phase MSI images,Vein phase MSI images.The image quality score,noise,signal to noise ratio(SNR),contrast noise ratio(CNR),the mean CT value,radiation dose(ED)and detectability of lesions were compared between VNC and TNC.Results:The scores of the 2 types of the VNC images are all more than 3 and each can meet the requirement of diagnosis;MSI has higher noise than TNC(P<0.05);MSI has lower SNR and CNR than TNC(P<0.05);MSI images has no significant difference with TNC in CT value(P>0.05);MSI and TNC have the similar performance of detection of the lung nodules or masses with CT characteristics of speculation,hare-ears sign,cavity,satellite lesions and calcification(>2mm),except some small calcified lesions.The effective radiation dose were reduced about 30%.Conclusion:On pulmonary nodule diseases,MSI images can satisfy the requirements for diagnosis,supply the accurate CT value,show the lesions perfectly.MSI may have the potential value to substitute for the conventional plain scan,thus reducing the ED and checking time obviously.