Feasibility Study Of Virtual Routine Three-phase Chest Scanning From Venous Phase With Spectral CT

[Objective]The feasibility of single-vein-phase scanning as an alternative to conventional plain scan plus dual-phase enhancement scanning was explored by comparing the virtual plain scan with the real plain scan and the virtual arterial-phase image with the real arterial-phase image obtained from spectral CT chest-enhanced venous-phase images in terms of objective image quality,subjective scoring,and lesion diagnostic efficacy.[Method]A retrospective collection of 130 patients who underwent spectral CT conventional chest plain and dual-phase enhancement scans.Virtual Non-Contrast(VNC)and 40 ke V Virtual Monoenergetic Image(VMI)were obtained by venous-phase image post-processing for Virtual arterial-phase images(Vart).The objective image quality,subjective scores and lesion diagnostic efficacy of True non-contrast(TNC)versus VNC,Conventional arterial-phase images(CIart)versus Vart were compared.The objective evaluation indexes included CT values,background noise,SNR and CNR of artery,muscle,T4 vertebral bone cancellous,fat.Subjective scores of VNC/TNC/CIart and Vart were evaluated using a 5-scale.The diagnostic efficacy evaluation of the lung window VNC included assessment of lung nodules and detection of inflammatory lesions.Pulmonary nodule assisted diagnosis system automatically output all nodule details,recording the diameter and density of nodules in the range of 8-30 mm in length.Imaging signs of nodules were evaluated and recorded,including shape,margin,lobar sign,and so on.Inflammatory lesions included exudative shadow,solid shadow,and so on.The diagnostic efficacy of the mediastinal window VNC was evaluated including enlarged lymph node display,and the detection rate of calcified foci.The diagnostic efficacy of Vart included,using CIart as a criterion,the assessment of vascular invasion in all lung tumor patients in the sample and the detection rate of intrapulmonary emboli in patients with pulmonary embolism.Objective indices such as CT values,SNR,CNR,and lung nodule size were analyzed using paired t-test.Image quality scores of TNC,VNC,CIart and Vart were analyzed using Wilcoxon rank test.Diagnostic efficacy were analyzed using Mc Nemar’s test;Differences in the detection of calcified foci between TNC and VNC,and analysis of vascular invasion in patients with CIart and Vart tumors were analyzed using the Wilcoxon rank sum test.Differences in the number of detected pulmonary emboli in patients with CIart and Vart pulmonary embolism were analyzed using the χ2 test.P<0.05 was considered a statistically significant difference[Results]1.Quantitative analysis revealed no significant differences between TNC and VNC in most tissue(P>0.05)except for the fat and cancellous bone(P<0.05).2.Objective indexes of Vart were higher than those in CIa(P<0.05).3.Subjective score in VNC/Vart was the same as that in TNC/CIart(P>0.05).4.Diagnostic efficiency in lung window,like subjective and objective indexes of nodules and inflammation detection rate,in TNC and VNC were no significant difference(P < 0.05).5.The overall detection rate of VNC for calcified foci was 88.53%,which was significantly lower than that of TNC(P < 0.001).VNC showed better display of granular and mass calcified foci,but poorer display of punctate calcified foci.6.There was no statistically significant difference in the detection rate of intrapulmonary emboli in patients with pulmonary embolism and in the diagnosis of vascular invasion in patients with lung tumors at Vart compared with CIart(P > 0.05).7.The average effective radiation dose of single-stage venous scan was 66.46% lower than conventional scan.[Conclusion]Our study suggests that VNC and Vart derived from single venous-phase spectral CT can offer comparable assessment of major thoracic tissue compared with routine triphasic examinations.