Application Of Dual Source CT In Combined Computed Tomography Angiography Of Pulmonary And Lower Extremity Vein

Part ? Impact Of Dual Energy Virtual Monochromatic Imaging on Diagnostic Performance of Venous Thrombosis of Lower ExtremitiesObjective: To investigate the impact of dual energy noise-optimized virtual monoenergetic imaging algorithm?VMI+?on image quality and diagnostic performance of lower-extremity indirect computed tomography venography?CTV?combined with pulmonary angiography?CTPA?for venous thromboembolism,compared with Ultrasound.Methods: 53 patients who were clinically suspected pulmonary embolism?PE?and underwent CTPA-CTV examination on a third-generation dual-source CT system were retrospectively enrolled and analyzed in the study.Images were reconstructed with standard linear blending?F₀.5?,VMI+ at 40 ke V?VMI+40 ke V?,50 ke V?VMI+50 ke V?and 60 ke V?VMI+60 ke V?.Vascular attenuation values and image noise were measured;contrast to noise ratio?CNR?and signal to noise ratio?SNR?of VMI+ images and linear blending images were calculated.Three-point scales were used to evaluate the subjective image quality.In a subgroup of 37 patients who additionally underwent US check,the specificity,sensitivity,negative predictive value?NPV?and positive predictive value?PPV?of CTV for detection of deep venous thrombosis?DVT?were calculated.Kappa test was used to analyze the consistency of the two methods for DVT.Results: The value of attenuation and CNR were highest in the VMI+40ke V group?204.63±56.40 HU and 7.72±4.72,respectively?.The subjective assessment was highest in the VMI+40ke V?2.62±0.49?,superior to F₀.5?2.30±0.46,P<0.05?.Of the 37 patients who underwent CT and US examination,the sensitivity,specificity,NPV and PPV of CTV in diagnosis of deep venous thrombosis were 84.2%?16/19?,77.8%?14/18?,82.4%?14/17?,and 80.0%?16/20?respectively.Conclusion: Compared with the linear blending image,low-kiloelectron volt VMI+ can improve the image quality of CTV and diagnostic accuracy for DVT.Part ? Study on the Method of Improving Image Quality of CT Pulmonary Angiography in Dual Source CT Pulmonary Angiography and VenographyObjective : To investigate the feasibility of injecting contrast agent by stages on computed tomography pulmonary angiography and venography.Methods:50 patients with clinically suspected PE or DVT who underwent CTPA and lower-extremity indirect CTV examination were divided into two groups,A and B.A total of 1.2 ml/kg of contrast agent was injected at a rate of 4 ml/s.In group A,all contrast agents were injected once,and in group B,the contrast agent was injected in two phases,the first phase was injected with 30 ml of contrast agent,and the second phase was injected with the remaining contrast agent.CNR and SNR of pulmonary artery and lower extremity vein images were calculated.Three-point scales were used to evaluate the subjective image quality of pulmonary artery.Artifact index?AI?of the pulmonary artery was calculated.Results: The group B showed significantly higher CNR,SNR and subjective assessment of pulmonary artery than those in group A?P<0.05?.The group B showed significantly lower AI values of right pulmonary artery,right upper lobe artery and right interlobular artery than those in group A?P<0.05?.There was no significant difference in SNR and CNR of lower extremity vein between the two groups?P>0.05?.Conclusions: The method of staging injection contrast agent can reduce the influence of wire bundle hardening artifact on the image quality of pulmonary artery in computed tomography pulmonary angiography and venography.