Application Of Dual Energy Pulmonary Angiography With Dual-source CT In Pulmonary Embolism

Objective:The aim of this study was to assess the value of dual energy pulmonary angiography (DECTPA) with dual-source CT (DSCT) in pulmonary embolism (PE).Methods:A group:Twenty patients suspected of PE underwent DECTPA on DSCT in dual energy mode at tube voltages of 140 and 80 kV and a ratio of 1:3 between tube currents. Three groups of axial images were acquired, which were 80 kV,140 kV and merged images. The image was reconstructed into 1.5mm and the layer spacing was 1.0mm. Dual energy Lung perfusion imaging (DEPI) was generated through dual energy software (used the thin slice image of 140 kV and 80 kV images) while, vascular multi-planar reformation (V-MPR) maps was generated through DECT 3D software (used merged images). Two imaging specialists of the chest analyed the two angiographyies with naked eyes,wether there was pulmonary embolism (PE) in V-MPR or DEPI image.According to the display of embolism, pulmonary embolism was devided into three degrees:distinct (+),vague (±) and negative (-).List the results. Difference and combining superiority in showing directly emboli by using DEPI and V-MPR were compared. Another sixteen cases with confirmed dignosis of PE (B group) of thorax CTA with 64 slice spiral CT were reviewed retrospectively. The image was reconstructed into 1.5mm and the layer spacing was 1.0mm,and was transported to 3D Volume Wizard,acquiring the V-MPR image.Image quality of two groups were evaluated by two radiologists independently who were skilled in chest dignosis. The evaluation indicator contains the display of pulmonary artery and embolism,the general idea of image and so on.Results:There was no difference of image quality between A group and B group in the image qulity of both groups,the displaying of DEPI and V-MPR in showing the pulmonary trunk and Lobe pulmonary,displaying of embolism and the general idea of image.There was difference in displaying embolism of section and the section pulmonary artery.DEPI can be used to assess the blood change of lungtissue,while observing the embolism with V-MPR. (3) In DEPI, emboli of pulmonary artery trunks, lobar arteries and partial segmental arteries generated perfusion defects of lung parenchyma, while other segmental and subsegmental arteries did not result in perfusion defects of lung parenchyma.Conclusion:In pulmonary embolism, DECTPA can show the emboli clearly, as well as 64 slice spiral CT, additionally can assess perfusion of lung parenchyma were generated by emboli of pulmonary arteries.Significance:DSCT can complete pulmonary angiography and perfusion imaging at the same time with pulmonary contrasted dual energy scan, patient respiration control and contrast agent injection conducted simultaneously. This is superior than the former poly-slice row CT. Dual energy pulmonary angiography with DSCT can not only demonstrate clearly the emboli of pulmonary lobar arteries but also make no difference with 64-slice CT angiography in quality of images. Pulmonary perfusion imaging can detect emboli of pulmonary artery trunks and lobar arteries, and also can investigate blood flows change of the embolized lung parenchyma. Detection of emboli of segmental and subsegmental arteries is not as good as MPR images. So, combine vascular multi-planar reformation maps and lung perfusion imaging can assess pulmonary embolism in morphology and function,not only can find out the number of pulmonary embolism but also the change of pulmonary function.These can guide clinical treatment. In the future, with the development of DSCT and the understanding of dual energy pulmonary perfusion with dual-source CT more deeper, DSCT will play an important role in diagnosing pulmonary arterial embolism, evaluating pulmonary function and assessing therapeutic effectiveness.