Value Of The Dual-source CT Virtual Endoscopy In The Assessment Of Thoracic Aortic Dissection

ObjectiveTo explore the clinical value of the dual-source CT virtual endoscopy (CTVE) with ECG gating technology in assessment of the thoracic aortic dissection (TAD), and the influence of the the contrast agent concentration nearby the thoracic aortic dissection's break (≤1cm2) on the display of the break in the aortic lumen.Materials and Methods50 patients (35 male and 15 female) who were diagnosed as thoracic aortic dissection from August 2009 to March 2010 in the Qilu Hospital of Shandong University by using contrast-enhanced CT scanning with the ECG gating technology of DSCT were retrospectively analyzed. The ages ranged from 42 years to 75 years (mean age,57 years). The volume date obtained by DSCT scanning was reconstructed in the the post-processing workstation(Siemens syngo MMWP VE31A, Siemens AG).We used the axial and MPR images to identify the location of TAD break, then the CTVE images of the TAD break were generated.The imaging features including the scope and the configuration of the TAD break and the flap were reviewed according to the CTVE. At the same time, other technologies such as VR and MIP were also used to review the TAD. Both groups including the clear and unclear break groups were divided according to the evaluated results of the CTVE images in order to identify the association of the concentration of the contrast media with the display of the break. The difference in the CT value of the lumen near the break(<lcm2) were analyzed between two groups.ResultsThe patients with Stanford type A and B of the TAD were in 22 and 28 in a total of 50 patients in which the CTVE revealed the cases of the clear break group were 40 (80%), and those of the unclear group were 10 (20%).46 (92%)cases'TAD break could be clearly displayed in axial and MPR images, but all couldn't be clearly displayed in the VR and MIP images. TAD breaks were not found by CTVE and other technologies in 4 cases, and CTVE images didn't show well in 6 cases who, however, could be displayed clearly on axial and MPR images.The oval breaks in 16 and the irregular ones in 24 on CTVE images were shown in the clear bread group. On CTVE images, the tore flap could be shown clearly in 45 cases (90%) with spiral ones in 35 and others in 10. However, the tore flap of all cases could be shown in the axal and MPR images. The edges and traces of true and false lumen could be displayed to some extent in all cases by VR and MIP images. No defference in the mean CT value near the break (≤1cm2) in the lumen was shown between both clear group (n=40) and unclear group (n=6) of CTVE(P>0.05). However, the marked artifact and noise were identified in the area of the tear in the lumen.Conclusion1. The dual-source CTVE allows to display the three-dimensional structure of the tear and the flap of the thoracic aortic dissecions.2. The poor display of the breaks is not associated with the concentration of the contrast media near the break (≤1cm2) of the lumen in this study.3-Dual-source CTVE, compared to MPR,VR and MIP technologies, has obvious advantage to display the three-dimensional structure of the thoracic aortic dissection break, but axial and MPR images may reveal more breaks of thoracic aortic dissection than CTVE images.