Abstract: Objective: To evaluate the diagnostic value of 64 multi-detector helical CT angiography in aortic dissection.Methods: 88 cases suspected dissection of aortic dissection were performed with MDCTA.The data was transmitted to ADW4.2 workstation,and reconstructed by MPR,VR,CPR,VE and generally analyzed with original axial images.Results: All the 32 aortic dissection were demonstrated clearly by MDCTA,and it can reveal the types and shape of aortic dissection.The true and false lumen and the intimal flap of aortic dissection were clearly showed.The position,size and shape of lacuna and its relationship with aortic branches,were clearly demonstrated from the cavities.Conclusion: 64-MDCTA is reliable and accurate in evaluating aortic dissection,gradually becomes one of the first modality diagnose in aortic dissection.