Abstract: Objective To compare the tortuosity of aortic arch between patients with type B aortic dissection (TBAD) and healthy control. Methods An observational cross-sectional study was performed in 140 (114 males and 26 females with average age of 55.05±11.38 years) TBAD patients selected from ROBOUST and 124 healthy people (106 males and 18 females with average age of 56.97±10.59 years) who underwent CTA examination in the first medical center of Chinese PLA General Hospital from December 2016 to January 2017.There was no significant difference in baseline data,such as gender,age,BMI and hypertension,between the two groups.Based on center lumen line analysis on 3D CTA,the global and local tortuosity of proximal aorta in the TBAD and healthy control were evaluated respectively.The global tortuosity of proximal aorta was measured by Tortuosity index (TI).According to Ishimaru aortic arch definition,the description of maximal tortuosity angle was used to assess the local tortuosity across Zone 0 to Zone 2,respectively. Results The tortuosity index of proximal aorta in patients with type B aortic dissection was significantly higher than that of the healthy control group (1.27±0.07 vs 1.23±0.04,P<0.001).Compared to healthy people,more curved Zone 1 and Zone 2 were found in TBAD patients (Zone 1:24.21±8.45° vs 18.13±5.71°,P<0.001;Zone 2:30.76±8.62° vs27.07±7.58°,P<0.001).In contrast,less tortuous Zone 0 was observed in TBAD patients (28.48±5.03° vs 29.63±4.34°,P<0.001). Conclusion Compared with healthy people,the tortuosity index of proximal aorta is higher in patients with type B aortic dissection,which is due to more curved Zone 1 and Zone 2 and it has nothing to do with the changes of Zone 0.