[Time-density curve of 16-slice spiral CT quantitatively distinguishes true from false lumen of aortic dissection].

Objective: To use the time-density curves (TDCs) to quantitatively distinguish the true from false lumen of aortic dissection (AD).

Methods: 28 cases with AD underwent the dynamic scanning of 16-slice spiral computer tomography (SCT). We used the CT Dynamic Evaluation software to determine the circulation times of the true and false lumens of the AD and got the TDCs, and then analyzed the circulation times and CT values of the true and false lumens by using matched t-test for dependent samples.

Results: The TDCs of the true and false lumens of the AD were achieved in all 28 patients. The peak CT values [(71.87 +/- 35.14) HU] of the true lumen were higher than those [(45.58 +/- 24.00) HU] of false lumen (P < 0.05); while the time to peak [(23.43 +/- 5.73) s] of the true lumen were earlier than that [(29.46 +/- 6.27) s] of false lumen (P < 0.05). The patterns of TDCs of the true lumen appeared to be rapid rise followed by rapid decline in 22 cases (78.6%) and rapid rise with gradual decline in 6 (21.4%), while the patterns of TDCs of the false lumen showed gradual rise followed by gradual decline in 18 cases (64.3%) and rapid rise with gradual decline in 10 (35.7%).

Conclusion: The TDCs of the true and false lumens showed: the peak CT values of the true lumen were higher than those of false lumen; while the time to peak of the true lumen were earlier than that of false lumen. So, the time-density curve, is used as an original and quantitative method to distinguish the true from false lumen in AD.