心电门控技术64排CT测量正常胸主动脉弹性的初步研究

Primary Research on ECG-gated 64-Detector Row CT in Measurement of Thoracic Aorta Elasticity

目的探讨心电门控技术64排CT测量正常成人胸主动脉弹性的可行性。资料与方法 86名健康志愿者行胸主动脉CT血管成像(CTA)检查。所有受检者均采用64排螺旋CT(GE,Light Speed VCT),采用回顾性心电门控技术和分段数据采集方式。获得的原始数据分别在0%～95%R-R间期、间隔5%重组图像,然后在升主动脉中段和降主动脉起始部由两名熟悉心血管影像诊断的放射医师采用MATLAB图像分割软件,分别测量各重组期相主动脉的横断面积。受检者完成CT扫描后由专人常规测量血压。弹性值D(Pa-1)的计算公式为:D(Pa-1)=ΔA/A0.ΔP,ΔA代表管腔最大与最小面积的差值,A0代表心动周期内最小管腔面积,ΔP代表脉压差。结果升主动脉中段弹性值为(2.44±1.05)×10-5 Pa-1,降主动脉起始部弹性值为(1.99±0.76)×10-5 Pa-1;升、降主动脉弹性值D随年龄的增加呈递减趋势(r分别为-0.792、-0.691,P值均<0.01),男性与女性之间弹性值无统计学差异。结论心电门控技术64排CT可以客观、无创地测量正常胸主动脉弹性。

Objective To determine the feasibility of electrocardiogram（ECG） gated 64 detector row computed tomography（MDCT）in the assessment of arterial stiffness.Materials and Methods Distensibility of the aorta were measured in all 86 subjects,who underwent MDCT to evaluate the arterial lesions.Time resolved images were acquired with a 64 detector row CT scanner using a modified CT angiography protocol.Pulsatility related cross sectional area changes were calculated at the ascending aorta（AAo） between the origin of the coronary arteries and the brachiocephalic trunk and descending aorta（DAo） 5-6cm distal to the left subclavian artery by semiautomatic segmentation.Distensibility values were obtained using additional systemic blood pressure.Scan data were reconstructed at 20 phases between 0% and 95% of the R R intervals with an increment of 5%.Aortic distensibility（AD） was calculated as follows：AD=（maximal dimension-minimal dimension）/minimal dimension×pulse pressure.Results Aortic distensibility had a strong negative correlation with age（rAAo=-0.792,rDAo=-0.691,PAAo、DAo0.01）.there were no significant Differences of distensibility between the sexes.Mean distensibility was DAAo=（2.44±1.05）×10-5 Pa-1 and DDAo=（1.99±0.76）×10-5 Pa-1,respectively.Conclusion Multiphase analysis in ECG gated MDCT enables us to assess stiffness of the thoracic aorta objectively and noninvasively.