磁共振相位对比法对慢性高原病患者主肺动脉改变初步研究

Preliminary evaluation of main pulmonary artery changes in CMS patients with phase contrast MR imaging

目的探讨利用磁共振相位对比法(phase contrast MR imaging,PCMRI)评价慢性高原病(chronic mountain sickness,CMS)患者主肺动脉(main pulmonary artery,MPA)结构、血流动力学及平均压(mean pulmonary artery pressure,MPAP)的应用价值。材料与方法收集经我院临床诊断的22例成年男性CMS患者(CMS组)和20名来自同一海拔高度的健康成人志愿者(对照组)进行对比研究。利用Philips Achiva 1.5 T磁共振扫描仪对主肺动脉进行2D/QF序列扫描,获得其横截面积(cross-sectional area,CSA)、正向峰值流速(peak positive velocity,PPV)、反向峰值流速(peak negative velocity,PNV)、右心室搏出量(right ventricular stroke volume,RVSV)和反流分数(regurgitant fraction,RF),然后计算MPA相对扩张度(relative dilatation degree,RDD)和MPAP。结果 (1)结构参数:CMS组CSA及RDD分别为(7.52±0.71)cm2和(36.11±11.27)%;对照组CSA及RDD分别为(6.34±1.12)cm2和(52.08±7.54)%。其中CSA较对照组增大(P<0.01);RDD较对照组减小(P<0.01)。(2)血流动力学参数:CMS组PPV、PNV、RVSV和RF分别为(72.19±9.41)cm/s、(28.61±4.16)、(64.43±21.48)ml和(7.11±0.93)%;对照组PPV、PNV、RVSV和RF分别为(80.32±11.15)cm/s、(22.64±6.14)、(59.12±19.34)ml和(4.31±0.48)%。其中PPV较对照组减小(P=0.015),PNV较对照组增大(P<0.01),RVSV较对照组增大(P=0.411),RF较对照组增大(P=0.004)。(3)CMS组MPAP[(36.71±12.36)mm Hg]较对照组MPAP[(15.77±6.69)mm Hg]明显增大(P<0.01)。结论 CMS患者长期低压缺氧环境导致MPA横截面积扩张和弹性降低,血流速度改变,反流分数及MPAP均有不同程度增加,最终导致肺动脉高压。PC-MRI能无创、准确地提供CMS患者主肺动脉结构、血流动力学及压力的信息,从而达到初步评估主肺动脉改变特点的目的。

Objective:To evaluate the clinical application value of structure and hemodynamics of main pulmonary artery(MPA)and mean pulmonary artery pressure(MPAP)in patients with chronic mountain sickness(CMS)by using phase contrast MR imaging(PC-MRI).Materials and Methods:22 male adult patients with CMS(CMS group)and 20 healthy male adult volunteers(control group)from the same altitude were recruited.The 2D/QF sequence of Philips 1.5 T magnetic resonance scanner was used for main pulmonary artery to obtain its cross-sectional area(CSA),peak positive velocity(PPV),peak negative velocity(PNV),right ventricular stroke volume(RVSV)and regurgitant fraction(RF).Then,relative dilatation degree(RDD)and MPAP were calculated.Results:(1)Structure parameters:the CSA and RDD of CMS group were(7.52±0.71)cm2 and(36.11±11.27)%respectively,and those of the control group were(6.34±1.12)cm2 and(52.08±7.54)%respectively.CSA increased by(P<0.01)compared with the control group,and RDD decreased by(P<0.01).(2)Hemodynamics parameters:the PPV,PNV,RVSV and RF of the CMS group were(72.19±9.41)cm/s,(28.61±4.16),(64.43±21.48)ml and(7.11±0.93)%respectively,and those of the control group were(80.32±11.15)cm/s,(22.64±6.14),(59.12±19.34)ml and(4.31±0.48)%respectively.The PPV decreased by(P=0.015)compared with the control group,the PNV increased by(P<0.01),the RVSV increased by(P=0.411),the RF increased by(P=0.004).(3)MPAP(36.71±12.36)mmHg in the CMS group was significantly higher than that(15.77±6.69)mmHg in the control group by(P<0.01).Conclusions:Long-term hypobaric and hypoxic conditions in CMS patients resulted in MPA dilatation,flexibility decrease,changes of blood flow velocity and increase of RF and MPAP.PC-MRI can non-invasively and accurately provide the information of the MPA structure,hemodynamics and pressure,so as to preliminarily achieve the purpose of assessment of the characteristics of the MPA changes in CMS patients.