3.0T MR相位对比法成像定量测定正常人下腔静脉血流的研究

Quantitative measurement of hemodynamics of inferior vena cava in healthy volunteers with phasecontrast MR imaging at 3.0 T

目的 探讨3.0T MR相位对比法成像（PC-MRI）测定正常成年人下腔静脉（IVC）血流的可行性,并评价IVC管腔面积与血流流量、流速的关系.方法 收集50名健康成年志愿者行IVCPC-MRI检查,所有志愿者均为行胸部或腹部常规健康体检者,临床及常规腹部影像检查无异常,并经超声检查排除IVC病变.观察1个心动周期IVC上段与中段血管面积、平均流速、平均血流量、反流分数及其时间-流量曲线,对不同性别、年龄（18 ～ 30岁组、＞30岁组）及中段不同相位速度组间比较采用两个独立样本t检验；对IVC上段不同相位速度编码值（60、80、100） cm/s分组比较采用方差分析,IVC的管腔面积与流量、流速的关系采用Pearson相关分析.结果 50名受检者均成功完成检查.IVC上段面积、流量明显大于中段、流速明显低于中段,反流分数明显大于中段.男性（24名）IVC中段平均血流量高于女性（26名）,分别为（37.94±7.32）和（33.68±6.65） ml/s,差异有统计学意义（=2.49,P=0.017）.18～30岁组（27名）IVC上段与中段平均血流量分别为（54.89±10.98）和（38.29±7.54） ml/s,均高于30岁以上年龄组（23名）,分别为（44.96±8.49）和（32.65±5.59） ml/s,差异均有统计学意义（t值分别为3.34和2.15,P值均＜0.01）.60、80和100 cm/s相位速度IVC上段正向峰值流速分别为（55.36±6.30）、（61.30±12.42）、（62.55±13.09） cm/s,反向峰值流速分别为（42.37±19.18）、（32.79±24.67）、（24.61±21.20） cm/s,差异均有统计学意义（F值分别为4.258、7.794,P值均＜0.05）.不同相位速度编码值测定IVC上段与中段图像均清晰可测定（评分均在3分以上,3分11名、4分24名、5分15名）.IVC相位速度图与心动周期的关系为正弦波关系,呈多相型波形特征.IVC上段及中段管腔面积与流速为负相关（r值分别为-0.466和-0.765,P值均＜0.01）,与流量无直线相关关系（r值分别为0.259和0.046,P值均＞0.05）.收缩期及舒张期IVC均存在少许反流。结论 PC-MRI能够快速、准确且无创地测定IVC面积、流速、流量；不同年龄、不同性别及IVC不同解剖部位的血流动力学参数存在差异。

Objective To explore the feasibility of quantitative hemodynamics measurement of inferior vena cava （IVC） in healthy volunteers with phase-contrast sequence on 3.0 T MR system （3.0 T PC-MRI）,and to evaluate the relationship between IVC lumen area,blood flow,and velocity.Methods Fifty healthy adult volunteers prospective underwent IVC PC-MRI at 3.0 T MR system.All volunteers were from our hospital for the routine chest or abdomen examinations,no heart disease and lung disease always,heart rate,blood pressure,electrocardiogram was in normal range,no abnormalities were found in clinical and abdominal imaging examinations,and IVC disease was excluded by ultrasonic examination.The area （A）,mean velocity （MV）,mean flux （MF）,regurgitant fraction （RF） and time-flow curve of upper and middle segments of IVC during one cardiac cycle were observed.Independent samples t test was used to compare IVC lumen area and blood flow,velocity between different genders,different age groups （18 to 30 years old group,more than 30 years old group） and different phase velocity encoding value of IVC middle segment,one-way ANOVA was used to compare different phase velocity encoding value of IVC upper segment [（60,80,100）cm/s].Pearson correlation coefficient and regression equation were used to evaluate the relationships between area,blood flow,and velocity.Results Among 50 patients with successful completion of the examination,significant difference was found in A,MV,MF and RF between the different IVC segments.MF of the IVC middle segment were （37.94 ＆#177; 7.32） and （33.68 ＆#177; 6.65） ml/s in male （n =24） and female （n =26）,respectively ; significant difference was found in different genders （t =2.49,P =0.017）.MF of upper segment and middle segments of IVC were （54.89 ＆#177; 10.98）and （38.29 ＆#177; 7.54）ml/s in 18 to 30 years old group（n =27）,while MF of upper segment and the middle of IVC were （44.96± 8.49） and （32.65± 5.59） ml/s in older than 30 years old group （n =23） with significant difference（t =3.34,2.15,P 〈 0.01）.Peak positive velocity were （55.36±6.30）,（61.30± 12.42）,（62.55 ±13.09） cnm/s in different phase velocities （60,80 and 100 cm/s）,while peak negative velocity （PNV） were （42.37 ± 19.18）,（32.79 ± 24.67）,（24.61 ± 21.20） cm/s with significant differences （F =4.258,7.794,P 〈 0.05）.The overall image quality was good for quantitative measurement between different phase velocity encoding values of upper segment and the middle IVC （image evaluation are greater than or equal to 3,11 patients were three points,24 patients were four points,15 patients five points）.The relation between the PC flow image of IVC and the cardiac cycle was sine wave,the area and the velocity of upper and middle segments of IVC was negative （r =-0.466 and-0.765,P 〈 0.01）,and no linear correlation between the area and the flow of upper and middle segments of IVC （r =0.259,0.046,P 〉 0.05）.There were slight reverse flow during systolic and diastolic cycle.Conclusion The area,flow and velocity of IVC can be rapidly,accurately and noninvasive measured with PC-MRI,and different ages,different genders and different anatomical parts of IVC had obvious hemodynamic differences.