Revolution CT全胃灌注扫描时间间隔对正常胃壁灌注数据的影响

摘要

目的:探讨Revolution CT全胃灌注扫描时间间隔对正常胃壁灌注数据的影响.方法:前瞻性分析于我院行Revolution CT腹部灌注且无胃部疾病患者28例,按临床申请范围不同分为连续灌注组(A组)14例,间隔灌注组(B组)14例.两组灌注扫描均为轴扫模式,Z轴覆盖范围均为160 mm,A组连续采集25次,每次采集时间为2s(曝光0.5s,间隔1.5 s),总扫描时间50 s.B组在第15s即采集8次后进行全腹动脉期螺旋扫描,螺旋扫描模式与轴扫模式互相转换及扫描曝光时间12～16.2 s,再进行13次上腹轴位灌注扫描,共采集21次,总扫描时间50～54.2 s.所有图像经运动校正后传至工作站进行灌注成像分析.两名观察者分别测量胃体部大、小弯侧感兴趣区的灌注参数值,包括BV、BF、MTF、TP、PEI、MSI、IRF、Tmax,统计各组灌注辐射剂量.使用组内相关系数(ICC)对所得数据进行一致性检验,采用配对样本t检验及独立样本t检验比较两组内及组间各灌注参数的差异.结果:两观察者数据测量一致性较好.两组内胃大弯侧BV值((12.83±4.30)、(18.44±4.39) mL/(min· 100 g))、BF值((61.54±10.13)、(64.99±13.77) mL/100 g)均高于小弯侧BV值((9.73±3.87)、(14.28±5.40) mL/(min· 100 g))、BF值((47.77±12.29)、(47.09±10.52) mL/100 g),P值分别为0.027、0.004、0.002、0.000,其余灌注参数值(MTT、TP、MSI、PEI、IRF、Wmax)差异无统计学意义;两组间BV、PEI值在胃大、小弯侧差异均有统计学意义(P=0.002、0.004、0.017、0.032),MTT及Tmax值仅在小弯侧差异有统计学意义,在大弯侧差异无统计学意义,且A组均低于B组,余灌注参数值(BF、TP、MSI、IRF)两组间差异无统计学意义.A组剂量为14.46 mSv,B组为12.15 mSv,B组较A组降低15.97％.结论:Revolution CT全胃灌注扫描时间间隔对正常胃壁BV、MTr、PEI及Tmax等灌注参数有影响,但对BF、TP、MSI、IRF值无影响,且胃大、小弯侧BV、BF灌注值不同.%Objective:To explore the effect of sampling interval on normal gastric perfusion by revolution CT.Methods:Twenty-eight volunteers without gastric disease were studied using revolution CT scanner.Fourteen volunteers (group A) were scanned with standard continuous perfusion,and other volunteers (group B) were scanned with intermittent perfusion.Two groups of perfusion scanning were performed with axial scan mode and Z axis coverage of 160 mm.Group A collected perfusion images 25 times with sampling intervals of 2 s(exposure time of 0.5 s,interval time of 1.5 s),and the total scan time was 50 s.Group B obtained arterial phase image with spiral scanning mode at 15 s after 8 times perfusion.The conversion time from helical to axial scan mode and exposure time was about 12～16.2 s.And then another 13 times of perfusion data were collected,with a total scan time of 50～54.2 s.Three regions of interest were placed in gastric wall of greater and lesser curvature.The acquired data were used for calculation and analysis by a CT perfusion software package to measure 8 parameters:blood flow(BF),blood volume(BV),mean transit time (MTT),time to peak(TP),positive enhancement integral(PEI),mean slope of interest (MSI),IRF and Tmax.Radiation dosage was also collected.Perfusion parameters in the greater and lesser curvature of stomach in different groups were compared.Result:BV ((12.83±4.30),(18.44±4.39) mL/(min· 100 g)) and BF ((61.54±10.13),(64.99±13.77) mL/100 g) in the greater curvature were statistically higher than those of lesser curvature both in group A and B,with P values of 0.027,0.004,0.002 and 0.000.But the rest perfusion parameters (MTT,TP,MSI,PEI,IRF,Tmax) didn't show significant difference.Between the two groups of BV and PEI in the greater and lesser curvature,differences were statistically significant (P=0.002,0.004,0.017,0.032).And only in the lesser curvature there was a significant difference for MTT and Tmax,but no significant difference was found in the greater curvature.Values of group A were lower than those in group B.And there were no difference for BF,TP,MSI and IRF between two groups.Effect dosage of intermittent perfusion was reduced by 15.41％ compared with continuous perfusion.Conclusion:Sampling interval of gastric perfusion on revolution CT has an effect on BV,MTT,PEI and Tmax perfusion parameters,but not on BF,TP,MSI and IRF values.BV and BF values are different between greater curvature and lesser curvature.