不同压缩感知因子对磁敏感加权成像显示脑髓静脉的影响

Influence of different compressed sensing factors on susceptibility weighted imaging for displaying cerebral medullary vein

目的观察不同加速因子(AF)对压缩感知磁敏感加权成像(CS-SWI)显示健康人脑髓静脉的影响,并遴选最佳AF。方法前瞻性纳入40名健康志愿者,以不同AF(AF0、CS2、CS4、CS6、CS8及CS10)行头颅CS-SWI重建,测量双侧透明隔静脉(SV)、大脑内静脉(ICV)、丘纹上静脉(TV)、基底静脉(BV)及齿状核静脉(DNV)相位值(PV)和标准差(SD);以顶叶白质PV和SD为对照,计算各静脉图像信噪比(SNR)及对比度噪声比(CNR);行最小密度投影重建,以5分法对重建图像质量进行主观评估。比较不同AF序列图像各脑髓静脉SNR、CNR、PV及其质量评分,遴选观察及定量分析健康人脑髓静脉的最佳AF。结果相比AF0,CS6、CS8及CS10序列所获各脑髓静脉的SNR和CNR差异均有统计学意义(校正P均<0.05),CS6、CS8及CS10序列双侧SV、右侧TV,以及CS8及CS10序列所获双侧ICV、左侧TV及双侧BV的PV差异均有统计学意义(校正P均<0.05)。结论AF过高可降低CS-SWI显示脑髓静脉质量;CS4为观察及定量分析健康人脑髓静脉的最佳AF。

Objective To observe the influence of different acceleration factors(AF)on compressed sensing susceptibility weighted imaging(CS-SWI)for cerebral medullary veins of healthy people,and to screen the best AF.Methods Forty healthy volunteers were prospectively enrolled.Axial brain SWI images were obtained with CS technique under different AF(AF0,CS2,CS4,CS6,CS8 and CS10),and the phase value(PV)and standard deviation(SD)of bilateral septal vein(SV),internal cerebral vein(ICV),thalamus vein(TV),basal vein(BV)and dentate nucleus vein(DNV)were measured.Taken PV and SD of parietal white matter as controls,the signal-to-noise ratio(SNR)and contrast-to-noise ratio(CNR)of venous images were calculated.Then the original images were reconstructed with minimum intensity projection,and the subjective quality scoring of reconstructed images were performed using a 5-point scale.SNR,CNR,PV and quality score were compared among images under different AF,and the best AF,i.e.with the best performances for displaying and quantitatively analyzing cerebral medullary veins in healthy people was obtained.Results Compared with those acquired with AF0,SNR and CNR of all cerebral medullary veins acquired with CS6,CS8 and CS10 were significantly different(all adjusted P<0.05).Meanwhile,significant differences of PV in bilateral SV and right TV were found among CS6,CS8 and CS10,also in bilateral ICV,left TV and bilateral BV between CS8 and CS10(all adjusted P<0.05).Conclusion Excessive AF might decrease image quality of CS-SWI for cerebral medullary veins.CS4 was the best AF for displaying and quantitatively analyzing cerebral medullary veins in healthy people.