基于大鼠肾脏阶跃氧刺激的高时间分辨率动态 T₂^∗W 成像研究

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Abstract：ObjectiveTomonitorthechanges inoxygenationlevelsofratkidneysunder stepoxygen stimulationby high temporal resolution dynamic T2* weighted planar echo imaging （T2*W -EPI）. Methods Step oxygen stimulation was applied to SD rats （n=10） in the sequence of 2 min of hyperoxia （ 100% O2 ）-10minofhypoxia（ 10% O2）-10 min of hyperoxia （100% O2） Dynamic MRI data of the kidneys of multi-echo gradient echo （mGRE）sequence and gradient echo-planar imaging （EPI） sequencewere continuouslyacquiredona9.4Tsmallanimal magneticresonance scanner.The time resolutionof the two sequenceswere9sand1s，respectively.Asecond-order stepresponse model was established forthedynamictime series curvesof diferentregions of interest （ROIs）inratkidneys，andtheparametersof thestepresponsemodelwereobtained， including time delay Δt，natural frequency @n， damping constant D and oscillation period T The performance of two MRI imagingmethods withdiferenttemporalresolution inresponse tothestep oxygen stimulationintheKidneys wascompared. Results Compared with the control experiment results of mGRE， the dynamic T2*W. -EPI technologyproposed inthisstudy increasedthetemporalresolutionofmonitoringrenalstepoxygenstimulationby8foldsandimprovedthegoodnessoffitof the step response model. The model showed a shorter time delay Δt （shortened by 29.4% 42.6% 56.4% and 47.4% respectively， inthe CO， OsOM， IsOMand IM），a larger natural frequency ωn （increased by 21.1% 28.6% 52.2% and 61.9% respectively），and oscillation of each ROI （damping constant D<1 ）under the step oxygen stimulation. Conclusion Ina step oxygen stimulation model of rat kidneys， the high temporal resolution dynamic T2*W -EPI technique proposed in this study is capableofreal-timemonitoringofthechanges inrenaloxygenationlevelsfordetectionofabnormalrenalconditions. Keywords： echo planar imaging; step oxygen stimulation; kidney; oxygenation

肾脏是维持机体内环境稳态的重要器官，其功能依赖于充足的氧供应和细胞代谢之间的平衡[1-3]。（剩余16519字）