基于双极读出梯度的单重复时间腰椎定量磁化率成像

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Abstract：Objective To proposea single repetition time （TR）quantitative magnetic susceptibility imaging method for the lumbar spine using bipolar readout gradient，and compare the quantitative magnetic susceptibility measurement using single TRanddualTRmethodsforthelumbarspinewithdifferentbonedensities.MethodsAtranslationcorectionmethodwas proposedtocorrectspatial misalignment along thefrequencyencoding direction betweenpositiveand negativegradient readout images，and the phase diference between the images was eliminated using a phase correction method.Thedata of lumbar vertebrae L1-L5werecollectedusing single TRanddualTRmethodsfrom6normal individuals，2patients with osteopeniaand2patientsithosteoporosis.Themagneticsusceptibilitymapwasreconstructed，thequantitativersultsof singleTRbeforeandaftercorrctionwerecomparedwiththoseofthedualTRmethod.ResultsThelinearregressionresultof thelumbarspinemagneticsusceptibilityvaluesobtainedbythesingleTRmethodbeforecalibrationandthedualTRmethod is Y=0.64*X-11.61.Thelinearregressonresultof thelumbarspine magneticsusceptibilityvaluescoectedbythesingleTR method and the dual TR method is Y=1.03*X+0.25 .The results of the corrected single TR method were highly consistent with thoseof thedualTRmethod，andthecalibratedsingleTRmethodcouldefectivelydistinguishosteopeniaandosteoposis patients from normal individuals.Conclusion Thecalibrated single TRbipolar readout gradient method can generateartifactfree lumbar spine quantitative magnetic susceptibility distribution maps and reduce data acquisition time by 50%

Keywords： magnetic resonance imaging; quantitative susceptibility mapping; singleTR;lumbar spine; osteoporosis

定量磁化率成像（QSM）是一种可实现组织磁化率三维定量测量的磁共振成像技术，该技术使用梯度回波序列采集多回波的相位图去估计出 ΔB0 场图，然后利用磁场物理模型求解组织的定量磁化率。（剩余12932字）