核磁共振显微术的DESIRE效应模拟(英文)

要在合理时间內进行微米等级解析度的扫描时,核磁共振波谱的信噪比一直是一个很大的限制. DESIRE效应利用扩散现象来增强信号强度及解析度的概念被提出后,信噪比在一维的情况下大约可以增加一个数量级.在先期的研究中,模拟外加磁场的效应通常是使用叠代数值计算,而扩散的效应则是利用有限微分法解Bloch-Torrey e-quation ,这样的模拟方法通常很耗时.该研究中,分别使用Shinnar-LeRoux演算法及基于旋积的扩散模拟方法来加速计算出外加磁场及扩散对于信号的影响,因此可以节省大量计算时间以进行复杂的计算.利用一维模拟结果预测在不同参数实验中解析度的改变和信号增加值,并找出最佳的参数值.而由模拟结果指出,Sinc3脉冲波形可以得到最佳的信号增加量及不错的解析度.

Simulations of DESIRE Effect for NMR Microscopy

Within an advisable measurement time,the signal-to-noise ratio (SNR) is a major limitation of nuclear magnetic resonance microscopy at the spatial resolution of micrometers level.In previous reports,computer simulations showed the "Diffusion Enhancement of Signal and Resolution" (DESIRE) effect may provide potential signal enhancement of one order in one-dimensional case.However,the time-consuming calculations such as iterative matrix multiplications and finite-differential (FD) methods were utilized for simulating the external magnetic fields and diffusion propagations.In this work,we proposed to use the Shinnar-LeRoux (SLR) algorithm and convolution based diffusion method to accelerate the simulations.Therefore,extensive simulations can be conducted for optimization of pulse sequence.Considering the enhance rate and effective resolution in one dimensional DESIRE experiment,the simulated results indicated the pulse shape of Sinc3 with optimal parameters could achieve superior performance under practical experimental settings.