Bruker BioSpin AG, Faellanden, Switzerland.
Magn Reson Med. 2010 Dec;64(6):1685-95. doi: 10.1002/mrm.22516. Epub 2010 Oct 14.
In the recently proposed technique Sweep Imaging with Fourier Transform (SWIFT), frequency-modulated radiofrequency pulses are used in concert with simultaneous acquisition to facilitate MRI of samples with very short transverse relaxation time. In the present work, sweep MRI is reviewed from a reconstruction perspective and several extensions and modifications of the current methodology are proposed. An algorithm for algebraic image reconstruction is derived from a comprehensive description of signal formation, including interleaved radiofrequency transmission and acquisition of arbitrary timing as well as the relevant filtering and decimation steps along the receiver chain. The new reconstruction approach readily permits several measures of optimising the signal sampling strategy as demonstrated in simulations and imaging experiments. Employing a variety of radiofrequency pulse envelopes, water and rubber phantoms as well as bone samples with transverse relaxation time in the order of 500 μsec were imaged at signal bandwidths of up to 96 kHz.
在最近提出的 Sweep Imaging with Fourier Transform (SWIFT) 技术中，使用调频射频脉冲与同时采集相结合，以促进具有非常短横向弛豫时间的样本的 MRI。在本工作中，从重建的角度回顾了 Sweep MRI，并提出了当前方法的几个扩展和修改。从信号形成的全面描述中推导出了用于代数图像重建的算法，包括射频传输的交错和任意定时的采集，以及沿着接收器链的相关滤波和抽取步骤。新的重建方法可以方便地优化信号采样策略，如模拟和成像实验所示。采用各种射频脉冲包络，对水和橡胶仿体以及横向弛豫时间在 500 μsec 左右的骨样本进行成像，信号带宽高达 96 kHz。
