Department of Medicine, John A. Burns School of Medicine, University of Hawaii, Honolulu, Hawaii.
Magn Reson Med. 2019 Jun;81(6):3720-3733. doi: 10.1002/mrm.27693. Epub 2019 Feb 12.
To describe a simultaneous multislice (SMS) ultrashort echo time (UTE) imaging method using radiofrequency phase encoded half-pulses in combination with power independent of number of slices (PINS) inversion recovery (IR) pulses to generate multiple-slice images with short T * contrasts in less than 3 min with close to an eightfold acceleration compared with a standard 2D approach.
Radiofrequency phase encoding is applied in an SMS (N = 4) excitation scheme using "sinc" half-pulses. With the use of coil sensitivity encoding (SENSE) and controlled aliasing in parallel imaging (CAIPI) in combination with a gradient echo 2D spiral readout trajectory and IR PINS pulses for contrast enhancement a fast UTE sequence is developed. Images are obtained using a model-based reconstruction method. Sequence details and performance tests on phantoms as well as the heads of healthy volunteers at 3T are presented.
An SMS UTE sequence with an undersampling factor of 4 is developed using radiofrequency phase encoded half-pulses and PINS IR pulses which enables the acquisition of 8 slices at 0.86 mm resolution in less than 3-min scan time. UTE images of the head are obtained showing highlighted signal of cortical bone. Image quality and T contrast are comparable to the one obtained by corresponding single slice acquisitions with only minor deviations.
The method combining radiofrequency phase encoded SMS half-pulses and PINS IR pulses presents a suitable approach to SMS UTE imaging. The usage of coil sensitivity information and increased sampling density by means of interleaved slice group acquisitions allows to reduce the total scan time by a factor close to 8.
描述一种使用射频相位编码半脉冲结合与切片数无关的功率（PINS）反转恢复（IR）脉冲的同时多层（SMS）超短回波时间（UTE）成像方法，以在不到 3 分钟的时间内生成具有短 T*对比度的多层图像，与标准 2D 方法相比，加速倍数接近 8 倍。
在使用“sinc”半脉冲的 SMS（N=4）激发方案中应用射频相位编码。通过使用线圈灵敏度编码（SENSE）和并行成像中的受控混叠（CAIPI）以及梯度回波 2D 螺旋读出轨迹和用于对比度增强的 IR PINS 脉冲，开发了一种快速 UTE 序列。使用基于模型的重建方法获得图像。呈现了序列细节和在体模以及在 3T 下健康志愿者头部的性能测试结果。
使用射频相位编码半脉冲和 PINS IR 脉冲开发了一种具有 4 个欠采样因子的 SMS UTE 序列，该序列能够在不到 3 分钟的扫描时间内以 0.86mm 的分辨率采集 8 层。获得了头部的 UTE 图像，显示出皮质骨的高信号。图像质量和 T 对比度与相应的单切片采集获得的质量和 T 对比度相当，只有微小的偏差。
结合射频相位编码 SMS 半脉冲和 PINS IR 脉冲的方法为 SMS UTE 成像提供了一种合适的方法。通过使用线圈灵敏度信息和交错切片组采集增加采样密度，可以将总扫描时间缩短近 8 倍。
