Rahmer Jürgen, Börnert Peter, Groen Jan, Bos Clemens
Philips Research Laboratories, Hamburg, Germany.
Magn Reson Med. 2006 May;55(5):1075-82. doi: 10.1002/mrm.20868.
The application of 3D radial sampling of the free-induction decay to proton ultrashort echo-time (UTE) imaging is reported. The effects of T2 decay during signal acquisition on the 3D radial point-spread function are analyzed and compared to 2D radial and 1D sampling. It is found that in addition to the use of ultrashort TE, the proper choice of the acquisition-window duration TAQ is essential for imaging short-T2 components. For 3D radial sampling, a maximal signal-to-noise ratio (SNR) with negligible decay-induced loss in spatial resolution is obtained for an acquisition-window duration of TAQ approximately 0.69 T2. For 2D and 1D sampling, corresponding values are derived as well. Phantom measurements confirm the theoretical findings and demonstrate the impact of different acquisition-window durations on SNR and spatial resolution for a given T2 component. In vivo scans show the potential of 3D UTE imaging with T2-adapted sampling for musculoskeletal imaging using standard MR equipment. The visualization of complex anatomy is demonstrated by extracting curved slices from the isotropically resolved 3D UTE image data.
本文报道了自由感应衰减的三维径向采样在质子超短回波时间（UTE）成像中的应用。分析了信号采集期间T2衰减对三维径向点扩散函数的影响，并与二维径向和一维采样进行了比较。研究发现，除了使用超短回波时间外，正确选择采集窗口持续时间TAQ对于成像短T2成分至关重要。对于三维径向采样，当采集窗口持续时间TAQ约为0.69T2时，可获得最大信噪比（SNR），且空间分辨率因衰减引起的损失可忽略不计。对于二维和一维采样，也得出了相应的值。体模测量证实了理论结果，并展示了不同采集窗口持续时间对给定T2成分的SNR和空间分辨率的影响。体内扫描显示了使用标准MR设备进行具有T2自适应采样的三维UTE成像在肌肉骨骼成像中的潜力。通过从各向同性分辨的三维UTE图像数据中提取弯曲切片，展示了复杂解剖结构的可视化。
