Goelman G
Department of Radiology, University of Pennsylvania, Philadelphia 19104.
J Magn Reson B. 1994 Jul;104(3):212-8. doi: 10.1006/jmrb.1994.1078.
Fast Hadamard spectroscopic imaging (HSI) techniques are presented. These techniques combine transverse and longitudinal encoding to obtain multiple-volume localization. The fast techniques are optimized for nuclei with short T2 and long T1 relaxation times and are therefore suitable for in vivo 31P spectroscopy. When volume coils are used in fast HSI techniques, the signal-to-noise ratio per unit time (SNRT) is equal to the SNRT in regular HSI techniques. When surface coils are used, fast HSI techniques give significant improvement of SNRT over conventional HSI. Several fast techniques which are different in total experimental time and pulse demands are presented. When the number of acquisitions in a single repetition time is not higher than two, fast HSI techniques can be used with surface coils and the B1 inhomogeneity does not affect the localization. Surface-coil experiments on phantoms and on human calf muscles in vivo are presented. In addition, it is shown that the localization obtained by the HSI techniques are independent of the repetition times.
本文介绍了快速哈达玛光谱成像（HSI）技术。这些技术结合了横向和纵向编码以实现多体积定位。快速技术针对具有短T2和长T1弛豫时间的原子核进行了优化，因此适用于体内31P光谱分析。当在快速HSI技术中使用体积线圈时，每单位时间的信噪比（SNRT）与常规HSI技术中的SNRT相等。当使用表面线圈时，快速HSI技术比传统HSI在SNRT方面有显著提高。文中介绍了几种在总实验时间和脉冲要求方面不同的快速技术。当在单个重复时间内的采集次数不高于两次时，快速HSI技术可与表面线圈一起使用，且B1不均匀性不会影响定位。文中展示了在体模和人体小腿肌肉上进行的表面线圈实验。此外，结果表明通过HSI技术获得的定位与重复时间无关。
