Trading Spectral Separation at 3T for Acquisition Speed in Multi Spin-Echo Spectroscopic Imaging

Fast multiple spin-echo spectroscopic imaging, also called turbo spectroscopic imaging (TSI), may be enhanced in terms of acquisition speed by taking advantage of the higher spectral separation afforded at higher field strength and by further combining it with sensitivity encoding (SENSE). This article demonstrates the possibilities of this approach at 3T, resulting in scan-time reductions of up to a factor of 10. High-resolution, in vivo, single- and multiple-section spectroscopic imaging data are presented. One of the principal obstacles to the clinical adoption ofhigh resolution or 3D spectroscopic imaging is the long scan time required when using conventional chemical shift imaging pulse sequences. Consequently, various fastMR spec-troscopic imaging (MRSI) techniques have been implemented on research scanners, often derived from analogous fast imag-ing techniques.1 One approach, available as a product on clin-ical scanners, is based on multiple spin echoes,2 analogous to the rapid acquisition with relaxation enhancement (RARE) (also called turbo spin-echo [TSE] or fast spin-echo [FSE])3 approach in MR imaging. In this technique, also name