Chemical shift selective pulse

Fig. 7. Double spin-echo imaging sequence for chemical shift selective imaging. The sequence applies spectral-spatial excitation pulses as presented in Fig. 6. Refocusing is performed with standard slice selective 180° pulses. For the examples in Fig. 8 echo times were chosen to TEi = 20 ms and TE2 = 60 ms.

Selective pulses and chemical-shift-selective filters... 

As pointed out in the Introduction, the essential part of a successful transformation of an nD experiment into its ID analog is the selective excitation of spins. There are two distinct tools available for this purpose selective pulses and chemical-shift-selective filters. 

As an alternative to selective pulses, chemical-shift-selective filters (CSSF) were successfully used in ID COSY, ID RELAY and ID NOESY experiments when signals partially overlapping, but different in their chemical... 

An alternative to using selective pulses in selective ID TOCSY has been proposed [52]. The frequency selection is instead accomplished by using a homonuclear ( H) chemical shift selective filter (CSSF) [53, 54]. The chemical shift filter for frequency selection consists of a non-selective 90° pulse which is set at the frequency of the selected signal, and a systematic increment of the chemical shift evolution between this pulse and the... 

Fig. 7.2.6 [Haa3] Pulse sequences for CHESS-STEAM imaging. The NMR signals are the Hahn or spin echo (HE) and the stimulated echo (STE). (a) Basic sequence for chemical-shift selective measurement of HE and STE images, (b) Sequence for acquisition of n slice-selective images from CHESS stimulated echoes.

Chemical-shift selection The homonuclear dipole-dipole interaction among the abundant nuclei needs to be eliminated by use of a multi-pulse sequence like MREV8. Such... 

Fig. 10.22. Plots of normalized deviations from the sample-averaged proton polarizations (per spin) for nylon and PBZT protons in nylon/PBZT-40/60. MP refers to the multiple-pulse version of the spin-diffusion experiment (the modified chemical-shift selective Goldman-Shen experiment) PLS indicates the proton lineshape version (the T2-selective Goldman-Shen experiments with C detection). (Reprinted with permission from Ref. [82]. 1990 Huthig Wepf Verlag.)...

Localized MR spectroscopy was developed to obtain chemical as well as spatial information. Frequency offsets (caused by the inhomogeneous susceptibility or chemical shift distribution) can be recorded by introducing a further measuring domain, called the spectral-encoding domain. Thus, the dimension of the experiment is increased by one. The spatial distribution of compounds with distinct chemical shifts can be obtained as chemical-shift-selective maps. The spatial distribution of frequency offsets can be acquired by imaging pulse sequence, such as echo-time encoding. The method is suited for the... 

A method for 3D MRSI has been demonstrated at 7T that utilises the Spectroscopic Missing Pulse - steady state free precession acquisition scheme. Modifications of previous implementations of the sequence at 3 T were required to comply with the limits of the specific absorption rate as well as to accommodate hardware limitations. The combination of two spatially selective radiofrequency pulses and a dual-band chemical shift selective radiofrequency pulse for simultaneous water and lipid suppression were used in fast 3D MRSI measurements in the brain of healthy volunteers. Signals from NAA, tCr, Cho, ml, and glutamate plus glutamine (Glx) were measured. ... 

A simplification of the COSY H-n.m.r. spectra of oligosaccharides by use of a 2-ditnensional version of 3-dimensional HOHAHA COSY has been described. A new and economical (in spectrometer time) technique for assigning oligosaccharide n.m.r. specua, which employs selective excitation combined with a DANTE pulse train and chemical shift selective filtering (CSSF), was found suitable for problems of medium complexity, where each spin network contains at least one separate multiplet. It has been applied to hepta-O-acetyl-a-cellobiosyl ande as an example. ... 

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