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Spin-echo transverse magnetization detection

Because the induced NMR signal after switching off the 90° RF pulse decays so rapidly as mentioned above, spin echoes are often detected in many practical pulse sequences for MRI visualization. Spin echo is formed by an additional RF pulse applied to the sam-ple.The additional RF pulse is applied after an evolution period, r. This RF pulse that gives rise to inversion of the magnetization components causes the spins to rephrase and is thus referred to the 180° RF pulse as shown in Fig. 2. This rephrasing process contributes to recover the transverse magnetization which had lost in dephasing process and results in the formation of an echo . We detected the echo by the receiver coil. The time from when the 90° RF pulse is applied to when the echo forms is referred to as the echo time , TE and is equal to twice the time between the 90° and 180° pulses, i.e. 2r. [Pg.204]

Preparation, evolution and detection are the time periods of pulse sequences described for. /-modulated spin-echo and polarization transfer experiments. The basic FT NMR technique operates without any evolution period tt immediately after generation of transverse magnetization (preparation) its free induction decay S(t2) is detected. Subsequent Fourier transformation provides the FT NMR spectrum S (f5). [Pg.87]


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See also in sourсe #XX -- [ Pg.95 , Pg.130 ]




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Echo Detectability

Spin detection

Spin echo detection

Spin magnetism

Spin magnetization

Transverse /-spin magnetization

Transverse magnetization

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