a. False. STIR is not specific and the signal from all tissues with a T1 close to that of *** will be suppressed; these include mucoid tissue, haemorrhage, protein-rich fluid and gadolinium or melanin at specific concentrations.
b. False. On its own, out-of-phase imaging is only useful in suppressing signals from voxels containing a mixture of *** and water, mainly for diagnostic purposes.
c. True. This selectively tips the longitudinal magnetization of into the transverse plane, where it is dephased by a spoiler gradient before the excitation pulse is applied. therefore cannot contribute to the signal in the image.
d. True. The chemical shift between *** and water is proportional to field strength; therefore, the use of a higher magnetic field strength makes the design of frequency-selective pulses easier and avoids the risk of unwanted saturation of the water signal. This is why chemical shift-selective saturation pulses are not normally used at lower field strengths, e.g. less than approximately 0.3 T.
e. False. The signal from non-adipose tissue is virtually unaffected by frequency-selective *** saturation. In contrast, an inversion recovery pulse affects magnetization of all tissues, lowering the overall SNR.
