1. Gradient echo.
Gradient echo. An excitatory radiofrequency (RF) pulse causes transverse magnetisation and initiation of a free induction decay signal. This signal rapidly de-phases following the application of a magnetic field gradient. Application of a second magnetic field gradient with a slope of equal amplitude but in opposite direction to the first causes some rephasing. The signal increases again at time TE to a maximal signal termed a gradient echo. The maximum amplitude of the gradient echo is dependent on the specified TE and the T2* relaxation rate of the tissues in question. This figure is only reproduced in colour in the online version.
Stuart Currie et al. Postgrad Med J 2013;89:
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