The architecture of a sequence consists of the essential components on one hand, and the various options, on the other. The building blocks of the sequence are radiofrequency pulses and gradients.
The essential components for any imaging sequence are :
The options consist of other radiofrequency pulses, gradients or variable reconstruction methods to :
Finally, the user must choose the sequence parameters (TR, TE, flip angle, turbo factor, field of view matrix) to find the best compromise between contrast, spatial resolution and speed.
With the exception of inversion-recovery, the optional techniques to modify the contrast of a sequence will be examined in a dedicated chapter. Likewise, the treatment of artifacts and parallel imaging methods will be dealt with in separate chapters.