STE Imaging
Are stimulated echoes used for imaging? I've never heard of that.
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The most common pure application of stimulated echoes is in volume-selective MR spectroscopy, where it is commonly referred to as the STEAM (STimulated Echo Acquisition Mode) technique. Here three RF pulses are applied simultaneously with slice-select gradients along the x-, y-, and z-axes. This produces a STE from the voxel at the intersection of the three planes.
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Stimulated echoes techniques have also found limited applications in such diverse areas as diffusion imaging, chemical-shift selective imaging, Zoom imaging, and flow imaging.
Though not used as the primary signal generators for most sequences, STEs make major contributions to the total signal and image contrast produced in many short-TR, steady-state gradient echo sequences such as FISP, PSIF, SSFP, CISS, and FIESTA. How this occurs will be the subject of several later Q&A's.
More often than not, unwanted STEs occur in pulse sequences as the result of partially coherent spins subjected to multiple RF pulses. These STEs create image artifacts and reduced contrast. Pulse sequence designers have to make special provisions to eliminate or minimize STEs such as applying crusher, rewinder, or spoiler gradients at the end of each cycle.
Though not used as the primary signal generators for most sequences, STEs make major contributions to the total signal and image contrast produced in many short-TR, steady-state gradient echo sequences such as FISP, PSIF, SSFP, CISS, and FIESTA. How this occurs will be the subject of several later Q&A's.
More often than not, unwanted STEs occur in pulse sequences as the result of partially coherent spins subjected to multiple RF pulses. These STEs create image artifacts and reduced contrast. Pulse sequence designers have to make special provisions to eliminate or minimize STEs such as applying crusher, rewinder, or spoiler gradients at the end of each cycle.
References
Haase A, Frahm J, Matthaei D, et al. MR imaging using stimulated echoes (STEAM). Radiology 1986;160:787-790.
Haase A, Frahm J, Matthaei D, et al. MR imaging using stimulated echoes (STEAM). Radiology 1986;160:787-790.
Related Questions
What is a stimulated echo?
What is a stimulated echo?