T2*-weighted imaging

However, in real systems, there are minor differences in chemical environment which can lead to a distribution of resonance frequencies around the ideal.

For molecules that aren't moving, the deviation from ideal relaxation is consistent over time, and the signal can be recovered by performing a spin echo experiment.

T2*-weighted imaging can be created as a postexcitation refocused gradient echo (GRE) sequence with small flip angle.

The sequence of gradient echo T2*-weighted imaging (GRE T2*WI) requires a high uniformity of the magnetic field.

[2] T2*-weighted sequences can be used with MRI contrast, mainly ferucarbotran or superparamagnetic iron oxide (SPIO), to depict liver lesions.