Check Your Progress 1

You should be able to observe the signals decaying over time. Precisely, this is the so-called T₂* signal decay of MR signal which results from water protons losing phase coherence over time. The mechanism of T₂* decay is complicated because it is due to factors such as field inhomogeneity/diffusion/imperfect shimming, etc. Although QSM mainly works with phase images, magnitude images can be very useful because they share similar (but not always the same!) contrasts, therefore, have the potential to improve the quality of QSM maps.

Back to Exercise 1.