Relaxation time contrast

T1- and T2-weighted imaging
The work horses of clinical imaging:
Always available, reliable and require little post-processing
Sensitive to pathology


T1- and T2-weighted sequences.  

Transversal T2-relaxation
Loss of signal due to dephasing of spins
Reversible loss caused by inhomogeneity
Irreversible loss caused by spin-spin interactions, elastic and inelastic

 Longitudinal T1-relaxation	
Return of Mz to equilibrium
caused by inelastic spin-spin interactions only (so T2<T1)