Effect on T1 relaxation due to the application of the gradient

1. What affects T1 relaxation time?
2. What happens during T1 relaxation?
3. What does the T1 relaxation time represent?
4. What factors determine the T1 and T2 relaxation time of a tissue?

What affects T1 relaxation time?

T1 relaxation is fastest when the motion of the nucleus (rotations and translations or "tumbling rate") matches that of the Larmor frequency. As a result, T1 relaxation is dependent on the main magnetic field strength that specifies the Larmor frequency. Higher magnetic fields are associated with longer T1 times.

What happens during T1 relaxation?

T1 relaxation is the process by which the net magnetization (M) grows/returns to its initial maximum value (Mo) parallel to Bo. Synonyms for T1 relaxation include longitudinal relaxation, thermal relaxation and spin-lattice relaxation. The meanings and implications of these synonyms will become apparent shortly.

What does the T1 relaxation time represent?

T1 (longitudinal relaxation time) is the time constant which determines the rate at which excited protons return to equilibrium. It is a measure of the time taken for spinning protons to realign with the external magnetic field.

What factors determine the T1 and T2 relaxation time of a tissue?

Factors affecting T1 and T2 relaxation times of different tissues are generally based on molecular motion, size and interactions.