Chapter 10 Relaxation Flashcards
What is relaxation?
the process by which the spins return to thermal equilibrium
Relaxation consists of 2 simultaneous but independent processes:
T1 and T2 relaxation
What is T2 relaxation?
-Spin-Spin relaxation (or interaction)
-an interaction among spins
-spins in the high energy state give energy to spins in the low energy state (they lose phase coherence)
-results in a decay of detectable magnetization in the transverse plane which results in decay of signal
for registry- spin-spin, exchange of energy, and decay transverse magnetization
What is T1 relaxation?
-Spin-Lattice Relaxation
-spins in high energy state give up or lose their energy to their molecular lattice
-as energy is lost, longitudinal magnetization recovers along the direction of B0
-for registry - spin-lattice, loss of energy and longitudinal magnetization recovers
T2 relaxation results in _____ of______magnetization.
decay of transverse
T1 relaxation results in _____ of______magnetization.
recovery of longitudinal
T2 decay is ______in its rate of decay
exponential
a tissue’s T2 relaxation time is defined as _______ has decayed.
63% of transverse magnetization
the T2 relaxation time of a tissue is affected by:
the tissue type
Fat has a ___T2 relaxation time
short
water has a ___T2 relaxation time
long
T2 relaxation times are effected by
slightly by field strength
temperature
tissue
molecular tumbling rate
a tissue’s T1 relaxation time is defined as with ________________ has recovered.
63% of the longitudinal magnetization
Fat has a ___T1 relaxation time
short
water has a ___T1 relaxation time
long
