In: Physics
Why T1 relaxation time is temperature dependent?
Why T2 relaxation time is temperature dependent?
Explain it with theory.
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Answer:-
Accuratemeasurement of tissue relaxation characteristics is dependent on many factors, including field strength and temperature. The purpose of this study was to evaluate the relationship between sample temperature, viscosity and proton spin-lattice relaxation time (T1) and spin-spin relaxation time (T2).
A review of two basic models of relaxation
(a) the simple molecular motion model and
(b) the fast exchange two state model is given with reference to their thermal dependencies.
The temperature dependence for both T1 and T2 was studied on a 0.15 Tesla whole body magnetic resonance imager. Thirteen samples comprising both simple and complex materials were investigated by using a standard spin-echo (SE) technique and a modified Carr-Purcell-Meiboom-Gill (CPMG) multi-echo sequence.
A simple linear relationship between T1 and temperature was observed for all samples over the range of 20°C to 50°C. There is an inverse relationship between viscosity and T1 and T2.
A quantity called the temperature dependence coefficient (TDC) is introduced and defined as the percent rate of change of the proton relaxation time referenced to a specific temperature