We are daily seeing FLAIR and STIR. What are the T1 values of Water and Fat? Is it 2500ms for water and 160ms for fat?
T1 value of water is ~4200ms and for fat it is ~ 230ms.
After the inversion pulse in FLAIR or STIR, longitudinal magnetization begins to recover according to T1.
The magnetization of a given tissue passes through zero after a time equal to approximately 69% of the tissue T1 value.
If the TI is selected to equal this time, no magnetization is available from that tissue at the start of the host sequence, and signal from that tissue is suppressed.
In FLAIR the TI selected is ~2500ms (in our case) and in STIR it is 160ms, when the magnetization equals zero for water and fat respectively.
Further study : An Interactive Taxonomy of MR Imaging Sequences
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