T1 FLAIR

[aelster]

Dear Barrymagnetic,

Your question is in two parts:

1. A T1-FLAIR sequence is an alternative to a conventional short TR/short TE spin echo (SE) sequence for T1-weighted brain imaging. Because of the inversion pulse, tissues with different T1 values can be separated over twice the dynamic range. Hence it is often noted that the distinction between gray matter and white matter on T1-FLAIR is often superior to that on T1-weighted spin echo. In practice, T1-FLAIR may provide superior delineation of contrast-enhancement. See the example in this related Q&A:

http://mriquestions.com/best-t1-pulse-sequence.html

The benefit of T1-FLAIR is especially dramatic at 3.0T and above, where field-related prolongation of tissue T1 values makes short TR/short TE SE imaging impractical. At 1.5 T which one to use is a toss-up. The T1-FLAIR takes a little longer but looks nicer.

2. T1-weighting and FLAIR are interconnected but somewhat separate concepts. FLAIR simply means that fluid signal is being suppressed through an inversion recovery mechanism. This can be made to happen either with T1-weighting (T1-FLAIR) or T2-weighting (T2-FLAIR) of other tissues.

I hope this helps. Thank you for your question.