FIG 1. Illustration of the KRISP FLAIR pulse sequence.

A, Three transverse slices through the brain.

B, Diagram shows T1 recovery curves for brain and CSF and illustrates sampling (with a 90° pulse at each data collection) at three progressively increasing TIs: , ß, and , with CSF nulled at time ß.

C, Diagram shows mapping of k-space for each of the three slices. In TR1, lines are mapped as shown with the first sample at TI = to the first strip of k-space in slice 1; sample 2, at TI = ß to the second strip of slice 2; and sample 3 at TI = to the third strip of k-space in slice 3. For TR2, the sample at TI = is mapped to the first strip of slice 3, the sample at TI = ß to the second strip of slice 1, and so on.

D, Diagram shows the end result for each slice with the first strip of k-space mapped with TI = , the middle strip with TI = ß, and the third strip with TI = . Since the signals from tissues and fluids vary with TI as a function of their T1 value, this applies a tissue- and fluid-specific T1 filter across k-space, which is the same for each slice