Perfusion imaging by un-inverted flow-sensitive alternating inversion recovery (UNFAIR).

A new pulse sequence for estimating cerebral blood flow called UNFAIR, which uses a combination of sequential hyperbolic secant preparatory pulses, is introduced. This sequence is based on the same generalized conditions as previously introduced inversion recovery techniques except that the spins in the image slice of interest always have +z magnetization and the in-flowing spins are alternately inverted and uninverted. CBF-weighted images of rat brain under conditions of normocpnia and hypercapnia are presented and demonstrate the expected CBF response. A model describing the signal response to this pulse sequence is also presented and compared with in-vivo data acquired from gray and white matter.