Approximating Water Exchange In Vivo in a Rat Model

Colleen Bailey^1,2, Firas Moosvi^1,2, Greg J. Stanisz^1,2

Intracellular-extracellular water exchange is an important marker of apoptotic cell death. In this study, the feasibility of measuring exchange in nude rats was examined. Data from three separate steady-state gadodiamide concentrations and an SPGR sequence with at four flip angles were fit to a two-pool model with exchange. The χ² value was 55% lower than a similar model with the same number of parameters that assumed fast exchange. The exchange value in muscle, 0.24 0.10 s^-1, was consistent with that found in previous studies.