Quantitative magnetic resonance imaging of fresh and frozen-thawed trout

Magnetic resonance imaging (MRI) has been used to visualise the major organs and muscular-skeletal framework of fresh rainbow trout (Salmo gairdneri) in two dimensions, and to identify the spatial distribution of lipid- and collagen-rich tissues. Quantitative MRI provides the MR parameters (T1, T2, M0, T1sat, Msat/M0, and the Magnetisation Transfer (MT) rate) for the tissue water; variations in those parameters enable distinction to be made between a freshly killed trout and one which has been frozen–thawed. The effects of freezing method, repeat freeze–thawing, and storage time on the MR parameters are discussed.