Changes in NMR relaxation time associated with local inflammatory response.

T1 and T2 relaxation values and water contents of rat and rabbit tissues have been measured during the course of local inflammatory reaction to turpentine. For rabbits, NMR transverse sectional images were also obtained by spin-warp imaging. Elevations in T1 values around the injection site occurred within 24 h. In rats, T1 values of fibrosed muscle at the centre of the reaction continued to rise as a cyst formed, encapsulating the turpentine. T1 values of the surrounding muscle decreased towards normal as the reaction progressed. Good correlation between relaxation rate and water content was observed. In the rabbits. T1 values measured in vitro around the injection site were compared with the values obtained from NMR images of living and dead rabbits, T1 values obtained immediately after death were consistently lower than values of the same tissues before death. Factors affecting a comparison of T1 values obtained by the different methods are discussed.