Compartmental relaxation and diffusion tensor imaging measurements in vivo in λ‐carrageenan‐induced edema in rat skeletal muscle

Abstract

Integrated diffusion tensor T(2) measurements were made on normal and edematous rat muscle, and the data were fitted with one- and two-compartment models, respectively. Edematous muscle exhibited a short-lived component (T(2) = 28 +/- 6 ms), with diffusion characteristics similar to that of normal muscle, and a long-lived component (T(2) = 96 +/- 27 ms), with greater mean apparent diffusion coefficient (ADC) and lower fractional anisotropy (FA). With this two-component description of diffusion and relaxation, values of ADC and FA estimated with a conventional pulsed-gradient spin-echo sequence will depend on the echo time, relative fraction of short-lived and long-lived water signals, and the intrinsic ADC and FA values within the tissue. On the basis of the relative differences in water diffusion properties between long-lived and short-lived water signals, as well as the similarities between the short-lived component and normal tissue, it is postulated that these two signal components largely reflect intracellular and extracellular water.