We investigated the effect of structural differences in fibrin fibers on the T2 relaxation time. Fibrin fibers have the unique characteristic of orienting themselves parallel to high magnetic fields during polymerization. Two fibrin gels were polymerized from a fibrinogen solution with and without a 7.05-T magnetic field. Water molecules in the fibrin gel that was polymerized in the high magnetic field exhibited only one relaxation time, T2 = 0.35 s, whereas water molecules in the fibrin gel that was not exposed to a magnetic field during polymerization had at least two exponential components in the T2 relaxation. The long component, T2 = 0.35 s, was the same order as the T2 of the fibrinogen solution (= 0.41 s) and the fibrin gel polymerized in the high magnetic field. The short component was T2 = 0.07 s. This difference is attributed to a change in the magnetic dipole-dipole interactions between water molecules and fibrin fibers.
