MR imaging of hepatic injury in the LEC rat under a high magnetic field (7.05 T)

Visualization of copper-induced hepatitis (CuH) in LEC rats was performed b y using an MRI apparatus equipped with a magnet producing a high magnetic f ield of 7.05 T. When three groups of LEC rats (6-16 [pre-hepatitis], 15-26 [acute hepatitis] and 40-77 [chronic hepatitis] weeks old) were examined by MRI under T-2-weighted imaging conditions which are suitable for the diagn osis of human hepatitis, hypointense MR images of the livers were, as a who le, obtained in all groups, suggesting that these conditions were not adequ ate for imaging of CuH of LEC rats. The shortening of the T-1 and T-2 relax ation times of livers due to an excess amount of paramagnetic irons under t he high magnetic field was responsible for the lowering of MR signal intens ities of the livers, especially those of 15 to 26-week old rats showing acu te hepatitis. However, theoretical calculation of the MR signal intensities using the T1 and T2 relaxation times of the livers indicated that their im aging might be possible under proton density-weighted conditions even with a high magnetic field. Experimental results showed that hepatic injury was visualized as hyperintense regions in the MR image of the liver in the acut e-phase rat.