小動物用磁気共鳴画像法（MRI）を用いたin vivo非侵襲的毒性評価への応用

抄録

Magnetic resonance imaging (MRI) with a high-frequency magnetic field is a powerful, non-invasive tool to detect and monitor addicted human brain. MRI can also be applied to small animals in non-clinical toxicological studies. This approach enabled us to evaluate time-course changes in pathological and anatomical findings and their reversibility in the same animals. It can also detect the presence and location of induced lesions and/or deposition of abnormal proteins, assisting with the selection of sections for subsequent histopathological examination. In fact, MRI has been used to detect amyloid plaques by using amyloid-beta precursor protein transgenic mice; this demonstrates the usefulness of MRI as a complementary tool for conventional histopathology. Thus, MRI widens the range of potential non-invasive imaging modalities, expanding the scope of non-clinical studies. However, the widespread use of MRI systems in non-clinical studies are hindered by obstacles. With progress in design technology, a novel compact MRI system with a high-field permanent magnet (~1.0 tesla) has been developed. The new system is portable and self-shielded; it can be placed in most institutions. Compared with conventional MRI systems, the new system has been utilized in several non-clinical studies, including those on hepato- and neuro-toxicities. However, no evidence has been found on the evaluation of addiction and drug abuse, and reproductive toxicity in vivo by MRI. I discuss the usefulness of a ready-to-use, novel compact MRI platform in evaluating their toxicity.