| Research Abstract |
We tried to make a high-resolution intra-oral coil for the examination of dental-pulp diseases and periodontal diseases with MRI. Before making the new coil, we had two problems of setting angulations of the intra-oral coil and metallic artifact of dental material.
About setting angulations, the coil gain will be decease by setting coil vertically toward the magnetic direction. We made experimental study to measure the coil-signal gain during the changing angulations of coil. When the coil set in 60 degree toward magnetic direction, we recognized that the signal gain became strongest.
About the metallic artifacts, we made an experimental study with dental crowns. We confirmed that the influence by the metallic artifact would be extended widely. Before taking MRI, we should remove the metallic materials.
We made some type of coils and measured the signal gain. From them, we selected two types of coils that were the flat type and the saddle type for the strength of signal gain and volume of the high signal area. We developed a phased array coil that was made with the intra-oral coil and the extra-oral surface coil. With this phased array coil, we could get high signal gain that was 16 times of usual extra-oral coil.
We took MRI of volunteer' s oral cavity with two types of the phased array coils that were combined the surface coil with flat-type coil or saddle-type coil. With the phased array coil made with the surface coil and saddle-type coil, we could detect the structure of the gingival and the alveolar bone.
We took MRI of periodontal disease patient's oral cavity with the phased array coils that were combined the surface coil with saddle-type coil. In the images, we could detect the infection in the gingival that was found in the pathological examination.
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