Usefullness of cone beam CT '3D Accuitomo F17^[○!R]' for the visualization of temporomandibular joint structures

3D Accuitomo F17は頭頸部領域を対象としたコーンビームCT装置である.5種類の撮影領域(field of view:FOV)(40×40mm,60×60mm,80×80mm,100×100mm,170×100mm)が搭載され,5つのボクセルサイズ(80μm,125μm,160μm,200μm,250μm)で画像の解像度を変えることができる「ズーム再構成」の機能を持つ.本研究の目的は,本装置の顎関節構造の描出能を検討することである.最初に1体のヒト乾燥頭蓋骨を,全てのFOVで撮影,そのうち最も大きいFOV(170×120mm)で得られた画像データをもとに全てのボクセルサイズでズーム再構成を行った.次に変形性顎関節症を疑った3名の患者に対し同様の検討を行った.その結果,FOVが小さいほど画質は良好であり,大きなFOVで撮影しても小さなピクセルサイズで再構成することで明瞭な画像が得られた.以上より本装置においては,大きなFOVで両側の顎関節を撮影することで,両側下顎頭の滑走運動の協調性を評価でき,さらに小さなボクセルサイズで再構成することで高解像度の画像が得られることが明らかになった.今回の検討により3D Accuitomo F17は顎関節構造の描出において有用であることが示唆された.
3D Accuitomo F17 is cone beam computed tomography (CT) unit for examination of maxillofacial area. It adopts five kinds of field of view (FOV) (40×40mm, 60×60mm, 80×80mm, 100×100mm, 170×120mm) and developed "zoom reconstruction" function that provides five kinds of voxel size (80μm, 125μm, 160μm, 200μm, 250μm) to change the image resolution. The purpose of this study is to evaluate the usefulness of this unit for visualization of temporomandibular joint (TMJ) structures. Firstly, we scanned one dry human skull by all of FOV, and underwent zoom reconstruction by all of voxel size using image data were obtained in largest FOV (170×120mm). Secondary, we performed similar examination to three patients were suspected osteoarthrosis of TMJ. As the results, the image quality of TMJ structures were good so that FOV was small, and clear images were obtained when we reconstructed them at small pixel size even if we we scanned it in large FOV. Therefore, it seems that we can evaluate of coordination of in the condylar movement by scanning bilateral movement in large FOV, and we can obtain clear images at small voxel size. This results of this study suggest that 3D Accuitomo F17 is very useful cone beam unit for the visualization of TMJ region.