Simple and rapid Determination of bone mineral content in small experimental animals

本研究の目的は, 小動物の骨の骨塩量を, 組織を破壊することなく, 簡単に測定する方法を開発することであった。測定は, 骨試料と同時に撮影したハイドロキシアパタイト(HA)で作製した濃度基準尺の軟X線画像から得られた黒化度とHA密度(対数)の間に成り立つ直線関係にもとづき, 測定領域の軟X線画像の黒化度を単位面積当たりのHA量に換算することによって行った。ラットの大腿骨を測定して得られた骨塩量(BMC : Bone Mineral Content)は, 骨を灰化して得られた灰分重量と高い相関を示した。また, 同一試料の繰り返し測定によって得られたBMCとBMD(Bone Mineral Density)の変異係数は, それぞれ1.6,および1.7%と低い値を示した。以上の結果から, 本研究によって開発された方法は, 小動物の骨塩量を測定するための有用かつ信頼性のある方法と考えられた。The objective of the present study was to develop a nondestructive simple method for the determination of bone mineral content (BMO in small experimental animals. Determination was performed by analyzing the grey levels of soft X-ray microradiographic images of bone specimens with an image analyzer. All of the images analyzed were fed into a video camera at magnifications of 10-20 times. Since a linear correlationship was found between the grey levels (0-255 steps) and the logarithm of hydroxyapatite (HA) content/mm^2 by analyzing the images of standard stepwedges made of synthetic hydroxyapatite plates with different thicknesses, we could determine the BMC in the desired bone area using the measured grey level of the area. The results of measurement of rat femurs showed that there was excellent agreement between the measured BMC by the present method and the ash weight determined chemically. Precision error for BMC and BMD (Bone Mineral Density) was 1.6 and 1.7%, respectively. We concluded that the present method is reliable and useful for measuring the BMC of bone in small experimental animals