切開・剥離法（ESD）時代の胃癌の術前診断―直接型平面検出器（flat panel detector）搭載Cアーム型X線透視装置―その有用性と問題点

The Usefulness of and Problems with the Diagnosis of Early Gastric Carcinoma by Means of the C-arm-type Fluoroscopic Apparatus with an On-board Direct Flat Panel Detector

要旨　胃癌の術前精密X線検査における平面検出器（FPD）の有用性について，当院でESDを施行した早期胃癌症例を対象に，従来のフィルム-増感紙による撮影系（CFSS）あるいはFPDで撮影された画像を用い，見直し診断による浸潤範囲の描出能とその画質を比較検討した．二重造影像においては病理組織再構築像と対比した浸潤範囲の描出能に両者間で差はなかった（p＞0.05）．しかし，①病変の輪郭や病巣内の微細な陰影，②非癌部の胃小区像の輪郭は画像処理を加えたFPD画像のほうが鮮鋭で読影しやすい画質が得られる頻度が高かった（p＝0.044，p＝0.047）．またCアームを用いた斜入撮影法を使用することで，病変を正面像としてとらえることが可能であった．ESDの適応拡大により多彩な病変をより厳密に診断する必要性があり，FPDは今後浸潤範囲診断に寄与するものと考えられる．

　In making diagnoses for reconsideration and image quality in early gastric carcinoma patients who received ESD in our hospital, an investigation was made concerning the usefulness of a flat panel detector (FPD) in preoperative precision X-ray examination of gastric carcinoma. X-ray images taken with a conventional radiographic system using film and intensifying screen (CFSS) and those taken with FPD were compared regarding the ability of the CFSS and FPD to visualize the infiltration range. As a result of comparison of double contrast radiograms and the findings of histopathological reconstruction (p＞0.05), no difference was found between CFSS and FPD in the ability to visualize the infiltration range. However, FPD images compared with CFSS images dealt with by image processing showed sharper image quality with easier image-reading with a high frequency with regard the following features. 1 )The contours of lesions and minute shadows of the inside of focus (p＝0.044) ; and 2 )the contours of images of the gastric area in the non-cancerous region (p＝0.047). The employment of an oblique radiographic technique using the apparatus of C-arm type enabled the determination of a lesion as an en face view. Due to increasing indications for ESD, some lesions need to be diagnosed more rigidly. It is considered that, in the future, FPD will contribute to the diagnosis of infiltration range.