腸管三次元CT診断の実際―大腸腫瘍におけるCTCの有用性─存在診断を中心に

Usefulness of CT Colonography in the Diagnosis, Mainly Detection, of Colonic Tumor

要旨　CT colonographyの大腸腫瘍の存在診断における有用性について自験例をもとに検討した．大きさ5mm以上の病変の描出能は良好であるが，表面型腫瘍は隆起型腫瘍に比べて有意に低いため診断精度のさらなる向上が求められる．大腸癌術前検査として，注腸X線検査はCT colonographyで代替可能である．造影CT colonographyによる大腸癌術前シミュレーションは，腹腔鏡下大腸癌手術において，安全かつ迅速に施行するために必要不可欠な術前情報を提供する．大腸癌による内視鏡不通過例に対して閉塞部の口側腸管の検査法として有用性が高い．盲腸まで内視鏡を挿入できない全大腸内視鏡検査不成功例では深部大腸の精査は注腸X線検査に替えてCT colonographyで行ってもよい．腸管外病変のスクリーニングとしても有用性が高い．今後，CT colonographyは大腸癌診断法の有力なmodalityとしてわが国でもニーズが高まることが予想される．

　We reviewed our cases to investigate the usefulness of CTC（CT colonography）in the detection of colonic tumor. Although the detection rate of colonic tumors 5 mm or larger is excellent with CTC, superficial tumors are significantly more difficult to detect with it as compared with protruding tumors. Therefore, further improvement in diagnostic ability is required. Barium enema study can be replaced by CTC as a preoperative examination for colon cancer. Preoperative simulation by contrast-enhanced CTC provides essential information for safe and rapid performance of laparoscopy-assisted surgery for colon cancer. CTC is useful as a preoperative examination method in Japan for oral-side obstruction caused by colon cancer in cases where a colonoscope has failed to pass through the obstruction. In cases where insertion of a colonoscope to the cecum is unsuccessful, CTC can be used in place of barium enema for examination of the whole large bowel. CTC is also useful in screening for extracolonic lesions. In the future, CTC is expected to be widely used in Japan as a diagnostic modality for colon cancer.