カプセル内視鏡

Colon Capsule Endoscopy

要旨●大腸カプセル内視鏡は2006年に開発され，現在，第2世代内視鏡が汎用されている．従来の小腸用カプセル内視鏡と異なり，両側2か所にカメラが内蔵され，1秒間に4枚の撮像が可能である．大腸カプセルの場合，腸管洗浄度と撮影時間内に盲腸〜直腸まで全大腸観察が可能かどうか問題となる．内視鏡治療が必要である10mm以上の大腸ポリープの検出率における感度は88％，特異度89％と良好な成績が報告されている．また，本邦3施設で行われた多施設共同研究による大腸ポリープ検出の特異度は94％であった．今後，大腸がん検診における役割として期待されるが，運用コストや前処置，排出率などの問題点が挙げられ，今後の検討が必要である．

　CCE（colon capsule endoscopy）has been used since 2006. CCE2, which is a new-generation endoscopy procedure, was developed in 2009. In Japan, the examination of CCE2 has been available for public insurance only indication to insufficient ordinary colonoscopy for two years. CCE2 allows for an excellent detection rate（sensitivity＝88% ; specificity＝89%）of polyps of diameter>10mm.

　The CCE2 technique is very simple compared with colonoscopy. Patients only have to swallow a capsule and there is no discomfort during the examination for colon cancer. However, this technique has several limitations. Firstly, it is necessary to clearing inside the colon before the examination, similar to colonoscopy. Further, patients have to drink polyethylene glycol solution as a booster for natural capsule excretion within the battery life of the capsule（approximately 10h）. This examination technique itself is expensive. Secondly, well-experienced endoscopists should examine the existence of polyps using“RAPID 8^®”software to decrease the miss rate for detection. Four pictures per second are automatically captured from both sides of the capsule. In our study, only one picture showed a small polyp, which was pointed out by a well-trained endoscopist.

　In our country, the mortality rate due to colon cancer is increasing. Therefore, the use of CCE2, instead of colonoscopy, should be increased to examine colon cancer. This should solve the above-mentioned problems.