新しい画像検査・診断法と今後の展開―CT三次元画像による消化管診断

Diagnostic Application and Efficacy of Three-dimensional Images for GI Diseases using Multislice Helical CT Scanners

要旨　マルチスライスCT（MSCT）により，高速でより詳細な画像が得られるようになった．そこで胃癌，胃粘膜下腫瘍，大腸癌等の消化管病変に対してvirtual endoscopy（VE）がどの程度診断に寄与できるか検討した．胃癌ではVE所見を3群に分類し深達度診断を試みると，そのT stage深達度正診率はMSCTで90.9％であった．VE所見と内視鏡診断，X線二重造影像を比較検討すると，これらはお互いに補い合うmodalityと考えられた．また，小腸でも病理所見を反映するVE所見を得た症例を経験した．大腸ではMSCTにより全大腸が短時間で正確に描出された．MSCTによるVEでは従来に比しより精細で高い解像度を持ち，さらなる発展と応用が期待された．

　Multislice helical CT scanners (MSCT) provide a precise image of the GI tract within an extremely short inspection time. With this in mind, we attempted to utilize virtual endoscopy (VE) for the assessment of GI diseases such as gastric cancer, GIST, and colon cancer.

　On VE images, tumor invasiveness of gastric cancer was conventionally classified as intramural type (type 1), extramurally extended type with smooth outer surface (type 2) and extramurally extended type with irregular outer surface (type 3). When these three types were histologically analyzed, overall accuracy for VE using MSCT was 90.9 ％. Comparison with optical endoscopy and double contrast barium examination revealed that VE is a new modality that can be used to help each of the other examinations. For colon disease, VE was able to reveal total colon appearance using MSCT.

　In conclusion, VE using MSCT revealed a precise image with high resolution of GI diseases. We expect that further development and utilization of VE will provide a new modality to estimate GI diseases.

　1) Department of Internal Medicine Hokkaido Gastroenterology Hospital, Sapporo, Japan

　2) Department of Radiology Otaru Ekisaikai Hospital, Otaru, Japan

　3) Fourth Department of Internal Medicine, Sapporo Medical University, Sapporo, Japan