難治性潰瘍性大腸炎における体外式超音波所見の有用性

Clinical Usefulness of Transabdominal Ultrasound for Patients with Refractory Ulcerative Colitis

要旨　潰瘍性大腸炎における体外式超音波法（ultrasonography法；US法）の活動性評価は，従来のBモード画像による壁肥厚や層構造の観察に，ドプラ法による血流シグナルの解析を加えることで，より正確な診断が可能になった．US法は，内視鏡検査と異なり前処置が不要で簡便かつ非侵襲的であることから，積極的に臨床応用すべきmodalityである．近年の超音波造影剤やflash echo imaging法の開発により，消化管壁内の微細血流評価が可能となり，従来の検査法では診断できない詳細な病態が把握でき，難治例の予測診断などに応用可能であり，さらなる発展が期待される．

　We report the diagnostic usefulness of transabdominal ultrasound in patients with refractory ulcerative colitis (UC). Transabdominal ultrasound is a noninvasive, inexpensive, and repeatable method that does not require special preparation. It can be used in clinical practice, not as a substitute for biochemical, radiologic or endoscopic studies, but as a complementary protocol in the follow-up of patients with refractory UC. Previous studies have shown that a combination of B-mode and Doppler ultrasonography provides an additional noninvasive procedure for precise determination of disease activity in patients with UC. Furthermore, development of ultrasound contrast agents and a flash echo imaging method that uses intermittent pulse transmission under a low mechanical index allows us to evaluate blood flow in small-diameter vessels and at a low flow velocity, which is difficult to achieve with conventional Doppler ultrasonography. These new technologies provide for non-invasive determination of a disease activity index in patients with UC. Adding these ultrasonography methods to conventional diagnostic methods, including endoscopy and radiologic studies, may be useful in determining appropriate treatment strategies and in understanding patients' pathophysiologic conditions.