4) 体外式超音波検査

Sonographic Diagnosis of Small Bowel Diseases

要旨　体外式超音波を用いた小腸疾患の診断に関して概略を述べた．超音波により肥厚した腸管壁を検出し，その部位，分布，さらには層構造や壁外の変化などを評価することで多くの疾患においてその検出，診断，治療効果判定に有用である．加えて近年開発された造影超音波法により消化管の微細循環の描出も可能となった．ただしこれら体外式超音波検査の特性を生かすためには機器性能，検者の技量，さらには被検者の観察条件が一定のレベルを満たしていることも必要であろう．非侵襲的で簡便な体外式超音波検査は，今後小腸疾患におけるスクリーニングを含めた第一選択的検査法となることが期待される．

　An outline of the sonographic diagnosis of small bowel diseases is described. The neoplastic diseases are usually demonstrated as thickening of the focal wall, often with the loss of wall stratification when the tumor invasion is transmural. There are a variety of sonographic features in inflammatory disorders, therefore the image obtained has to be analyzed from many aspects such as wall stratification, site and distribution, and so forth before making diagnoses. In addition, contrast ultrasound using intravenous injection of contrast agents (Levovist^TM, Sonazoid^TM) provides clear images of minute blood flow in the small bowel wall, which is extremely helpful in diagnosing ischemic and hemorrhagic disorders. Although ultrasound examination is known to be operator-dependent, it can be a very effective non-invasive modality for the detection and diagnosis of small bowel diseases.