造影ハーモニックEUSによる消化管粘膜下腫瘍の診断

Contrast-enhanced Harmonic EUS for Differential Diagnosis of Submucosal Tumors

要旨●EUSは上部消化管粘膜下腫瘍（SMT）の診断に用いられているが，上部消化管SMTの良悪性鑑別には限界がある．本稿では，造影ハーモニックEUSによる上部消化管粘膜下腫瘍の診断に関する前向き研究1報と後ろ向き研究6報の合計7報の研究をもとに上部消化管SMTの鑑別診断について調べた．造影ハーモニックEUSによるGISTとそれ以外の上部消化管SMTの鑑別診断に関する3つの報告では，hyper-enhancementがGISTの造影ハーモニックEUS所見であり，診断能は感度84.5〜100%，特異度73.3〜100%であった．一方，low-grade malignancy GISTとhigh-grade malignancy GISTの鑑別診断に関する4つの報告では，造影ハーモニックEUSによるhigh-grade malignancy GISTの診断能は感度53.8〜100%，特異度63〜100%であった．またhigh-grade malignancy GISTでは造影ハーモニックEUSにおいてirregular vesselsが高率に認められた．hyper-enhancementか否かおよびirregular vesselsの有無を確認することで上部消化管SMTの鑑別診断が可能であることが示唆された．

　EUS（endoscopic ultrasonography）is a diagnostic method with a high sensitivity for detecting subepithelial tumors ; however, it is generally difficult to distinguish between benign and malignant disease using conventional EUS. One prospective study and six retrospective studies have reported the usefulness of CH-EUS（contrast-enhanced harmonic EUS）for the characterization of subepithelial lesions in the upper digestive tract. Three studies have investigated the use of CH-EUS for distinguishing between GISTs and the subepithelial lesions in the upper digestive tract. These reports showed that hyper-enhancement was a sign of GIST, sensitivity ranged from 84.5% to 100%, and specificity ranged from 73.3% to 100% for the diagnosis of GISTs. Four studies have reported on CH-EUS for distinguishing between low-grade malignancy and high-grade malignancy GISTs. These reports showed that the sensitivity ranged from 53.8% to 100%, and specificity ranged from 63% to 100% for the diagnosis of high-grade malignancy GISTs. Among these, three reports showed that irregular（or intratumoral）vessels were a sign of high-grade malignancy GISTs. These studies that used CH-EUS for the characterization of subepithelial lesions in the upper digestive tract enrolled a small number of patients ; therefore, further studies are warranted.