Diagnostic accuracy and influencing factors of microprobe endoscopic ultrasound for gastrointestinal subepithelial lesions: a multicenter retrospective study

BACKGROUND: Microprobe endoscopic ultrasonography (MEUS) has been widely adopted in primary hospitals due to its affordability, ease of use, and simple operation. This study aims to assess the diagnostic accuracy of MEUS in classifying gastrointestinal subepithelial lesions (SELs), identify key influencing factors, and explore strategies for improvement. METHODS: A retrospective analysis was conducted on 855 patients with histopathologically confirmed SELs across five Chinese hospitals. The overall diagnostic accuracy (DA) of MEUS for SELs was calculated. Independent factors were identified using univariate and multivariate logistic regression analyses, followed by subgroup analysis. RESULTS: Among 896 lesions across 31 SEL types, the overall DA was 70.31%. Non-gastrointestinal stromal tumor (GIST) and non-neuroendocrine tumor (NET) lesions, along with gastric location, were identified as risk factors for lower diagnostic accuracy, while rectal location was protective. In the subgroup analysis, gastric leiomyomas had a DA of 9.85% with 99.17% incorrectly classified as GISTs, compared to 94.78% for gastric GISTs, 84.24% for gastric NETs, and 31.2% for other lesions. Lesions with inhomogeneous echoes were 20 times more likely than those with homogeneous echoes to be diagnosed as gastric GISTs compared to gastric leiomyoma. Additionally, the inhomogeneous echo patterns of gastric GISTs were characterized by hyperechogenic spots in 93.67%, marginal halos in 18.99%, and cystic changes in 13.92%. CONCLUSION: MEUS is effective for classifying SELs, although differentiating between gastric GISTs and leiomyomas remains challenging. Improved assessment of echo heterogeneity and expanded knowledge of atypical and rare cases may enhance diagnostic accuracy.