title: Digital image analysis of endoscopic ultrasonography is helpful in diagnosing gastric mesenchymal tumors.
abstract: BACKGROUND
  Endoscopic ultrasonography (EUS) is a valuable imaging tool for evaluating subepithelial lesions in the stomach. However, there are few studies on differentiation between gastrointestinal stromal tumors (GISTs) and benign mesenchymal tumors, such as leiomyoma or schwannoma, with the use of EUS. In addition, there are limitations in the analysis of the characteristic features of such tumors due to poor interobserver agreement as a result of subjective interpretation of EUS images. Therefore, the aim of this study was to evaluate the role of digital image analysis in distinguishing the features of GISTs from those of benign mesenchymal tumors on EUS.
  
  
  METHODS
  We enrolled 65 patients with histopathologically proven gastric GIST, leiomyoma or schwannoma on surgically resected specimens who underwent EUS examination at our endoscopic unit from January 2007 to September 2010. After standardization of the EUS images, brightness values including the mean (Tmean), indicative of echogenicity, and the standard deviation (TSD), indicative of heterogeneity, in the tumors were analyzed.
  
  
  RESULTS
  The Tmean and TSD were significantly higher in GIST than in leiomyoma and schwannoma (p < 0.001). However, there was no significant difference in the Tmean or TSD between benign and malignant GISTs. The sensitivity and specificity were almost optimized for differentiating GIST from leiomyoma or schwannoma when the critical values of Tmean and TSD were 65 and 75, respectively. The presence of at least 1 of these 2 findings in a given tumor resulted in a sensitivity of 94%, specificity of 80%, positive predictive value of 94%, negative predictive value of 80%, and accuracy of 90.8% for predicting GIST.
  
  
  CONCLUSIONS
  Digital image analysis provides objective information on EUS images; thus, it can be useful in diagnosing gastric mesenchymal tumors.
authors.affiliation: Department of Internal Medicine, Pusan National University School of Medicine and Biomedical Research Institute, Pusan National University Hospital, Busan, Korea. doc0224@pusan.ac.kr.
authors.forename: Gwang Ha
authors.initials: GH
authors.lastname: Kim
authors.forename: Kwang Baek
authors.initials: KB
authors.lastname: Kim
authors.forename: Seung Hyun
authors.initials: SH
authors.lastname: Lee
authors.forename: Hye Kyung
authors.initials: HK
authors.lastname: Jeon
authors.forename: Do Youn
authors.initials: DY
authors.lastname: Park
authors.forename: Tae Yong
authors.initials: TY
authors.lastname: Jeon
authors.forename: Dae Hwan
authors.initials: DH
authors.lastname: Kim
authors.forename: Geun Am
authors.initials: GA
authors.lastname: Song
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003937:Diagnosis, Differential; D019160:Endosonography; D005260:Female; D046152:Gastrointestinal Stromal Tumors / Q000000981:diagnostic imaging*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007889:Leiomyoma / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D009442:Neurilemmoma / Q000000981:diagnostic imaging*; D011237:Predictive Value of Tests; D013274:Stomach Neoplasms / Q000000981:diagnostic imaging*