Objective: This study aimed to evaluate the imaging characteristics of gastric submucosal mesenchymal tumors on contrast-enhanced computed tomography (CT).

Methods: A retrospective case series was conducted on 144 patients diagnosed with gastric submucosal mesenchymal tumors, confirmed by histopathology and immunohistochemistry. All patients underwent contrast-enhanced CT prior to treatment for lesion characterization. Data were collected at the University Medical Center Ho Chi Minh City between January 2016 and November 2023. Patients were included if they fulfilled the predefined inclusion and exclusion criteria. Convenience sampling was used for case selection.

Results: The sex ratio between men and women was similar for both general mesenchymal tumors and some common mesenchymal tumor subtypes. The average age was 60.4±13.5, with the most common age group being over 60 years old (-58.3%). Submucosal mesenchymal tumors (SMTs) are most common in the stomach body (-66.7%), followed by the cardia, the fundus and finally the pylorus. Most SMTs exhibited exophytic growth (-42.7%). In this study, 100% of gastric SMTs presented as well-circumscribed mass. Gastrointestinal stromal tumors (GISTs) have the highest proportion of tumors with necrosis, leiomyomas schwannomas and other tumor groups had no cases of necrosis. GISTs also showed a higher rate of heterogeneous enhancement (63.2%), than homogeneous enhancement, whereas other tumors have no cases of heterogeneously enhancing tumors. GISTs and schwannomas both demonstrated a moderate degree of enhancement as the highest rate among the 3 degrees (81.2% and 100%, respectively). However, leiomyoma showed a nearly equal ratio between poor and moderately enhancing tumors with no cases of high enhancement. Among the characteristics of the tumors in this study, the tumor's location, growth pattern, necrosis, types and degree of enhancement correlated with the type of tumor.

Conclusion: The SMTs are typically well-circumscribed masses. The common SMTs are GISTs, leiomyomas, and schwannomas. The sex ratio between men and women is similar in both SMTs in general and among common SMT subtypes. The age group most commonly affected by SMTs is over 60 years old. Among the characteristics of SMTs on CT scans, necrosis and enhancement properties are the most significant.

Keywords: computed tomography; gastric; submucosal mesenchymal tumors; Gastrointestinal stromal tumor