DIAGNOSIS OF GASTROINTESTINAL SUBEPITHELIAL LESIONS USING A NOVEL ENDOSCOPIC ULTRASONOGRAPHY IMAGING TECHNIQUE

BACKGROUND: Gastrointestinal stromal tumors (GIST) are the most common malignant subepithelial lesions (SELs) in the GI tract. Due to GIST’s notable vascularity and deep location, endoscopic ultrasound (EUS) is the first-line diagnostic approach. Color-doppler EUS, power-doppler EUS, and e-FLOW EUS, are useful for real-time vascularity detection; however, they are not effective for fine/slow flow vessel detection. Therefore, contrast enhanced EUS (CE-EUS) is proposed as a first-line approach. To avoid contrast-related adverse events, a novel diagnostic method, detective flow imaging endoscopic ultrasonography (DFI-EUS) has emerged.
AIM: To evaluate the utility of DFI-EUS in the diagnosis and differentiation of gastrointestinal SELs (GIST and leiomyomas) in comparison to CE-EUS.
METHODS: A single-center, prospective, diagnostic study was conducted between December/2022 and October/2023. The study protocol was approved by the IRB and was conducted in accordance with the Declaration of Helsinki. Patients ≥18 years old with suspected gastrointestinal SELs were enrolled for EUS vascularity assessment. Patients with contraindication for contrast agent administration, any clinical condition rendering EUS-DFI or CE-EUS unfeasible were excluded. SELs’ assessment was performed by two expert endosonographers (blinded to patient’s clinical information) using DFI-EUS, followed by a CE-EUS examination (using Sulphur hexafluoride contrast agent) for diagnostic confirmation. The identification rate along with diagnostic accuracy of DFI-EUS and CE-EUS based on histopathological confirmation was the primary endpoint. The type of vascularization (microvascular/microvascular) along with endosonographic appearance (hyper/hypovascular) were also recorded.
RESULTS: A total of 24 patients were included; 54.2% females. The examined lesions were 70.8% GIST and 29.1% leiomyomas. Predominantly, lesions were found in the stomach (91.7%) and within the muscularis propria layer (91.7%). All GIST were hypoechoic and mainly heterogeneous, larger than leiomyoma (>2 cm; p < 0.001). Tortuous vessels were significantly identified in GIST (p 0.045). Both CE-EUS (94.1%; p 0.003) and DFI-EUS (94.1%; p< 0.001) successfully detected GIST (Table 1). The overall sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of DFI-EUS was comparable to CE-EUS with rates of 94.12% vs 94.12, 100% vs 99.64%, 100% vs 99.85% and 87.5% vs 99.64%, respectively (Table 2). A strong inter-rater agreement between CE-EUS vs DFI-EUS was detected with a kappa of 0.903 (p<.001).
CONCLUSION: DFI-EUS proves to be a reliable diagnostic tool, exhibiting high diagnostic accuracy, comparable to that of CE-EUS in the differentiation of GIST and SELs in the GI tract. Larger multicenter studies are necessary to position this alternative for SELs' differentiation in clinical practice.