Endoscopic Ultrasound Advanced Techniques for Diagnosis of Gastrointestinal Stromal Tumours

Abstract

Gastrointestinal Stromal Tumors (GISTs) are subepithelial lesions (SELs) that commonly develop in the gastrointestinal tract. GISTs, unlike other SELs, can exhibit malignant behavior, so differential diagnosis is critical to the decision-making process. Endoscopic ultrasound (EUS) is considered the most accurate imaging method for diagnosing and differentiating SELs in the gastrointestinal tract by assessing the lesions precisely and evaluating their malignant risk. Due to their overlapping imaging characteristics, endosonographers may have difficulty distinguishing GISTs from other SELs using conventional EUS alone, and the collection of tissue samples from these lesions may be technically challenging. Even though it appears to be less effective in the case of smaller lesions, histology is now the gold standard for achieving a final diagnosis and avoiding unnecessary and invasive treatment for benign SELs. The use of enhanced EUS modalities and elastography has improved the diagnostic ability of EUS. Furthermore, recent advancements in artificial intelligence systems that use EUS images have allowed them to distinguish GISTs from other SELs, thereby improving their diagnostic accuracy.

Keywords: artificial intelligence; fine-needle aspiration; fine-needle biopsy; subepithelial lesions.

Figure 1

Endoscopic ultrasound (EUS) images of malignant gastrointestinal stromal tumors (GISTs): (a) A large submucosal lesion originating from the fourth layer of the gastric wall. Echopattern is inhomogeneous with irregular borders. (b) Another large subepithelial gastric mass with echoic foci, calcifications, and irregular profiles. (c) Cystic spaces are visible in EUS images.

Figure 2

Endoscopic ultrasound (EUS) images of gastrointestinal stromal tumor (GIST) of the stomach: (a) The originating layer is visible when the ultrasound transducer is placed at the peripheral portion of the lesion. (b) Contrast-enhanced harmonic EUS (CH-EUS) demonstrated a hypervascular pattern. Moreover, CH-EUS allowed for the identification of irregular large vessels and avascular areas inside the tumor. (c) EUS-guided fine-needle biopsy was performed using a 22-gauge end-cutting needle while trying to avoid avascular areas previously defined using CH-EUS. Histology confirmed a GIST with a high replicative index.

Figure 3

Endoscopic ultrasound elastography (EUS-E) images of gastrointestinal stromal tumor (GIST) of the stomach. The lesion shows a blue color, indicative of a hard tissue, compared to the red color of the gastric wall.