Post written by Yosuke Minoda, MD, PhD, from the Department of Medicine and Bioregulatory Science, Graduate School of Medical Sciences, Kyushu University, and the Department of Endoscopic Diagnostics and Therapeutics, Kyushu University Hospital, Fukuoka, Japan.

This study presents a new method to differentiate a GI stromal tumor (GIST) from a non-GIST in gastric subepithelial lesions (SELs) by evaluating impedance values, which are electrical resistance values of the lesions.

Most gastric SELs encountered during screening endoscopy are small. Nevertheless, diagnostic accuracy for small lesions is inadequate. We considered that there is room for improvement in diagnostic methods for small SELs.

Evaluation of the impedance value is a new concept in the endoscopic field. This evaluation method for gastric SELs has high diagnostic accuracy and appears to be less affected by lesion size.

In the future, it could be applied to lesions outside the GI tract where EUS-guided fine-needle biopsy is performed.

With the recent development of endoscopic treatment methods, even small SELs can be resected endoscopically.

On the other hand, these lesions are often difficult to diagnose prior to treatment. We believe that it is important to diagnose small lesions before endoscopic treatment in order to reduce unnecessary intervention.

Principles of impedance measurement using conventional probe and EUS-guided FNA/biopsy (EUS-FNA/B) needle probe performed in this study. A, Schemata showing transcellular (left) and paracellular (right) pathways of electric current flow obtained with high-frequency impedance (H-impedance) and low-frequency impedance (L-impedance) measurement, respectively. B, Schema showing H-impedance measurement values of normal mucosa and neoplastic tissues with conventional probe in study 1. C, Schema showing H-impedance measurement with conventional probe in study 2. The H-impedance value of exposed subepithelial lesion was measured after incising the mucosa covering the subepithelial lesion. D, Schema showing H-impedance measurement value of nonexposed subepithelial lesion with EUS-FNA/B needle probe in study 3.

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