Contrast-Enhanced Ultrasound Adds Diagnostic Value for Risk Stratification of GISTs

Researchers from a multicenter international study found that contrast‑enhanced harmonic endoscopic ultrasonography (CH‑EUS) improved the diagnosis of leiomyomas and risk stratification of gastrointestinal stromal tumors (GISTs). 

“In this field, where B‑mode EUS and EUS‑TA are not always able to guarantee a definitive and reliable diagnosis and where surgery can involve inevitable risks and sequelae, every incremental diagnostic yield has to be considered crucial,” the study’s authors stated.

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CH‑EUS showed higher sensitivity (66.7% vs 0%) and accuracy (88.9% vs 83.3%) than B‑mode EUS in diagnosing leiomyomas. Diagnostic specificity was not comparable between the 2 methods due to the lack of leiomyoma cases solely diagnosed by B‑mode EUS. 

For the evaluation of GIST malignancy, CH-EUS performed better than B-mode EUS in terms of sensitivity (100% [63.1%‑100%] vs 62.5% [24.5%‑91.5%], P =0.08) and accuracy (86.1% [70.5%‑95.3%] vs 78.9% [62.7%‑90.4%], P =0.76), but similar specificity (82.1% [63.1%‑93.9%] vs 83.3% [65.3%‑94.4%], P =0.48).

In contrast, CH‑EUS did not provide any additional benefit for the differential diagnosis of GIST. B-mode EUS showed higher sensitivity (95.0% [83.1%‑99.4%] vs 85.0% [70.2%‑94.3%], P =.05) and diagnostic accuracy (85.2% [72.9%‑93.4%] vs 77.8% [64.4%‑88.0%], P =.16) when compared with CH‑EUS. Specificity was set at 57.1% ([28.9%‑82.3%], P =1.0) for both methods. However, CH‑EUS showed improved specificity (50.0% [23.0%‑77.0%] vs 7.1% [0.2%‑33.9%] for B-mode EUS, P =.01) when comparisons were established considering GIST, undetermined lesions vs leiomyoma, and other gastric submucosal tumors (SMTs). 

Inter-observer agreement between 7 expert endosonographers improved for the diagnosis of leiomyomas (kappa =0.54 in CH-EUS vs kappa=0.13 in B‑mode EUS) and GISTs (kappa =0.655 in CH-EUS vs kappa=0.447 in B‑mode EUS). A slight improvement was also observed for the prediction of GIST malignancy (kappa =0.317 in CH‑EUS vs kappa=.237 in B‑mode EUS).

These findings were obtained from the retrospective analysis of 54 patients (median age = 64, interquartile range 55‑75, 29 female) diagnosed with GIST (n=40; 8 high-risk), leiomyomas (n=9), or rare SMTs (n=5).

Reference

Lefort C, Gupta V, Lisotti A, et al. Diagnosis of gastric submucosal tumors and estimation of malignant risk of GIST by endoscopic ultrasound. Comparison between B mode and contrast-harmonic mode (with videos). Dig Liver Dis. Published online July 13, 2021. doi:10.1016/j.dld.2021.06.013