Estimation of malignant potential of GI stromal tumors by contrast-enhanced harmonic EUS

Background: Contrast-enhanced harmonic EUS (CEH-EUS) is a new sonographic technique that uses US contrast agents and depicts intratumoral vessels in real time. Objective: To evaluate whether assessment of tumor vascularity by CEH-EUS can predict the preoperative malignancy risk of GI stromal tumors (GISTs). Design: Prospective study to observe GIST vascularity.. Setting: Kinki University School of Medicine. Patients: Between June 2007 and September 2009, 76 consecutive patients suspected of having subepithelial lesions underwent CEH-EUS. Intervention: CEH-EUS was performed by using a prototype echoendoscope in an extended pure harmonic detection mode. Main Outcome Measurements: Resected GIST specimens in 29 patients who underwent surgical resection were divided into high-grade (n = 16) and low-grade (n = 13) malignancy groups based on mitotic activity. The abilities of EUS-guided FNA and CEH-EUS to diagnose the malignant potential were compared. The sensitivities with which contrast-enhanced multidetector CT, power-Doppler EUS, and CEH-EUS detected intratumoral vessels in high-grade malignancy GISTs also were compared. Results: CEH-EUS identified irregular vessels and thereby predicted GIST malignancies with a sensitivity, specificity, and accuracy of 100%, 63%, and 83%, respectively. Diagnosis of high-grade malignancy GISTs by EUS-guided FNA had a sensitivity, specificity, and accuracy of 63%, 92%, and 81%, respectively. Contrast-enhanced multidetector CT, power-Doppler EUS, and CEH-EUS detected intratumoral vessels in high-grade malignancy GISTs with sensitivities of 31%, 63%, and 100%, respectively (P < .05). Limitations: A single center was involved in this study. Conclusions: CEH-EUS successfully visualized intratumoral vessels and may play an important role in predicting the malignancy risk of GISTs. (Gastrointest Endosc 2011;73:227-37.)