Estimation of malignant potential of GI stromal tumors by contrast-enhanced harmonic EUS (with videos)

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.