Dynamic imaging of GISTs by contrast-enhanced harmonic EUS

Introduction: Contrast-enhanced harmonic EUS (CEH-EUS) is a new sonographic technique that employs ultrasound contrast agents and depicts microvessels in real-time.

Aims: To evaluate whether vascularity evaluate by CEH-EUS is related to the preoperative malignancy risk of gastrointestinal stromal tumors (GISTs).

Patients and Methods: Between June, 2007 and September, 2009, 76 consecutive patients suspected of having a subepithelial lesion underwent CEH-EUS. CEH-EUS was performed using a prototype echoendoscope in extended pure harmonic detection mode. Resected GIST specimens in 29 patients who underwent surgical resection were divided into high- (n=16) and low-grade (n=13) malignancy groups based on mitotic activity. The abilities of EUS-FNA and CEH-EUS to diagnose the malignant potential were compared. The sensitivities with which contrast-enhanced multidetector computed tomography (CE-CT), power-Doppler EUS (PD-EUS) and CEH-EUS detected intratumoral vessels in high-grade malignancy GISTs were also 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 malignancies by EUS-FNA had a sensitivity, specificity, and accuracy of 63%, 92%, and 81%, respectively. CE-CT, PD-EUS, and CEH-EUS detected intramural vessels in high-grade malignancy GISTs with sensitivities of 31%, 63% and 100%, respectively. (P<0.05).

Conclusions: CEH-EUS successfully visualized microvessels and may play an important role in predicting the malignancy risk of GISTs.