Abstract
The development of the second generation ultrasound contrast Sonazoid which produces a second harmonic component with low acoustic power has enabled vascular assessment in the field of EUS. With the use of the echoendoscope provided by OLYMPUS-ALOKA, contrast-enhanced EUS is performed in the eFLOW mode which depicts fine vessels without Doppler-related artifacts or in the ExPHD mode which enables perfusion imaging by selective depiction of signals from microbubbles. The echoendoscope should be manipulated in order to position it as close to the target lesion as possible. Contrast-enhanced harmonic EUS depicts fine vessels in the lesions 10-20 seconds after the infusion, and subsequently parenchymal perfusion with strong contrast with the pancreatic duct, biliary system and surrounding tissue. In the pancreato-biliary region, contrast-enhanced harmonic EUS is useful for detection and characterization of small lesions, particularly discrimination between benign and malignant lesions. In GISTs, specific tumor vessels can be observed with contrast-enhanced harmonic EUS. It is also useful for differentiation between benign and malignant lymphadenopathy. Visualization of the microcirculation and perfusion imaging in EUS which has high spatial resolution may further improve imaging of the digestive organs.
