Real-time visualization and quantitation of canine gastric mucosal blood flow by contrast-enhanced ultrasonography

Abstract

Objective. Contrast-enhanced ultrasonography has become a method of choice for evaluating gastric blood flow, but intermittent scanning techniques can sometimes distort the results. Low-mechanical index imaging using Definity as the injected contrast material has been advocated for real-time evaluation of microperfusion in other organs. We investigated the reliability of low-mechanical index imaging using Definity in the evaluation of gastric mucosal blood flow. Material and methods. Under general anesthesia, 10 beagle dogs weighing 9–10 kg underwent real-time harmonic imaging under low acoustic power (mechanical index = 0.2) after intravenous contrast injection using Definity (60 mg/kg). Laser Doppler flow measurement was also performed to evaluate gastric mucosal blood flow. After administration of a diclofenac sodium suppository, low-mechanical index imaging and laser Doppler flowmetry were repeated. Results. Real-time visualization of gastric mucosal blood flow was successful in all dogs undergoing low-mechanical index imaging with Definity. Quantitative assessment of gastric mucosal blood flow was successful in eight dogs. After diclofenac sodium administration, gastric mucosal blood flow measured by both laser Doppler flowmetry and contrast ultrasonography decreased in seven of eight dogs; in the other dog, gastric mucosal blood flow increased slightly. A strong positive correlation was evident between blood flow measured by laser Doppler flowmetry and low-mechanical index imaging (r=0.777, p<0.005). Conclusions. Low-mechanical index imaging with Definity is a non-invasive way to evaluate gastric mucosal blood flow in real-time, high-resolutional images, which may have additional important gastrointestinal tract applications.