DISCRIMINATION OF INTRAVASCULAR LUMEN AND DISSECTIONS IN SINGLE INTRAVASCULAR ULTRASOUND IMAGES USING SUBTRACTION, CONVENTIONAL AVERAGING AND SALINE FLUSH

With current 30-MHz intravascular ultrasound systems, flowing blood ma y cause considerable backscatter which in real-time images is characte rized by dynamic speckle. However, in a single intravascular ultrasoun d image (still-frame) the discrimination between arterial lumen and wa ll may be difficult due to the frozen intraluminal speckle, particular ly in the presence of dissections. We compared subtraction, averaging and saline flush as methods to improve the discrimination between arte rial lumen and wail in a single image. The real-time images served as gold standard. In 22 patients who underwent peripheral balloon angiopl asty, ultrasound images obtained from 84 sites were examined. The sens itivity and specificity of detecting dissections were in the subtracti on image 85% and 100%, in the averaged image 57% and 96%, and in the s aline flush image 58% and 86%, respectively. Subtraction is a promisin g method to outline the irregular lumen in a single image.