VAPORIZATION DETECTIONIMAGING: A TECHNIQUE FOR IMAGING LOW-BOILING-POINTPHASE-CHANGE ONTRAST AGENTS WITH A HIGH DEPTH OF PENETRATION AND CONTRAST-TO-TISSUERATIO

Phase-change contrast agents (PCCAs) possess advantages over microbubble contrast agents, such as the ability to extravasate and circulate longer in the vasculature that could enhance the diagnostic capabilities of contrast-enhanced ultrasound. PCCAs typically have a liquid pet-fluorocarbon (PVC) core that can be vaporized into echogenic microhubbles. Vaporization of submicron agents tilled with liquid PFCs at body temperature usually requires therapeutic pressures higher than typically used for diagnostic Imaging. but low-boiling-point PCCAs using decatluorobutane or octaftuoropropane can be vaporized using pressures In the diagnostic imaging regime. Low-boiling-point PCCAs produce a unique acoustic signature that can be separated from tissue and bubble signals to make images with high contrast-to-tissue ratios. In this work, we explore the effect of pulse length and concentration on the vaporization signal of PCCAs and a new technique to capture and use the signals to make high contrast-to-tissueratio Images in vivo. The results Indicate that using a short pulse may be ideal for imaging because it does not Interact with created bubbles but still produces strong signals for making images. Furthermore, it was found that capturing PCCA vaporization signals produced higher contrast-to-tissue ratio values and better depth of penetration than imaging the bubbles generated by droplet activation using conventional contrast imaging techniques. The resolution of the vaporization signal images is pa cause of the low frequency of the signals, but their high sensitivity may be used for applications such as molucular imaging, where the detection of small numbers of contrast agents is important. (C) 2018 Published by Elsevier Inc. on behalf of World Federation for Ultrasound in Medicine az Biology.